ERoEI for Beginners

The Energy Return on Energy Invested (ERoEI or EROI) of any energy gathering system is a measure of that system’s efficiency. The concept was originally derived in ecology and has been transferred to analyse human industrial society. In today’s energy mix, hydroelectric power ± nuclear power have values > 50. At the other end of the scale, solar PV and biofuels have values <5.

It is assumed that ERoEI >5 to 7 is required for modern society to function. This marks the edge of The Net Energy Cliff and it is clear that new Green technologies designed to save humanity from CO2 may kill humanity through energy starvation instead. Fossil fuels remain comfortably away from the cliff edge but march closer to it for every year that passes. The Cheetah symbolises an energy system living on the edge.

I first came across the concept of Energy Return on Energy Invested (ERoEI) several years ago in Richard Heinberg’s book The Party’s Over [1]. I had never contemplated the concept before and I was immediately struck by its importance. If we used more energy to get the energy we need to survive then we will surely perish.

Shortly thereafter I joined The Oil Drum crew and had the great pleasure of meeting Professor Charles Hall,  the Godfather of ERoIE analysis who developed the concept during his PhD studies and first published the term in 1977. ERoEI would become a point of focus for Oil Drum posts. Nate Hagens and David Murphy, both Oil Drum crew, have now completed PhDs on ERoEI analysis aided and abetted by the conversation that the Oil Drum enabled.

But recently I have received this via email from Nate:

10 years on the same questions and issues are being addressed – (and maybe 40 years on for Charlie). A new tier of people are aware of EROI but it is still very fringe idea?

Are we wrong to believe that ERoEI is a fundamentally important metric of energy acquisition or is it simply that the work done to date is not sufficiently rigorous or presented in a way that economists and policy makers can understand. At this point I will cast out a bold idea that money was invented as a proxy for energy because ERoEI was too complex to fathom.

And I have this via email from my friend Luis de Sousa who did not like the Ferroni and Hopkirk paper [3] nor my post reviewing it:

On the grand scheme of things: PV ERoEI estimates range from 30 down to 0.8. Before asking the IEA (or whomever) to start using ERoEI, the community producing these estimates must come down to a common, accepted methodology for its assessment. As it stands now, EROEI is not far from useless to energy policy.

And while I disagree with Luis on a number of issues, on this statement I totally concur. So what has gone wrong? Professor Hall points out that it is not the concept that is at fault but non-rigorous application of certain rules that must be followed in the analysis. In this post I will endeavour to review the main issues and uncertainties, and while it is labelled “for Beginners”, I will flirt with an intermediate level of complexity.

What is ERoEI?

ERoEI is simply the ratio of energy gathered to the amount of energy used to gather the energy (the energy invested):

ERoEI = energy gathered / energy invested

Note that in common vernacular the term energy production is used. But in fact humans produce very little energy, but what distinguishes us from other species is that we have become very efficient at gathering energy that already exists and building machines that can convert the energy to goods (motor cars, televisions and computers) and services (heat and light and mobility) that collectively define our wealth.

This began by gathering fire wood and food and progressed to gathering coal, oil and natural gas. This led to gathering U and Th and learning how to convert this to enormous amounts of thermal and electrical energy. And now we attempt to gather solar energy through photovoltaics, wind turbines and liquid biofuels.

The prosperity of humanity depends upon the efficiency with which we gather energy. 100 years ago and 50 years ago we hit several jackpots in the form of vast coal, oil and gas deposits. These were so rich and large that energy virtually spewed out of them for next to no energy or financial investment. Examples include the Black Thunder coal field (USA), the Ghawar oil field (Saudi Arabia) and the Urengoy gas field (Russia) to name but a few. But these supergiant deposits are now to varying degrees used up. And as global population has grown together with expectations of prosperity that are founded on energy gathering activities, humanity has had to expand its energy gathering horizons to nuclear power, solar power and energy from waste. And it is known that some of the strategies deployed have very low ERoEI, for example corn ethanol is around 1 to 2 [2] and solar PV between 1 and 5 [2,3] depending upon where it is sited and the boundaries used to estimate energy costs. Consider that an ERoEI greater than 5 to 7 is deemed necessary to sustain the society we know (see below) then it is apparent that we may be committing energy and economic suicide by deliberately moving away from fossil fuels.

Low ERoEI is expected to correlate with high cost and in the normal run of events investors should steer clear of such poor investment returns. But the global energy system is now dictated by climate concern, and any scheme that portends to produce energy with no CO2 is embraced by policymakers everywhere and financial arrangements are put in place to enable deployment, regardless of the ERoEI.

Net Energy

Net energy is the close cousin of ERoEI being the surplus energy made available to society from our energy gathering activities. It is defined simply as:

net energy = ERoEI-1

If we have ERoEI = 1, then the net energy is zero. We use as much energy to gather energy as energy gathered. The “1” always represents the energy invested. If ERoEI falls below 1 we end up with an energy sink. Low ERoEI systems are effectively energy conversions where it may be convenient or politically expedient for us to convert one energy carrier into another with little or no energy gain. Corn ethanol is a good example where fertiliser, natural gas, diesel, electricity, land, water and labour gets converted into ethanol, a liquid fuel that can go in our cars. But it does leave the question why we don’t just use liquefied natural gas as a transport fuel in the first place and save on all the bother that creating corn ethanol involves?

The Net Energy Cliff

Many years ago during a late night blogging session on The Oil Drum, and following a post by Nate Hagens, I came up with a way of plotting ERoEI that for many provided an instantaneous understanding of its importance. The graph has become known as the net energy cliff, following nomenclature of Nate and others.

Figure 1 The Net Energy Cliff shows how with declining ERoEI society must commit ever larger amounts of available energy to energy gathering activities. Below ERoEI = 5 to 7 such large numbers of people would be working for the energy industries that there would not be enough people left to fill all the other positions our current altruistic society offers.

The graph plots net energy as a % of ERoEI and shows how energy for society (in blue) varies with ERoEI. In red is the balance being the energy used to gather energy.

It is the shape of the boundary between blue and red that is of interest. If we start at 50 and work our way down the ERoEI scale moving to the right, we see that energy invested (red) increases very slowly from 2% at ERoEI=50 to 10% at ERoEI=10. But beyond 10, the energy invested increases exponentially to 20% at ERoEI=5 and to 50% at ERoEI=2. At ERoEI = 1, 100% of the energy used is spent gathering energy and we are left with zero gain.

This is important because it is the blue segment that is available for society to use. This pays for infrastructure, capital projects, mining and manufacturing, agriculture, food processing and retailing, education, healthcare and welfare, defence and government. In fact it is the amount of net energy that powers everything in society as we know it today. The net energy from past energy gathering has accumulated to create what we identify as capital and wealth. Nothing could be more important, and yet the concept remains on the fringe of energy policy and public awareness. One of the problems is that measuring ERoEI consistently is difficult to do. One problem is retaining objectivity. If you manufacture PV modules you are unlikely to claim that the ERoEI is less than 5, and there are a multitude of variables that can be adjusted to provide whatever answer is deemed to be good.

This depiction of Net Energy is also useful in defining that all energy and labour can be divided into energy and labour used in the energy industries and the industries that support them and energy and labour used by society that consumes the surpluses produced by the energy industries. More on this later.

It has been assumed by many that ERoEI > 7 was required for the industrial society we live in to function although the source of this assertion remains elusive. But the blue-red boundary provides a clear visual picture of why this may be so. Below 7 and humanity falls off the net energy cliff where a too large portion of our human resources and capital need to be invested in simply staying alive to the detriment of the services provided by net energy such as health care, education and pensions.

System boundaries

Energy Inputs

One of the main uncertainties in ERoEI analysis is where to set the system boundaries. I have not found a simple text or graphic that adequately explains this vital concept.

Figure 2 A simplified scheme for an energy system divided into construction, operation and decommissioning with accumulated inputs and outputs. Graphic from this excellent presentation by Prieto and Hall

Figure 2 provides an illustration of the life cycle of an energy system divided into three stages 1) construction, 2) operation and 3) decommissioning. Energy inputs occur at each stage but energy outputs will normally only occur during the operational phase. It should be straight forward to account for all the energy inputs and outputs to calculate ERoEI but it isn’t. For example many / most of our energy systems today are still operational. We do not yet have final numbers for oil produced from single fields. And the decommissioning energy costs are not yet known. Most wind turbines ever built are still operational, producing energy and the ultimate energy produced will depend upon how long they last. And then perhaps some turbines are offered a new lease of life via refurbishment etc.

Energy inputs can normally be divided as follows [2]:

  1. On site energy consumption
  2. Energy embedded in materials used
  3. Energy consumed by labour
  4. Auxiliary services

Moving from 1 to 4 may be considered expansion of the ERoEI boundary where energy embedded in materials and energy consumed by labour are added to on-site energy consumption. There follows some examples of ambiguity that remains in deciding what to include and what to leave out. These examples are given for purely illustrative purposes.

No one should question that the electricity used by a PV factory should be included. But do you include electricity / energy used to heat or cool the factory? Or just the electricity used to run the machines? Including heating or cooling  introduces a site specific variable which will mean that the energy inputs to a PV panel may vary according to where it was manufactured. There are many such site specific variables like transport, energy costs, labour energy costs, health and safety energy costs etc, which when combined in our globalised market has made China the lowest energy cost centre for PV manufacturing today.

It is clear to me that the energy cost of all materials used in the energy production process must be included. And this should include materials consumed at the construction, operational and decommissioning stages. In the oil industry this will include the materials in the oil platform, the helicopter and the onshore office. In the solar PV industry this will include all the materials in the panels, in the factory, and in the support gantries and inverter. As a general rule of thumb, massive energy gathering systems that contain a huge amount of materials will have reduced ERoEI because of the energy embedded in those materials.

It is also clear to me that the energy cost of all labour should be included in the ERoEI analysis for construction, operation and decommissioning. But it is far less clear how it should be calculated. The energy consumed by labourers varies greatly from country to country and with time. Should we just include the energy consumed by a labourer on his/her 8 hour shift? Or should we include the full 24/7? Should the energy consumed by labourers getting to and from work be included? – of course it should. Should the energy consumed on vacations be included? – not so clear. And how can any of this be calculated in the first place?

The standard way to calculate the energy cost of labour is to examine the energy intensity of GDP. For most countries, the total amount of primary energy consumed  is roughly known and the total GDP is known. This provides a means of converting MJ to $ and we can then look at the $ earnings of a labourer to get a rough handle on the notional energy use that may be attributed to his salary scale. This is far from perfect but is currently the only practical method available.

Auxiliary services become even more difficult to differentiate. Some argue that the energy cost of the highway network, power distribution network and services like schools and hospitals should be pro-rated into new energy production systems. My own preference is to generally exclude these items from an ERoEI analysis unless there are good reasons for not doing so. I think it is useful to go back to the question are we expending energy on energy gathering or are we expending energy on society and most of the infrastructure upon which new energy systems depend was built using prior surpluses allocated to society. In my view it becomes too complex to pro-rate these into an ERoEI calculation. The power grid delivering power to the PV factory already existed. But if a new power line needs to be built to export renewable electricity then that should be accounted for.

Energy Outputs

One might imagine that measuring the energy output would be more straightforward, but it is not so. Many earlier studies on the ERoEI of oil set a boundary at the well head or on site tank farm. And it is relatively straightforward to measure the oil production from a field like Forties in the North Sea. But crude oil itself is rarely used directly as a fuel. It is the refined products that are used. To actually use the oil we need to ship or pipe it to shore and then on to a refinery. The energy cost of transport may add 10% to energy inputs and refining may add yet another 10%. It has been suggested that one approach is to calculate ERoEI at Point of Use. Crude oil on an offshore platform is of no use to anyone. Gasoline in a filling station is what we want and all the energy inputs involved in getting the gasoline to the forecourt need to be counted.

But here we meet another dilemma. The refinery may produce paraffin and gasoline. The ERoEI of both are likely to be similar at the refinery gate. But the gasoline is burned in an engine to produce kinetic energy used for transport and in so doing about 70% of the energy is lost as waste heat. The paraffin may be burned in a stove with near 100% conversion efficiency to space heating. Do we reduce the ERoEI of gasoline by 70% to reflect energy losses during use?

This introduces the concept of energy quality where we know that final energy conversions are in three main forms 1) heat 2) motion and 3) electricity that has a myriad of different uses. Is it really possible to compare these very different energy outputs using the single umbrella of ERoEI? The routine followed by ERoEI analysts to date is to adjust ERoEI for energy quality though I’m unsure how that is done [2]. Another option that I like is to hypothetically normalise all outputs to a single datum, for example MWh of electricity (see below). But this again gets to a level of complexity that is beyond this blog post.

There are some other important energy quality factors. Dispatch for electricity is one. Producing a vast amount of electricity from wind on a stormy Sunday night has little to no value. While the ability to produce electricity on demand at 6 pm on a freezing Wednesday evening in January (NH) is of great value. Curtailed wind should clearly be deducted from wind energy produced in the ERoEI calculation. Just like the oil spilled from the Deep Water Horizon in the Gulf of Mexico should not be counted as oil produced from the Macondo field.

External environmental factors may also have to be considered as part of the energy quality assessment. It is clear that the oil spilled from the Deep Water Horizon had to be cleared up immediately and the energy cost of doing so almost bankrupted BP. But it is less clear that the energy cost of eliminating CO2 emissions needs to be borne by the energy production industries. For example, the cost of carbon capture and storage would fall on the consumer and not the energy producer.

Using energy proxies

In ERoEI analysis direct energy use can normally be measured, for example gas and diesel used on an oil platform or the electricity used in a factory. But the indirect energy consumed by, for example materials and labour, are less easy to measure and are often based on proxies.  It is nearly impossible to measure the energy embedded in an offshore oil platform. Instead the mass of steel and the number of man days of labour used in construction can be estimated and from these the energy expended and now embedded in the platform can be estimated.

As already discussed, the standard way of estimating the energy cost of labour is to use the energy intensity of GDP data from the countries in question combined with workers salaries.

For materials Murphy et al [2] provide this useful summary (Figure 3)

Figure 3 The estimated energy content of common materials [2]

From this the most striking feature is the vast range within certain materials and between materials. For example aluminium ranges from 100 to 272 GJ/tonne. Steel 9 to 32 GJ/tonne. Part of this will be down to methodological differences in the way the numbers are derived. But part of it may be down to real differences reflecting different energy efficiencies of smelting plants.

ERoEI of Global Fuels and Energy Flows

So what is the current status of ERoEI in the global energy mix? Hall et al 2014 [4] provide the following summary table which is the foundation of the summary graph below.

Figure 4 Summary of the ERoEI for a range of fuels and renewable energies.

Figure 5 Placing main energy sources on The Net Energy Cliff framework shows that hydro-electric power, high altitude kites and perhaps nuclear power have very high ERoEI and embracing these technologies may prevent humanity from falling off the Net Energy Cliff. The new bright Green energies of bio-fuels, solar PV and buffered wind (see below) are already over the cliff edge and if we continue to embrace these technologies human society may perish as we expend too large a portion of our energy endowment simply getting energy. Fossil fuels remain comfortably to the left of the cliff edge but are marching ever closer towards it with every year that passes. Eeq = electricity equivalent (see below).

In order to compare fossil fuels with electricity flows on a single diagram it is essential to reduce all of the energy types to a common datum. Its quite simply not valid to compare the ERoEI of coal at the mine mouth with nuclear power since in converting the coal to electricity, much of the energy is lost. The easiest route is to rebase everything to electricity equivalent (Eeq) where I follow the BP convention and adjust the ERoEI of  fossil fuels by a factor of 0.38 to account for energy conversion losses in a modern power station.

In an earlier thread, Owen posted a link to a pre-print by Weisbach et al [5] who follow similar methodology reporting all data as electricity. To a large extent their numbers are similar to those reported here with the exception of nuclear that is quoted to be  75. Weisbach report values for solar PV and wind that are “buffered” to include the energy cost of intermittency. This reduces the ERoEI for solar PV by about half and wind by a factor of 4. “Buffered” ERoEIs are therefore also included in Figure 6.

The inclusion of high altitude kite is based on a calculation provided by site sponsor KiteGen. I have checked the calculation and am satisfied that the ERoEI is potentially >>50. This will be the subject of another post. But suffice to say here that wind speed at altitude may be double that on the ground and power increases by the cube of wind speed. And the mass of the KiteGen structure is a small fraction of a large wind turbine. Hence it is theoretically straightforward to reach an ERoEI at altitude that is many multiples of the ERoEI of a wind turbine.

Figure 6 At altitude the wind speed may be double that on the ground. Accessing that kinetic energy resource provides potential for a 2 to 4 fold uplift in the power available for wind generation. This calculation does not include further uplift from higher capacity factor and reduced intermittency at altitude.

The key and fundamental observation from Figure 6 is that three energy sources potentially have ERoEI >> 50 making them vastly superior to all others using this metric. These are hydroelectric power, possibly nuclear power (depending upon whose numbers are believed) and possibly high altitude wind power once the technology matures.

These primary high ERoEI sources are followed by coal and natural gas which are the most viable and easily accessible energy sources for electricity today. And yet energy policies are dictating that coal be phased out. This will not matter for so long as natural gas remains plentiful at high ERoEI. The high ERoEI group may also include nuclear power depending upon whose ERoEI numbers one believes.

Biofuels are already over the net energy cliff and should never have been pursued in the first place. Solar PV is at best marginal, at worst an energy sink.

There is a vast range in estimates for nuclear power from 5 to 75 [4, 5]and it is difficult to make sense of these numbers. Nuclear power either sits close to the cliff edge or is a high ERoEI low carbon saviour of humanity. Oil will not be used for electricity production and the fact it sits close to the cliff edge today in Eeq form does not matter too much since the energy quality of oil has a special status as an essential transport fuel and this will unlikely change much in the decades ahead.

Concluding thoughts

The concept of ERoEI is vital to understanding the human energy system. 50 years ago, our principal sources of energy – oil, gas and coal – had such high net energy return that no one need bother or worry about ERoEI. Vast amounts of net energy were simply available for all who had the level of technological development to build a power station and a transmission grid. It is part of human nature to “high grade” mineral deposits targeting the richest seams first. In economic terms these return the biggest profit and in energy terms when it comes to oil, gas and coal, they return the highest levels of net energy. An inevitable consequence of this aspect of human nature commonly known as greed is that we have already used up the highest ERoEI fossil fuel resources and as time passes the ERoEI of new resources is steadily falling. This translates to a higher price required to bring on that marginal barrel of oil.

At the present time, our energy web comprises a myriad of different resources. The legacy supergiants – Ghawar, Black Thunder and Urengoy et al – are still there in the mix supplemented by a vast range of lower ERoEI (more expensive) resources. The greatest risk to human society today is the notion that we can somehow replace high ERoEI fossil fuels with new renewable energies like solar PV and biofuels. These exist within the energy web because they are subsidised by the co-existing high ERoEI fossil fuels. The subsidy occurs at multiple levels from fossil fuels used to create the renewable devices and biofuels to fossil fuels providing the load balancing services. Fossil fuels provide the monetary wealth to pay the subsidies. Society is at great risk from Greens promoting the new renewable agenda to politicians and school children whilst ignoring the thermodynamic impossibility of current solar PV technology and biofuels ever being able to power human society unaided. The mass closure of coal fired power stations may prove to be fatal for many should blackouts occur.

Wind power, and in particular high altitude wind power, may be different although in the case of ground-based wind turbines care must be taken in moving offshore to ever larger devices that consume ever larger quantities of energy in their creation. And to be viable, ground based turbines must be able to prove they can deliver dispatchable power without subsidies.

It is proposed that money was invented as a means of exchange for the work energy does on our behalf. If we lived in a society with a single global currency (the EJ) and without taxes or subsidies, then money may represent a fair proxy for ERoEI although distortions would remain from the different efficiencies with which that money (EJ) was spent. However, in the real world, different currencies, interest rates, debts, taxes and subsidies exist that allow the thermodynamic rules of the energy world to be bent, albeit temporarily. We are at risk of exchanging gold for dirt.


The post was much improved by comments provided by Prof Charles Hall.


[1] Richard Heinberg: The Party’s Over – oil, war and the fate of industrial societies. Pub by Clairview 2003

[2] David J. Murphy 1,*, Charles A.S. Hall 2, Michael Dale 3 and Cutler Cleveland 4: Order from Chaos: A Preliminary Protocol for Determining the EROI of Fuels (2011): Sustainability 2011, 3, 1888-1907; doi:10.3390/su3101888

[3] Ferruccio Ferroni and Robert J. Hopkirk 2016: Energy Return on Energy Invested (ERoEI) for photovoltaic solar systems in regions of moderate insolation: Energy Policy 94 (2016) 336–344

[4] Charles A.S. Hall n, Jessica G. Lambert, Stephen B. Balogh: EROI of different fuels and the implications for society: Energy Policy 64 (2014) 141–152

[5] D. Weißbacha,b, G. Ruprechta, A. Hukea,c, K. Czerskia,b, S. Gottlieba, A. Husseina,d (Preprint): Energy intensities, EROIs, and energy payback times of electricity generating power plants

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213 Responses to ERoEI for Beginners

  1. Yvan Dutil says:

    Energy Costs of Energy Savings in Buildings: A Review

    «It is often claimed that the cheapest energy is the one you do not need to produce. Nevertheless, this claim could somehow be unsubstantiated. In this article, the authors try to shed some light on this issue by using the concept of energy return on investment (EROI) as a yardstick. »

    • Euan Mearns says:

      Yvan, here in Aberdeen the government is spending a lot of money and energy upgrading old residential tenement blocks making them both look a lot nicer and improving their energy efficiency. I instinctively support this. But do need to know the £ and EJ costs before unqualified support is offered. ERoEI needs to be reserved for the efficiency of energy production. Another metric that can be linearly added to ERoEI is required for schemes that improve the efficiency of energy use.

      • mark4asp says:

        The cost-benefit of such efforts are certainly in doubt and could yield two or three new articles here.

        Prof. M. J. Kelly reckons such efforts are probably not cost-effective.

        a) Page 5, column 2:

        “Lessons from technology development for energy and sustainability”, MRS Energy & Sustainability : A Review Journal, pp 1-13, 2016, doi:10.1557/mre.2016.3

        In support of his argument he cites:
        b) Kelly M.J. : Energy efficiency, resilience to future climates and long-term sustainability: The role of the built environment . Philos. Trans. R. Soc., A 368 , 1083–10839 (2010). DOI: 10.1098/rsta.2009.0212

        c) My own (Kelly’s) detailed study remains unpublished. The typical costs of order £150K per household from an exemplar project to retrofit exemplar houses to achieve a 60% reduction in energy under the UK’s ‘Retrofit for the Future’ programme, ( https://retrofi ) have been reduced to £50K per household on the assumption that benefi ts of a learning curve will have been captured.

        • Euan Mearns says:

          As I said Mark, I’d like to see some numbers. But tenement flats in Aberdeen are highly energy efficient as collective heat rises up through the building. But in a warm climate the opposite may be true where everyone is trying to stay cool.

          I’d be surprised if demolition and new build was more energy and cost effective.

          Of course building to high standard to last 500 years at the outset would have been the way to go.

          • gabs says:

            It is always the same with such calculations.
            a) if you anticipate a perfecly repaired or newly built house as a starting point of the retrofit, and want all actions done during the retrofit be financed by energy savings, this will not work.
            b) in reality the houses which get a retorfit are old and worn out, and only the basic structure is fit for further use. So most of the work would have to be done anyway, with or without thermal retrofit, to make the building fit for the next decades of use. Which means the thermal retrofit only needs to pay for the insolating materials and similar, and therir direct installation during the process of repairing the building. And then it easily pays for the thermal retrofit. It just can not pay for a complete restoration of the building.
            So both things are true: it is uneconomical to thermaly retrofit a new roof. But it is also uneconomical not to thermally retrofit a roof which is under restauration. The same accounts for every other part of a house, and the discussion is very similar to the boundary discussion of EROI.

        • Euan Mearns says:

          Thanks for the link. I don’t understand why folks elect to use energy return metrics that are not ERoEI. Photovoltaics do not have a unique value. It is constantly changing with time as technology evolves and it varies with latitude, orientation and maintenance.

          • Ajay Gupta says:

            True for all fuels. Even nuclear plants have different transportation requirements etc. Personally, I’ve been thinking for some time that real-time (sort of) point source EROI for all fuel types is an opportunity both for better understanding our relations to energy and communicating with policy. Just my dream.

      • Yvan Dutil says:

        My experience is that energy payback time is between 6 and 12 times shorter than the monetary paypack time. Hence, if you do no get an EROI of roughly 10, there is money to save either.

        However, EROI unlike prices is rather stable, Hence, while this rule of thumb is true on average at some point in this will be completely false.

        A good example is the economic situation in North America under the current natural gas prices that are so low that it makes no economic sense to try to save it, neither to produce it actually.

  2. erl happ says:

    In command economies some silly things happen. The Russian coal mine that consumed all the energy produced by the power station that it fuelled may be mythical…..but it does happen when market forces get distorted. The Chinese towns that reputedly have no residents. Perhaps its a fiction, perhaps not.

    And now power from the sun and the wind. This is not the market at work.

    Its a dangerous business to become reliant on government subsidies.

    Its always counter-productive to set up industries at the expense of the taxpayer. These become a running sore. It’s good to see the Australian Car industry finally go. Successive ‘Car Industry Plans’ could not retrieve the situation.

    We should be careful what we ask governments to do for us. Let them stick to the basics.

    • Euan Mearns says:

      Knowing where to draw the lines of government intervention is the trick. I think most would agree that tax is an essential evil. But the moment this is introduced it creates distortions in our energy system. For example, more people may be brought into the energy consuming population.

    • gabs says:

      Be aware that there are a lot of tenders on the market which allow energy to be produced by conventional power plants as well as renewables, and many of them are won by a version of rnewable power – depending on the region by Solar, Wind, and Hydro.
      Subsidising happens to the biggest parts in markets where there are at the moment no huge amounts of conventional power stations are under construction, so competition would be against variable costs of already existing and payed conventional plants.

  3. Javier says:

    As a biologist I have no problem with the concept of ERoEI. Species thrive or go extinct on their capacity to keep their net energy flux positive over a constantly changing environment and the competition from other species.

    However I do not find the concept of ERoEI useful when referring to our energy needs because it has a boundary problem. Different people come with different numbers depending on what they include and what they leave out. And is extremely complicated to calculate. For example to do it for a nuclear plant one would have to dig a lot of paperwork from before it was constructed for all the energy expended during planning and getting the permits, and then materials and construction, and so on. All that work would not make it easier to calculate ERoEI for a different nuclear plant as most are unique in their design and have different energy input.

    However we are very good at keeping track of money and we usually know how much we have invested on something, and to a certain point ERoEI is reflected in the real cost of things, as energy is the great enabler and most things are priced in terms of the energy needed to obtain them.

    We know that many modern renewables are costing a lot and returning little. We know that without subsidies if you install PV panels on your roof and you are paid free market price for that electricity you will never see that money back. They are installed only when subsidized. Their ERoEI therefore is significantly lower than our current mix.

    We know that tight oil is unsustainable below $80/b, so we know its ERoEI is significantly lower than OPEC oil. If OPEC oil used to be good at $20/b and now requires $55/b it means its ERoEI has gone down because a bigger part of the energy obtained is consumed by the OPEC country.

    So real cost (the cost to produce, not the selling price) is a good enough proxy for me and an awful lot easier number to obtain.

    The consequence is clear. We are going down the energy cliff real fast since about 2002 when oil costs started to skyrocket. The type of policies that are being implemented with respect to renewables and carbon are actually making things worse, so accelerating our fall. In a few years we will start to feel the crunch in the form of economic malaise that doesn’t go away. This is not a problem. It is a predicament.

    • Thats a good starting point.
      The last studies by Siemens on their operational Windturbines suggest EROEI between 60-70 (lower for offshore).
      KiteGen claims EROEI from 370 (stem configuration) up to over 4000 for multi GW carousel plants.
      Material and cost savings in high altitude wind should be revolutionary.
      They have come a long way in the last 20 years.
      There should be no environmental concerns stopping them.

      There is a new testsite for high altitude wind in Scotland where some UK company is going to start long term testing with a permanent 500m permit.

      • Euan Mearns says:

        A review of high altitude wind power is on its way in a few weeks. KiteGen are based in Turin were first movers and have the majority of international patents. In Scotland we have Kite Power Solutions and in Holland The University of Delft. KiteGen are a few years ahead of these competitors. I think one key differentiator is that KiteGen have a patented two rope system that provides control. The competitors have a single rope and thus a flight control system that flies below the kite pulling “strings”.

        • I have been following all of the efforts since at least 20 years.
          KiteGen is one of the leading players.
          Most are European coming out of TU Delft, ETH Zürich or from Milan/Turin around KiteGen/SequoiaAutomation.
          Automation and control is sayed to be the critical enabler to the technology.
          Another company I’d put in front is German  Skysails who’s kites are already deployed on ships. Thus you could say they already produced some MWh over their lifetime (offsetting shipping fuel). They use a single line design with a control unit beneath the kite.
          Ampyx is also one to watch.

          But keep at it with KiteGen. Sounds as clean as it gets.

          I don’t see the potential as high as the Jetstream winds, 500-1500m onshore should suffice and work almost anywhere.
          Airspace rights seem to be the main concern in most discussions but with modern radar it is possible to even evade flocks of bird and once you start building multi GW plants you’d probably get the same airspace restrictions like nukes.

          Your posting systems sucks btw

      • robertok06 says:

        If you look on internet you’ll find “kitegen-type” aero-generators being proposed 10 years ago at least (2006 is the oldest paper I’ve seen so far, but there may be older ones around)… and I still have to see a couple of MWh being produced and sent to some grid, even a local one… there’s always the catch-phrase “will be tested soon”, or “prototype is under construction”… if it goes on like this it will beat this project…

        … which has taken FORTY FOUR years to come to completion and go critical!… 🙂 … welcome Watts Bar 2.

        Also, om high-altitude wind generation, I have seen a paper, a couple of years ago, written on a peer-reviewed journal about atmospheric studies, where the author(s) dismissed the idea of using such source, since, I think I recall it correctly… “at those altitudes the higher wind speeds do not mean that there is more momentum transfer”, which is what generates thrust and power. I can’t find it right now, hope I’ll have more time and luck later… too many papers on my hard disc…. 🙁


        • Eugenio Saraceno says:

          “at those altitudes the higher wind speeds do not mean that there is more momentum transfer”

          What does it mean in phisical terms? That a wing profile would not be able to exploit energy from a fluid when it exceeds a certain speed? It’s just a little bit clumsy. Please link the paper if you can find it.

          • robertok06 says:

            The paper I was thinking of should be the one linked here…


            … and dismissed here below by Massimo Ippolito.

            I am not an expert in this subject, but I must say that, as a physicist, the paper makes sense to me.


          • Euan Mearns says:

            Roberto, I don’t think anyone is seriously contemplating the jet stream at present. Massimo’s prototype 3 MW machine has 2000 m of rope on it. Going to the Jet stream would be a lot of rope (mass) and a lot of drag. And as we know the jet stream is not everywhere and moves around.

            The KiteGen (and many competitors) concept at present is to simply to tap into the stronger and more constant winds at altitude. And doing so using a different concept that is much less massive than a turbine – higher wind speed, less energy invested. Turbines have gotten bigger and bigger and more and more massive trying to reach that higher altitude wind.

            I hope I have got this approximately correct:

            And I agree with Massimo that it is curious that folks from Max Plank should be discussing energy using the units of power (TW). But saying things like “there’s not enough kinetic energy in the atmosphere to make a difference” would apply equally if not more to the wind next to the ground.

        • Euan Mearns says:


          Interesting time line for the history of Vestas and wind turbines.

        • @Roberto,
          the paper you cited was L.M. Miller, F. Gans and A. Kleidon from max Planck, here I’ve summarised how much is flawed:

          Gustavson (1979) believes that 130 TW can be exploited – 10% of what is dissipated naturally – with an explicit attention to the climate by the author, which in my opinion remains the most credible person who has understood and said everything that there was to understand and say. Another great work is Sorensen’s, which overlaps almost perfectly with that of Gustavson.

          Going back to the confusion between power and energy on the paper by L.M. Miller, F. Gans and A. Kleidon, the reader has to be very lenient and approximate to accept these formulations:
          “Archer and Caldeira (2009) estimated the potential of jet stream wind power as “… roughly100 times the global energy demand.” If we take the present global energy demand of 17TW of 2010 (EIA, 2010), then this estimate would imply that 1700TW of wind power can be sustainably extracted from jet streams.

          • robertok06 says:

            Hello Massimo, and thanks for the comment.
            I do not understand your last paragraph, though, as the text that Gans et al reported is exactly what Caldeira and Archer have said in their paper published on the journal Energies.

    • Euan Mearns says:

      Its been a while since I engaged in the ERoEI debate and agree that a major failing is the boundary and consistency issue. But it remains useful to track ERoEI of fuels with time (next post maybe) and to compare those with ERoEI >50 with those <5.

      We can take our ERoEI 20 FF and invest them in ERoEI 50 sources and make a huge energy profit. Or we can invest them in <5 and make a loss. Our policy makers have lost their heads electing to promote loss making activities.

      I think the amount of net energy can equate with rent and taxes paid. We have got ourselves into a zero interest rate environment because the energy sources we are following cannot survive in one where 10% interest fell due on capital.

      • Tom S says:

        “We can take our ERoEI 20 FF and invest them in ERoEI 50 sources and make a huge energy profit. Or we can invest them in <5 and make a loss. Our policy makers have lost their heads electing to promote loss making activities."

        No, because you make an energy profit whenever you construct an energy gathering device with an ERoEI higher than 1, regardless of the ERoEI of the energy used to construct it.

        For example, if you collect 1 tonne worth of oil at ERoEI 20, then burn it in a generator and generate electricity with it, then you have an ERoEI of 20 (ignoring waste heat losses for now). If, however, you use the same amount of oil to manufacture pv cells with an ERoEI of 5, and then generate electricity from the pv cells, then the AGGREGATE ERoEI of the entire thing put together (oil extraction plus solar panels) is 20*5 = 100. You invested 1 unit of energy to get the oil, then used the oil to build solar pv panels, then will get back 100 units of energy for the entire effort for 1 unit of energy invested.

        This is one reason why ERoEI is just not important by itself. What matters is the non-energy resources we must use (labor, capital) per unit of NET energy obtained. ERoEI should be seen as an INTERMEDIATE calculation which is fairly useless by itself.

        The net energy per unit of non-energy resources invested, is HIGHER for renewables than for electricity generated from FF. This can be inferred from the PRICE of renewable electricity which at present is lower than electricity from FF. As a result, it does not matter what their ERoEI is, as long as it is higher than 1, which it certainly is.

        -Tom S

    • Willem Post says:


      Using biomaterials for energy to replace fossil fuels does not look very promising.

      To replace the Btu value of annual crude oil production with the same Btu value as corn kernels, about 2.949 billion acres would be required of the 12.137 billion acres currently used for food production, of which about 28% is in annual crop production.

      There is no equivalence, as crude oil is much more useful for various tasks than corn kernels.

      Corn crop: 160 bu/acre/y x 56 lb/bu x 7000 Btu/lb x (1 – 0.15) = 53,312,000 net Btu/acre/y, equivalent to 9.6 barrels of oil/acre/y.

      World crude oil production = 80 million/d x (1 – 0.03) x 365 d/y = 28,324 million net barrels/y.

      Land area = 2.949 billion acres.

      World land area for food production = 18,963,881 sq mi x 640 acre/sq mi = 12.137 billion acres.

      Replacing coal and natural gas would require additional acreage.

    • Ikemeister says:

      Javier, I tend to agree with you, especially after reading this excellent “intro” blog post. I did notice that some use of monetary quantification is used for labour but I too wonder if it wouldn’t be better to accept that due to the many complexities in aggregating all inputs (and agreeing on an aggregation “profile”) whether a simpler (and possibly more accurate) quantification wouldn’t be possible using money as the common proxy.

      Euan, what would be wrong with using money as a (or “the”) proxy? Has this been considered? If so why would that not be a reasonable approach?

      A related question, what’s the progress towards some sort of accepted EROI profile (what inputs are included, which are not)? Or would it be reasonable to have different ERoEI profiles such that it’s understood from the get-go that comparing profiles would be comparing apples and oranges?

      Another aspect that relates to ERoEI is the aspect of CO2 emissions and the “hidden” energy costs i.e. mitigating CO2 emissions now so as to avoid risk of future energy costs to repair damages. Has anyone delved into that particular rabbit hole?

  4. Pingback: ERoEI for Beginners (Energy Return on Energy Invested ) – Climate Collections

  5. Willem Post says:

    There are folks who think we can have renewables take care of 10 billion people and their economies by 2050 or 2100.

    No such thing will ever happen.

    The cost of going that route would be well beyond the world’s economic system.

    I recently calculated what it would take for Vermont, 0.625 million people, to transform to an electric economy with EVs and heat pumps.

    The transformation would be about $20 billion from 2016 to 2050.

    Prorating that up for 10 billion people by 2050 would be $20 b x 20000/0.626 = $640 trillion

    The GWP is about $78 trillion.

    However, large items of costs are not included, such as having a transformed transportation system, various transformed industries, healthcare systems, defense systems, education systems, etc., all that to be built with renewables. Sure!!

    No such thing will ever happen, unless massive nuclear capacity is built, and that capacity would have to provide at least 80% of all world energy.

    It is nice to look at ERoEIs of various energy sources (after folks have a worldwide agreement on boundaries), but it amounts to a fool’s exercise, in view of the above numbers.

    • Willem Post says:

      Sorry, I made an error.

      $20 b x 10000/0.625 = $320 trillion.

      The rest of my comment remains unchanged.

      • mark4asp says:

        This green fallacy is called: Petitio Principii: (circular reasoning, circular argument, begging the question). It has some elements of the naturalistic fallacy in it.

        However, I think calling it “circular reasoning” is too kind. Fallacy victims do not reason. They are caught in a language trap, or tautology that avoids reasoning entirely. That may explain why it is so widespread.
        * It’s sustainable because it’s renewable.
        * Renewable energy is sustainable energy
        * Wind is free, the sun is free.

        • Pedro Prieto says:

          Mark, let me appropriate the idea I have been dealing with many times and expressed here very convincingly.

          I used to state and try to clarify to people that wind turbines and solar PV modules (or parabolic through mirrors, or tracked mirrors focusing on one tower in the case of CSP) are NOT renewable systems, but just not renewable systems able to temporarily capture, transform and concentrate a part of the renewable, disperse energy flows in Nature. I agree that it is very difficult to make fallacy victims to reason.

      • Willem Post says:

        Addition to above comment:

        In 2015, world spending on renewables was about $300 billion. Some people, after the Paris conference, called for it to be increased to $1.0 trillion.

        But the above numbers indicate at least 320/34 years = $9.41 trillion/y would be required to avert “calamity” by 2050, and 320/84 = $3.81 trillion/y would be required to avert “calamity” by 2100.

        Exercises in EIoEI would not change those facts.

    • mark4asp says:

      The problem with transitioning to a 100%-RE economy, WWS, or otherwise is not the financial cost but the impossibility. Low ERoEI values for renewable energies tell us that no such 100%-RE economy will ever happen. If Vermont tries it they will spend vast money on renewables while continuing to burn lots of fossil fuel. Just like Germany is doing.

      By defining their energy sources as “sustainable” and “renewable”, greens continue to bypass the debate on ERoEI, and energy economics. When an energy source is “sustainable” and/or “renewable” it must, by definition, be able to sustain itself! So the green fallacy is just a tautological trap – a cul de sac imposed by language and circular thinking. In reality, so called sustainable and/or renewable energies are not.

      • Tom S says:

        “Low ERoEI values for renewable energies tell us that no such 100%-RE economy will ever happen. ”

        Low ERoEI values would not tell us that. ERoEI is useless by itself, and is useful only for calculating the non-energy cost (labor, capital) per unit of NET energy.

        Anyway, renewables do not have low ERoEIs. Wind has an ERoEI of 18 or so. That is for ELECTRICITY generation. If you are comparing that to the ERoEI of FF generated electricity then you must SUBTRACT waste heat losses from the power plants which are not energy returns. When this is done, renewables have ERoEI figures which are comparable to, or higher than, FF generated electricity.

        -Tom S

    • Tom S says:

      “No such thing will ever happen.”

      I think you are mistaken.

      “The cost of going that route would be well beyond the world’s economic system.”

      But renewables are CHEAPER than FF electricity. At least we can provide electricity with renewables when the sun is blowing, and that would be within the world’s economic system.

      Do you really know what electricity storage will cost in 2100? The price of batteries for electric vehicles has dropped enormously in the last 5 years.

      “The transformation would be about $20 billion from 2016 to 2050.”

      That is $941/person/year in Vermont, where salaries are high enough to pay.

      “Prorating that up for 10 billion people by 2050 would be $20 b x 20000/0.626 = $640 trillion… The GWP is about $78 trillion.”

      You are making a big mistake here, IMO. You’re assuming that everyone in the world consumes as much energy as people in Vermont, which is a wealthy province in a first world country. Providing renewable energy to India or sub-Saharan Africa would cost far, far less than that, and that’s where most people live. If you assume that people in the developing world will have 1st-world living standards in the future, then your world GWP figure ($78 trillion) would need to be adjusted upwards by a factor of at least 3. Bear in mind that the GWP figure is the YEARLY gwp, whereas you are calculating energy costs for 34 years at once.

      If these things are adjusted, then the cost of a renewable system is within reason. The combined GWP for 34 years with economic growth would be ~$5000 trillion and the figure for converting the economy to renewables would be $640 trillion, so we would need to spend ~13% of world GWP yearly on renewable electricity and electric vehicles. I suspect that’s about what we spend for electricity and cars now.

      -Tom S

  6. Asteroid Miner says:

    Recycling spent nuclear fuel multiplies the nuclear ERoEI by 3 to 100, depending on how you recycle the spent fuel. Reducing safety to a reasonable level [yes, nuclear really is too safe] would also help. ERoEI of 5 for nuclear is nonsense generated by some “green.”

  7. RDG says:

    There are other factors that EROEI doesn’t capture such as the immense multiplier effect of oil in that it can be used in 1000’s of different ways and stored in durable goods such as plastics. In the natural gas powered ALL electric society, its winnowed down to nothing but electricity. What do you do with it when its expensive and nobody wants to pay the bills?

    If natural gas has more and more functions (example: transportation) placed upon it, how does the price of ng not go up significantly resulting in the same problem as the spike in crude oil? Wind and solar is supposed to help but the EROEI on solar is poor and the costs of wind will not go down in the future.

    If Saudi Arabia still has lots of ng, does that mean it will remain a very wealthy society for its huge population? Or is there a fundamental difference between crude oil and natural gas besides EROEI calculation that prevents easy accessible wealth for the masses?

    The economic fate determined by the combination of physical and chemical properties of petroleum versus methane are not completely appreciated. Its not obvious that thoughts concerning various means of substitution and eroei calculation capture why quality petroleum was always essential in providing what appears to be “instant wealth” (as we see in SA which has no economy).

    To me, this all-electric society with EV’s powered by natural gas and renewables is impossible. It seems mass electrification can only work with hydro dams and that can only support a fraction of the existing population. I don’t think it even qualifies as a command economy. More like a deliberate attempt to abandon most of the population to slums while profiting from it.

  8. steve says:

    As if it were not already complicated enough, the embodied energy portion of the EROEI analysis is an area that needs much more attention. Emergy analysis as developed by H.T. Odum and others is an attempt to create a framework to set boundaries and enable consistent results in puzzling out the embodied energy of materials. While it is better than using GDP and money as proxies, it is by no means easy. We’ve never had to worry about it till now, so in essence a new science is in the process of being created.

    You can see where their work has progressed to over at “A Prosperous Way Down” website.

  9. Beamspot says:

    Just few points to note, from my skewed point of view:

    Electronics is never considered when calculating many many things, including ERoEI, and usually underestimated when talking about renewables and their lifespan. With >70 elements of the periodic table required to keep it going, lifspans in the 8 to 10 years, best case, and the amount of energy and resources embedded inside them, I find that this is a big blindspot. But after all, I’m an electronic engineer, so I’m biased here.

    Second, the issue is not what ERoEI is required to sustain our lifestyle or our society (and I find 5:1 to be very low, probably the minimum for a hunter-gatherer), but which can hold our economy.

    Some time ago, years in fact, I realized that peak oil was not about lack of energy, but about lack of economic viability of it.

    It is our economy what will collapse, and with it, our society and culture, because there is a big, strong force behind our wild consumption of resources and energy that is cultural.

    An economist (something strange) put it clear:

    Gail Tverberg also has the same predicament.

    So, in the short time, I thing that even if the real concept is the deep reason about it, the problem with defining boundaries renders it useless for people not willing to discuss it, or strongly biased (that makes up for 99% of people, though).

    OTOH, I found much easy (and devastating given the results), to talk about ESOI, Energy Stored on Ivestment, something that I was working on, not quite clear, though, since 2011, when I was an R+D engineer on Electric Vehicles in Nürmberg.

  10. mark4asp says:

    On Nuclear Power.

    Greens, of course, dispute high ERoEI values for nuclear power. They claim nuclear power has an ERoEI = 5, citing a 2013 review (written by journalist: Mason Inman) in Scientific American. Others claim nuclear power ERoEI values >= 50, up to 78. Several people have written studies which imply nuclear power has a low ERoEI but only one person is influential outside of green fanatic circles: Manfred Lenzen.

    Low ERoEI figures ultimately come from Manfred Lenzen. He’s cited by IPCC AR5. The data used is now 36 years old. I emailed Charles Hall about this and he was gracious enough to reply. I was surprised his reply was so pessimistic for nuclear power. I quote him:

    “6) Mason may not have done much original research but he knows the field and is very conscientious.
    7) Lenzen’s review was very useful but if you look carefully there are no data newer than about 1980!!!! Thus his results are essentially based on the old Oak Ridge work of Ralph Rotty etc.
    I am surprised that we do not have a good up to date recent study, but I have no reason to think the results would change a great deal. I have a grad student working on nuclear and he may have something different to say, at least eventually.
    8) The main reason for the variation in nuclear, at least in those days, was whether or not the electricity (in thermal units) was multiplied by 3 or more to take care of the quality of the output.
    9) The EROI of nuclear today might be higher because the plants are lasting longer, or lower because of the lower grade fuel used (when mined, but most is recycled bombs), accidents, environmental issues (needs to be considered for all fuels etc etc.) Basically our plants today are running off fossil fuels burned during the cold war!

    So any way I do not have a reason for thinking that the number of 5:1 (thermal) – 15:1 (quality corrected) is not a reasonable number — although I would not be surprised if a good new study might led me to conclude something else. Weisbach did get much higher values for nuclear but his sources did not include eg power used in France to upgrade Swedish fuel.”

    Refs (to low nuclear power ERoEI claims):
    * Mason Inman: “How to Measure the True Cost of Fossil Fuels”
    * Mason Inman: “Behind the Numbers on Energy Return on Investment”
    * Manfred Lenzen, “Life cycle energy and greenhouse gas emissions of nuclear energy: A review,” Energy Conversion and Management (2008) doi:10.1016/j.enconman.2008.01.033
    * Charles Hall : email

    • Yvan Dutil says:

      You can pretty much trust the number of Lenzen. They are based on old dat because few nuclear powerplant has been build recently. Nevertheless, they are now much more expensive they used too due to increase safety level.

      • Andy Dawson says:

        Except that the most energy intensive part of the fuel production process isn’t extraction – it’s enrichment. And since 1980, ALL of the old gaseous diffusion plant has been replaced with centrifuges.

        Centrifuges are hugely less energy intensive per “SWU” – “Separative Work Unit” – the definition of an SWU being given here:

        This will give a good overview of the difference between the processes.

        It gives energy input for a centrifuge process as 40-50kWh per “SWU”, and 2400 for a typical GD plant – a difference of a factor of 55.

        There’s the potential for a similar step change with the application of laser-enrichment processes, at least one of which is ready for pilot-plant roll-out, albeit held given low prices for enrichment at the moment

        • Andy Dawson says:

          Sorry,, a little more on that…


          Suggests that enrichment, for a plant operated in the 1990s incurred about 55% of the total through-life energy input.

          At that stage, somewhere between 50% and 75% of enrichment would have been via GD, and the remainder by centrifuge.

          So the impact of removing GD and replacing it with 100% centrifuge would be to reduce the input to enrichment from an average of (0.63*2400+0.37*45)kWh per SWU to 45kWh taking the mid range of the GD proportion.

          That’s from 1530 to 45 – a 97% reduction. So, the total input energy for the plant over life is reduced by (0.55*0.97) = 53%.

          Basically, it means the EROI on the plant has been doubled by going from GD enrichment to centrifuge.

        • Tom S says:

          The enrichment process isn’t the only thing to have changed, either. The lifespan of nuclear reactors was originally estimated at 30 years. Now, however, it’s apparent that nuclear plants can last 60 years. As a result, the energy investment in plant construction per unit of energy returned, is half what was originally estimated.

          -Tom S

      • mark4asp says:

        I can’t trust numbers from someone who can’t be bothered to get the most up-to-date numbers. I’m just comparing his standards with mine. I would’ve bust a gut to get up-to-date data.

        Back in the 1970s:
        * capacity utilization factors of NPPs were much lower than today.
        * much uranium enrichment used gas diffusion which is about 30 times more energy intense than gas centrifugation. There are no working gas diffusion plants left today.

    • gweberbv says:

      I cannot believe the low ERoEI values for nuclear power.

      The German NPP Grohnde produced 350 TWh of electricity so far (within 32 years of operation).

      According to the table in Fig. 3 this amounts to roughly 3.5 x 10^10 tons of steel produced. (I hope I did not miss/add a few zeros here.) A really big one-family house might have 20 tons of steel embedded in the concrete. Thus, Grohne provided energy for the steel in 1 billion houses.

      Or, you can compare to the annual electricity consumption in Germany which is something like 550 TWh. If not shut down for political reasons (that I support), the Grohne plant would easily reach this number in the years to come. Does anybode seriously believe that the energy that was necessary to build the plant and to provide its fuel comes close to about 10% of the annual electricity consumption of whole Germany (assuming an ERoEI of roughly 10)?

      Without looking at the details, one must conclude the ERoEI of nuclear power is for sure much, much higer than 10.

    • robertok06 says:

      “Basically our plants today are running off fossil fuels burned during the cold war!”

      With all due respect for Charles Hall… this is not true… a small fraction of the nuclear reactors on this planet have run for a while (I think the program is now over) on downblended weapons’ plutonium… I remember that in the USA they used to say something like “50% of US household have their lights on thanks to russian plutonium”… I may be wrong with the percentage, but the fact is there.
      Also, none of the 813 TWh/year of European nuclear electricity is coming from “old” plutonium which has been obtained burning coal during the cold war…. it is all plutonium coming from La Hague, or Sellafield, which has been generated in PWRs (France’s) in the last 30 years, fissioning uranium enriched in Tricastin with 100% nuclear electricity.

      The data of Lenzen are simply wrong, they underestimate the ERoEI of nuclear by a large margin. Lenzen even considers as possible, and puts them in the average, values of gCO2/kWh as high as 280 g… (if I recall correctly, do not have the paper on this tablet)… which would be possible only if a 10 year energy payback time is taken for a 40-year reactor which has 100% been built, fuelled and will be decommissioned using coal electricity at 110 gCO2/kWh… which is not wrong, more than that, it is irrational.


      • Roberto says:

        1100 gCO2/kWh, that is , sorry

      • Jose A. says:


        Quoting Uranium 2011: Resources, Production and Demand (the so called Red Book):

        “In 2010, world uranium production (54 670 tU) met about 85% of world reactor requirements (63 875 tU), with the remainder of supply coming from uranium already mined (so-called secondary sources) including excess government and commercial inventories, low-enriched uranium (LEU) produced by downblending highly enriched uranium (HEU) from the dismantling of nuclear warheads, re-enrichment of depleted uranium tails and spent fuel reprocessing.”

  11. robertok06 says:


    “There is a vast range in estimates for nuclear power from 5 to 75 [4, 5]and it is difficult to make sense of these numbers. Nuclear power either sits close to the cliff edge or is a high ERoEI low carbon saviour of humanity. ”

    Nice piece, Euan, really.

    I’d just like to comment that ERoEI of the order of 5 for nuclear are completely wrong, they MUST be completely wrong because there’s simply no way that a reactor running for 40 years would need 8 years worth of its electricity production. No way.
    A 1 GWe reactor at 80% capacity factor generates in one year 7000 GWh, or 25.2 PJ.
    Eight times this much would mean 202 PJ: the nuclear part of any reactor is basically steel, a PWR’s pressure vessel with 2 steam generators is less than 1000 tons, even adding the piping. Add a large turbine and a moltitude of pipes again, not much energy worth in them.

    The remainder is steel reinforced concrete… I do not have the time to look for the energy equivalent, but can’t be that much… otherwise hydro and other forms of electricity production (like on-shore wind, for instance) would be off the cliff just because of that.

    I have looked at the papers by Hall and Day, and Hall and Murphy, and all they do is to cite a “5 to 15” range for the ERoEI of nuclear, and their only serious reference is Lenzen’s paper of 2008

    which (wrongly!) says things like this:

    “The most popular reactor types, LWR and HWR, need between 0.1 and 0.3 kWhth, and on average about 0.2 kWhth for every kWh of electricity generated. These energy intensities translate into greenhouse gas intensities for LWR and HWR of between 10 and 130 g CO2-e/kWhel, with an average of 65 g CO2-e/kWhel.”

    He has simply done a review of published papers on the subject, and among his references that are also some completely crazy calculation (unfortunately published on peer-reviewed journals) of the anti-nuclear duo van Leeuwen and Smith.
    Most of the articles/papers that Lenzen has reviewed for his meta-analysis are old stuff, from the 70s!… and the range of values for the kWh_th/kWh_el (and gCO2/kWh_el) that he quotes give a good idea of how a nice collection of papers can be mis-used against nuclear.
    He cites the lowest-highest values as 0.106-0.726 kWh_th/kWh_el and 5.7-248.4 gCO2/kWh_el.

    The highest range of both quantities is simply absurd: just take the case of France’s 58 (+1) PWRs: the energy (and emission) “costs” of mining and milling are known and are low… the energy/emission costs of enrichment are low/non-existent (everything’s done in France using 100% nuclear electricity, in Tricastin)… same for the downstream part of the cycle, separation of isotopes, storage of depleted uranium, re-injection of Pu in the cycle for MOX fuel (done using 100% emission-free nuclear electricity in La Hague). Lenzen wrongly says that the high energy cost of nuclear come from these two phases, upstream (extraction, enrichment, fuel fabrication) and downstream (isotope separation)… and in addition to this he assumed (back in 2007 when the paper was written and based on most old references) that the diffusion process had been used for enrichment, while today that technique is obsolete and almost disappeared, for the much less energy-hungry centrifuge process (and the laser-assisted one, even less energy).

    I’d say that a modern analysis of the nuclear cycle today would hield completely different numbers, as compared to Lenzen’s… and the corresponding ERoEI would fall in the “several” tens… 40-50 at least. And, last comment, this is true for present day LWRs, of the PWR and BWR type… once one factors in the possibility of using breeders then the ERoEI skyrockets out of range…. you’d need a logarithmic scale to show it on the same graph as the other technologies/sources… 🙂

    • Yvan Dutil says:

      Well, a nuclear reactor is used almost exclusively to operate the Tricastin enrichment facility.

      • Pedro Prieto says:

        The big question mark for nuclear power EROIs is the energy required to eliminate highly toxic and highly radioactive waste. There is no rational form to include this energy input (Ei) expense in the equation. If we put the 4 reactors of Fukushima now in the balance and include the never ending energy expenses going on probably for centuries (should the government have resources to continue doing it for centuries) to try to clean (an euphemism consisting in taking the radioactive shit form one place and putting it in another one) the debris.

        Who is able to sign that we will be able to completely and orderly dismantle the 450 reactors in place, most of them close to the life time for which they were designed, and the loaded refrigerated pools and completely neutralize the thousands of tonnes of wasted fuel rods?

        Until this problem is solved and the problem of nuclear warfare proliferation arising from the use of wasted plutonium (part of which has been taken obviously form wasted fuel from the civil use plants) is duly assessed in terms of potential energy input required costs to repair the potential damages that may be caused by them, I will not believe or consider a single EROI data given for nuclear power.

        • Andy Dawson says:

          “The big question mark for nuclear power EROIs is the energy required to eliminate highly toxic and highly radioactive waste”


          Radwaste treatment isn’t a particularly high energy process – in fact, used in fast or epithermal reactors, it’s energy-positive.

        • robertok06 says:

          “The big question mark for nuclear power EROIs is the energy required to eliminate highly toxic and highly radioactive waste. There is no rational form to include this energy input (Ei) expense in the equation. ”

          Of course there is!… what are you talking about? Highly toxic and radioactive waste is MINIMAL, in quantity, 0.3 mg/kWh_el… that’s what it is, for a PWR like Spain has and France too.
          This means that a 1 GWe reactor at 75% capacity factor (typical of France) generates 1.97 ton of high-activity and long-lifetime waste (the remainder is not a problem at all)… at a average density >10 ton/m3 it is 2 m3/year… compare that with 600 thousand tons of coal ashes (which can contain a lot of radioactive isotopes and are stored on the surface, exposed to the air that you breath)… is is nothing.
          The danger, cost, and all the rest of the “problems” related to nuclear waste issued from civil reactors is non existent, it is a creation of some “green” mind who realised that one can scare a lot of people using this fake argument.
          In particular, to stay with your statement above about energy impact, it is minimal… the amount electricity used in La Hague to reprocess all of the 58 reactors of France (fuel) plus fuel elements coming from other countries (Italy, for one), is known and, once normalized to the amount of kWh that the said fuel had generated, is practically “too low to meter”. 🙂

          • Pedro Prieto says:

            Let’s talk with more rational arguments when all the thousands of tons of nuclear wasted fuel rods in the actively refrigerated pools in many of the nuclear power reactors have been eliminated (not just transported to somewhere else and sold as “cleaned”). If it is so easy, why on hell the nuclear industry has not yet eliminated them? We could have saved the problems of Fukushima, should have already removed all the wasted fuel rods that melted with the corium there. This is a far from negligible part of the energy invested is going to require, a chapter that is going to remain open in energy invested expenses probably for centuries. Are you of those that after Chernobyl and Fukushima are still selling the “inherent security” of the nuclear power plants and signing that this is not going to happen again? Are you so sure, for instance, that the 14 nuclear power reactor in Ukraine are so safe, when the government is in complete bankruptcy?

          • Roberto says:

            ‘at a average density >10 ton/m3 it is 2 m3/year…’

            0.2 m3/year, obviously, sorry.

          • Roberto says:

            @pedro prieto
            ‘Are you of those that after Chernobyl and Fukushima are still selling the “inherent security” of the nuclear power plants and signing that this is not going to happen again? Are you so sure, for instance, that the 14 nuclear power reactor in Ukraine are so safe, when the government is in complete bankruptcy?’

            1) Ukraine is a bigger problem to world security for reasons other than nuclear.
            2) it will happen again, an accident, I’m convinced… but at the same time I know that the absence of nuclear power, even with accidents, would kill more people than Chernobyl and Fukushima together. Just look at the data, Pedro!… 30 deaths power electric TWh, this is the alternative that Germany is paying, and they produce more than 200 TWh/year (6000 deaths and ~10x more illnesses/year) with lignite and coal, do you prefer that?
            3) the absence of electricity kills more than nuclear accidents, just ask any non-developed nation.

          • renewstudent says:

            More deaths without nuclear? Only if you say the choice is nuclear or coal …

          • Euan Mearns says:

            Do you have any data on annual deaths in the solar PV industry from manufacturing through installation and maintenance?

          • renewstudent says:

            I have no hard data to hand on actual solar deaths (people do fall of roof tops and there are toxic material issues) but CWIF claimed that had been 150 installation and maintenance deaths associated with wind turbine accidents by 2014 globally.
            No public deaths or injuries I know of, although some claim health impacts from wind turbine noise. See my book:
            Hard to see that comparing to major nuclear accidents…or of course coal use.

          • robertok06 says:


            “More deaths without nuclear? Only if you say the choice is nuclear or coal …”

            You are right, there is also hydro (killed >150k in one single accident, Bangqiao, China, in the 80’s), and there is gas. The former is not scalable at will, and is already generating, at the penetration level of today IMMENSE destruction of natural resources and human lives… just look at the disaster which is happening right now along the Mekong river, which has been dammed by several countries…
            Gas, on his part, is not much better either… if you, as I gather from the tone of your messages, are a environmentalist you should know that natural gas is an environmental killer, with its fugitive emissions… and let’s not talk about the fracking one!… that’s terrible (I’m pretending to recite the anti-fracking mantra)… also, the non fracked one comes mainly from countries which are not, on the political scene, too well seen at this time (Russia, algeria, libia, arabian peninsula)… so, once you discard the un-scalable ones, the politically un-correct (and dirty poisonous ones, plus there is not much gas either around), I’d say that my dichotomy “either coal or nuclear” holds.
            Wait a minute!… aren’t you by chance suggesting that there is ANOTHER alternative?… like using wind turbines and photovoltaic panels? Nahhh.. you are a smart guy, you can’t possibly think about such a lousy and un-physical possibility, aren’t you? 🙂

            Nice try, though.

        • robertok06 says:

          “If we put the 4 reactors of Fukushima now in the balance and include the never ending energy expenses going on probably for centuries (should the government have resources to continue doing it for centuries) to try to clean (an euphemism consisting in taking the radioactive shit form one place and putting it in another one) the debris.”

          Another flawed argument against nuclear! Three Mile Island’s reactor, partially melted, has been cut in pieces and the melted corium with it in a matter of 7 years (if Iremember correctly). Again, it is a difficult task, nobody says otherwise… but ENERGETICALLY it is a piece of cake, probably requiring less energy than it is required to run hydro-sprayers to clean PV panels in large on-ground PV power stations in dusty areas… I read recently, for instance, that in your country the few thermal solar concentration tower power plants use a lot of water to keep their mirrors clean, just ot make an example.
          The thousands of workers cleaning up Fukushima’s site use a limited amount of energy, like any large scale industrial clean up project…. plus, compared to the cleaning that they had to do after the tsunami, it will add a small percent to the total… remember, there are several million tons of debris of houses, factories, anything which has been washed away by the tsunami which is slowly floating on the Pacific headed for the US west coast.

          James Hansen, the famous climatologist who, surprisingly is in favor of nuclear power, has analysed the whole thing and has come to the conclusion that even including FUkushima, Chernobyl and all the other accidents and pollutions nuclear is the best solution to de-carbonizing the production of electricity:


          • Pedro Prieto says:

            So, put your fantastic knowledge at the service of he Japanese government, if it is so easy to handle, cut, pack and neutralize the corium of Fukushima. They will thank you a lot. They have been working so hard for at least five years and still even robots cannot approach were the corium is supossed to be. Go and tell them how to do it.

          • gweberbv says:

            A wise man once wrote that PV, wind and all the other stuff is hazardous like crossing the street. -> Many people dying, but nobody is afraid of.
            But nuclear power is hazardous like an airplane crash. -> Very few people are dying, but a lot of people are afraid of.

            What I can say for sure with respect to Germany: If we had an accident like Fukushima, the affected region would stop functioning. A lot of people will simply put their families in a car and drive a few hundred km away. They will give a sh*t on what government or experts are telling them. If this happends to a region like the Frankfurt area, it is game over. How do you run all the critical infrastructure, when the staff is stuck on the road in the longest traffic jam in history?

          • Euan Mearns says:

            I imagine Frankfurt would be totally flattened by the magnitude 9 Earthquake but I’d guess that the reactors would remain intact and given that the Earthquake is onshore, no tsunami would follow.

          • Pedro Prieto says:

            I can imagine many other situations in which the nuclear power plants can become unmanageable. For instance, a bombing of the plant, like already Israel has warned to do several times to Iran (Bushehr plant) or its uranium enrichment plants in Natanz and elsewhere (to which they are supposed to be entitled) and already did with Iraq (Tammuz/Osirak), even here, the French technicians were already warned by Israelis and retired few days before the bombing the nuclear fuel and that was a small experimental plant of few MWe.

            I can imagine a huge problem if the weakened Ukraine electric network collapses for whatever the reason and paradoxically they could not refrigerate the pools with the wasted fuel rods, if the emergency generators (heavy duty intended) end failing also. Or just simply a bombing any of the reactors very close to the conflicting regions between the present government and the pro Russian minorities. One recent blow out of a power line to Crimea from the rest of Ukraine, was in the verge of creating a total chaos in the national grid in Ukraine.

            Global terrorism is having growing destruction capabilities and access to sophisticated weaponry and diminishing moral concerns about damages to civil populations. They can easily rocket o shot tens of mortars in less than one minute not over the apparently resistant reactor domes, but over the substations evacuating the electricity to the network and simultaneously to the generators building.

            I have witnesses personally the bombing of a fuel oil 500 MW plant in Baghdad and we were three days with the skies darkened by the smoke. But two weeks after, people was again living few meters from the devastated plant. I wonder if it would be the same, should anyone bomb a nuclear power plant, which is the worst scenario of a nuclear catastrophe of the three possible ones (a catastrophic failure type Chernobyl or Fukushima, a 1 Megaton nuclear blast or the third a nuclear blast of a 1 Megaton over a 1 GW nuclear power plant. Scientific American).

            There is a nuclear power plant in Spain (Asco), which is in the course of Ebro river at 50 m over the sea level and in the very banks of the river and has the Mequinenza dam 50 km. upstream containing some 1,530 Hm3 of water (called “the Sea of Castila”). Should this dam break for whatever the reason and perhaps the effects on Asscó could be even worst than those of the tsunami over Fukushima.

            Many other nuclear plants are at sea level not much higher than Fukushima.

            Any catastrophic failure in the electric grid of a nuclear nation (is this scenario so impossible for some minds, considering that former Yugoslavia was abated by NATO by bombing with graphite bombs some key installations?) may create another nightmare due to the paradox of a nuclear plant unable to refrigerate the wasted fuel rod pools if the blackout is prolonged and the emergency generators do not work.

          • Jose A. says:

            Here comes the FUD.

            Pedro Prieto said:

            “Should this dam break for whatever the reason and perhaps the effects on Asscó could be even worst than those of the tsunami over Fukushima.”

            The Mequinenza dam is 70 km upstream, the plant is 20 m above the normal level of the river Ebro and the european stress tests already analysed a scenario with successive rupturing of the dams located on the river Ebro upstream of the site concluding “that the maximum level that would be reached on the site would be 48.11 m, with a margin of almost 2 metres with respect to the plant grading level elevation”.

          • robertok06 says:

            @pedro prieto
            “So, put your fantastic knowledge at the service of he Japanese government, if it is so easy to handle, cut, pack and neutralize the corium of Fukushima. They will thank you a lot. They have been working so hard for at least five years and still even robots cannot approach were the corium is supossed to be. Go and tell them how to do it.”

            Your reply here above confirms to me that you are affected by an irrational fobia… too bad for you, as I said.
            Instead of argumenting via rational, scientific means, you’ve chosen the direct, ad hominem, attack… “put your fantastic knowledge at the service… blah… blah… blah…”.

            I have never said it is going to be a piece of cake, to clean up Fukushima and dismantle everything… I’m simply saying that it is already known how to deal with this kind of accidents, as it has already happened in the past… TMI first and foremost.
            What I say is that the Fukushima Daiichi site will be off-limits for decades, many decades… but I don’t think, correct me if I’m wrong, that precluding the japanese people to profit from 4 km2 land surface more than the remainder of the country (which, if the “environmentalist” post-nuclear delirium tremens goes on will need a much bigger surface of the country devoted to PV panels and turbines) will change the life of Japan as a whole.
            A priori anti-nuclear people like you should realize one simple thing: even at the magnitude of the FD-1 disaster, 3 nuclear reactors’ cores melting and one large fuel pool burning, the amount of ADDITIONAL radiation in the environment is a SMALL fraction of the natural radiation. Just think of this: volume of the Pacific Ocean? 640 million km3. Natural radiation of 1 m3 of ocean water? 12 thousand Becquerels.
            Total emitted Cs and I (the remainder is peanuts)? of the order of few 1E+17 Bq (I could check the exact number if you don’t believe me).
            Ratio of additional radiation (Cs and I) to natural one?

            5E+17/640E+6/1E+9/12000=5E+17/7.68E+21=6.5E-5, or 0.0065% more.


          • robertok06 says:

            @pedro prieto

            “I can imagine many other situations in which the nuclear power plants can become unmanageable. For instance, a bombing of the plant, like already Israel has warned to do several times to Iran (Bushehr plant) or its uranium enrichment plants in Natanz ”

            On the other hand, a bunch of fanatics, in the early 2000s have hijacked 4 commercial flights, killed more than 3000 people, and the political/military response to this has annihilated one country, directly killed or maimed a million people, destabilized the whole planet.

            By your way of reasoning, there should not be a single plane flying anymore.

            An irrational, emotionally-motivated, anti-nuclear comment, again.

          • robertok06 says:

            @pedro prieto

            “may create another nightmare”

            Nightmare is what nightmare does… another nightmare like Fukushima Daiichi 1?… zero people killed by radiation so far, and not many more in the future?… to generated tens of thousands of TWh of emission-free electricity?… baseload, at low cost?… when the alternative is coal/gas and the related health and political problems?… not to mention the carnage in terms of human lives (epidemiological studies on this exist, and are reliable)?

            I take nuclear and its “terrible” risks over any other technology ANY DAY.

        • robertok06 says:

          “(part of which has been taken obviously form wasted fuel from the civil use plants) ”

          Another fake/flawed argument!… unbelievable how someone rational like you can take at face value many of the workhorses of anti-nuclear organizations!… depressing…

          A very small part has been taken from civil reactors… as anybody knows (if you don’t know I tell it to you now) that the reactors used to produce electricity have as large burn-up values (in MW*day/kgU) as possible, which are obtained by keeping the fuel inside of the reactors’ cores as long as possible (compatibly with the reactor type and fuel enrichment, amont other factors)… but in doing this several different isotopes of Pu are generated, which make the use of Pu straight from the reactor almost impossible. Plus, a 1 GW reactor generates way too much Pu, for weapons’ use.
          If yo are worried about potential costs, you should worry more about the costs when PV and wind will not generate enough, and blackouts will ensue… a recent study here in Switzerland has calculated that each hour of blackout may cost up to a billion swiss francs just for industry and commerce damages.
          Tghe fact that you repeat here, you’ve done it last week or so in another message, that you don’t even want to consider nuclear means simply that you are affected by an irrational fobia, too bad for you.


      • Flocard says:

        Not anymore. Since the start of George Besse II (centrifuges) , France has regained the equivalent of a 2 GW plant.
        It can be seen in the evaluation made by RTE when discussing the safety of French grid.

      • robertok06 says:

        Exactly, so zero gCO2/kWh and there is a factor of 3 improvement with respect to Lenzen’s kWh_th/kWh_el (which he uses to derive the ERoEI value and energy payback time) because the reactor sends to the enrichment facility next door (200 m away) electricity, not thermal kWh which need to be transformed to electricity later, like when you burn coal).

        This is what the renewables should and probably will NEVER do, run their production process 100% on their own electricity output… wind may make it, with difficulty, but PV for sure never will… unless PV module factories will run only 8 months/year because during 4 months/year PV production is almost non existent.


      • mark4asp says:

        Yvan Dutil says: “a nuclear reactor is used almost exclusively to operate the Tricastin enrichment facility.”

        No one anywhere in the world has used Gaseous diffusion since 2012/2013. How does Yvan Dutil get away with writing nonsense?

      • Andy Dawson says:

        From what I can find on line, the enrichment plant (George Besse II) uses around 50-75MW.

        Your numbers seem to pertain to the old “George Bess I” diffusion plant.

    • Euan Mearns says:

      1000 tonnes = 1000*30 GJ per tonne = 30,000 GJ embedded in steel for core

      1 GW * 24 * 365 * 0.8 = 7008 GWh / year

      BP says 1 kWh = 3600 kJ so 1 GWh = 3600 GJ

      7008 GWh = 25.2 PJ (peta = 10^15) per year

      It takes the reactor 10.5 hours to produce the energy to procure the steel for a 1000 tonne core.

      I read Lenzen’s paper many years ago. I guess there is a lot of flexibility in allocating energy invested in decommissioning and waste storage. I’m suspicious of both end member numbers 5 to 75. If nuclear was so good then we’d all be out buying shares in EDF.

      • robertok06 says:


        “If nuclear was so good then we’d all be out buying shares in EDF.”

        I wouldn’t put much faith into everybody’s rational thinking, capacity of buying the best product, and making the best choice… otherwise MS Windows would not be the computer operating system of choice by billions of internet users.
        Judged and the merits of its performance, MS shares would be bought only by bad companies (“bad” in the financial sense).


        • Euan Mearns says:

          Well Apple are the company of choice and the EPR may be a good analogy for Windows. I think Areva is stuffed and will need to be taken out of EDF and if they are to survive need to buy a competitor.

    • wawa says:

      Don’t forget thé energy spent in HNO3 synthesis need in plutonium dissolution, it’s not nothing and not fossil fuel free. But probably better than open cycle ( burning U 235 without plutonium MOX.

      • robertok06 says:

        You are right, all energy inputs should be considered, this is what is done in the Environmental Product Declaration documents which one can find easily on internet (just type , for instance, “Vattenfall environmental product declaration nuclear” on a google search).
        In the specific cse you mention, the amount of energy to produce HNO3 is, in mathematical terms, “an infinitesimal epsilon”.


    • Emile Nijssen says:

      Most estimates of low ERoEI for nuclear plants include decommissioning and waste storage, which in any current estimate (barring near-future waste burning processes) would require structures able to withstand a few thousands of years of weathering and societal change. These are incredible commitments, and shouldn’t be swept under the rug when doing these kinds of calculations.

      In general; this is where lots and lots of ERoEI calculations go off the rails: estimating the true impact of decommissioning and consequence losses. The calculations become impossible at that point. What sense does a coal power plant make when taking global warming into account?

  12. robertok06 says:


    Sorry to bother you euan… but a moment ago I posted a rather long message… unfortunately I’ve used the wrong username/ID… and the message doesn’t appear… could you please look and see its whereabouts?… I’d hate to have to re-write it. 🙁

    I have used my username robertok06 but from the wrong e-mail address…

    Anyway, good posting, congratulations.

  13. gweberbv says:

    I would like to highlight one aspect that seems to be widely ignored in the ERoEI discussion: A technology with an ERoEI of 5 might be problematic when you want to power the society with it. But it might look not too bad when you use it as a second stage for the high, but declining ERoEI energy source. For example try to think of PV (assuming it has a positive ERoEI) not as a replacement for coal, but as a measure to extend the range of coal. Like a heat pump does not replace a coal plant, but it adds to each kWh produced by the coal plant between 2 to 4 additional kWhs from an (to a good approximation) infinite energy reservoir.

    • Willem Post says:


      That is a fallacy, as FF eventually run out and RE would be the mainstay.

      As above noted, eliminating fossil fuels from electricity production is one thing, but it is quite another to eliminate fossil fuels from the thousands of industrial processes and millions of products that consist of fossil fuels, such as plastics, drugs, etc. That second, very important part, usually is ignored by RE fanatics.

      • Beamspot says:

        There are other issues with many of these points you correctly stated, that must be applied to ERoEI and that are usually overestimated.

        One of them is the 3:1 for almost all forms of energy when it is substituted by electricity.

        There are calculations and data from real world, as en example, that EV’s have a plug-to-wheel efficency below 70%. Even Tesla gave some figurea in this ballpark (and their cars are pretty efficient due oversizing).

        But, in example, what about glass processing? It can’t be done directly by electricity itself, and the approach I saw was to generate H2 and burn it with the resulting O2 from electric hydrolysis, with a really low efficency (below 70%), thus with a real result electricity:fossil gas of bout 1:2, just the reverse.

        And quite often also, electricity generation efficiency is dismissed, specially in front of other forms of energy generation that can be used directly.

        Sun is good at heating, with efficiencies in the 70% range quite often, while at doign electricity is much smaller, but even more complex and energy intensive in PV manufacturing, but the former is never considered, even when our society needs >50% of heat and only <21% of electricity.

        Why this obsession with electricity?

        • gweberbv says:


          the need for low grade heat is basicly given by space heating in houses, offices, shops, etc.
          This could be reduced relatively easily by a factor 2 to 3 when the buildings are upgraded to state-of the-art heating system, insulation and venting. In fact, this is already happening in some countries, but the building renovation is too slow to see dramatic effects (taking into account that the walled space that is used by the population is steadily growing).

          For electricity I do not know of a trick that will reduce demand by such factors.

          • Andy Dawson says:

            Except that the greenest way of providing low-grade heat in Northern European latitudes is via heat pumps – which, of course demand electricity (a typical system delvers 3-4kWh of heat for each kWh of input power).

          • gweberbv says:


            you better install a heat pump in a building that is already very well insulated. Otherwise it is not possible to reach the low temperatures of the heating water that are necessary to reach a reasonable values of the coefficient of performance. As an additional benefit, your well insulated building can switch off the heating system for up to one day while losing just 1 to 2 degrees Celsius room temperature.
            Maybe, I am wrong but I see the electrification of space heating as a huge chance to make use of intermittent wind power production in the winter.

          • Beamspot says:

            The issue with heat pumps is that this 3:1 ratio of pumping stands only if the delta temperature is low. In northern Europe I guess this difference lowers to less than 3:1 for sure.

            But then, the real result is less obvious. We use heating in winter because it is cold. And it is cold because there is no sun.

            Thus energy consumption and sun are complementary. The seasonality variation doubles, and does that much bigger as you move close to the poles, while much lower when you move to equator.

            And what about EROEI when we include these heat pump systems and all the energy required to build them?

            And what happens if we, instead, use passive solar heating instead?

            I still have to see a single ERoEI study on non electrical forms of renewables.

            I also begin to think about the Kitegen compressin air instead of using electricity. Many factories use compressed air for many many uses, as well as heat, that could be supplied, even partially, by renewable means, without the losses due energy conversion and transmission by electricity as vector.

            Concentrators and solar generated Steam can be used to power many things also, and it has some controllability and storage (that both are part of the same) embedded, much better than electricity in this case.

            And just as a sidenote, I can see many places where electric lights are on the whole day. Why then can’t simply use something as complex as windows? (Of course, this is a rethoric question: I already know the reason).

            So, I sitll don’t have the point about the All Electric reasoning, besides the anything but transparent concept of Meter.

      • gweberbv says:


        as things look at the moment, FF will run out anyway and this will bit by bit destroy a good portion of global society. Anything that can delay this process is helpful.

        • Willem Post says:

          Like a more prolonged water torture?

        • robertok06 says:


          “Anything that can delay this process is helpful.”

          Problem is… intermittent renewables are anticipating the process, not delaying it.

        • Euan Mearns says:

          IMO, the only thing that could delay the bad impacts of declining high ERoEI FF is to introduce to the global energy mix an energy source that has higher ERoEI than the fuels they have to replace.

          Introducing low ERoEI energy sources simply makes things worse.

          • gweberbv says:


            look how things work in Germany: The money for installing PV and wind is not taken from the investment budgets of the energy industry, but from the pockets of electricity consumers (and here mainly from the small ones). What is happening here is that purchasing power that would otherwise flow into buying smartphones, holiday trips, cars, etc. (all having an ERoEI equal to zero or even negative) is directed into the energy sector.

          • Gw

            In many cases you can add purchases of food, heating clothing etc as previously noted on the several links supplied to you by posters regarding fuel poverty in Germany.

            But who are you to decide how a person should spend (after tax) their money?

          • gweberbv says:


            I regard fuel poverty as a joke.

            For sure, if you take an average US household with more than 10,000 kWh annual consumption and expose thesese people to German rates, they will take a severe economic hit. But the average German household is around 3000 kWh per year. Thus, the average German household, while paying three times the rate per kWh is as energy poor/energy rich as the average US houlsehold.

            If you are interested what drives people into poverty in Germany than look ar the recent increase in house/flat renting costs. This is much (!!!) more important as the electricity bill.

            By the way: Nobody why is nobody talking about fuel poverty? Germans (and most Europeans) are paying more taxes per gallon gasonline (soemthing like 3.3 $/gallone) than their US cousins are paying for the gallone all together. But no problem!

          • robertok06 says:


            “What is happening here is that purchasing power that would otherwise flow into buying smartphones, holiday trips, cars, etc. (all having an ERoEI equal to zero or even negative) is directed into the energy sector.”

            Are you kidding or what???

            You “forgot” to factor in the huge, immense, incommensurable losses of the energy sector giant corporations. They are all broke, the Energiewende has destroyed them all, in Germany and abroad as well.


          • Tom S says:

            “Introducing low ERoEI energy sources simply makes things worse.”

            No, definitely not. Any source of energy with an ERoEI higher than 1 increases the AMOUNT of net energy generated by society, and so makes things BETTER.

            -Tom S

      • Tom S says:

        “but it is quite another to eliminate fossil fuels from the thousands of industrial processes and millions of products that consist of fossil fuels, such as plastics, drugs, etc.”

        Why don’t we go back to glass bottles for beverages instead of plastic ones? Drugs are produced in milligram quantities per person and other sources of carbon could be used for this purpose. Why don’t we use silicone instead of plastic?

        There are fairly obvious substitutes for all uses of oil, although many of them are more expensive.

        -Tom S

  14. sod says:

    The concept is difficult, as in the end the real use of the energy source should make a difference.

    Even i do agree, that Diesel has a pretty high energy density. But what if it is used to move a car forward in 10 meter “jumps”?

    in a surprise move (an d basically unnoticed, even by people following these kind of subjects), Deutsche Post has developed and built a “Streetscooter” electric transporter to deliver parcels.

    so in this case, to understand final “EROI”, we need to factor in the wasteful use of diesel by the way these cars get used. (And we should also factor in the pollution caused in cities.)

  15. Leo Smith says:

    The idea of an ‘energy cliff’ is very similar to Tainter’s* ‘complexity cliff’ as a ‘death of civilisation’ marker.

    His thesis is that as societies grow in size to exploit natural resources, less and less people are involved in actually extracting the resource,whilst more and more are involved in essentially bureaucratic processes of distributing it, until as the resource dwindles, the whole society and its organisation becomes top heavy and a rapid positive feedback loop causes its total collapse, or takeover by a ‘strong and simple’ invader.. Where are the Mayans who built Chichen Itza today? Working in the hotels, or scratching a living on small plots of land. The bureaucratic elite died, the workers live on..

    In his case human lives are the metric. At a given point keeping all the top heavy bureaucracy going, costs more than can be afforded, and a rapid population die back to whatever is the sustainable resource level happens. Instead of ‘peak oil’ its ‘peak bureaucracy’ .

    I have been extremely interested throughout my life in the philosophical implications of game theory and system theory. Both offer almost irrespective of human thought processes interesting pictures of why societies develop the way they do, and why they collapse. This ERoEI is an example of system analysis applied to large areas of society. As is Tainter’s thesis, if he but knew it.

    Another aspect I am working on, in a difficult attempt to make comprehensible something I can picture, but cannot yet describe, is the relationship between stable societies and the belief structures necessary to guarantee their stability. And how little or not these beliefs need to correspond to a reality that we presuppose must exist beyond them.

    Is it in fact a mark of a stable society that it believes in something demonstrably wrong (or indecidabale) , yet which gives cohesion to and structure to, and a survival potential for, the individuals that comprise it?

    Does belief in sky fairies make society stronger, or weaker, for example?

    But I digress. Keep up the good work Euan, and dont mind my philosophical ramblings..

    *The Collapse of Complex Societies: Joseph Tainter.

    • robertok06 says:

      “Is it in fact a mark of a stable society that it believes in something demonstrably wrong (or indecidabale) , yet which gives cohesion to and structure to, and a survival potential for, the individuals that comprise it?”

      This is the perfect definition/translation for “Energiewende”. Wrong at its roots (physical, ecological and economical) but believed by the populace at large and THEREFORE right.
      Unfortunately for the populace, it won’t survive long, a couple of decades at most.

  16. confused mike says:

    The net energy cliff visual I like as it highlights that much greater than one is needed to be a ‘ sensible’ investment.

    Does the Levelised Cost of electricity (LCOE) concept determining the breakeven price of power needed for an investment to go ahead help in terms of the economics?
    This should take into account the life of the project and decommissioning costs but presumably still suffers with the fully built up cost of construction uncertainty

    This should be(IMHO) the driver for choices – if the price is too high either it wont/shouldn’t be built or requires subsidies which with the identified lifetime of the project can totalled and spread over the consumer population in terms of price per unit (Kwh)

    It was used for UK HMG Feed in Tariff (FiT) discussions to prioritise first of a kind demonstration projects and enable Carbon pricing to be added but did not as far as I can recall include back up costs for intermittency ( I did not get involved in Solar or Wind project economics) but should not be impossible if the debate has been used for the ERoEI discussions?

  17. renewstudent says:

    Yes EROEI analysis is complicated, with views differing on the boundary conditions. For example some (Harvey, Gagnon) put the EROEI for nuclear at only16:1 and likely to fall, as lower grade uranium ore has to be used, down to 5:1 and maybe less. Others (Weißbach, et al) seem to ignore the energy debt of fuel inputs. That, predictably, disadvantages most renewables, which have no fuel inputs, and puts nuclear in the lead:
    Unsurprisingly there has been a continuing debate on the EROEI methodology used: – aff1
    And clearly it goes on!

    • mark4asp says:

      Harvey, Gagnon ignore the potential of breeder reactor technology which would entirely remove the fuel bottleneck. None of the early nuclear power pioneers imagined that mature nuclear fission would mean PWR reactors, with a once through fuel cycle discarding 96% of the fuel. PWRs owe their practical existence to the US Navy wanting a quick fix reactor that would fit in a submarine. Nor are breeder reactors “high tech”; they are politically spiked by regulators and anti-proliferation agencies. With the right regulatory framework we could start building breeders tomorrow.

  18. I have been following all of the efforts since at least 20 years.
    KiteGen is one of the leading players.
    Most are European coming out of TU Delft, ETH Zürich or from Milan/Turin around KiteGen/SequoiaAutomation.
    Automation and control is sayed to be the critical enabler to the technology.
    Another company I’d put in front is German  Skysails who’s kites are already deployed on ships. Thus you could say they already produced some MWh over their lifetime (offsetting shipping fuel). They use a single line design with a control unit beneath the kite.
    Ampyx is also one to watch.

    But keep at it with KiteGen. Sounds as clean as it gets.

    I don’t see the potential as high as the Jetstream winds, 500-1500m onshore should suffice and work almost anywhere.
    Airspace rights seem to be the main concern in most discussions but with modern radar it is possible to even evade flocks of bird and once you start building multi GW plants you’d probably get the same airspace restrictions like nukes.

    • Euan Mearns says:

      KiteGen also provided this progressive view of the wind resource accessed by a kite as opposed to a turbine.

      If I understand correctly, a turbine only captures about 45% of the wind energy on the frontal area of the blades. While a kite may capture about 90% of the wind energy on the face of the kite and because the kite moves across the sky, it stays at about 90%.

      Here they get 4 to 10 times the energy for a fraction of the mass.

      Sorry about the comment posting mess. Works OK for some and not for others. Best to ignore duplicate comment messages.

      • Andy Dawson says:

        Euan, at face value that seems to be a contradiction of Betz’s law.

        • Euan Mearns says:

          Need Massimo to answer that one Andy. I don’t have a good understanding of Betz’ Law. But I can visualise with a turbine standing in one place that the energy in the wind down stream would be reduced. For a kite pulling out a rope parallel to the wind direction I can see that there would also be a reduction of wind energy downstream from the kite.

          But a kite flying across the sky is somehow different.

        • We started the KiteGen project without having the awareness of the gradient, more constant and more strong wind in altitude, Our knowledge was: “OK, there is the jet stream with stronger winds, however could be unpractical to reach such altitudes”.
          We early focused, as the main advantage for kite wind power, exactly the opportunity to avoid the Betz limit. Betz law is describing the ideal braking of the wind applied to a WT. If you fully brake the wind the resulting power is null, the same null power if no wind brake occur. There is an optimal braking that allows to extract the maximum power from the specific flow tube, the well known 16/27.
          This means that a natural wind of i.e. 9m/s will be released downwind by the WT at about 3 m/s because blades insist in the same disk. Betz also gave the answer about the wind speed close the blades that is useful for aerodynamic computations and is the mean between input and output wind, then 6m/s.
          The KG flying wing is unable to brake effectively the wind because the huge wind front available, the kite can always exploit fresh, undisturbed natural wind with a sort interleaved path in the airspace. Then the available natural wind to the wing is always close to the input 9m/s of the example, only slightly reduced. So, the specific power available to the wing is proportional to 9^3 compared to the WT that is 6^3, giving an extra kite performance of 3.3 times compared to WT with the same natural wind speed. In our opinion this was an incredible achievement sufficient to decide to investigate deeply the concept and develop prototypes, after that, we discovered also the altitude wind gradient that is a further cherry on the pie, BTW much more important than the original motivation 🙂

          • Andy Dawson says:

            If I’m following you, you appearar to be saying since the kite isn’t static, Betz doesn’t strictly apply. I disagree- it mean you should be stating the efficiency in terms of energy recovery from the whole (to use your term) flow tube from the trajectory described by the kite.

            To do otherwise is like the evasions that have been tried by proponents of various ducted wind turbine designs when they use only the blade disc area instead of the whole cross section.

          • gweberbv says:


            the formation of the various layers of air in front of and around of the object you place in the wind should take a time span that correlates with sonic speed. In other words: very fast. As soon as the air flow around the object has reached a steady state, the Betz formula should apply (if I understood correctly).

            I doubt that your kite moves with supersonic speed. Probably the blades of wind turbines move much fast than the kite.

          • Euan Mearns says:

            @ Andy, Massimo and Gunther

            I woke this morning thinking about Betz’ Law. As far as I understand, there are two factors that will determine power. The first is the force on the rope on the drum (this is like a fishing reel) and the speed the rope is being pulled off the drum (the rate of drum rotation). To generate a force on the rope the kite needs to “fight” the wind while flying with it. To fight the wind will mean that some wind is spilled around the kite.

            If the kite flew away at the speed of the wind (it doesn’t have to fly at speed of sound) there would be no spill, but I’m not sure there would be any force either. So the question is where the optimum balance lies between flight speed and power.

            But another factor I don’t fully understand is that the Kite is shaped like a wing that provides significant aerodynamic lift mid way between a sports kite and a glider.

          • @Andy
            Attention, I’ve not said that Betz doesn’t apply, I said that the wing doesn’t need to look for the betz optimisation. Paradoxically the flying kite could be considered inefficient with Betz metrics, however the kite flying crosswind at 1000m intercept/scan about 1 square km of wind that is about 100 times the 3MW wind turbine. Therefore, the kite having available 100 times the natural resource vs. turbines, can improve what I’ve just said 3.3 times, with the same conditions (wind speed, aerodynamic surfaces, aer. efficiency).
            The kite is designed to fly at 80m/s that is enough to topologically exploit always fresh wind. Before the kite come back to the same previously exploited region of the flow, it last 30 – 60 sec allowing this region speed to be fully recovered.

            This part of the wind exploitation theory is not new and no exclusive of KiteGen, it was deeply discussed and formalised during the transition from synchronous/fixed speed to variable speed HWT, perhaps somebody remember passionate discussions about this new opportunity dating around 2003. The maximum efficiency ever reached of a wind turbine is slightly less than the asymptotic 32%, at nameplate power and nominal wind. However the variable speed HWT could rotate slower in case of lower wind that imply less wind braking effect gaining in efficiency up to 42% (48% claimed by Enercon).


          • robertok06 says:

            @massimo ippolito

            “however the kite flying crosswind at 1000m intercept/scan about 1 square km of wind that is about 100 times the 3MW wind turbine”

            Sorry, but Idon’t buy into this argument… if this were true than the dimension of the kite itself (the flying part other than the rope) wouldn’t matter at all, and any little kid playing with a toy kite would be lifted off the ground and taken away.
            What matters is the combination (via some physical laws) of the surface of the kite and the wind speed, as is the case of the conventional static ground turbine… the only thing you can claim for sure is tha the average speed of the wind grows with the altitude, the bad thing is that measuring on the ground (and, say, 80-100 m above it) is relatively simple, while measuring it at 1000-2000 or more m is going to be much more of an enterprise.
            A 130 m rotor diameter, 90 m off the ground nacelle turbine will need a fraction of 1 km2 “clear” (the wake effect), but in your case even a small kite wil need a much bigger area clear on the ground, at least the whole area of the circle having the rope’s lenght as a radius… and this clear of any high-voltage lines (off the ground, on pylones), buildings, factories, homes… I personally wouldn’t feel too well knowing that a (I guess) 100 kg kite would be flying above my head 24h/24. Multiply this by 1000s and you get the picture, at least I do, good for semi-desertic areas (like the south-west USA, or parts of Spain which I’ve seen from the airplane while flying to Portugal), but certainly not much applicable to countries like Italy.

            Anyway, I may be wrong of course, the best thing would be that you were finally able to fly “the real thing”, a (at least) few-100s kWe kite, in a stable and reproducible way, injecting quasi-baseload electricity into the grid, why reasonable LCOE costs.

            I sincerely wish you and your company good luck.

          • Euan Mearns says:

            Roberto, I have these explanations from Eugeneo via email. The force that unwinds the rope is derived from the aerodynamic shape of the kite (wing) and the speed it flies across the sky. The first 4ms-1 of wind speed goes to keeping the kite in the air (250 kg). There after each additional ms-1 adds 1 ms-1 to the unwinding rate. To reach 3 MW needs 10ms-1 unwinding and so 14 ms-1 total wind speed. These “cut-in” and optimal wind speeds seem similar to conventional turbines. But perhaps easier to find 14 ms-1 at altitude.

            The alternators deal with the lift force that raise when you fly at 80 m/s, it depends on the efficiency of the profile and, as power is F*v then you have 100 kW for each kN when unwindling the ropes at 1 m/s. The nominal condition take place when you have 150kN per rope and 10 m/s of unwindling

            Depending on the aerodynamic efficiency of the wing 3-5 m/s of wind speed are required just to maintain the nominal force of 150 kN per rope. Each additional m/s of wind speed yelds one more m/s of rope unwindling speed.
            If, say, 4 m/s are required to reach the nominal force then 14 m/s enable unwindling at 10 m/s and having the nominal power. Usually these speed are frequent over 1000 m of altitude.
            A more efficient wing means having more nominal force at lower wind speed i.e. having 200 kN @3 m/s means 3,2 MW @11 m/s and so on.

          • Euan Mearns says:

            Roberto, you are right to be sceptical. On the air traffic safety issue, this I believe is more of a hindrance at the prototype testing stage than the operational stage. If someone comes up with a high ERoEI cheap, subsidy free renewable energy source then the skies will be cleared in areas where it needs to operate. I agree that at first these areas are likely to be wilderness.

            On flight reliability we await publication of extensive test flight data. KiteGen are attempting a quantum leap from flying sports kites a few years ago to flying a 130 m2 semi-rigid aerodynamic composite material kite studded with motion sensors and in kite flight control + ground flight control. It works in the flight simulator but awaits field trials.

            The physics of flight and electricity production push my boundaries. I’m a geologist and understand digging carbon 😉 The energy production side of the ERoEI equation comes down to “rated capacity” and “capacity factor”. These again require verification from field operational data.

            I have never before looked into high altitude wind. The thing that hooked my attention was the promise of higher and more constant wind speed at altitude combined with much lower mass of the devices designed to capture it leading to higher ERoEI. So lets imagine the ERoEI is 50 to 100 then one could choose to either over dimension generation and curtail it to match demand or convert 50% of production to chemical storage to balance load.

            But while Massimo is convinced this will work, the sceptics will wait for proof.

          • @roberto

            What matters is the combination (via some physical laws) of the surface of the kite and the wind speed, as is the case of the conventional static ground turbine…

            this is obvious, and is a very basic computation, then matters even more the resource management, as I just tried to depict.
            Ok is a step forward but I’ve assumed that some understanding about wind and aerodynamic was available.

            while measuring it at 1000-2000 or more m is going to be much more of an enterprise.

            False, we made a wide assessment campaign in Italy with sodars, learning that the weather models available on high winds are much more accurate than our needs and is easy to check the resource consistency each hours everywhere and also there are forecasts.

            but in your case even a small kite wil need a much bigger area clear on the ground, at least the whole area of the circle having the rope’s lenght as a radius

            False, hundred generators could share the same site.

            I personally wouldn’t feel too well knowing that a (I guess) 100 kg kite would be flying above my head 24h/24.

            Bizzarre concerns.
            The clearance around and over Olkiluoto Nuclear power plant is enough wide to harness about 20GW of altitude wind power, with the same ground occupation.

            I am afraid that is so complex to explain and understand, nobody read the papers and disseminate all aspect in a blog is quite tricky.

          • Eugenio Saraceno says:

            in response to the message of robertoko6 below
            (Euan: do not know why cannot reply directly to him, too many nested comments?)

            Roberto said:
            ” if this were true than the dimension of the kite itself (the flying part other than the rope) wouldn’t matter at all, and any little kid playing with a toy kite would be lifted off the ground and taken away.
            What matters is the combination (via some physical laws) of the surface of the kite and the wind speed, as is the case of the conventional static ground turbine… ”

            do not forget the efficiency of the wing. The kid’s kite is small and has low efficiency, it pulls few kilograms; a sport kite is larger and has low efficiency (say 5-8) it pulls up to a ton. A power kite must be larger and have high efficiency (>20) in order to pull tenths of tons. A 400 ton aircraft with a 400 m2 wing has usually an efficiency about 12-17 while a glider has 30 to 70

            “the only thing you can claim for sure is tha the average speed of the wind grows with the altitude, the bad thing is that measuring on the ground (and, say, 80-100 m above it) is relatively simple, while measuring it at 1000-2000 or more m is going to be much more of an enterprise.”

            You do not have to measure phisically to have the approximate average speed. The Global Forecasting System model of the NOA does it for you every few minutes so you can have the forecasts at different altitudes as in
            A new LIDAR instrumentation is able to measure up to 5000 m (older devices went up to 700m)
            KiteGen has also a patent of a drone based wind speed measure device (useful up to 1000-2000 m)

            “I personally wouldn’t feel too well knowing that a (I guess) 100 kg kite would be flying above my head 24h/24.”

            There is no other way than going in remote areas with no fly zones on it until the technology reaches the TRL9 as a constrained flight would anyway be much safer than airplane flight. By the way many people live near airports and we everyday see aircraft of hundreds of tons over our heads. There is an accurate power kite FMECA report done by the Wuppertal university within the European project kitves.
            In few words: having a 200 kg kite constrained by two ropes assure that if one of the ropes break or even the kite breaks in two every force disappear as the aerodynamic profile is displaced this means that there is no fatigue on the other rope and that the event of breaking the remaining rope is very unlikely. This enable the ground machinery to pull quickly the broken parts that will fall nearby the plant.

  19. Jacob says:

    The ERoEI concept is a good concept as a thought exercise, but impossible to measure, which makes it practically an useless concept.

    You state: “ERoEI > 5 to 7 is needed to sustain society”.

    This is very nebulous on both sides of the equation. What does “sustain society” mean? The modern “consumerism” idea says that we consume too much, anyway, without being able to define how much is ok and how much “too much”. An American consumes about 55k$ per year, an Indian about 6k, many others much less. So, which “society”, or what level of consumption do we seek (do we need an ERoEI > 5 for) ?

    Fortunately, we have the objective and common denominator of money, which is a good proxi for resources use. The more we spend on energy (directly or through subsidies) the less is available for other needs. We should always seek the cheapest available source of energy, as this leaves more to spend on “other things”. (Equally, we seek the cheapest of anything we use, not only energy).

    An unresolved question is: how can we put a price tag on future, unknown (but possible) damages of our current activities. (For example: do you include the costs of the Chernobil and Fukushima disasters in your ERoEI calculations and how do you do it?).

  20. Some new data about US oil and gas EROEI:

    Eroei is a strange metric. Consider, for example, a box which accepts 100 watts and outputs 101 watts. Clearly the box has an eroei of 1.01, but if you chain 1000 of these boxes together, you consume 100 watts and produce 1000 watts, for an eroei of 10.

    Concept of the EROEI, also, got other problems and is a “thing in itself”.

    • 1000 boxes…
      Looks like the EROI stays the same.

      • Tom S says:

        No, he means in series.

        For example, assume a PV plant with an ERoEI of 2 and which requires only electricity and materials to construct (for simplicity). You could use the net energy to construct 2 other PV plants which provides net energy of 4, for 1 unit of energy invested invested. You could use the net energy from those two PV plants to construct 4 more PV plants, and so on. If you did this for 10 generations, the AGGREGATE ERoEI of the entire thing would be 1,024:1, even though the individual units had an ERoEI of only 2.

        This is why ERoEI is not important by itself. What matters is the non-energy cost (labor, capital) of net energy. That figure is not affected by adding units together in series and considering them in aggregate.

        It is the non-energy cost of net energy which is important, and that figure is better at present for renewables than FF electricity. Renewables have an intermittency problem, but not a net energy problem.

        -Tom S

    • I disagree, in your example the 100W *1000 boxes = 100kW, either in series or in parallel.
      ERoEI is an easy and straightforward metric, historically heavily falsified only to force RE policies and commercial or advertising reasons.

  21. Roger Andrews says:

    Can anyone explain to me why society needs ERoEIs in the 5-7 range to function? Why can’t we get by on an ERoEI of 2 or 3?

    • Ajay Gupta says:

      My answer: growth

    • Stuart Brown says:

      Not even growth, I think. The human body emits about 100W give or take, so an ERoEI of 1 equates to sitting in a fruit tree and just eating 100Wh of fruit per hour. Equally, if you run around catching rabbits or whatever then you’d better make sure you catch enough of them to keep your weight up!

      If you want to feed your wife and 2 children aren’t we up to 3 or 4 already, if they are lazy? A society that includes footballers, mime artists, beauty therapists and solar panel manufacturers, and in which granny is not to be left out as lion food surely needs 5 to 7 at least!

      My simplistic view anyway

    • Pedro Prieto says:

      Very easy, Roger. Look first to the picture of the cheetah in the article of Euan on EROI for beginners. That beautiful and ultra efficient machine, needs an EROI of about 3:1 (sped three times less energy running for the prey, that the energy contained in the prey it is going to eat. That’s a metabolic minimum EROI for mammals.

      Being the minimum EROIext for any live being (mammals in particular) 2-3:1 in average, to be kept alive as species and for the couple to successfully breed their offspring (minimum of 2-3 per couple), probably Charles Hall is very right to state that a minimum EROI of 5:1 is required to have a minimum (very primitive and elemental) of civilization, beyond us living as naked apes.

      Sumerians were the first ones in being able to release kings, priests and military from productive works with the net energy surplus left once we pass to the Neolithic, domesticated animals and plants and stored them in the form of available energy surplus.

      If we pick the latest Sankey Diagram of the International Energy Agency (IEA), and take in one side the 13,137 MToe/year (or 17 TW of equiv. power) of primary energy and what the IEA calls “own use” (self consumption), which is 784 MToe/year, we get a rough global energy EROI of about 16:1. Should we use it the final energy values after losses (8,917 MToe/year), then we get roughly a 10:1 EROI and this is extended.

      If we consider that in the final uses there must be a number of human activities also related to the energy uses, which are not included in the “own use” consideration of the IEA (i.e. allow me the joke, the energy spent by Fatih Birol in his trips as main responsible of this entity) and many others, we may well be having a global EROIext of one digit.

      Conclusion: a complex industrial and technological society may need a minimum EROI >10:1 (note: the important here is the concept, not the decimals) to stand still and even with the mighty fossils already dwindling in net EROI we may be reaching a tipping point.

      On the other hand, if you conclude that a given energy source and associated system gives only for instance 3:1, this may suffice for a hunter-gatherer society, which can thrive with this EROI.

      But then there is a contradictio in terminis, because hunter gatherers were not known for building up complex clean chambers with their micrometer air filters or sophisticated machines to cut in fractions of millimeters the ingots to produce the wafers, robotic soldering machines with micrometric precision to make the silver connections between cells, or electronic factories to produce the solid state power devices like the IGBT’s of the inverters.

    • Euan Mearns says:

      There’s an interesting story there. For years bloggers have maintained 5-7 citing Charles Hall. But when I asked him for the reference he said he’d never published that. But he may have mentioned it to someone over a beer. He currently says ERoEI of at least 7 for society to function.

      But I hope I can answer your question. At ERoEI = 1 there is no net energy and by definition everyone is working in the energy industries making the cost of energy hugely expensive. This of course cannot happen. But at ERoEI = 2 then perhaps 50% of the population are engaged in energy industries and 50% of the energy produced gets used to get more energy not leaving much net energy (or people) to work in manufacturing, schools hospitals etc. To have same net energy that we have available today the amount of gross energy being produced may have to double from where we are at present and it would be prohibitively expensive.

      Its really in the range of 5 to 10 that manageable amounts of energy are invested in getting more energy (10 to 20% of total energy) with significant amounts of net energy becoming available.

      • sod says:

        “But I hope I can answer your question. At ERoEI = 1 there is no net energy and by definition everyone is working in the energy industries making the cost of energy hugely expensive.”

        I disagree. take a look at the solar roads (with a horrible RroEI, by the way).

        If we invent a machine, that is making solar roads out of the stuff that it collects on the way, even a terrible ERoEI (like 1.1) could make sense. And basically nobody would work in that industry.

        There is a similar problem with wind power: If Kites (which do not exist) have a good ERoEI value, while turbines that do exist have a very bad one, the concept has a problem.

        The solar PV road, by the way, benefits from the fact that it is replacing a road. It can have a much worse ERoEI than a dedicated solar panel. The same is true for roofs (and windows) which i expect to be simply made out of solar PV panels in the future.

        • gweberbv says:


          indeed, such dual-use facilities that produce energy just as a byproduct might have a significant influence on the ERoEI disucssion. However, PV modules as a roof cover (instead of putting them above the roof structure) are still very rare – even in Germany. And if you use PV as a front cover for your house, you will throw away a lot of efficiency.

          Thus, it look like applying PV in this context is at least not a sure-fire success.

      • Pedro Prieto says:

        Euan, apart from the common sense of minimum EROI 5:1 to be something else than the minimum 3:1 of a hunter gatherer society (tribal, nomadic, living in caverns), like any other mammal, except, perhaps for the use of exosomatic energy of fire in the last 500,000 years or so, Charles Hall depicted several years ago a “Balloon Diagram” he may not remember, where it was oil in the 30’s of last century, in the seventies (much lower and in the date of publication (even lower), as well as other fuel sources like coal or gas in different stages and even wind and solar. In this drawing, he drew a line at 5:1 and marked it up as “minimum required for civilization”.

        I believe I still have the picture.

        • gabs says:

          The problem is, that the required EROI is defined by the borders in which you calculate this EROI. If you widen the Border of Prieto and Hall only a bit, to include also the army protecting the plant (and many other things) in the country, and similar things, you include the whole society in the calculation noone exempted, because all entertainment (holidays, theaters, etc….) also goes into the caldulation step by step. If it is avoided to double calculate things then, the borders are clear, and also the required EROI is clea, it is 1,0, so all energy needed by the society needs to be generated by the society.
          But on such a wide calculation, money is a much more convenient base of the calculation, than GJ or MWh. Because most things have a exact price in money, but none in energy.

          • Thinkstoomuch says:

            Price does not equal cost.

            Quote from Christopher Anvil from [i]Top Line[/i] in “War Games”, a scifi writer.

            Q: “How can something be worth more than it costs? Isn’t everything ‘worth’ what it costs?”
            A: “No. That’s just the price. …
            Christopher Anvil from [i]Top Line[/i] in “War Games”

            Cost is a very poor comparison for energy and especially sustainability.

            Everything sold is worth more to the buyer than the seller. It is how economies work.

            So while money may be convenient it fails miserably as an adequate measure.


      • Joris van Dorp, MSc says:

        The EROEI 5-7 assumption bloggers have been using may have come from watching this video of a lecture by Dr. Hall.

      • Joris van Dorp, MSc says:


    • I guess it’s only in a resource restrained environment that you can’t get by with lower EROEI.

      Now imagine a self replicating source of energy. If there is some exergy left over the replication of the source only has to speed up to provide the needed energy to society.
      In this case it doesn’t matter if 50% or 99% go into the self reproduction…
      There is always looming Singularity though…

    • Eugenio Saraceno says:

      Think to a farmer
      he grows a low yeld grain, sows one unit of seeds to get a harvest of say 2 units. EROI of the process is 2 (we neglect the work of plowing oxen as they dont eat grains).
      The farmer must store one of the two units harvested each year in order to sow the next year. The other unit is for the farmer’s family to survive.
      You can imagine a drought or any other issue that reduces the yeld; it means the starvation of the farmer.
      A society that relies on a such low eroi just cannot survive
      Things are better when EROI is 3 or more but if you want a complex and resilient society you cannot use 1/3 of your energy stocks just to get energy. EROI 5 means no more complexity than a feaudal society. EROI>7 means a society that can afford division of labour, education, social security, and complex bureaucracy; each of these features of a civilization needs its slice of the energy pie. The less the slice of the enegy pie dedicated to harvest energy itself is, the more complex features a civilization can afford.

      • Jacob says:

        These are nice stories, beau letters, not quantitative calculations based on actual data.

      • Tom S says:

        “EROI 5 means no more complexity than a feaudal society.”

        No! It’s IMPOSSIBLE to calculate the net energy obtained by civilization from ERoEI alone. The minimum ERoEI for civilization might by 2, or it might be 50, depending upon the NON-energy resources (labor, capital) required to obtain a unit of NET energy.

        For example, as a thought experiment, assume you can build a cold fusion reactor using nothing but duct tape and wire, in 5 minutes, for $5. The device requires 500 watts electricity to operate and produces 1 kilowatt electricity, for an ERoEI of 2. Since they are so cheap to make, civilization could manufacture 2 billion of them, using the energy from earlier devices. The net energy available to civilization would be 1 terawatt of electricity (500 watts net, times 2 billion).

        On the other hand, assume a 1GW fusion reactor like the one being built in France, but it’s so complicated and labor-intensive that we can build only ONE of them, and it has an extremely high ERoEI of 10,000. In that case, the net energy available to civilization would be approximately 1GW.

        As a result, the net energy obtained for civilization would be 1,000 times higher from the low ERoEI source (ERoEI of 2), as from the high ERoEI source (ERoEI of 10,000).

        -Tom S

    • Tom S says:

      “Can anyone explain to me why society needs ERoEIs in the 5-7 range to function? Why can’t we get by on an ERoEI of 2 or 3?”

      It is a mistake. It is based upon confusing ERoEI with total net energy obtained.

      For example, as a thought experiment, suppose you could build a 1GW cold fusion nuclear reactor out of duct tape, wire, and flour for $5. The reactor requires 500W input in order to run and outputs 1KW, continuously over 30 years, so it has an ERoEI of only 2. If you required more NET energy then you could simply build more of them. The ERoEI indicates NOTHING about total net energy obtained by you.

      Net energy increases with every energy obtaining device we make. As a result it is NOT possible to calculate a “minimum ERoEI for civilization” or anything similar. You would need to use a different figure for that, namely, the non-energy investment (labor, capital) per unit of net energy obtained.

      -Tom S

  22. cafuccio says:

    Euan, maybe you could mention the attempt made by IEA to standardize EROI approaches at least concerning PV:

    Note that this paper was suggested by Pedro Prieto on Ugo Bardi website, which also tries to make some noise on PV EROI. But with different results!

    And maybe you should also have a look at Maugei latest paper on UK power plants EROI by fuels. Mostly in accordance with your values…

  23. Ajay Gupta says:

    Dr. Mearns thanks again for a wonderful post! This is a great primer for EROI information and I hope to spread it accordingly. The comments especially remind me of the kinds of problems we had at ESF during my short stay, concerning methodology protocols, problems in data, and lack of scientific community input. When working on my own thesis there, pretty much all of PV information was in some way disputable or inadequate. So glad to see this discussion!

  24. stone100 says:

    I’m left puzzled at how discussions about EROI seem to conflate investment of human time (ie man/woman hours) with investment of energy. They are not quite the same thing. The post says that if EROI falls then we will spend all our time gathering energy. EROI isn’t the only factor involved in how much time gets taken gathering a unit of energy. Hypothetically, it might be imagined that some kitegen type project might need to be sewn by a skilled worker and require lots of maintenance. It might take many more hours of highly trained human labour for every MWh than say a PV panel made on a production line and then left for decades on a roof with no human intervention. Decades of bureaucratic wrangling with NIMBYS could have the same sort of effect. Money cost takes into account both the energy investment and the human time investment. Perhaps simply looking at the financial cost of energy makes more sense than EROI? A source of energy that doesn’t entail an “energy quality” upgrade and delivers an EROI <1 will be infinitely expensive in an undistorted market. I'm not sure that EROI captures anything that money doesn't and misses out the important factor of human time invested.

    • Greg Kaan says:

      Euan’s very last sentence summs up why money is not used, even though it is theoretically the ultimate, levellised measurement.

      However, in the real world, different currencies, interest rates, debts, taxes and subsidies exist that allow the thermodynamic rules of the energy world to be bent, albeit temporarily.

      You should, in fact, reread the whole last paragraph of the article.

      • stone100 says:

        I still think that last paragraph is mistaken. I totally agree that energy is a crucial link in the chain of human endeavour, but it is only one link. Energy is important however Labour and Capital are also important and they embody a lot more besides energy. This blog is called “Energy Matters”, let’s not slip into the mistake of imagining that “Only Energy Matters”.
        Let’s imagine that you could time travel back to 1970 and wanted to make an iphone. No amount of free energy would enable you to do that. You would need knowledge and expertise and machinery as well as energy. All of that is embodied as Labour and Capital. Energy can be accounted for in terms of Labour and Capital but not vice versa.

        • robertok06 says:

          “Energy can be accounted for in terms of Labour and Capital but not vice versa.”

          No. Without energy (first), a surplus of it, there is no Labour and no Capital (later).
          Energy created this universe (exact details not yet known) not Labour or Capital. Energy is everything and the most important single entity/quantity/whatever you want to call it, that manking as.

      • Tom S says:

        “However, in the real world, different currencies, interest rates, debts, taxes and subsidies exist that allow the thermodynamic rules of the energy world to be bent, albeit temporarily.”

        Those things do not allow the thermodynamic rules of energy to be bent, not even for a moment.

        -Tom S

    • Euan Mearns says:

      It is the energy component / cost of human time that is counted. Total energy consumed / total GDP for an economy gives J/$. You then take the salary of the worker times the energy intensity to pro-rate the amount of energy consumed by the worker that becomes embedded in the energy system. And yes, if an energy system is labour intensive then the energy cost of embedded labour is high.

    • gweberbv says:


      just have a look at a chart of the oil price over the last ten years (or other commodities). It is unlikely that the energy/labour required to obtain a barrel of crude oil did change by a factor of 5 during that time – but prices show such erratic behaviour. Similar features you will encounter for all prices of products, where supply cannot follow as quickly as demand changes. Thus, looking at the price of a product can be very misleading when you want to know about the invested energy/labour.
      Maybe, it works when you average over a decade or longer.

  25. Harquebus says:

    There is also the environmental costs that are never included.

    “There’s not one step of the rare earth mining process that is not disastrous for the environment.”

    “Polysilicon production produces about four tons of silicon tetrachloride liquid waste for every ton of polysilicon produced.”

    Environmental losses reduces nature’s ability to gather and store energy.

    • gabs says:

      …. and is a s such directly going back in the destillation process and is being recycled, next step then trichlosilan in the hydrogenation reactor, and then goes ito the Simens or FBR-process, where again tetrachlossilicon is a byproduct, which goes back into the step one of the polysilicon production process.

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  27. Geo-realist says:

    Proponents of renewables often cite storage as the solution to intermittency. It would be interesting to calculate the ERoEI for wind and solar with this factored in, or does the buffered figure already include some element of this?

    • Andy Dawson says:

      No – in fact, part of the controversy about Ferroni and Hopkirk’s paper was that it included pumped storage buffering.

      You raise a valid point, though. If by including an intermittent source in the overall system, I require back-up from a dispatchable source, I will presumably operate that dispatchable source less frequently than I otherwise would – which reduces the EROEI for that backup source.

    • Euan Mearns says:

      The cost of intermittency is currently no being met by the RE industries. Most of this is falling to the utilities and then passed on to the consumer. But in the real thermodynamic world there is of course an energy cost of intermittency that should in my opinion be counted. As Andy points out, Ferroni and Hopkirk included this in their extended boundary analysis of high latitude solar. And Weissbach et al also provide a “buffered” figure to include the energy cost of intermittency. The latter reduce ERoEI for solar by a factor of 2 and wind by a factor of 4 to include storage. This sounds about right since wind at ground level is much less predictable and requires unrealistic vast storage to become disptchable. The alternative would be to calculate the energy cost of back up and balancing reserve.

      • Including the energy costs of intermittency as a storage cost is invalid because it isn’t going to be done that way. No country that I know of presently stores any large amount of wind and solar for re-use, nor is ever likely to given the immense size of the storage required. All of them balance their wind solar-production against load with FF or hydro and/or by imports-exports, and will continue to do so because that’s the only way they can do it.

        Solar is also a tougher storage proposition than wind, indicating that the factors of 2 for solar and 4 for wind are the wrong way round. Figures 6 and 8 in show that adding wind to solar can in fact decrease the storage requirement in some cases.

        The right way to do it is the alternative – calculate the energy cost of back up and balancing reserve. This cost, however, will increase exponentially as wind and solar grid penetration increases.

        • Euan Mearns says:

          Roger, I agree and disagree 😉 If you want to set the system boundary at delivery of dispatchable power then storage costs would have to be added and as we both know this gets impossibly expensive and will never be done. But you yourself have shown that at low latitude annual cycle can be overcome by over-dimensioning your PV array – that’s adding a lot of energy cost. Plus batteries to cover the daily cycle. At high latitude its impossible to cover annual cycle. So for solar, storage is possible at low latitude. For wind, we need to bridge a 7+ day lull – its impossible.

          I agree then in practical terms that it is best to calculate the energy cost of load balancing and backup. But in so doing one needs to accept that solar and wind turbines are always going to be parasitic.

          • at low latitude annual cycle can be overcome by over-dimensioning your PV array

            Good point Euan. 🙂

            You could probably make some estimates with this graph:

        • gweberbv says:


          how should the backup costs increase with increased penetration? The backup fleet will consume less fuel and will experience less wear and tear as renewable penetration increases.

          At very high penetration the backup costs normalized to the kWh procuded by the backup fleet might go through the roof – ok. But this number is not important.

          • robertok06 says:

            “how should the backup costs increase with increased penetration?”

            It doesn’t increase linearly with penetration but it does increase. There are already studies using available data that one can find.

          • Stuart Brown says:

            “The backup fleet will consume less fuel and will experience less wear and tear as renewable penetration increases.”

            But as we’ve seen in all the discussions about Ireland that’s exactly what doesn’t happen. CCGTs like to run at a constant speed ideally, and if they don’t they definitely experience ‘more wear and tear’ not less. That’s equally true for nuclear or coal powered steam turbines. If they use less fuel overall, they still use more per KWh generated canceling out some of the benefit of the renewables.

            You know this – it’s been said and proved here before.

            If we are only talking about ERoEI then we’re better off never making any solar or wind generation in the first place, according to the papers quoted in this post. If the objective is to reduce CO2, then that’s a different story, and you have to somehow show the worth of the CO2 not produced.

            It’s one of my problems with the concept – what’s more important? Money, efficiency, avoiding nuclear Armageddon, or CO2 reduction – and how do you compare them to choose? (I would choose the classical French route of loads of nuclear if anyone doubts it 🙂 )

          • The way it actually works is that as you increase wind capacity more and more wind gets curtailed and the backup gas plants have less and less work to do until at high levels of wind penetration both are operating at capacity factors of 10% or less. You also have far more installed capacity than you need (maybe 350GW to service a ~60GW peak demand.) The system, in short, is highly inefficient. More on this in

          • gweberbv says:


            in the discussion of the Irish situation I was explicitly asking for a balance of accounts for the FF fleet with reduced fuel costs and reduced running hours on the one side and increased ramping and reduced efficiency on the other side. But nobody was able to give an answer.

          • Stuart Brown says:

            GW – I’ve been struggling to answer you, and I hereby admit I’ve failed, sorry. I can’t find any figures on O&M for CCGT plants that would show they are seriously harmed by ramping up and down. Firstly the O&M costs are a small fraction (4%?) of the running (fuel) costs anyway and secondly they are somewhat similar to the jet engines that are constantly ramping up and down so that people can get off the planes!

            I started trying to dig into Tynagh, but although that halved its gas consumption between 2010 and 11, did that impact the profits? Did it hell, they made a mint on subsidy payments! I seem unable to find the electricity generated to match up with the Annual Enviromental Report that shows the gas consumed.

            Wil gave a better answer than I can –

            I know you felt this wasn’t a good example, but the more wind digs into the demand some of the time, but not all of the time, the closer it gets to what he’s saying, surely?

            Anyway, I’ve decided that having dug myself a hole, not being able to dig myself out, and no-one having rescued me, I will just say sorry for assuming I can contribute intelligently on a subject I am no expert in and stop doing so. This will be my last post, though I will continue to read with interest.

            All the best, Stuart

          • Greg Kaan says:

            An OCGT is exactly or almost exactly like a plane jet engine.

            A CCGT is not due to the steam turbine stage heated by waste heat recovery. Steam turbines are easily damaged if the temperature falls low enough for water droplets form so this secondary stage (which is what boosts the efficiency well beyond that of the OCGT) needs to be managed carefully in the context of the total heat output from the gas turbine(s).

            Also, a frame CCGT is considerably more solidly constructed than an OCGT as it is designed for extended running while the OCGT is designed for far shorter runs and the ability to ramp up and down quickly.

            Guenter is trying to obfuscate by asking for exact figures for net loss of income. The requirement for a capacity market to prevent the closure of the CCGT plants speaks enough for me and should be enough for any disinterested observer.l

          • gweberbv says:


            I fully understand that the owners/operators of CCGT plants (or any other power plant) are struggling to recover their costs, not even to say make a profit, when the running time of their plants is singificantly reduced below the design value. But this is not what I am interested in in the first place. A society has to pay for its energy infrastructure or it will deterioate. The channels of money are of secondary importance. Be it payments per kWh generated or per kW of installed capacity available.

            What in the end is interesting for Ireland as a society is how much they have to spend (money/energy/labour) for keeping the necessary CCGT plants available. It would be a travesty if the *total* amount of ressources allocated to the CCGT fleet would go up while their usage is reduced (as wind penetration increases). This would mean that society has to face rising payments both for renewables (=wind) AND for the FF fleet. But I doubt that this is the case.

            I would expect that the reduced usage of gas (which Ireland has to import) and the reduced wear and tear due to reduced running hours offset the increase in costs of more frequent ramping. The fact that the CCGTs need an additional payment as their traditional business model is no longer working, is just a detail on how society manages to channel the money to the places where it is needed (of course this is very important for the struggling owners).

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  29. Roberto,
    we effectively made and successfully operated the research prototypes since 2006 up to 2013 in order to fix and validate the requirements. Unfortunately nobody proposed a FIT to high wind exploitation in order to follow painlessly the natural learning curve of the new technology. It was quite demotivating to be obliged to sell energy at no more than €30/MWh in the wholesale market and in the meantime PV was early supported with more than 700 €/MWh (capex aid and FIT). I’ve asked several time to Italian gov the same PV help in order to enable the improvement up to auto-breeding even if limited to few years.
    Europe as Italy in this issue are violating the State Aid laws and are perpetuating a misunderstanding: the subsidies could not be a perpetual deployment support, subsidies must be intended only as an investment to matures the new energy technologies because energy have to support humans not vice-versa.

    • Beamspot says:

      I agree with you assumptions. In fact, my major concern is that subsidies, governments and all green dreamers, only support PV, while no other ideas are even questioned. Is not only that I don’t like to focus research only in electricity, but that it seems that only PV and Wind Turbines are allowed to do anything and the remaining has to be deprecated.

      The narrow view and myopic point of view of the research and efforts, as well as government grants are working against diversity and a broader solution portfolio that would help.

      In energy, like in economy, diversity is a key.

    • gweberbv says:


      did you ever tried to contact the likes of Elon Musk?

    • robertok06 says:

      Thanks for the info and the clarifications… in fact they confirm what I’ve been telling some italian guys on italian energy/climate blogs for years… that PV is an absolutely disastrous technology which has gone against the interest of decarbonizing the generation of electricity, if nothing because it has not allowed other competing technology, like yours, to get their chance of being tested.
      Italian green blogs are happy enough writing useless articles which show how good the policy in italy has been, which has allowed the country to have the highest penetration of PV on the electricity production of any country on the planet, almost 8%.
      At the same time it is siphoning out of the wallets of the italians 6,7 billions Euros/year for 20 years… for a meager 24 TWh/y… intermittent.

      • World record of PV in Italy…
        Perhaps there is a link with the followings
        Italy ranks among the highest CO2 emitters
        Italy ranks first in number of economically inactive population
        Italy has lowest proportion of citizens with higher education
        Italy has more poor than any EU member … living in “serious material privation”

        • robertok06 says:

          @massimo ippolito

          “World record of PV in Italy…”

          Yes, Italy is demonstrably the country in the world which has the biggest coverage of its electrical consumption via PV.

          I am no fan at all of PV (I call it “una tecnologia farlocca”)… but I certainly am a fan of data-based reasoning… so, please, believe me, italy is no.1 in that respect. Which is sad, very sad, as it obliges its citizens to spend 6,7 billion Euro/year just to get 23.5 TWh, intermittent and highly seasonal. A total disaster, of course.

          On the remainder of your statements, with me “tu sfondi una porta aperta”… you rush into an open door (???), I’m italian like you, and have always been very vocal of the inadeguacy of the italian educational system in terms of scientific literacy, not to mention simply writing proper italian text for tv newscasts… 🙂


  30. Stuart Ellison says:

    ERoEI is an important concept but it is not possible to calculate it for any isolated power generation technology.

    I believe ERoEI can only be calculated for our civilisation as a single entity (a closed system).

    Because to calculate the ERoEI for solar you need to use prices, manufacturing methods, by-products, labour costs, etc that are specific to an economy dominated by fossil fuels. The presence of fossil fuels in the model pushes down the prices of everything and reduces the energy needed to build a wind turbine (more steel mills are viable, more roads are maintained, nearer mines are viable when the economy includes fossil fuels).

    If you wanted to know the true ERoEI for solar you would need to model an entire economy powered only by solar. If you wanted to know the true ERoEI for oil you would need to model an entire economy powered only by oil. I don’t think this is possible.

    Therefore I find it erroneous to compare the ERoEI of one power technology to another in any quantitative way. It’s possible to say some are better or worse, but I don’t think it can be quantified in any meaningful way.

    My second point is a much simpler concept of why ERoEI is important.

    Basically if the world had an ERoEI of 20 then the energy industry would represent 5% of the world economy. For every 1 joule invested in energy there would be 19 joules surplus for the rest of the economy.

    If the world has an ERoEI of 10 then the energy industry would represent 10% of the world economy.

    If the ERoEI was 5 then the energy industry would represent 20% of the world economy.

    But in an economy we do not make decisions based on the lowest joules, our decisions are based on lowest price. That’s why people in London wear T shirts made in Taiwan, we eat lamb from New Zealand. We think nothing of jumping in the car and moving 2 tonnes of steel over 10 miles of paved road in order to purchase 1 pint of milk. But all of these crazy things we do when aggregated give us the most effective and efficient way to exploit our resources, it’s the theory of free market capitalism. Capitalism looks crazy at the micro level (driving for milk) but at the macro level free pricing has proven to be by far the most effective way to organise the world.

    At the macro level one dollar should by the same amount of energy no matter if that energy is invested in the industry or exported as surplus. This fungibility of money with energy activities and all other economic activities means that at the macro level money is the best medium of comparison.

    From a quick search it seems that the world spends around $6-7 trillion on energy annually and global GDP is around the $80 trillion mark.

    Therefore it seems the ERoEI for the world is somewhere around 11 to 13.

    It should be possible to calculate the historical ERoEI in this way and to see if it peaked around the mid 1970’s which is what I would expect to see.

    As the global ERoEI decelerates it means energy will become more expensive as humanity will have to allocate a greater percentage of our resources to gathering energy.

    Also the maximum size of our physical economy is limited by ERoEI. Some economic activities that are viable at an ERoEI of 30 may not be viable when our ERoEI is below 10. Because our value chains are so long and complex it’s extremely difficult to model which parts of the economy would be most sensitive and how the loss of one activity might impact prices and the viability of other activities.

    This is why it’s not possible to stop using fossil fuels. The choice we face is do we want global warming or do we want a much smaller economy where 20-30% of global GDP is dedicated to the energy sector. Basically the rest of the economy will shrink drastically whilst the energy sector will completely take over.

    Global warming is real but the medicine is worse than the disease. Still nobody understands the reflexivity of green policy, you cannot simply replace 1kWh with another 1kWh even if they are the same price today. Because the price will change dramatically when the macro energy mix changes because the ERoEI is different. That’s why it is impossible to accelerate adoption beyond the rate of adoption determined by free market pricing.

    What the world really needs to do is to adapt, shunning fossil fuels to avoid emissions is the least sustainable option of all. But I am rather apathetic about it all, I now believe the world has to go down that road before anyone will believe where it leads.

    As I have said previously a better policy is to tax emissions and to use the tax revenue to purchase climate change insurance. The insurance will be priced according to the risk appetite and the tax rate can float to meet the premium. This is self regulating and does not destroy the economy. It also motivates people to find mitigating actions as governments could get cheaper premiums by building sea defences, storm drains, etc.

    Current policy is archaic and pathetic. It just creates an even bigger problem that will make millions/billions of people to desolate.

    • Thinkstoomuch says:

      Carbon Tax is a wonderful way to get rid of industry without actually improving the CO2 emissions. Unless you also have a world government … Good luck with that. Unless of course you are going to impose carbon tariff’s … Talk about King Canute. I can’t even find a bucket.

      As a poor example compare Texas and California both of which nominally operate under a single nation’s laws. I am just going to compare state renewable generation to both Generation and Sales of electricity. Adding trend lines just to show which one is doing more.

      Notice which one has improved renewable (more CO2 Efficient) generation and which one has seemed to have gotten rid of its generation in comparison to sales. Did an awesome job getting more renewable energy though.

      So sure lets impose a carbon tax and off shore or move more businesses. The UK doesn’t need those steel mills anyway. Germany doesn’t need those PV panel plants. And so forth.

      Thank you but no,

      • Stuart Ellison says:

        Your chart just shows that in California (more wind than solar) the wind sometimes blows in the night, whereas in Texas (more solar than wind) the sun shines in the daytime.

        Meanwhile sensible industrial multinationals such as BP are proposing a carbon tax as a means of managing the energy mix.

        • Thinkstoomuch says:

          Last point as we left ERoEI way behind.

          After the report got to the point of saying it was next to impossible to implement I stopped reading. That is the point!

          Not to mention the fact that it doesn’t seem to be the way to go. Texas in 2001 produced next to none renewable (by the way TX produces next to no solar, almost all wind.) In 2015 they produced 47,159 thousand MWH.

          CA in 2001 generated 21630 thousand MWH renewable they boosted it up to 46, 498 thousand MWH in 2015.

          Yet despite CA enacting a carbon tax, having a running start on biomass and geothermal. Texas produced more renewable electricity in 2015. CA just exports their requirement. “CO2 not produced here no siree Bob.” Thus not enough new thermal plants in CA.

          So the Carbon Tax makes all kinds of sense in the “ideal world” it makes NO sense in a planetary sense. All you do is export the carbon to someplace else where there economy grows and their people live better. Not to mention cheaper.

          As an aside now that PV has gotten much cheaper and Texas has those new high voltage lines leading to great solar areas the no solar will probably change. Though it is subsidized to high heaven in both places. Which is where economics and ERoEI part company.

          Have fun,

  31. Stuart Ellison says:

    Your chart just shows that in California (more wind than solar) the wind sometimes blows in the night, whereas in Texas (more solar than wind) the sun shines in the daytime.

    Meanwhile sensible industrial multinationals such as BP are proposing a carbon tax as a means of managing the energy mix.

  32. Pedro Prieto says:

    Answer to Jose A.

    Are these European stress tests as reliable as the Japanese ones that did not foresee that electric supply from outside the nuclear plant itself and the emergency generators could fail simultaneously? So difficult and unthinkable was this scenario for those experts to keep them being credible?

    I like over every other consideration that the maximum altitude of the river avalanche in case of rupturing the dam will reach 48.11 meters with TWO DECIMALS!!! so that we can sleep all relaxed, because it is about two meters (without decimals this time) below criticality.

    Both Europeans and the US said about one thousand times, when Chernobyl blew up, that this was only something that could happen to those bloody commies or lousy Russians, not to the mighty European or USA technology. I also remember that they also said that in the theoretical (10 a la minus many) case of melting of a mighty Western reactor, we could be safe because our technology will keep the corium in place within the containment vessel, not like the lousy commies. I would vote for these ‘experts’ to volunteer first to clean the debris of Fukushima, if they can find them or approach the reactors. And not to live until the last milligram of radioactive waste has been completely expedited and neutralized They deserve it, don’t they?

    So, shal we still stick to the stress tests carried out by people thinking like that?


    Ascó nuclear power plant is 50 meter on the sea level and 20 meters on the river level, Mequinenza dam holding up to 1,530 Hm3 of water is 90 meters over these level upstream, even it is 50 Km in straight line and about 70 in the river course.

    Side note:

    Vandellos I is a reactor of a nuclear plant with originally two, close to the ones of ASCO but refrigerated by the sea, now converted into a concrete pyramid for nobody knows how long, due to a fire in the turbines area (class 3 accident) that forced the shut down. Another successful milestone in the accident probability of ten a la minus many of the nuclear industry that was originally promised to generate energy that will be “to cheap to meter”

    • robertok06 says:

      @pedro prieto
      “that this was only something that could happen to those bloody commies or lousy Russians, not to the mighty European or USA technology.”

      … and they were right, in fact in Fukushima there has been no graphite fire burning in open air for days, melting the fuel rods and disseminating plutonium and strontium all over the area and Europe.
      Your ignorance of nuclear technology is becoming more and more clear, at every message you post, Pedro. Why expose yourself like this? It’s a pity.


    • robertok06 says:

      @pedro prieto

      “Vandellos I is a reactor of a nuclear plan”

      Vandellos I was, guess what?, a graphite-moderated reactor (Chernobyl had graphite as moderator too).
      The vast majority of western reactors are light-water reactors of the BWR or PWR type, which are completely different, no graphite as moderator, no positive-void coefficient like the RBMK in Chernobyl…
      The fire at Vandellos started in the turbine area, which is NOT a nuclear component, could happen in any power station… look at this atypical one for instance: 🙂

    • sod says:

      I would prefer to continue the discussion about ERoEI. Nuclear is a sideshow (and i am actually pretty sure that nuclear will struggle to compete with renewables under EroEI similar conditions).

      But i would like to support some of Pedros points. I was really shocked when i read the report about German reactors in 2011. Floods would turn some of them into islands and for some reasons people thought that relevant entrances should be build just centimeters above the relevant 10000 years max. flood level. Several failed to achieve level 1 out of 3.

      • Pedro Prieto says:

        I would too apreciate to focus on EROI, but it seems there is a lot of aggressivity when a critic to nuclear energy appears here. I believe it is clear that I have no Interests whatsoever in nuclear, fossil or Renewable energies, except that I own a 50 kW plant, manage a 1 MW plant and have helped to build, and have designed and audited about 30 MW in solar PV plants, which did not preclude me from concluding with a low EROIext for 4 GW solar PV systems in The sunniest country of Europe.

        My last comments on the nuclear issues: the too cheap to meter was proclaimed by Lewis Strauss on September 1954, while being Chairman of the US Atomic Energy Commission. Even he did not specificaly mentioned to what type of electricity he was referring to, I do not think one has to be a genious to discover it. Be that the only existing one, fission, 61 years after, we can conclude he was not the type of expert to trust if receiving from him some stress tests. If he was referring to fusion, even worst, unless we consider that, in effect, 0 MWh generated to date do not deserve any meter. Last but not least: that Fukushima is a nightmare does not need further clarification, nor this precludes coal, oil, or gas to be also nightmares; not even fossils to be still totally underpinning and making possible and feasible the very existence of nuclear energy. That’s all, folks.

        • robertok06 says:

          @pedro prieto

          “I would too apreciate to focus on EROI, but it seems there is a lot of aggressivity when a critic to nuclear energy appears here. I believe it is clear that I have no Interests whatsoever in nuclear, fossil or Renewable energies, ”

          1) The “aggressive one” is you, Pedro.
          2) You are not “critic” of nuclear technology in a scientific way, as a scientist… you have only reported anecdotes, urban legends, and so on, about nuclear. Not a single number, nothing.
          3) It was you who pulled out of nothing this nuclear thing… if you didn’t want to discuss it you could have skipped it.
          4) ERoI of the highest power density source of electricity existing on this planet (by orders of magnitude on the others) will forcefully and naturally always have a higher ERoEI as compared to the competition. You can add triple 3m-wide containment, quadruple and redundant emergengy diesels, and so on… E=mc2 will ALWAYS put to rest all this, and anything else you or others may claim. It’s simple physics.

        • robertok06 says:

          @pedro prieto:

          “My last comments on the nuclear issues: the too cheap to meter was proclaimed by Lewis Strauss on September 1954, while being Chairman of the US Atomic Energy Commission. Even he did not specificaly mentioned to what type of electricity he was referring to, I do not think one has to be a genious to discover it.”

          For the record and not for propaganda:

          “It is often (understandably but erroneously) assumed that Strauss’ prediction was a reference to conventional uranium fission nuclear reactors. Indeed, only ten days prior to his “Too Cheap To Meter” speech, Strauss was present for the groundbreaking of the Shippingport Atomic Power Station where he predicted that, “industry would have electrical power from atomic furnaces in five to fifteen years.”
          However, Strauss was actually referring to hydrogen fusion power and Project Sherwood, which was conducting secret research on developing practical fusion power plants.”

          You are right on the “not need to be a genius”, in fact one simply needs to get a rational thinking and look for proper documentation.


        • robertok06 says:

          @pedro prieto
          “If he was referring to fusion, even worst, unless we consider that, in effect, 0 MWh generated to date do not deserve any meter. ”

          Well, if you consider that the total amount spent on it corresponds to maybe 2 years of “incentives” to PV in Germany… I’d say it is normal.

          Anyway, 0 MWh is what all PV installations generate at night, which is by definition at least 50% of the time… not much better.

        • robertok06 says:

          @pedro prieto

          “that Fukushima is a nightmare does not need further clarification, ”

          “Nightmare” in what sense?

          1) Economically? Not true, easy to demonstrate;

          2) Environmentally? Not true, easy to demostrate;

          3) Public health? Not true, easy to demonstrate… you just type this…

          … and look for literally hundreds of peer-reviewed papers in epidemiology and other related disciplines. Find one which, in your opinion, would show a disaster in the making… and motivate it.

          For instance this one…

          … on the nightmarishly effects on japaneses’ thyroid glands… widely recognized as the worst effect on human health.


      • robertok06 says:


        “Nuclear is a sideshow (and i am actually pretty sure that nuclear will struggle to compete with renewables under EroEI similar conditions).”

        Virtual reality: “nuclear is a sideshow”


        830 TWh/year of the cleanest electricity which the human race can make… and it is like this since ~ 30 years (was higher, to tell the truth, but the german Energiewende geniuses decided it was too good to be true, and in addition was putting their useless intermittent alternatives in bad light).. and it will go on for 15-20 years.
        830 TWh/year, 27% of all the electricity consumed by almost 600 million Europeans… “a side show”!… c’mon man!… you’ve got to be kidding me/us, right? It’s euan mearns’ blog here, not some “green” blog, most of the readers/posters here are not monkeys on trees, have an functioning brain. Please?

        Question: do you really, but think carefully before replying, to you really think that all this would have been possible with an ERoEI of 5?


        • sod says:

          “Question: do you really, but think carefully before replying, to you really think that all this would have been possible with an ERoEI of 5?”

          I actually do not know what you mean with “all of this”, but i do actually think that it is possible.

          On a much more important and directly influencial ratio, we saw similar numbers.

          Typical yield ratio in medieval times was between 1:3 and 1:5.

          so yes, a society can grow on such a ratio (obviously).

          In my personal perspective, i do not accept any ERoEI number which ignores negative environmental impacts.We do no longer sit in a stone age cave, and need (high ERoEI) fire burning to survive the winter (not caring about our life being shortened by the smoke we breath).

          Today, most people would happily change from ERoEI 7 (and their kid getting asthma) to ERoEI 4 without the illness.

          a final short response on nuclear (i will not comment on it any further under this topic): A ERoEI calculation has to include waste treatment. And it has to include waste treatment based on technology readily available today in the specific place that is in need of it (we just had a long ERoEI discussion about solar in Swiss and Germany, actually being based on slightly outdated product costs).
          Under these condition, nuclear waste treatment in Germany is causing infinite costs, leaving zero ERoEI.

          • robertok06 says:


            “In my personal perspective, i do not accept any ERoEI number which ignores negative environmental impacts”

            You means “environmental impacts” like (directly) CO2 emissions, particulate, heavy metals, arsenic, SO2, NOx, ozone precursors, etc…?… and (indirectly) their effects on human health?… not to mention the occupation of land?… if this is what your personal perspective needs than I have something for you:


            … and…


            … and…


            … and…


            Now you have lots of reading to do, sod… do it and then come back and we can discuss it further, if you like.
            But, beware!… “personal perspectives” in science and technology matter and can make a difference only if they are backed by solid data, models, and lots of rational thinking based on known physical laws. The rest, I’m afraid, is only good for philosophy or personal development “feel good” blogs.

            Have fun.

          • robertok06 says:


            “A ERoEI calculation has to include waste treatment. And it has to include waste treatment based on technology readily available today in the specific place that is in need of it (we just had a long ERoEI discussion about solar in Swiss and Germany, actually being based on slightly outdated product costs).

            Removing, storing for a decade or so (to cool down), cutting in pieces, dissolving in acids, isotopically separating the “good and the bad” (Pu for MOX, depleted uranium for future enrichment) is A VERY WELL KNOWN subject, sod!… no need to re-invent the wheel, it is being done since decades, and has VERY CLEAR costs, both capital, human, health and most of all ENERGETIC costs, which is what matters for ERoEI.
            In light of this, your statement above merits nothing more than this…


            “Under these condition, nuclear waste treatment in Germany is causing infinite costs, leaving zero ERoEI.”

            Why? Motivate it NUMERICALLY, please, show me/us that there is an infinite amount of energy which is and/or will be necessarily needed to treat (whatever this term may mean) the nuclear waste.
            I really don’t understand, believe me: storing waste fuel rods in a water pools? Even if it’s going to be for 50 years it won’t matter much, energetically. Putting the said fuel rods in CASTORs and burying them?… iinfinite energetic costs?… please explain, WITH NUMBERS or DATA.

          • Greg Kaan says:

            I actually do not know what you mean with “all of this”

            Roberto means all of what we are – from computers we type on, the internet and servers that present the pages to the clothes we wear, the food we eat, the housing we live in, the transportation we take…

            In short, our civilization and our very existence was developed and depends on high EROEI. The low EROEI that you postulate as being preferable in some circumstances is a statement of ignorance – advanced technology requires high EROEI to sustain it. Medieval yields leads to deterioration and breakdowns as demonstrated by Venezuela of late.

            Roberto’s reply to your statements on nuclear energy are better than anything I can come up with – you really need to learn something about the nuclear industry so you can make valid criticisms rather than purely emotive ones.

    • Jose A. says:

      The 48.11 m figure it’s from a very conservative, highly improbable and unfavourable worst case scenario, with the dams full and intense local rainfall. You can think on something worst? go ahead, make the calculations and inform the regulator. If not stop hand waving.

      And Vandellos I is scheduled to start final decommisoning in 2028 after a latency period for the radioactivity to decay. This is a common approach on graphite reactors.

  33. robertok06 says:

    @pedro prieto
    “nuclear industry that was originally promised to generate energy that will be “to cheap to meter””

    It’s incredible!… you are not able to write one-thing-one correctly about nuclear energy, Pedro!… not even this urban legend. The sentence you’ve reported did not deal with nuclear energy via fission reactors, it was said about thermonuclear fusion.

    Try better.

    • mark4asp says:

      Given fusion reactors did not exist in 60 years ago when the remark was made “too cheap to meter” is really just blue skies thinking. Otherwise known as hypotheses gone haywire. A modern phrase for “hypotheses gone haywire” is “renewable energy”, especially energy storage.

  34. robertok06 says:

    @pedro prieto

    “(class 3 accident)”

    A class 3 accident on the INES scale is close to nothing… here is an example of another accident of the same magnitude:

    A piece of a finger amputated to one person.

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  38. Tim Crome says:

    How does concentrated solar power rate, for instance:

    I wouldn’t expect it to do too well!

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