Electricity supply, electricity demand and 100% renewables

The difficulties of meeting cyclic demand for electricity with intermittent renewable generation have been addressed in a number of previous posts, but with wind, solar etc. usually considered separately. Here we will examine a hypothetical scenario involving a diversified mix of renewable energy sources that supplies 100% of electricity consumption in unspecified future year 20XX in Atlantis, an imaginary island country that is very much like, but not exactly the same as, the UK.

Details of the 20XX generation mix in Atlantis are summarized in the following Table.

This mix generates the same amount of electricity as the UK, and we will assume Atlantis too, generated from dominantly thermal sources in 2013 (380 vs. 374 TWh). Dispatchable capacity (biomass and hydro) provides 35% of total generation and non-dispatchable capacity (wind, solar, tidal) the remaining 65%.

And because Atlantis is very much like UK the scenario assumes that demand in Atlantis in 20XX will be the same as it was in the UK in 2013, so the 2013 Gridwatch data for the UK are used to define 20XX Atlantis demand. Atlantis generation in 20XX was estimated using the following simplifying assumptions:

Wind generation is the same as UK generation in 2013 but scaled up in proportion to the increase in output.

Biomass is assumed to provide constant baseload generation, although biomass plants would probably be able to operate in semi-load-following mode in the same way as UK coal plants do at present.

Hydro generation is used in either baseload or load-following mode with a maximum output of 13GW and no ramping restrictions. (Hydro supplying 15% of the UK’s energy is of course a pipe dream, but it’s not a problem in Atlantis.)

Solar generation is estimated using total solar radiation values for latitude 53 north on the 15th day of the month and is kept constant through the month.

Tidal power generation assumes tidal generators spaced around the coast of Atlantis in such a fashion as to cancel out diurnal and semidiurnal tidal fluctuations. (Tide times around the coast of UK vary enough to allow this to be done). Generation is estimated by straight-lining between a spring tide maximum of 5GW and a neap tide minimum of 1GW in accordance with the 28-day lunar cycle.

Imports and exports are not taken into account.

Cost is no object.

Generation from all sources was estimated at ~5 minute intervals to match the Gridwatch reading interval.

To keep the post to a manageable length only the power balances in the months of July and January 20XX, which are assumed to be “typical” summer and winter months both in the UK and Atlantis, are considered.

Figure 1 shows total renewables generation by source for July 20XX, with wind generation factored from the July 2013 Gridwatch data, tidal generation estimated assuming peak spring tides on July 1 and generation from the other sources estimated using the assumptions listed earlier. Wind generation often shows diurnal variations, but these are only occasionally in antiphase with solar generation. At other times they are in phase with solar or phase-shifted relative to solar. The overall impact is no net smoothing effect (R squared wind vs. solar = 0.00):

Figure 1: Generation by source, July 20XX, 100% renewables

Figure 2 shows the Figure 1 data on a stacked bar chart. Hydro appears as a flat line because no attempt has been made to match generation to load:

Figure 2: Total generation by source, July 20XX, 100% renewables

Figure 3 compares total generation with the July 20XX demand (load) curve, which is assumed to be the same as the July 2013 demand curve:

Figure 3: Supply & demand, July 20XX, 100% renewables

Demand and total generation tend to be synchronized because July solar output is closely correlated with the daily load curve. Total generation from the 100% renewables system is also higher than demand (~24,000 vs. ~22,000 GWh). As would be expected, however, there are numerous occasions when the system generates more or less power than is needed, resulting in power surpluses or deficits. We can easily eliminate the surpluses by curtailing excess wind generation, but how do we handle the deficits?

The first approach is to ramp up hydro to its assumed maximum output of 13GW during deficits and ramp it down during surpluses. This gives the result shown in Figure 4. The worst of the deficits are gone but we are still left with a number exceeding 5MW, all occurring between 6 pm and midnight:

Figure 4: Supply & demand, July 20XX, 100% renewables, hydro follows load, surplus wind curtailed

The Figure 5 bar chart shows the Figure 4 generation mix. Note that hydro ramping rates would be lower if biomass also contributed to load-following:

Figure 5: Total generation, July 20XX, 100% renewables, hydro follows load, surplus wind curtailed

How to get rid of the residual deficits in Figure 4? One solution would be demand management, which in this case would be facilitated by the fact that the deficits all occur at the same time of day. However, it would probably be easier simply to increase installed capacity until the deficits disappear. But which generation source should get the added capacity? Here’s a summary of how much extra installed capacity would be needed for each (numbers approximate):

Solar: No amount of added capacity will eliminate the deficits because the sun has set.
Wind: 140 GW
Tidal: 60 GW
Biomass: 10 GW
Hydro: 7 GW

Hydro wins, but there are always practical limits on how much additional hydro capacity can be installed, and we will assume that 13GW is pushing them on Atlantis. Assuming no fuel supply constraints there are no such limits on biomass, which therefore emerges as the logical choice. So with 10GW more biomass, which would represent only a comparatively minor cost increment, demand in July 20XX could be met 100% of the time.

Now let’s turn to January 20XX.

Figure 6 shows total generation by source for the month, with wind generation again factored from the January 2013 Gridwatch data, tidal generation estimated with peak spring tides on January 16 (counting lunar cycles back from July 1) and generation from other sources estimated as before. Wind generation more than doubles over July (from 6,600 to 15,300 GWh; the wind in Atlantis blows harder in winter, as it does in UK) but solar generation is down by a factor of more than four (from 4,800 to 1,100 GWh; the factor would be larger if increased winter cloudiness were allowed for):

Figure 6: Generation by source, January 20XX, 100% renewables

Figure 7 shows the Figure 6 data on a stacked bar chart. Solar generation has faded into insignificance:

Figure 7: Total generation by source, January 20XX, 100% renewables

And although monthly generation is equal to monthly demand (at ~29,000 GWh) the 65% non-dispatchable capacity in the generation mix again produces too much electricity when the wind is blowing and too little when it isn’t (Figure 8). Because of the minimal solar output there is also no “natural” synchronization of supply and demand, such as there was in July:

Figure 8: Supply & demand, January 20XX, 100% renewables

And the load-following hydro capacity can’t handle the resulting deficits. They are just too large:

Figure 9: Supply & demand, January 20XX, 100% renewables, hydro follows load, surplus wind curtailed

Figure 10 shows the adjusted generation mix in bar chart form. (Note that the demand shortfalls occur even when hydro runs at 13 GW maximum capacity for days on end. Whether hydro could sustain this level of output depends on how much of the 13GW is “conventional” hydro and how much pumped, but if it were all pumped more than a terawatt-hour of storage would be needed):

Figure 10: Total generation, January 20XX, 100% renewables, hydro follows load, surplus wind curtailed

Deficits of this size will not easily succumb to demand management, so we are back to considering how much extra capacity is needed to make them disappear. Here’s a summary of requirements by generation source (numbers again approximate):

Solar: No amount of added capacity will eliminate the deficits because the sun has set.
Wind: ~1,000 GW
Tidal: 90 GW
Biomass: 30 GW
Hydro: 25 GW

Adding another 25 GW of hydro is out, so the choice would be to add another 30 GW of biomass, thereby increasing total installed biomass capacity from 11 to 41 GW. This would allow the system to meet January 20XX demand, and since no other month is as problematic as January to meet demand through the rest of the year as well.

There is, however, no safety margin in this number. An additional ~10 GW would be needed to cover the worst-case scenario, which occurs when there is a coincidence of cold winter weather, high peak demand, little or no wind, darkness and neap tides. But after adding this extra 10 GW we have a generation mix containing 51 GW of biomass and 13GW of hydro. Assuming equivalence with UK this would be about equal to the capacity of the coal, nuclear and CCGT plants currently operating in Atlantis, and it performs the same function – supplying dispatchable baseload and load-following generation.

These results are of course subject to uncertainty, but what they basically tell us is this. Atlantis can install a 100% renewables generating system, but it will be capable of meeting demand only if the presently-existing thermal dispatchable generation is replaced kilowatt-for-kilowatt by renewable dispatchable generation.

As for non-dispatchable capacity, with adequate dispatchable generation it can be added at will. The problem is that the wind has a habit of blowing when we don’t need it to and not blowing when we do. Because of this up to 50% of the wind energy generated in July 20XX and up to 80% of the wind energy generated in January 20XX gets “spilt”, raising the question of why Atlantis installed so much surplus wind capacity in the first place.

That concludes the analysis of 100% renewables generation in the mythical country of Atlantis, where 100% renewables generation is actually less problematic than it would be in the UK because of the 15% hydro contribution, something the UK is unlikely ever to achieve. For those interested in a UK-specific analysis a study from the University of Glasgow identifies the same problems without coming up with any solutions:

Across the whole year (2025), there are large periods of electricity deficit during winter and large periods of electricity surplus during summer. The maximum supply deficit (electricity demand minus electricity production) present across the year in the model is 53.8GW, which is almost equal to the demand at that time (54.5GW). This occurs on January 21st at 17:00, which is also the time of maximum demand that day. By 17:00 on this day, the Sun had gone below the horizon and so solar production was nil. Additionally, wind production also happened to be very low at this time. This is an example of maximum demand coinciding with minimum production, which is one of the major problems that will challenge future grid designs.

While another from the Journal of Power Sources: indicates how 100% renewables generation might be made to work in the Eastern US, although after a detailed reading I’m not sure it would.  (H/T Dennis Coyne for the link):

Our model evaluated over 28 billion combinations of renewables and storage, each tested over 35,040h (four years) of load and weather data. We find that the least cost solutions yield seemingly-excessive generation capacity—at times, almost three times the electricity needed to meet electrical load. This is because diverse renewable generation and the excess capacity together meet electric load with less storage, lowering total system cost. At 2030 technology costs and with excess electricity displacing natural gas, we find that the electric system can be powered 90%–99.9% of hours entirely on renewable electricity, at costs comparable to today’s—but only if we optimize the mix of generation and storage technologies.

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51 Responses to Electricity supply, electricity demand and 100% renewables

  1. Willem Post says:


    Great imagination you have.

    A demand management solution, found by animals millions of years ago, is to hibernate or, for some, tough it out, or, for many, migrate south in the winter, say Morocco or the Sahara Desert. Plants cannot move, they just “go dormant”, i.e., hibernate.

  2. Joe Public says:

    Thank you Roger. A very thought-provoking article.

    Three points:

    1. “Deficits of this size will not easily succumb to demand management…..” Neither will the people.

    2. “There is, however, no safety margin in this number. An additional ~10 GW would be needed to cover the worst-case scenario…” One aspect of this is fuel storage for the BioMass plant. Here, it’s not so much an extremely low temperature peak demand, more a prolonged spell of ‘normal’ low temperatures. ie the circumstance which exhausts the line-pack + storage of our existing Nat Gas transmission system, and so triggers interruption of Interuptibles.

    3. In the UK, subsidies are flung at rent-a-roof domestic solar pv generators. IMHO Consideration should be given to scrapping those subsidies, and instead encouraging solar domestic hot-water tempering/heating. Every house needs hot water, and converting solar to thermal rather than electric, helps provide useful storage. Heck, the water storage cylinder can help with the space Htg as as thermal-store.

    Presumably Atlantis will not be wholly dependent upon ‘leccy (a la MacKay’s vision), and still have Nat Gas, LPG & oil for space heating and industrial process use?

  3. refurbn16 says:

    I like this analysis although I think that demand management has great potential and will be easier and cheaper than increasing capacity.

    Now what I would be most interested in is if you were to extend the thought experiment so that you’re not analysing a 100% renewables system but a nearly 100% renewables system with fossil fuel back up. Say there was still 30GW of dispatchable gas plant available in the mix. If that covered the deficits would Atlantis end up with an 80% renewable, 90% renewable or 95% renewable system? What would be the ghg intensity of the electricity?

    Personally I think a 100% renewable system is unnecessary when we could get most of the way there with some backup (as well as full exploitation of demand management) to cover the shortfalls. I just don’t know how far ‘most of they way’ is but it might be relatively straightforward to extend your analysis?

    • refurbn:

      Now what I would be most interested in is if you were to extend the thought experiment so that you’re not analysing a 100% renewables system but a nearly 100% renewables system with fossil fuel back up

      What the analysis shows is that you can have as much non-dispatchable renewable energy as you like so long as you back it up with enough dispatchable generation to cover demand when the sun doesn’t shine and the wind doesn’t blow. To get 100% renewables I have had to look to biomass to provide this dispatchable generation, but if emissions reduction is the goal nuclear would make a lot more sense.

      As to how far we can go with renewables, I did some work back in February from which I concluded (again) that you can add wind capacity to your heart’s content provided you have FF backup, but the system gets progressively more inefficient and less economic the more you add:


      The Journal of Power Sources article balances load with a lot of “grid integrated vehicle” storage, where people charge their EV batteries when there’s lots of renewable energy and discharge them back into the grid when there isn’t. This is arguably the most promising form of demand management, and it would be good if it could be made to work in practice. Whether it ever could, however, is questionable.

      • Leo Smith says:

        Do the sums. If every household had an electric car with a 50Kwh battery, it wouldn’t last two days let alone two weeks of capacity shortfall. I make it 41GW days. +-

        And the costs are…non trivial. Let’s say that instead of that £50,000 such a battery costs today it was £5000.

        20m households each investing £5,000 is £100bn.

        Even at silly current nuclear prices, £100bn will buy enough nuclear power to fully cover the UK baseload. 800 gigawatt years.

        I admit I haven’t gone as far as you have in analysing the case for renewable UK because I came up with silly numbers like that, and stopped. My scenario is full 100% fossil free, no fossil at all, anywhere not even for transport, and it looks at nearly all the issues I could think of, based on what I honestly believe is the only sane way forward: Massive investment into serious nuclear power and none whatsoever into ‘renewables’ at all. Simply because on a cost benefit basis, they cannot match the benefit to cost ratio of nuclear.

        There is, in short nothing renewables give you worth having that nuclear doesn’t do better, and cheaper.

        You may not be in love with nuclear – heck who is? But if you want a post modern technology based industrial and post industrial society to support 70m+ people on these islands, there ain’t no other way.

        Sane policy consists in following all the alternatives only far enough to eliminate them as a viable alternative to whatever is better and cheaper. We dont have horse and carts AND vans on the roads today. Diversity for its own sake is plain stupid. We have vans, because horses and carts simply cannot compete on cost. Our diversity is having LOTS of vans and trucks and roads, not in having horses as well.

        Nuclear power is simply better than renewable can ever be. Let alone with bolt on storage, and grid upgrades to handle peak charging flows.

        The challenge, once you accept that, is not to work out how to keep adding cost and complexity to renewables to make them work, but how to actually run a nation of 70m people off a pretty much ‘all nuclear’ grid, with no access to fossil fuels at all. Which may be the case in 2050 or later. And how to get nuclear costs down to the sorts of level they were in the 1970s before everyone was deliberately made super scared of what is, on paper, and in fact, the safest power generation technology man has ever invented.

        Note: Once you accept ANY nuclear power, there is no rational reason to not have as much of it as possible, and no renewable energy at all. DECCs crazy scenarios of lots of wind AND lots of nuclear is about as sane as having sails on a nuclear submarine. It’s political window dressing. The reality is there is nothing wind solar or tidal can do by way of actual reduction in fossil fuel and in terms of generating reliable electricity, that nuclear cannot do more reliably and cheaper.

        That was the motivation behind this scribbling, which I hope is of some interest.


        It assumes as its starting point that we have an all electric society, with (almost) no fossil fuels. It could apply to a renewable/storage one, but the costs are plain silly.

        It shows what we can easily do, and it shows what we cannot easily do.

        And that last one – what we cannot easily do – boils down to off-grid power, especially mechanical power. Its not an insoluble problem, but it comes with a price tag.

  4. Euan Mearns says:

    Its important to point out that in the real UK we have 1.5 GW of hydro that runs on a load factor closer to 15% (not 50%). Countries with hydro endowments of the scale modelled by Roger here are few and far between and those countries are indeed lucky.

    I would also raise concern about the scale of bio-mass burning. I asked Roger how much was needed and where it would come from? And he told me to go work that out for myself 🙁

    The stage I’m at with my on-going examination of the C cycle is that I believe virtually all CO2 emissions that are removed from the atmosphere goes via photosynthesis – trees on land and phytoplankton in the oceans. Burning trees for electricity is absolutely the last thing we should be doing. It adds CO2 and destroys a part of the sink – its crazy if your objective is to reduce atmospheric CO2.

    • Willem Post says:

      The average CF of biomass is 0.70, probably the best the UK can hope for.

      My better solution is to reduce the population to about 1 billion, the same it was in 1800. The world gross product would shrink in proportion, as would manmade CO2 emissions.

      It is not just the world population increase that is doing it to the world, it is the GWP/capita, AND the increased energy consumption/capita, AND the increase in the efficient use of that energy.

      In 1800, the Gross World Product, GWP, was $175.24 billion; population 1.0 billion.
      In 2012, the GWP was $71,830 billion, 407 times greater; population 7.0 billion.

      GWP/capita in 2012 = 407/7 = 58 times greater than in 1800

      In 1800, world per capita energy consumption was 20 GJ. In 2010, 80 GJ

      With 4 times the energy use per capita, 58 times the GWP/capita is achieved, i.e., energy/capita is used about 14.5 times* more effectively than in 1800.

      GWP multiplier from 1800 to 2010 = 4 x 7 x 14.5 = 407; an indication of environmental impact.

      NOTE: The wildlife animal population decreased 50% from 1970 to 2014, while the human population and GDP/capita, and CO2/capita increased!!

      * steam engines were 3% efficient, modern CCGTs are 60% efficient; Dutch wind mills were 2-4% efficient, modern wind turbines are at about half of the theoretical maximum of Betz’s Law of 59%; wood/peat OPEN fireplaces of 1800 had negative efficiency.

      Lay people usually do not get that point, as they know little about the efficiency of engineered systems.

      Because of the present effective use of energy, much more goods and services can be produced for consumption and more damage is done to the environment that debilitates the fauna and flora.

      It is a fantasy to think RE build-outs by mostly developed nations will reverse this situation, because underdeveloped nations continue to increase their use of fossil fuels, i.e., GW is a given for as long as fossil fuels are available.

      Here are some data I have posted earlier:

      Regarding world energy, near CO2-free, nuclear energy has decreased from 16.5% in 2002 to 10.2% in 2013; fossil has INCREASED from 65.0% to 67.9%; hydro remained steady at about 16.5%

      Regarding world RE, after an investment of about $1,700 billion from 2002 to 2013 (excluding investments for grid adequacy and capacity adequacy, about $400 – $500 billion), RE increased from 1.6% to 5.2%, of which wind from 0.3% to 2.6%, biomass from 0.9% to 1.6%, solar (PV + CSP) from 0.0% to 0.6%.

      Hydro + Solar increased from 18.3% to 21.7%

      Adding the 3.6% of RE required investments of $2.1 to $2.3 TRILLION!!!

      The RE craze is a high order folly that is affordable by only the richest of nations, such as Germany.

      Much greater CO2 reduction results would have been obtained, if all those investments had been used for only energy efficiency and life style changes.

      • Ed says:

        Our failure to control world population is mankind’s greatest failure. For example, Britain had about 50 million people in 1950. We could have got that down to 35 million with the right policies but instead we have 65 million today and that is increasing by 400,000 per year.

        On top of this we are still building roads, wanting to expand airports, and wanting to build high speed railways just as we are start our energy decent. 100% RE wont happen at our current rate of 200 kWh/day per person, this is for sure. Maybe at a rate of 10kWh/day per person may be achievable if we haven’t torn each other apart by then.

        • Willem Post says:


          Per capita use was about 20 GJ in 1800, equivalent to 20 GJ x 278 kWh/GJ /365 d = 15 kWh/d

          Considering we now use energy about 14.5 times more efficiently than in 1800, your 10 kWh/d should be enough.

          However, in 1800, Europe was deforested, and much of the on land fossil resources were used up within about 100 years,. i.e., RE would have to be used by default.

          A household of 4.5 people would use 15 x 4.5 x 365 = 24,638 kWh

          A 25 kW solar system in the UK produces about 25,000 kWh/yr over 25 years, plus thermal and battery storage systems (capacity of about 1 week each) would be required in case of no sun.

          We have not figured in 2 electric cars per family!!

    • Euan: A correction for the record. I didn’t refuse to calculate how much biomass would be needed to power ~50GW of capacity. I simply avoided the question by assuming there would be enough, knowing full well there probably wouldn’t. What I did refuse to do was calculate how much hydrogen storage would be needed to smooth out wind generation. Trying to do that on a spreadsheet is a short cut to insanity. 😉

      You’re right about burning trees being a bad idea if we want to cut emissions. Trees are where most of the CO2 sequestered from the atmosphere is now going. But I’m O/T already.

      • dennis coyne says:

        Hi Roger,

        Most of the CO2 sequestered is in the form of dissolved inorganic carbon in the Ocean not in the trees.

        • Euan Mearns says:

          Disagree Dennis. Most of it is removed by gravitational settling of dead phytoplankton in the oceans – 11 GtC per annum. And the main reason that land biomass doesn’t remove more is because we keep burning it. I’ll have a big post on this, probably Friday where we can thrash this out.

        • Euan Mearns says:

          Fossil fuel emissions and cement production 7.8 ± 0.6
          Net land use change 1.1 ± 0.8
          Total manmade emissions 8.9 ± 1.4

          Net land biomass uptake 2.6 ± 1.2
          Net ocean uptake (mainly biomass) 2.3 ± 0.7
          Atmospheric increase 4.0
          Total atmosphere + sequestered 8.9 ± 1.9

  5. Willem Post says:


    Another approach is require that all buildings be OFF THE GRID and be net zero energy or surplus energy. Here is how that would work for free-standing houses:

    Off the Grid, in Near-Zero-CO2 mode, With an Energy Efficient House:

    My starting point is a house, NOT grid-connected, that uses about 80% less energy for heating, cooling, and electricity than a standard house, a la Passivhaus.
    In winter it will be challenging, as several days may pass with near-zero electrical and thermal energy generation. At least a week’s consumption of electrical and hot water storage will be required.
    For living off the grid, in a near-zero-CO2 mode, the house would need to be equipped with:
    – A roof-mounted, PV solar system + a lead-acid battery system + a hot water storage tank with DC electric heater + a system with DC pump and water-to-air heat exchanger.
    – A gasoline-powered, 2 kW DC generator with 50-gallon fuel tank to provide electricity in case of too little PV solar energy during winter, due to fog, ice, snow, clouds, etc.
    – Any excess electricity would bypass the already-full batteries and go to the electric heater in the DHW tank. Any excess thermal energy would be exhausted from the DHW tank to the outdoors.
    – A whole house duct system to supply and return warm and cool air, with an air-to-air heat exchanger to take in fresh, filtered air and exhaust stale air at a minimum of 0.5 ACH, per HVAC code.
    – For space cooling, a small capacity, high-efficiency AC unit would be required on only the warmest days, as the house will warm up very slowly.
    – For space heating, a DC electric heater, about 1.5 kW (about the same capacity as a hairdryer) for a 2,000 sq ft house, in the air supply duct, would be required on only the coldest days.
    NOTE: Because PV solar systems have become much less costly, it would less complicated and lower in O&M costs to increase the capacity of the PV solar system to also provide electricity for DHW, instead of having an $8,000 roof-mounted solar thermal system for DHW; no tube leaks, freeze-ups, less moving parts, etc. With a properly insulated, large capacity DHW tank, say 250+ gallons, there would be enough DHW for a week.
    NOTE: About 70% of battery nameplate rating is available, as batteries are typically charged to a maximum of 90% and discharged to a minimum of 20% of capacity to prolong their useful service lives beyond about 8 years. Usually the charging and discharging is much less than 70%.
    NOTE: Battery charging loss is about 10% and discharging loss is about 10%, i.e., in 100 W in, store 90 W, out 81 W. DC to AC has a loss of about 10%, and AC to DC has a loss of about 10%, i.e., minimizing conversion by using DC devices (fans, pumps, etc.) avoids losses.
    NOTE: As space heating and cooling would be required for just a few days of the year, an air-source heat pump would be overkill and too expensive in this case.
    NOTE: A future plug-in vehicle could be charged with DC energy from the house batteries by bypassing the vehicle AC to DC converter, provided the house batteries have adequate remaining storage capacity, kWh, for other electricity usages. During some winter days, this may not be feasible, as not enough PV solar energy would be available; public chargers would be needed.
    NOTE: The PV solar system needs to be oversized to ensure adequate electrical and thermal energy during winter when the monthly minimum winter irradiance is about 1/4 – 1/6 of the monthly maximum summer irradiance. See below URL of monthly output from 2 monitored solar systems in Munich; 1/6 is about right in South Germany. Whereas, the daily or weekly maximum solar output may be up to 60% of installed capacity, kW, during a very sunny period, it may be near zero, due to fog, ice, snow, clouds, etc. The same is true in Vermont.
    NOTE: The above example shows to provide standard houses (energy-hog instead of a la Passivhaus) with PV solar systems, they would need to be of such large capacity that the costs would be prohibitive, if zero-energy/near-zero CO2 is the goal.


    • Leo Smith says:

      Try building an off grid city for 5 million peole with off grid factories, and off grid everything else, or actually having off grid refrigerated supermarkets…

      The green tendency obsesses about ‘children’ and ‘home’ Only 30% of our energy is consumed domestically. The rest goes into making sure you have a home to start with, and can fill it full of things you need.

      • Willem Post says:


        One has to start with something that is feasible and affordable right now with existing technology.

        I agree, my “project” would only take care of a small percentage of the building stock, but much of that building stock and the stuff in it would be reduced.

        The energy-inflated existing structure needs to be collapsed from within by innovation.

        To add RE to replace fossils and essentially keep the existing structure is an impossible folly.

        Here is how well the world did since 2002:

        Regarding world energy, near CO2-free, nuclear energy has decreased from 16.5% in 2002 to 10.2% in 2013; fossil has INCREASED from 65.0% to 67.9%; hydro remained steady at about 16.5%

        Regarding world RE, after an investment of about $1,700 billion from 2002 to 2013 (excluding investments for grid adequacy and capacity adequacy, about $400 – $500 billion), RE increased from 1.6% to 5.2%, of which wind from 0.3% to 2.6%, biomass from 0.9% to 1.6%, solar (PV + CSP) from 0.0% to 0.6%.

        Hydro + Solar increased from 18.3% to 21.7%

        Adding the 3.6% of RE required investments of $2.1 to $2.3 TRILLION!!!

        The RE craze is a high order folly that is affordable by only the richest of nations, such as Germany.

        Much greater CO2 reduction results would have been obtained, if all those investments had been used for only energy efficiency and life style changes.


  6. Why can’t you convert some the surplus wind derived electricity to hydrogen and then maybe methane, to store until needed for gas turbines to meet wind lulls. Some of the excess electricity can also be converted to heat for thermal storage, as part of a CHP/DH network, which may be cheaper than the wind to gas approach. We had both in our near 100% renewables by 2050 UK scenario produced for Pugwash, plus some DSM and supergrid imports to help balancing .We tested an 80% renewables version (with 40% energy saving) on DECCs 2050 pathways model and it met demand even under the low wind high demand stress test, but DECCs model wouldn’t allow us to replace the remaining fossil fuel with wind to gas to get to 100%! It just exported all the surplus wind derived power. £15bn worth p.a! And imported biomass. We wanted no biomass imports. DECC’s model had our 80% renewables mix costing slightly less than an equivalent nuclear scenario. Going to 100% might not change that much.
    Dave Elliott

    • David:

      My scenario was based on the use of only proven large-scale technologies, and the only proven large-scale technology for storing surplus wind at this time is hydro, as the Danes, Swedes and Norwegians will attest. We should certainly pursue hydrogen storage but it’s still a long way from large-scale commercialization.

      As I noted in the text at least a terawatt-hour of storage would be required to handle surplus wind generation with 100% renewables. This exceeds current UK pumped hydro storage capacity by a factor of more than thirty.

    • Leo Smith says:

      Dear David. As a simple and amusing exercise, I would like you to attempt to calculate how many Hiroshima sized atomic bombs worth of energy are consumed each day in the UK.

      Then ask yourself how many bombs worth is represented by say – two weeks of no wind and no sun.

      And then ask yourself it after all, you wouldn’t rather live next door to a nuclear power station instead of a methane or hydrogen store capable of levelling London and most of the home counties?

  7. David Hirst says:

    This is a good and useful piece of work, and the 5 minute interval is appropriate, as there are many means of dealing with shorter term variations (most useful of which are fridges).
    It provides a pretty convincing demonstration that some form of electricity storage is vital, and using the parameters of hydro can give a useful assessment of the capacities required. The model might be more helpful if Atlantis could have two forms or storage – realistic storage (which can reflect hydro realities) and hypothetical hydro, which can be infinite in its storage and delivery capabilities. This would set the target required for the new storage (or virtual storage) to be added. Wind, instead of being curtailed can be used to fill up the hypothetical hydro. If there is just too much, it can be “spilled” from the hypothetical hydro until there is a reasonable storage capacity.
    This then opens the debate about the nature of the electricity storage (or virtual storage) needed by Atlantis. I see several sources.
    • Appliances. My own guess is that dishwashers can provide about 8GWh, and laundry machines perhaps another 15GWh or so. So equivalent to about 3 Dinorwigs. This is virtual storage, and is achieved by shifting the time of consumption. That would likely cover most of the July deficits.
    • Battery cars. 1m cars, with 60kWh batteries, gives a total storage of 60GWh. Perhaps only 10% can meaningfully contribute, so 6GWh. The UK car population is ~31m cars.
    • Abstinence. Extravagance in lighting and other consumptions may be reasonable at average prices, but in extremis, wholesale prices are sometimes capped at 3,000% – 30 times average prices. If you really had to pay 30 times average at times of scarcity, it would not be difficult to automate the switching off of significant loads when prices go above thresholds you (or companies) choose. I think there may well be energy intensive industries that would choose to shut down for the days of scarcity. There may be compensating increases (warmer homes), but we may see people “storing up” TV programs to watch on cold calm nights (and days).
    The model also assumes curtailed wind, but that is equivalent to saying that the electricity curtailed is free. I am quite sure there are energy intensive industries (such as hydrogen electrolysis) that would see this as an attractive opportunity, and this would “balance” the inconvenience (or joys) of having winter days off. Hydrogen can be stored.
    Of course, these do assume that there is some coherent and intelligent method of influencing demand, and so far there is little by way of intelligent policy thinking in this space. As the blog post says, it seems so much easier just to build more generation.
    But that is not cheaper, and creates temptations just to emit from fossil fuels – a cost that is becoming infinite.

    • David:

      Adding up your dishwasher, washing machine and EV storage numbers gives 29 GWh. The amount of storage needed to handle January wind power fluctuations would be at least thirty times larger.

      If you really had to pay 30 times average at times of scarcity, it would not be difficult to automate the switching off of significant loads when prices go above thresholds you (or companies) choose. I somehow doubt the public would “choose” punitive thresholds. They would have to be imposed on them, whereupon I suspect their reaction would be to elect a different government at the next election.

      we may see people “storing up” TV programs to watch on cold calm nights (and days). Best of luck with that one too.

      I think there may well be energy intensive industries that would choose to shut down for the days of scarcity. More likely they would start looking for another country to relocate to.

      The problem with demand management schemes is that they all assume to a greater or lesser extent that the public will accept the lifestyle sacrifices that a “sustainable” future will impose on them, such as not being able to make a cuppa when they want to, driving their cars in accordance with a strict load-following schedule and occasionally freezing in the dark. Something tells me that this just ain’t gonna happen.

      • David Hirst says:

        Roger, Thanks,
        There is no doubt that we will have to accept some lifestyle changes, but we do need to think through what we are asking, and what can be automated.
        Some lifestyle changes are already tolerated as normal, particularly around low budget flying. There was a time when a ticket was priced by class, but now most flying is done by price, choosing a time when the flying suits out budget, and putting up with some inconvenience as a result.
        While I agree there are some demands for electricity which are not easily shifted in time, like wanting a cup of tea, or wanting light, ther are many where the electricity is a critical component of some other service, like clean laundry or dishes. If the dishwasher (say) is aware of price over time, it can plan its consumption, and offer you as end user, a menu, with prices and times traded off. Urgent and expensive, or cheap and ready later. Similarly with car charging. If you let your car know your plans, it can decide when best to charge up.
        The metering system we have was largely dictated by the available technology if the time, and was later enhanced to have two (or more) registers, so that two (or more) different rates could be applied. And we have grown our demand culture around this. Flat tariffs, highly predictable, with little scope for savings by shifting in time. Nuclear power did offer the white meter, mostly to find a use for overnight nuclear electricity.
        But it is not difficult to let meters know the price over periods ahead, and for meters then to do the sums. All sorts of devices can be told the price, and then all you need is to let it know the maximum price you are prepared to pay. If we do it with airline (and bus and train) tickets, then there will be lots of opportunities for changes. All we need is some sensible price setting arrangements, set to help influence behaviour (mostly of devices) and not set in order to maximise the bamboozlement impact on consumers (as now). By and large, the smart meter gives more opportunities for bamboozlement, and is just not designed around the variability imposed by renewables.
        I agree that we will likely need a lot more storage than my calculations show. And it would be good to find out quite how much by adding pseudo storage to the Atlantic model. Then we can come to a view as how big a contribution electric cars (which are much bigger consumers than appliances) can make to the need. I see no reason why people should not be willing to adjust (or even abandon) their travel plans according to winter weather, particularly if there is some opportunity to plan (perhaps 3 days in advance) and particularly if the saving could become significant.
        As another comment mentioned, the cost of filling the gaps with generation is very high indeed. If fuelled, they can expect utilisation percentages in single digits.
        It is pretty disgraceful that we have not already taken more steps to “level” the daily load curve. But with renewables, the need to adjust demand according to ambient conditions becomes overwhelming, and we need to deveop approaches that allow it to happen.
        Today’s utility models will not do.

      • dennis coyne says:

        At some point, prices rise and people must make choices. If there is peak pricing and people can see, if I run my dishwasher or dryer now it will cost me a lot more than If I wait until prices fall. Nobody needs to be forced, an appliance can be installed which tells a customer the price will be x for the next y number of hours (usually weather can be forecast fairly accurately a few hours out), the customer then chooses if they want to run high wattage appliances based on price.

  8. A C Osborn says:

    I take it you have read Clive’s latest post.
    Over £50B invested for a maximum output of 6GW on just 1 day of the year, so your 90GW at 30%, ie 30GW will cost way over £500B and still be totally unreliable.
    Why would any sane person even think of going there?

    • Leo Smith says:

      Greens are not sane.

      The whole green mythology is admirable in intention, but is simply childish fantasy in terms of implementation.

      Its as if a (thoroughly spoilt) child at kindergarten was given some crayons and an art pad and told to ‘design the car they wanted’ .

      With absolutely no regard to safety., cost, or practicality.

      Because they are superior to engineers, they do ‘art’ – whereas engineers are ignorant plebs with dirty greasy hands who bolt together their Ikea kitchens for them.

  9. Yvan Dutil says:

    Similar studies have been done for Japan and Israel. I cant find the paper unfortunately. By memory, you can go 100% renewable or close to it with 1/3 of dispatchable power and 1/3 of storage. Consumption is likely to change also.

    A fully renewable energy supply is a very different situation from that we have now (unless, you live in Quebec or the few similar place). Extrapolation is very tricky in most cases.

  10. Olav says:

    About storage of wind energy.

    Produce Hydrogen and Oxygen and use pipelines running around Atlantis as storage.
    Hydrogen is difficult to store in tanks or large diameter pipeline but smaller diameter pipeline
    can store hydrogen at high pressure. Producers (wind farms) utilize 50% or more of capacity for
    hydrogen production which is loaded into the pipeline. Users of hydrogen (making synthetic) fuel
    are spaced along the pipelines. Some Synthetic fuel methods also requires Oxygen. Making a needed product is more efficient than making electricity from hydrogen. As wind farms produces hydrogen on spot at windy days is less grid capacity needed.
    Hydrogen will move along pipeline towards the most needed point because of pressure. On low wind days reduce hydrogen production and this makes wind farm a less intermittent source, while synthetic fuel plants can run on stored hydrogen in pipeline.
    By producing some surely needed liquid fuel it will cancel out CO2 produced by some modern coal fired peaking plants. Coal is preferred as it is easy to store at site, gas is less suitable as peaking plants cannot get gas at best price due to their intermittent gas demand.

  11. A C Osborn says:

    Do any of you guys realise that each layer of “conversion” of Wind Power means a loss of the original efficiency which is abysmal to start with.
    Sometimes I despair.
    CO2 is PLANT FOOD, not a pollutant, increase it’s production and green the planet.

    • Willem Post says:

      A. C. Osborn,

      Here is a small write up of a biofuel folly in Vermont, USA

      Bio-diesel From Sunflowers in Vermont; another folly!!

      As part of the Vermont Bioenergy Initiative, GMP hopes to reduce consumer costs, CO2 emissions and other pollutants. It has teamed up with several “pioneering” farmers who grow sunflowers.

      An acre contains about 26,000 sunflowers yielding an average of 40 to 80 gallons of raw oil, which is refined to biofuel for diesels engines. Yields can be zero with poor conditions, such as bad weather, etc., or a maximum of 100 gallon under ideal circumstances.

      Plowing, fertilizing and seeding the soil, monitoring the growing crop, reaping, drying, running through a screw press, transporting the oil to a processor and process the oil to B100 all require fuel and electrical energy. The leftover solid hulls are used to feed chickens, pigs and beef cows.

      NOTE: The BioPro 190 refiner costs about $10,000, plus about $2,500 for shipping, installation and hook-up, processes about 50 gal/batch in 48 hours, capacity 7,800 gal/yr, if operated 365 days of the year, which is grossly optimistic; more realistic production would be 3,000 – 4,000 gal/yr, according to the quantities mentioned in testimonials. At 60 gal/acre and 10 acres per farm, it would take the sunflower crops collected from about 7 nearby Vermont farms to produce 4,000 gal/yr.

      NOTE: Starting with used cooking oil, the expensive cropping phase is avoided. Assuming 33 gal/month of used cooking oil is collected from 10 nearby restaurants at the cost labor, equipment and transport of $0.15/gal, or $600/yr for about 4,000 gallon. Assuming o% financing, a 15-year life, a write down of about $833/yr, O&M (labor, energy, chemical inputs, replacement parts, etc.) of about $1,500/yr, then the cost per gallon would be at least $2,933/4,000 gal = $0.733/gal; similar to the costs mentioned in testimonials. This approach is much less costly than buying diesel fuel.

      A 300-acre farm uses about 5,000 – 6,000 gallon of diesel fuel per year. That usage would increase with about 100 acres of sunflowers.

      Land required to produce 6,000 gal/(60 gal/acre) = 100 acres, about 1/3 of the farm’s area, greatly decreasing the land available for beef cows, etc.

      Of the 300 acres, not all are pasture and open, relatively flat land. In Vermont, this likely restricts the acreage for sunflower crops to several plots totally at most 20 – 40 acres per 300-acre farm.

      NOTE: Ukraine, with some of the best topsoil in the world, and with very large, flat areas of land, is the ideal country for such crops. It had 4,193,000 hectares in sunflowers (11,363,030 acres, almost twice the entire area of Vermont), seed yield 6,364,000 metric ton (2009 data), or 1.518 mt/Ha, or 1354 lb/acre, which produces about 65 gallons of oil, depending on the oil content of the seed, i.e., a 40-lb bag of sunflower seed produces almost 2 gallons of oil.


      Other energy crops are soybeans, canola, pennycress and camelina.

      The below URL contains a breakdown of costs for canola oil (thus far, I could not find a similar example for sunflower oil). The cost appears to be about $4.78/gallon, less $1.01/gallon for using the pulp as animal feed, or $3.77, i.e., the tax-free diesel fuel cost would have to exceed that just to break even!!

      NOTE: Several indirect costs items, such as land rent or land lease; land taxes; fixed costs of buildings; fixed costs of farming and transportation equipment, etc., are not listed.

      Based on the above, the cost of producing the biodiesel with Vermont’s small-scale conditions will be atleast 1.5 times the cost of diesel fuel. Only by ignoring equipment, labor, and other costs by rationales, such as “the farmer already owns the land”, “the farmer already has a tractor, truck and other equipment, etc.”, or “the farmhands are already on hand”, is the estimated cost per gallon made to appear less than diesel fuel.

      For GMP to use valuable money from ratepayers to subsidize such a folly is a travesty. It has nothing to do with electrical energy generation and the distribution of electrical energy. I am surprised the VT-PSB allows such projects by a foreign-owned, regulated utility.

    • Hi AC. To reiterate, I included biomass only because my scenario required 100% renewables, but now that people are beginning to realize that biomass isn’t exactly carbon neutral I suspect its days are numbered. That leaves nuclear as the baseload alternative if we want to cut carbon emissions. Nuclear is about as close to carbon-free as you can get, although it’s not renewable. Or is it?

  12. Jacob says:

    You write: “semi-load-following mode in the same way as UK coal plants do at present.”

    How do UK (or any other) coal plants achieve this “semi-load-following mode” ? (What does that mean exactly?)

    I suspect that, since it takes 4-8 hours to start a coal plant from cold state, the “load following mode” is achieved by keeping the fires (the coal) burning and producing emissions, even when the plant is unable to sell the electricity because of renewables, which get preference.

    So the “semi-load-following mode” is an illusion, as far as emissions are concerned.

    • Jacob:

      Not a particularly good term, was it? “Partial load following” would have been better.

      What I was getting at was this:

      Most of the load-following is done by gas, but coal generation contributes.

      I don’t know exactly how the coal plants are ramped or what the impact of ramping on emissions would be.

      • Euan Mearns says:

        I have a post on this tomorrow, asking questions, short on answers.

      • Jacob says:

        In the graph above most of the balancing is done by CCGT, not coal. Now, CCGT has the same problem of ramping up in the steam turbine part of it: you can’t heat up the steam instantly. You can run the gas turbine in open-cycle mode (without the complementary steam turbine), but then you get 50% less power for the same amount of fuel burnt.

      • Leo Smith says:

        shirt term coal ramping is simply turning stored boiler heat/pressure into power. longer term is by shovelling coal. This is all reasonably efficient with modern steam plant over a fairly wide range of dispatch.

        Its actually quite interesting to look at what’s on the grid and where such storage and dispatchable elements are.

        The least obvious and shortest term is actually the rotational inertia of dozens of turbines spinning away. every single load that is suddenly switched on actually causes a mechanical shock load on the generators and they start to slow down a bit. As they do that voltage drops a bit and that usually is what causes the load to lessen. If its a heater or a big motor. It its electronics, they just draw more current 🙂

        As frequency drops below nominal, several options are open to increase power.

        Any generator running below its capacity can be turned up. The fastest to respond are those using ether BIG steam boilers with lots of inherent energy storage, or hydro.

        The problem is that BIG steam boilers are not fashionable. They lose more heat and are less sufficient. Small ones are preferred. So that leaves hydro for the sort of ‘under a minute’ ramp up of power. Hydro can go from zero to flat out in less than a minute too.

        on a longer time scale -orders of minutes to tens of minutes – already running kit in either spinning reserve, or running at part throttle, can have heat input increased by adding fuel (or modulating the moderator rods in a nuclear plant) to get more power out.

        On a much longer time scale ranging from an hour to several hours or even days, in the case of a big nuclear plant, whole stations can be brought on-line, from cold. This however represents a huge investment in fuel before any electricity is generated. Eirgrid reckons it costs 10,000 euros to get one frame type gas turbine and steam plant up to temperature and generating power. All that fuel is effectively thrown away every time its switched off. BUT a CCGT set can be up in an hour or two from cold. whereas coal takes a few hours, and nuclear tends to take a day or so.

        (note that fuel wastage is not really an issue in a nuclear reactor, since the actual raw cost of uranium is trivial and its not a big deal even when processed into fuel rod. But the economics of nuclear power are all about leveraging very high capital cost into as much electricity as possible, so they tend to run baseload, because they can out compete any other technology on marginal cost. That is, a nuclear reactor costs the same to run as not to run, so anything its makes as gross income is net income as well – there is little direct cost of fuel at all)

        Managing this lot is non trivial and complex systems of energy supply contracts and a market in energy surplus and shortfall exists to try and allow it all to work pretty well, co-ordinated by the grid, which did pretty well.

        Until renewable energy came along.

        Government decreed that renewable energy would take priority at a fixed and higher price. The energy companies were required to take it at the subsidised price whenever it was available.

        The impact of this on the profitability and viability of other power stations has been horrendous, but that’s another story. In terms of the actual grid stability it has been a complete nightmare, as well.

        From the point of view of conventional plant on the grid, wind and solar is an unreliable and intermittent and even at times pretty unpredictable ‘negative load’ on the grid. So a falling wind pattern at the tail of a local or large scale low pressure system represents the equivalent of a sudden load being applied to the grid, whilst a good gust on a moorland windfarm is like someone stopping several trains at once..and all these fluctuations need to be managed to keep voltage and frequency within limits, and to minimise sock load on the spinning turbines which are seeing themselves a much more variable load than before.

        The exact effect of this is still being understood, but there are many reports of reduced lifetime and increased wear on conventional plant in response to having to handle a greater and more rapid load variation. There is certainly more fuel being burnt per conventional unit electricity as stations are ramped up and down to attempt to balance the wind and solar variability. No one is quite prepared to say its more than the fuel saved by having the renewable energy, but some have claimed it might be.

        And finally, the knock on effects of the much less tightly controlled frequency and voltages – especially high speed variations – have actually damaged some factory equipment in that bastion of renewable idiocy, Germany. To the point where they are using the equivalent of vast uninterruptible power supplies to isolate themselves from the mains and generate a proper fixed voltage and frequency for their equipment. Or else are moving to a country where this is the norm anyway.

        Worse, the vast imbalances in geographical distribution of renewable energy, which tends to be (wind especially) well away from population centres where the demand is, has meant that high priced transmissions lines are need to carry peak flows around, and these are under utilised and costly white elephants if the sun is not shining or the wind is not blowing hard.

        And if as happens in Germany, you are expecting someone else’s grid (Czech republic) to carry it for you, dont be surprised if they threaten to cut you off if it destabilises their grid…

        The reality of the political requirement to add renewable energy has been a nightmare for consumers, grid operators and power companies alike. IT is not a success story. It is a story of monumental efforts and costs being made and incurred to make it happen at all, whilst green theorists gaily wave their hand in the air and say ‘well just add storage’ or ‘the wind is always blowing somewhere’!

        The sheer naivete and arrogance of these statements is unbelievably insulting to the everyday engineers who have to try and make this political Heath Robinson assembly of childish dreams actually generate a reasonably stable electricity supply. As for whether it saves any fuel or carbon emissions, we have zero way of knowing right now. It most certainly isn’t saving any money. Or adding any energy security.

        And of course with the whole AGW hypothesis under serious challenge in a world which has simply stopped warming, the nagging doubt that any of it was necessary in the first place remains.

  13. Posts like this invariably stimulate suggestions as to how intermittent renewable energy can be made to work by disconnecting people from the grid, by programming dishwashers, heaters, televisions, electric vehicles and energy-intensive industries to do things when the wind is blowing and not to do things when it isn’t and/or by using surplus energy to produce hydrogen and store it in tanks for re-use, but there are always questions as to whether these proposals will work in practice.

    At the end of the post I link to an article which claims to have found a way renewables can be made to work in part of the Eastern US, although it requires very careful system balancing (28 billion runs were required to define the optimum case), about 900 GWh of storage in hydrogen tanks, electric vehicles and lithium titanate batteries and some fossil backup. I was wondering if anyone had any comments on it.

    • Graham Palmer says:

      The Budischak simulation is notable for its low load factor. Applying a small discount to allow for their optimistic capacity factors and adding a small reserve margin (which is not explicitly factored in), the resulting load factor is calculated at around 9 % based on the “99.9 %” scenario from Budischak et al. Table 3 – in additional to the 51,900 MW of storage. Turning this around, this means that the generation capacity has an effective idle capacity of 91%.

      • A nine percent overall load factor is what I estimated at high levels of wind penetration into the UK grid – see Table 4 in:


      • Graham Palmer says:

        Budischak has kicked an own-goal in showing just how difficult it would be to get to 100% renewables, even though the safety of a desktop simulation offers –

        a) perfect hindsight
        b) the benefit of all-knowing central planning
        c) freedom from most of the usual economic, environmental, social, financing, and planning constraints
        d) freedom to ignore nearly all of the practical engineering and network issues
        e) freedom to ignore the macroeconomic consequences

  14. A C Osborn says:

    I have a few.
    1. “Wind and solar are parameterized as GW capacity”, but then they go on to say “used a typical commercial wind tubine’s power curve to calculate the hourly wind power output with the wind speed input from NOAA buoys”. So they identified the location of the Turbines and then used the wind speed to calculate the output for each turbine? So they are not actually using real world typical output.
    2.”During times of excess renewable generation, we first fill storage, then use remaining excess electricity to displace natural gas. When load, storage and gas needs are all met, the excess electricity is “spilled” at zero value,” They have calculated that the total Grid is 30GW and at times of max output the RE system can produce 3 times the requirement. So they appear to have installed 90GW of RE. See my note above about costs for the Wind part of RE.
    3. After about 3pm there is no Solar to speak of so the only RE input for the grid until the next morning will be Wind. No Wind – no input, so there could be long periods where the storage will have to cope in it’s own or use Gas. They then assume the storage CAN be recharged using RE while supplying the grid?
    4. They have assumed that by dispersing the RE there will always be somewhere where RE is generating, but they don’t say what percentage or what distances would be involved. As we know large areas of the EU can be in the doldrums at any one time, so I assume it is the same in the US.
    5. “We simplify our grid model by assuming perfect transmission within PJM (sometimes called a “copper plate” assumption)” So no losses over this Dispersed generation area?
    6, 900GW of storage would appear to last just over 30 hours at peak power and would then be exhausted.

    All in all I would really like to see the computer (Model) runs that they did with regards to the weather and grid requirements over the 4 Year modelling period. Note their data was based on 1999–2002, before its recent growth.

    • AC. Some valid observations there. But I still think the critical question is whether their 900 GWh of battery, EV and hydrogen storage – all of them technologies unproven at the commercial scale – has any chance of working. If it doesn’t they’re back to fossil fuel backup again.

      • Leo Smith says:

        900 GWh of battery, EV and hydrogen storage ?

        No chance whatsoever.

        900GWh is 775 kilotonnes of TNT or about 50 Hiroshima bombs. Enough to keep the UK going one day in winter.

        Anyone who :

        (a) opposes nuclear power and
        (b) considers battery or hydrogen or methane/propane/butane storage on this scale is safe….

        …is certifiably insane.

        The biggest energy related loss of life ever was a similar amount of ‘renewable’ energy released when a Chinese dam collapsed.

        The safest energy store we have is actually uranium plutonium and thorium nuclei. You really have to work hard to get any energy out at all, but when you do there is lots there.

        Next is coal. bulky, but pretty safe usually.

        then heavy, then light oils. Diesel is quite safe. Petrol less so.,

        Gas is the worst

        But a battery? ever shorted a REALLY big battery?

        Or seen a big dam go?

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