El Hierro Renewable Energy Project – End 2015 Performance Review and Summary

The Gorona del Viento (GdV) plant on the Canary Island of El Hierro is a flagship project designed ultimately to provide the island with 100% renewable electricity and to demonstrate that hybrid wind/pumped hydro systems can be used to generate 100% renewable electricity in other parts of the world. GdV comprises a wind park with 11.5 MW capacity and a pumped hydro storage plant with 11.3MW gross (9.2MW net) capacity, installed at a total cost of €84 million. This is the fourth in a series of operational updates. Details on GdV plant layout, operation and capacities are given in the September update.

The data accumulated since full operations began on June 27, 2015 are sufficient to show that the GdV plant as presently structured is not capable of supplying 100% of El Hierro’s electricity demand for 100% of the time. (According to a recent study by Hubert Flocard an annual average of about 50% renewables is the most that could be expected.) As a result the island of El Hierro will remain dependent on diesel generation from the Llanos Blancos plant that GdV was designed to replace for a secure supply of electricity. Instead of acting as a flagship project to demonstrate the feasibility of 100% generation from intermittent renewable sources GdV has in fact succeeded in highlighting the severe, and in many cases insuperable difficulties involved in achieving it.

Cost information is also now available. According to recent reports GdV expects a total reimbursement equivalent to €0.81/kWh for renewable energy delivered to the El Hierro grid in 2015.


According to grid data published by the Red Eléctrica de España (REE) 30.7% of the power sent to the El Hierro grid over the 188-day period between commencement of full-scale operations on June 27, 2015 and December 31, 2015 was renewable electricity from GdV and the remaining 69.3% fossil fuel electricity from Endesa’s Llanos Blancos diesel plant. Table 1 summarizes monthly and total generation statistics:

Since full operations began the 11.5MW wind farm has run at an average capacity factor of 13.2% and the hydro plant at an average capacity factor of 1.5% (calculated relative to the 9.2MW net capacity of the hydro turbines).

Figure 1 plots November and December generation based on 10-minute REE data. These plots are added so that monthly plots of all the 10-minute REE data since full operation commenced are available (the last published monthly plot was for October).

Figure 1: November and December generation, 10-minute REE grid data

Figure 2, which plots average daily generation between startup on June 27 and December 31, 2015 illustrates how GdV output is hostage to wind conditions. Generation was highest during the high-wind period that extended through June, July and most of August but fell off to low levels during the low-wind period that persisted during September, October and most of November. Generation improved during two higher-wind episodes in November and December but has still to regain July levels.

Figure 2: Average daily generation, June 27 to December 31, REE grid data

Figures 1 and 2 show four sources of power generation – diesel, wind to grid, wind to pumping (which as discussed elsewhere mostly gets wasted) and hydro. As discussed in previous updates REE gives separate generation data for diesel and hydro but only one for wind. This number is positive when the wind generation is sent to the grid and negative when sent to pumping. The sum of diesel + hydro + wind sent to the grid equals grid demand. Further details are given in the September update.


We will begin with some basic precepts. If GdV is to succeed in supplying El Hierro with 100% renewable energy for 100% of the time, which is the ultimate project goal, it must meet the following criteria:

1. The wind farm must be capable of generating enough electricity during the year to fill annual El Hierro demand (about 45GWh, representing an average output of about 5MW).

2. The pumped hydro reservoirs must have sufficient capacity to store the surplus wind energy generated when wind farm output exceeds demand for re-use during periods when wind farm output is less than demand.

3. Large amounts of wind power must be admissible to the El Hierro grid without compromising grid stability.

4. The plant should be dedicated to supplying power to the grid and not required to supply significant amounts of power for off-grid uses.

As outlined in the point-by-point discussion below, however, the GdV plant meets none of these criteria.

1. Wind Farm Output

With an installed capacity of 11.5MW the GdV wind farm would have to operate at an average capacity factor of at least 45% to generate the 45GWh of power El Hierro consumes in a year. This is maybe twice what it would be capable of generating even if the wind turbines were allowed to run flat out all the time. (The wind at GdV often does not blow strongly enough to turn the turbine blades. For a total of 960 hours since the beginning of September – about a third of the time – the GdV wind farm generated no power at all.)

Compounding the problem is the fact that the wind farm does not run flat out. Much of its potential output during high-wind periods is curtailed. Figure 3 shows total wind generation (wind sent to the grid plus wind sent to pumping) during July 2015, the windiest month to date. The flat spots shows the curtailment thresholds, which are set generally between 5 and 7MW. There is no way of knowing how much wind power was curtailed above these thresholds, but visualizations of what the plot might have looked like without curtailment suggest that it was significant:

Figure 3: Total wind generation during July 2015, 10-minute REE grid data

Figure 4 further shows that curtailment levels were generally fixed at or close to grid demand (black line), implying that there was nowhere to send wind power that exceeded demand:

Figure 4: Total wind generation during July 2015 with demand superimposed, 10-minute REE grid data

Which brings us to criterion 2:

2. Storage capacity of the pumped hydro system

GdV’s pumped storage system is intended to store surplus wind energy for re-use during low wind periods, yet Figures 3 and 4 shows that surplus wind energy was curtailed rather than stored during July. Why was this? According to reservoir balance studies performed by Hubert Flocard in this earlier post and in the study linked to in the introduction the physical reason was that GdV’s reservoirs remained fully charged during the month, leaving no room to store any more energy.

The underlying problem, however, is that the ~270MWh storage capacity of the GdV reservoirs is totally inadequate. According to calculations documented in the October review at least 5,600MWh of storage, approximately 20 times the system’s current capacity, would be needed to cover the wind power shortfall just over the six-week period between September 12 and October 31, and the existing reservoirs are already as large as topography and foundation conditions allow. Barring orders-of-magnitude breakthroughs in storage battery costs, inadequate storage capacity is the Achilles’ Heel that will likely preclude 100% intermittent renewables generation not only on El Hierro but in other places where similar approaches are implemented (including the proposed Chira-Soria project on the island of Gran Canaria, which is a scaled-up version of GdV).

3. Grid Stability

Figure 5, which plots the REE 10-minute generation data for July 28 through July 31, 2015, exhibits two interesting features. The first is that diesel generation is maintained at constant “baseload” levels of 1.6 or 3.2MW while a roughly equal amount of wind generation is sent to pumping, where according to Hubert Flocard’s reservoir balance calculations approximately 80% of it gets wasted by being pumped to the upper reservoir and allowed to flow back to the lower reservoir without generating any electricity. So why wasn’t this wind power used to replace diesel generation?

Figure 5: Generation by source versus demand, 10-minute REE grid data, July 28 through 31, 2105

No firm details are available but all the evidence points to the fact that too much wind power destabilizes the El Hierro grid. As a result grid operator REE is unwilling to admit more than a fraction of GdV’s output during periods of high wind generation. (In the 4,512 hours of full operation since June 27 2015 wind power sent to the grid has been allowed to exceed 5.25MW – half the capacity of the GdV wind farm – for a total of only five hours.) GdV staff, quoted in this October BBC News Magazine article acknowledge that this is a problem and are hoping that REE will eventually relax its stance: “there is a learning curve for those operating the plant, and … the energy company, Red Electrica, also needs to be convinced that diesel output can be safely reduced”. Eighteen months into the learning curve, however, REE still remains unconvinced.

A fundamental question that arises here is whether El Hierro is an isolated case or whether other grids could also be destabilized by high levels of wind power. If so this could pose another serious obstacle to the expansion of renewable energy. Comments from experts are solicited.

The second interesting feature of Figure 5 is that during high-wind periods generation is matched to demand by switching wind output between the grid and pumping. Using wind to follow load while diesel generation plods along in baseload mode is a curious way of doing it, but presumably operating experience has shown it to be the most effective.

4. Diversion of wind energy for other uses

GdV was originally conceived as a project to pump fresh water up to an elevated reservoir from which it could be distributed to El Hierro’s towns and farms, and according to reports it is now performing this function as well as supplying power to the grid. GdV should be credited for the power consumed in doing this, but since the power is off-grid it receives none. It is likely that only a comparatively small amount of power is involved, although the exact amount cannot be quantified because no data are available on fresh water withdrawals from the upper reservoir. The main impact is to add another level of complexity to an already complex project.

One perplexing feature is why GdV’s hydro system generates so little power. Hydropower is sent to the grid in short and irregular bursts only during periods of low wind generation. (The most power the hydro turbines have so far supplied to the grid during a period of continuous operation was 53.5MWh, representing only about 20% of the storage capacity of the GdV reservoirs, between 1250 hours on August 8 and 1000 hours on August 9.) One possibility is that it has to do with the need to keep the lower reservoir as full as possible to guard against potential overloads when the wind starts blowing again. (If the lower reservoir is empty when surplus wind energy appears there will be no way of “wasting” it.) But whatever the motivation the fact remains that at its current level of contribution the GdV pumped hydro system might as well not be there.

Cost Of GdV Electricity

According to a number of recent web articles (in Spanish) the Ministry of Industry has approved a payment of between €8 and 9 million to GdV for power produced during 2014 and 2015: Universo Canario posts the following (my English translation):

Gorona del Viento, a millionaire gold vein

Gorona del Viento, the company that manages the Central Hidroeólica de El Hierro, will receive around 8 million euros in remuneration for the years 2014 and 2015, as approved this week by the Ministry of Industry. For 2015 alone Gorona del Viento expects to charge 7 million euros …

These payments seem to be based almost entirely on a clause that guarantees GdV a return on investment. Payments for energy actually delivered are negligible in comparison.

And dividing the expected €7 million reimbursement for 2015 by the 35,662 kWh of renewable energy generated by GdV in 2015 gives an average cost of €0.81/kWh.

Electricity rates in Spain are the same everywhere so these costs will be borne by the Spanish taxpayer and not by the residents of El Hierro. One nevertheless has to wonder what the reaction of the Herreños would be if they were added to their electricity bills.

Concluding comments:

First, the text of this post contains a number of links to studies performed by Hubert Flocard that have made invaluable contributions to our understanding of how GdV works. The opinions expressed in the text, however, are entirely mine, and while I believe them to be substantially the same as Hubert’s there may be cases where they differ. So Hubert, if you disagree with anything I’ve said please say so.

Second, it has not been possible to carry out a fully diagnostic review of GdV because of the lack of data on certain key variables – in particular data on reservoir balances, which have been requested from GdV without a response. As a result there is a chance that some of the conclusions arrived at in this post are wrong. If so GdV staff are encouraged to point them out in comments, o en Inglés o Español.

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110 Responses to El Hierro Renewable Energy Project – End 2015 Performance Review and Summary

  1. oldfossil says:

    It sounds to me as if someone needs to invent a kind of flywheel to smooth out the minute to minute variations in wind power that destabilize the grid. If they do they will become billionaires. (Enter Bill Gates?)

    • Euan Mearns says:

      I’ve been wondering about that. Its not a subject I know enough about, but I’ve heard that a stable grid needs large stable (voltage and frequency) generators for it to remain stable. Small amounts of fluctuating load can be added to it but not beyond a certain level. They did that 100% renewables test run and maybe learned something.

      You can see they are using the hydro more and more, but only in small doses.

  2. singletonengineer says:

    I am intrigued by several issues that emerge from this post. My apologies for its length.

    Firstly, Load following. Why not normally use the 11.3MW hydro generation capacity to load follow, although I admit that this is limited due to the size of the upper and lower ponds and the starting conditions for each generating event. Hence, use as peaking plant. But this seems not to be the preferred philosophy, which involves a combination of curtailed wind plus significant pumping via a circuit, which is energy lost. Hydro is used for peaking, eg 19th December, but not routinely so.

    Thus, the dispatch order is important. Somewhere, a decision has been taken, not only to use diesel in blocks of baseload at 1.6 or 3.2 MW, but also to use a combination of (a) round trip hydro pumping, ie to waste wind energy to load-follow, instead of hydro generation which would capture the value of earlier wind generation and (b) curtailment of wind during periods of high capacity, which is simply wasted opportunity.

    Second, what are the engineering factors behind the dispatch order decisions?
    1. Are both upper and lower pondages habitually kept full, thus maximising water availability over cost of electricity considerations?
    2. What is the interaction between diesels and desalination? Are blocks of diesel at 1.6MW dedicated to similarly sized blocks of desal load – if so, that might go a long way towards explaining the nature of these blocks – is diesel allocated in this way because the desal plant is deemed to need the security of diesel plant, rather than the variability of wind (weather) and hydro (availability of water)?
    3. If both ponds are normally kept full and the operators are reluctant to overfill the lower pond and thus lose water to the ocean, this might explain the apparent decision to use the hydro to absorb (waste) excess wind power via round trip pumping.
    4. If so, and because the Spanish taxpayer is paying, is cost of production simply not a concern?
    5. Is security of water the over-riding consideration, above efficiency of operation of the electrical power system?

    Third, considering frequency control, this is readily available via both diesel and hydro generation but not wind. Load following operates in both directions. A fully loaded generator lacks the essential headroom necessary to ramp up in response to loss of generating capacity elsewhere in the system, or to follow increased loads. Ramping down is commonly associated with decreasing demand: both diesel and hydro plant typically can ramp down rapidly to follow decreases in demand, wind less so. The diesel and hydro in this system should be more than adequate to maintain frequency within acceptable limits. Why use recirculating pumping to do this, at the expense of diesel fuel? There is a strong argument in favour of running diesels, if at all, close to half load and thus retaining their ability to follow loads both up and down. There is an equally strong argument for operating hydro, especially, as in this case, hydro with limited available water, as peaking plant. Whether the hydro is also counted as fast response capacity is not able to be determined from available data – that could be clarified by examining the system operator’s operational philosophy and the dispatch order records.

    What is happening here? I suspect that each in-service diesel is being operated at or close to its nameplate rating when in service, thus not providing spinning reserve (“headroom”) which is essential for ramping up. Examples of loss of generating capacity include shutdown of a plant item such as a wind or hydro turbine, perhaps due to failure of a minor component in the switchyard or control system, not necessarily mechanical or electrical failure of a whole unit.

    I do not know the actual nameplate ratings of the diesel plant, so this is conjecture: Operation of the diesels in blocks of 1600 and 3200 kWh strongly suggests small diesels of 1.6 MW capacity. If so, then in-service diesels would be able to ramp down to follow lost load, but not to ramp up to follow lost capacity. Out of service diesels are presumably either on standby or maintenance. It appears that ramping up is achieved by decreasing the amount of wind power which is lost via pumping around a circuit, thus resulting in the same system effect as ramping up.

    To solve this conundrum, we need to know:
    The records of day by day dispatch merit order, including linkages to water storage levels.
    The diesel plant sizes and operating philosophies, eg linkage to operation of desalination trains.
    The water management philosophy – Maximum storage? Political directives? Perceived risks to other than just electricity generation?
    The operating levels of both upper and lower pondages, daily, though the study period.
    Who carries the commercial risks.
    Who stands to gain commercially.
    Who makes the decisions. REE?

    Until these questions have answers, it appears to me that the operational principles are:
    1. Maximise reliability and availability of water supplies.
    2. To continue traditional matching of diesel generation with desalination loads.
    3. Enhanced hydro generation capacity cannot be relied upon because of the small sizes of the pondages.
    4. Wind power is unreliable and comes from a zero cost demonstration plant paid for by the taxpayer.
    5. GdV’s profits are not affected by wasteful operating practices. They have no motive to minimise costs. In fact, increased diesel consumption might llink to increased profit.
    6. REE lacks commitment to the project as a test bed and is happy to remain comfortable with acceptable system availability figures for water and electricity, regardless of cost – which is voted by the Spanish Government. It has no skin in the game, hence no commitment.

    • Euan Mearns says:

      Roger has been sending GdV emails inviting them to join the discussion and explain strategy but they don’t seem to want to play ball.

    • Roger Andrews says:

      Singleton: Your comments are useful and appreciated. I can’t answer most of your questions because as Euan points out we can’t get the information from the project operators, and this has left us in the position of having to use what Sherlock Holmes called “analytical” reasoning, i.e. given the results, determine the steps that led to them. However, I can provide some additional data on a few of them:

      Are both upper and lower pondages habitually kept full? According to Figure 8 in Hubert’s earlier analyses (http://oi59.tinypic.com/2v01fl3.jpg) the upper reservoir is kept full and the lower reservoir empty. For reasons outlined in the text I suspect that the lower reservoir may be kept full too, but without reservoir balance data (which has been requested twice from GdV and once from the Island Water Council without response) it’s impossible to say exactly what was done.

      because the Spanish taxpayer is paying, is cost of production simply not a concern? If GdV gets paid simply for being there, as the 2015 payment suggests it does, then we can assume it isn’t.

      Is security of water the over-riding consideration, above efficiency of operation of the electrical power system? Unquestionably. El Hierro can live without electricity but not without water. But the surplus wind energy sent to pumping will have pumped far more fresh water up the hill than the island’s desalination plants can deliver and far more than the island needs for irrigation or other purposes, which is why we think most of it came back down again.

      I suspect that each in-service diesel is being operated at or close to its nameplate rating when in service, thus not providing spinning reserve (“headroom”) which is essential for ramping up. According to the sources below the Llanos Blancos diesel plant consists of units with nameplate ratings of 0.78, 1.1, 1.46, 2.0 and 2.34MW aggregating 13.8MW. There are no 1.6MW units and I can’t make the individual units add up to 13.8 MW either.



      • Adam says:

        Here’s how to get 13.8MW using those types of generators:

        2.34 * 4 + 1.46 + 1.1 * 2 + 0.78 = 13.80

  3. Flocard says:

    My opinions concerning the way GdV is managed have evolved over time. Presently I’d be tempted to say that it is the return on the investment which explains why it is so strange. As Roger quoted GdV is a gold vein for the investors. Communication (GdV is a “flagship” as Roger writes) is also playing a role. On the other hand I now believe that ecology and the interest of Spanish customers play none.

    What Roger says about the technical limitations which will always prevent reaching the advertised goal (electric auto-sufficiency) is correct. But they must have been obvious to competent electric engineers well before the construction of the project.

    In addition as mentioned by Roger even within these limitations GdV is not operated to maximize the renewable fraction. In particular he pointed out, the hydro component of GdV is almost not used. Although the power of the turbines exceeds 11 MW at no moment did they deliver more than 3.5MW and never more than 0.5 MW since September. The graphs in the text above also show that they are used in short bursts delivering a very small cumulated energy over 6 months.

    It is the consideration of who are the partners of the consortium what contract they managed to get the Spanish State to sign that can give us significant clues to understanding how GdV is managed.

    The consortium is owned 60 % by the island’s local government, 10 % by a local technical institute and 30 % by the electric company ENDESA. Of these three partners, only ENDESA has the competence to effectively manage GdV. It is the one who holds the reins within the regulations imposed by REE.

    Moreover ENDESA also owns the diesel-fired power plant at Llanos Blancos. In addition, since GdV will never be in position to reach the auto-sufficiency the investment cost and operational costs in the fossil-fired plant will always be there. For instance over the last 6 months for a time equivalent of more than 45 days the electric demand was covered by the diesel plant at a level exceeding 99 %. It is certainly in the interest of ENDESA to achieve a financial optimization of the coupled operation of both systems and not let GdV ruins its previous investment into the diesel plant until it has been reimbursed.

    Let us now consider the contract signed between the consortium and the Spanish State. What is remarkable is that the energy provided by GdV plays almost no role in the definition of the amounts paid. At one point it is mentioned that it is paid 15.57 €/MWh. On the other hand one is told that for 2015 only GdV will be paid 7 M€. At the above rate the amount of money associated with the energy produced in 2015 by GdV only represent 3-4 % of this sum. The rest correspond to another “service” rendred by GdV : “POTENTIAL contribution to the stability of the electric system of El-Hierro” (note that I capitalized “potential”).

    Indeed, the contract makes sure that if, thanks to its electric turbines, GdV is in position to help the stabilization of the grid if requested, it is paid for the amount of time of readiness. The fact that this contribution is not used because the diesel-fired plant can do the job (and does it) is not considered in the contract. GdV has just to show that it is ready to perform the task. The terms of the contract also show that if the state of readiness for the full power of the turbines (11 MW) exceeds 30 % of the time over a year, the investment of 46 M€ made by the consortium (the rest of the construction cost 36 MW is a present by the Spanish and Europeans citizens) will be reimbursed given the estimated lifetimes of GdV components.

    It is then in the interest of the consortium to maximize the time of readiness above 30 %. This turns around the priorities. It is certainly not in the financial interest of GdV to produce electric energy with the hydraulic turbines. On the other hand the water management becomes crucial. According to the contract GdV must demonstrate that using wind energy solely it has pumped some energy in the form of water into the upper reservoir. It must be able to show REE that the lower reservoir has sufficient room left to accept water running down for a given power (it is potential hydraulic power that gets paid) and a given period of time (a new evaluation of this potential contribution to stability is performed every week). Indeed the contribution to stability comes only from hydraulic turbines Of course as Roger wrote, it is important that some water be present in the lower reservoir to make use of any wind contribution to replenish the upper reservoir.

    Well ! it is a cleverly written contract whose terms must have been dictated by the ENDESA people and which the Spanish government was all eager to sign in order to boost its ecological image at the cost of Spanish taxpayers (in Spain the contribution to renewables is transformed as national debt)

    With the increasing presence of renewables in the electric systems the notion of “capacity factor” in which installed power is paid, not to be used, but only for the the insurance that its being there offers to grid stability is of course something discussed everywhere in Europe.

    The irony of the GdV contract is that before GdV there was no stability problem. Thus the hydro component of GdV is paid as an insurance for a problem that its wind turbine component has created. Moreover it is not a flat annual fee. The less this insurance is used the more money GdV receives.

    In France we would say ” Bravo l’artiste ! “.

    • oldfossil says:

      You’re saying then that the dream of 100% renewable energy has met its armageddon in the twin crucibles of bad planning and investor greed. GdV has an incentive to manage the resource as inefficiently as possible.

    • Roger Andrews says:

      Hubert: Thanks for that. I’ll be replying at length later but right now I have a doctor’s appointment. Just to let you know I’m not ignoring you. 😉

    • Grant says:

      Based on that analysis of the probably contract terms one has to say that one of the negotiating parties clearly had a good eye for spotting potential and creating an opportunity.

      I have come across (indirectly as not intimately involved) one similar example (nothing to do with Energy by the way) of a contract whereby the client could be charged extra for all sort of things that gave total flexibility to the supplier. The supplier then under performed, pointed to the watertight 5 yr contract, demanded full payment up front to escape and activated less than obvious penalty clauses for under using the service (compared to estimated usage which would have allowed significant additional billing) and projected those losses over 5 years of nominal growth and opportunity.

      That was a well known large multinational who had at least some reputation for writing contracts that were far better constructed than the products and services they offered.

      The service delivered in the first year of the contract (actually apparent from day one) was so bad the client paid up.

      This one sounds like there may not have been much thought given to the consequences by those paying the bills. Did they have visions of a “bigger picture” I wonder?

    • Hubert:

      I’m going to comment on just one of your comments:

      What Roger says about the technical limitations which will always prevent reaching the advertised goal (electric auto-sufficiency) is correct. But they must have been obvious to competent electric engineers well before the construction of the project.

      Well, I’m not sure they were..

      In previous posts I’ve linked to a 2012 engineering study which estimated that 64.56% of El Hierro’s annual electricity demand would be supplied by the GdV plant as presently configured. Here’s the link again:


      And here are the relevant quotes from the study:

      The production strategy for the hydro-wind plant is based on the following principles:
      — Maximize wind generation capacity to supply electricity demand, thus minimizing primary energy losses;
      — If the wind resource is higher than the expected demand, the excess will be used for pumping;
      — If the wind resource is lower than the expected demand, the difference will be covered by hydraulic production;
      — Under high reservoir scenarios, the combined plant will cover up to 100% of electricity demand; and
      — Under low reservoir scenarios, the combined plant will cover part of the electricity demand.

      Following this strategy, a production study has been carried out for the hybrid hydro-wind plant. The results obtained are that total demand on the island is 47.4 GWh. Available wind energy is 49.6 GWh. Wind energy that can reliably be produced during periods of demand is 25 GWh, with 9.2 GWh for pumping and 1.8 GWh for synchronous compensation. Hydroelectric production is expected to be 5.6 GWh, and in the end the hydro-wind plant is expected to provide 30.6 GWh during periods of demand, for a total of 64.56% of total energy needed for the island.

      But so far the hydro-wind plant has provided only about 30% of the island’s energy. Where did the study go wrong?

      First, it overestimated wind generation. Operating experience now shows that the wind at GdV doesn’t blow often enough or hard enough to achieve 30.6GWh of annual wind + hydro output. So one has to assume either the engineers were working with inadequate and/or inaccurate historic wind records or they ignored or misinterpreted the records they did have.

      Second, no allowance was made for wind power wastage caused by grid stability constraints, which was recognized as a potential problem at the time (see link below) and has since turned out to be one.

      Third, the naive comments about how pumping will be used to fill demand during low wind periods etc. indicate that no serious attempt was made to calculate how much storage would actually be needed to do this. It just seems to have been assumed that the reservoirs would be large enough.

      Fourth, no allowance was made for off-grid energy used for irrigation pumping.

      Hubert, I’ve seen a lot of engineering studies carried out by competent engineers which conclude that the project concept as endorsed by management is sound whether it is or not, and I’m sure you have too. I suspect that this may be another one of them.

      • Flocard says:

        I am not disputing anything in your comment. Still ..

        How could these engineers be so wrong at the start ? It is hard to believe. For a company like ENDESA, GdV is a small project which its engineers must have had no difficulty to see completely through. Were they asked to shut up by the direction of ENDESA or REE ? It is certainly the case that the ecological image provided by the project must have appealed not only to the local government the Spanish government but also to ENDESA which is bound to use it in its communication.

        The wind data must have been availbale from long ago. In addition electric engineers working either for REE or ENDESA (whose diesel plant provided electric energy and grid stability well before GdV existed) must have been aware of the constraints imposed by grid stability.

        Did the financial constraints associated to the civil engineering of the reservoirs lead to an already too costly (82M€) but still insufficient water storage system ? At that point could the strategy have been the following : let us make the most in communication terms as long as it remains possible and let us make sure we won’t loose money. ? Even if at one point the other two partners realize that they have been selling to the world a project that would never achieve their sale pitch, at least they would be satisfied that they earn a lot of money from the GdV gold mine. It certainly will be a strong argument in future elections on the island. At one point for citizens money is more important than a failed dream.

        May be the engineers realized as the project was developping that the best they could achieve was to recover the investment as quickly as possible before the thruth would become common knowledge. At the present rate, it seems that the initial investment (46M€) will be reimbursed in six years while the contract has been signed for 20 years. May be they will change their mangement strategy of GdV once they have made sure that they got all their money back ?

        Knowing that the project as advertised would fail it became important to prepare a wording of the contract which at no point correlates payments made to GdV to reaching or getting even close to autosufficiency. While the Cabilde of El-Hierro was left to maintain alive the fiction the ENDESA engineers help their financial department prepare a contract which completely changed the nature of the project.so that GdV would be less paid for the energy it produced (as you say 30.6 % of the electric demand in the last six months of 2015) than for a potential service which would be maximized if the lower reservoir was remaining empty (given the difference in volume of the two reservoirs the service to grid stability is POTENTIALLY maximal when the lower reservoir is left empty and only replenished – without production of hydraulic energy – when there is an excess of wind to be used).

        I have a hard time thinking that the Spanish engineers were not competent enough to see what people like us have understood from a minimal amount of data – not provided by GdV it is true but by REE -.

        On the other hand I am willing to believe that these engineers were asked to keep quiet just as you can be sure that there will be no official statement from REE as to the real performance of GdV (it is my experience from France and RTE that the grid management is never going to say anything against renewables as it is not politically correct to do so). REE and in France RTE protect themselves by openly providing data knowing that these data will be ignored by the vast majority (>99.9 %) of people writing on the subject.

        • Roger Andrews says:

          Hubert: A few quotes from GdV’s project writeup:


          The final aim of the project is to cover the island’s consumption needs with energy from renewable sources. (note: this is the “final aim”, with no time frame for achieving it specified).

          With the hydro-wind plant, an intermittent energy source can be transformed into a controlled constant electrical supply, thus optimising the use of wind energy. In this way, the thermal plant operates as a backup by way of reserve, only during periods when there is an absence of wind, minimising the consumption of fossil fuels. (note: fossil fuel backup is still needed)

          the use of renewable energy ….. has the inconvenience of affecting the stability of the electrical system, especially when wind energy, which is difficult to manage, is used. (They knew about the problem)

          The control system will regulate the operation of the set in such a way that the supply is guaranteed, during adequate conditions, to maintain the stability of the distribution network. (But the solution hasn’t worked).

          Based on these quotes and others like them it seems to me that GdV’s engineers were generally aware of the project’s limitations but were swamped by the worldwide “green euphoria” it generated.

          What would have happened had they concluded that renewable energy from GdV would now be supplying only a third of El Hierro’s electricity needs and that it would never be capable of supplying all of them? During my career as a mining consultant I was fired more than once for telling a client that his project was a dog.

          • Flocard says:

            I agree that engineers may lie, most of the time by omission (another technique is to use a conditionnal knowing that media will transform into an indicative or a future knowing that media will make it into a present) but if really pushed by the commercial department or even higher in their firm they may even serve outright lies to the media. It is part of their job as employees. This does not mean that they are not competent and did’nt foresee the problems and the limitations of the project.

            For me the terms of the contract the consortium – in my opinion ENDESA – negotiated with the Spanish government is a good sign (for me convincing) that they knew GdV would never deliver the promises. So they wrote the contract it so that at least the financial interests of their electric firm were safeguardred. There are good signs that it is indeed.

            To establish the final accounting it would also be good to know how much is paid the kWh hour produced by the diesel-fired plant which has covered nearly 70 % of demand over the last six months. (how much money is lost by the diesel plant owned 100 % by ENDESA for every kWh produced by GdV that ENDESA only owns at a 30 % level)

          • To establish the final accounting it would also be good to know how much is paid the kWh hour produced by the diesel-fired plant which has covered nearly 70 % of demand over the last six months. (how much money is lost by the diesel plant owned 100 % by ENDESA for every kWh produced by GdV that ENDESA only owns at a 30 % level)

            Hubert, I have no way of knowing. But the following calculations may be of interest:

            In 2015 renewable energy from GdV supplied 8.64 million kWh that would otherwise have been generated by diesel to the El Hierro grid. So because of GdV Endesa lost the profits from the sale of 8.64 million kWh of diesel power.

            But this was offset by Endesa’s 30% share of GdV’s 2015 income, which works out to 0,3 * 7 million = 2.1 million euros. I would guess that this is considerably more than the profit Endesa would have made by selling 8.64 million kWh of diesel power to the grid.

          • Jose A. says:

            Probably you’ve already read it but back in 2014 when the plant started to work a couple of engineers that worked on the project were quite critical with the way it was portrayed in the media. It’s worth reading.

            Central Hidroeólica de El Hierro: Una visión crítica

          • Flocard says:

            Thank you. A very interesting text indeed. Very lucid.
            They predict a maximum renewable fraction at 55 % when no conditions are imposed on grid stability. Using the wind and demand data of the last six months, one finds a maximum at 46 %. Pretty close really.
            What they do not say because they stick to technical comments and don’t consider the real financial aspects (contract signed with the Spanish state) is that one should expect even lower renewable fraction such as the 30 % observed over the last six months.
            They signed as engineers of GdV. That’s even more remarkable. Are they still on the staff ?

          • Roger Andrews says:

            Hubert: The footnotes at the end of the article indicate that they are no longer with the project.

            (*) Sergio González Martín. Ingeniero de Caminos, Canales y Puertos. Jefe de Infraestructuras de Gorona del Viento (2009-2013).

            (**) Juan Lorenzo Falcón Domínguez. Ingeniero Industrial Jefe de Explotación de Gorona del Viento (2008-2012).

    • abetancort says:

      That’s what happens when government tries to play the role of the invisible hand… It simply generates ineffective and inefficient “arrangements” that cost the taxpayers (EU and Spanish) more than if they had otherwise let the market to its own devices.

      • David Walters says:

        Abatancourt…that is a-historical nonsense. None of these large projects would be possible without gov’t intervention. Capitalists won’t invest without the risk at least being partially covered. There isn’t a large civil engineering project in the world that could ever have been built without some intervention. The entire economic growth of the United States, for example, during it’s period of largest growth, say 1790 through 1830…was based on the huge intervention of the tariff, aimed at mostly British attempts to foist not the Americans, “Free trade”.

        It’s a-historical to argue for a 100% “let the market” decided.

        • abetancort says:

          I’m sorry to let you know that you know that you assumptions are a fallacy, although well extended and entrenched in Europe.

          Large projects, outside the fields of basic science research, don’t need of direct government intervention to happen. The government role is setting the right incentives from an strategicly point of view and let the invisible hand play the tactics. When governments pretend to go from its strategic role in the economy to direct intervention in the tactical plays this is what usually happens.

          We can use as examples Tesla Motors and SpaceX cases, the US government decided on some medium and long term goals for electric green cars and space shuttling, established the incentives, the same ones for all players, and let the invisible hand play…

          In the electric car field some private projects went belly up, Tesla is delivering more than it was expected both in quantity, quality, the change of the model of car ownership while diversified in other unexpected fields related to Green Power, the traditional car manufacturers are being pushed down this road as the perceive the real threat of new the incumbents, new companies are being born today of wich some will succeed and some will fail.

          The strategy to change space shuttling (as a step to lower the direct government intervention in the making and manning of space vehicles) from NASA to a market economy where more than few players are working their butts out to make it more efficient while retaining reliability, has already yielded companies that are making it, some that didn’t make the cut, a few are trying to enter the market, but above all it has delivered advances that have the potential to change how far (is USD) is that last frontier.

          That’s does not negates the fact that Defense Programs, where neither money or sustainability is no objection, yield advances in multiple areas of knowledge… but the objectives of those expenditure are primarily “Bragging Rights”, secondary but much more important are the long term sustainability of an “Empire” and with it the economic returns.

          • David Walters says:

            What I’m saying still stands. Without the massive nationalization of the energy sector in France, they never would of completed their massive conversion to nuclear. Even in the US the massive intervention and huge subsidies in R&D for nuclear assured the development of nuclear here. Every dam project ever built in the US and Canada was accomplished though direct gov’t financing and/or ownership.

            This is true throughout US history and most other histories: from the rail roads to the Federal dam projects to the highway system to flood control and waterways. And the list is endless. The a-historical “liberatarian” perspective defies how developing big capital projects took place.

            Space-X and Tesla are interesting and exceptions, though commodity production of automobiles has always been more or less private financing and organization (though if you investigate the massive loans to Tesla and the huge tax advantages from the gov’t you might be surprised). Space-X is being subsidized by guaranteed markets from one customer. Even the owner of Space-X concedes that without the massive almost trillion dollar R&D project called “NASA” they never would of been able to establish the company. But they are pretty exceptional. Without out the US taxpayer, Space-X would never exist…they are the ones to pay the bills.

            The future of nuclear energy or, for that matter, any energy source, the importance of entrepreneurial initiative notwithstanding, won’t exist without huge gov’t financing and regulations. And that’s a good thing, not a bad thing.

  4. David McCrindle says:

    It seems to me that they have made things more complicated by mixing up the integrated renewable system with the water supply system. It will therefore never be a true test of the viability of the renewable energy system.

    Years ago the Japanese were looking at salt water pump storage systems where the bottom reservoir was the sea – only one reservoir to build. Is anyone still looking at that as part of an integrated renewable system?

  5. Sorry, but there is no deselination plant at all. It was canceled due to cost concerns.

    • Roger Andrews says:

      Andreas; Do you have a link for that?

      • Only a german language one – in german language Wikipedia (not in the english version). However, have a look at your own comment for the last El Hierro update (Oct, 2nd: “La Central Hidroeólica no cuenta con desaladora asociada”). Your translation is correct.
        So the opinion (of whoever), that their priority must have been desalination cannot be correct.

  6. And btw, thanks for your lucid analysis – which is, roughly speaking, understandable even for non technicians like me. I appreciate it very much !

  7. David Walters says:

    Fascinating essay and, commentary as well.

    I think we have to recognize some limitations in this scenario:

    1. it is an island. Thus not part of any regional or national grid.
    2. The typography of the island limits the pump storage. Pump storage is rare option and can’t be used in 99% of cases since you need to have those reservoir (or potential ones) available. In that pump storage is thus not an option in 99% of the worlds cases, it is an extra bonus that should of helped the islanders maintain their grid…clearly it did not. BTW…what happens to the level in the reservoir during droughts? I’m curious.
    3. Was their no roof top solar? I’m just curious about that since Spain is such a big solar country.

    But I think this goes to analysis put forward by the essayist: 100% renewables is a pipe dream.

    • abetancort says:

      I think they got the Open West Atlantic Ocean from the western tip of el Hierro just until Haiti (near the US) washing 24/7/365 almost 180° its shoreline. Maybe they could have invested that money in becoming experts on how to harness that energy instead of wasting it in learning that doing so consciously will make **_”You think today was a happy day, but tomorrow you regret that same day because now it only makes you feel sorrow”_**.

  8. Wow. You know more about this project than anyone who actually lives in this country. Great work.

    I once tried to find out key details about this project but as often happens googling you find mostly PR fluff. In fact this summer they reported that they had gone 100% renewable!

    Although it’s true that for some days wind was contributing nominally 100% of demand, even then substantial diesel consumption remained, as much of wind was diverted to pumping. So to use language like ‘demostramos que sí se puede alcanzar el 100% sólo con fuentes limpias en un sistema aislado, potenciar las renovables y dejar, con ello, de consumir combustibles fósiles’ is massively misleading.

    And since summer wind generation has collapsed. Little press coverage of that.

    PS: I’ve given up with the media at this point, but really, 100% of electricity is not 100% of energy.

    • Alberto:

      GdV did in fact go 100% renewable – for two hours on August 8. The event was probably orchestrated for publicity purposes and as you point out proved nothing.

      One interesting fact is that El Hierro has dropped almost entirely out of the news in the last few months. The only sources that still carry reports on it are local newspapers, none of which are prepared to admit that things maybe aren’t going as planned:




      • Flocard says:

        You write
        “But this was offset by Endesa’s 30% share of GdV’s 2015 income, which works out to 0,3 * 7 million = 2.1 million euros. I would guess that this is considerably more than the profit Endesa would have made by selling 8.64 million kWh of diesel power to the grid.

        In 2010 I wrote an anlysis of the electric situation in Guadeloupe, the only French island of the Caraïbes (about the latitude of El-Hierro) which as a significant wind power (>25 MW and trade winds) an already too large solar PV power (it has to be turned off at times to maintain stability) some geothermal power (there is a volcano) and some seasonal biopower (burning remnants of suger cane industry) and still gets more than 90 % of its electricity from a diesel-fired plant.

        The price paid for diesel-produced electricity in Guadeloupe was at that time above 120 €/MWh. Applied to your figure of 8640 MWh it gives a 1.04M€ lost income for ENDESA. From the point of view of ENDESA one should also take into account that the efficiency of a diesel plant coupled to a wind park is reduced. There is no gain on personnel and maintenance at the diesel plant which has to be available 100 % of the time. In addition ENDESA has to recuperate its investment of 46 x 0.3= 13.8M€ plus its share of the operational costs of GdV (personnel + maintenance + desalinated water to compensate evaporation).

        ENDESA probably made sure that the contract would at least make it get even. In my opinion the real financial winners in the long term (the gold mine) are the other two partners : the Cabildo of El-Hierro and the local public technical institute.It is a very wise investment of local tax money (at the expense of course of tax money paid by the rest of Spain, not to mention Europe which contributed to the 36M€ of subvention). Who says that all politicians are stupid ?

        It was crucial for ENDESA to be a partner in GdV in order not to loose money. Of course it was also crucial for GdV to have ENDESA as a partner since only ENDESA has the adequate technical competence.

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  10. Flocard says:

    You wrote :
    “GdV did in fact go 100% renewable – for two hours on August 8. The event was probably orchestrated for publicity purposes and as you point out proved nothing.”

    In my opinion these two hours 1/2h on wind solely and 1h and a half on a mix where hydro part was growing could also be a commisioning test requested by REE Although I don’t know for sure I suspect that it is REE that will pay the 7M€ to GdV for 2015. Who REE will turn to to get reimbursed I do not know. Only in the end. we know that the sum will be added to the national debt which the Spanish state is building on account of its renewable policy (already close to 25 billion €).

    Indeed since GdV is paid mostly for the stability it could, be asked to offer to the grid, some minimal demonstration that it can do it has to be made. Thus I suspect that from time to time we are going to see the repetitions of such short tests at least once a year.

    They may even try to make them longer every year if only to revive the enthousiasm of the media which no doubt will have a complete coverage of these “miraculous” minutes as El Pais characterized them last august

  11. Bernard Durand says:

    Roger, is the diesel consumption by kWh produced, on an annual average basis, lower now than before the implementation of renewables?

  12. stone100 says:

    Might liquid air be a possible energy storage option for them?
    I attempted guestimates at volume requirements for renewable energy storage and got
    Wood pellets 3200kWh/m^3 then perhaps 33% efficiency of conversion to electricity but better to space heating.

    liquid air 80kWh/m^3

    Water at the top of Dinorwig pumped storage facility:- 9GWh from 7million m^3 =1.3kWh/m^3

  13. Bernard Durand says:

    stone 100, what is the energy efficiency of a liquid air storage, i.e. if you need 100 kWh of electricity from the grid to produce liquid air, how many of those can you reintroduce in the grid ?

    • David Walters says:

      Bernad brings up the biggest problem with storage tech. What you put into the storage you don’t send into the grid. Solar Thermal plants (CSP) have this huge problem because they have to take the *majority* of their generation at any one time and store it in molten salt. This means it doesn’t go to the grid in day time and thus their capacity factor falls hugely. This is why the cost per MWhr of these hugely wasteful systems are so high, higher than nuclear. A 100MW CSP plant all of a sudden only can send about 30MW to the grid because 70MW is used as heat storage. Not good. And…if there are more than so many hours of cloud coverage, then this becomes impossible.

    • stone100 says:

      On page 11 of http://www.lowcarbonfutures.org/sites/default/files/potential-guide.pdf it says “At commercial scale (10-250MW), LAES is expected to have a ‘round trip’ efficiency of 60%.”
      I’ve seen somewhere that this might be improved further if liquid air turbines combine with using waste heat from a thermal powerstation (eg biomass or perhaps nuclear).

  14. stone100 says:

    Projects such as this (necessarily) get lots of government (and EU) support. Given that, I think they ought to have an obligation to disclose a lot of detailed information as to how and why things pan out as they do. Everyone needs to learn from this. There seem to be mysteries about why diesel power is used so much even when the wind is blowing. It shouldn’t be left to speculation as to why that is the case. Could future energy project grants be made conditional on there being more thorough disclosure?

  15. steven F says:

    “A fundamental question that arises here is whether El Hierro is an isolated case or whether other grids could also be destabilized by high levels of wind power. If so this could pose another serious obstacle to the expansion of renewable energy. Comments from experts are solicited.”

    Take a look at Kodak island. They upgraded and old hydro facility and add 6 GE 1.5MW wind turbines. Since 2014 they have been routinely generating 99% of there power from renewables.

    “It sounds to me as if someone needs to invent a kind of flywheel to smooth out the minute to minute variations in wind power that destabilize the grid.”

    Kodak did that due to the installation of a new crane at the sea port.


    Also Costa Rica has also achieved 99% renewable using hydro, wind, and geothermal energy.


    So why is El Hierro having problems? Perhaps they are in a drought and don”t have enough water to run the storage system at design capacity. It appears the island has not gotten any rain since November and local farms have been forced to irrigate there potato crop.


    • Flocard says:

      I suspect that Costa Rica uses mostly hydro and geothermal energy essentially just as Iceland. It is therefore not remarkable. If a lot of renewable of this type is availbale why not use it. It does not help countries which do not possess such hydro or geothermal resources.

      On top of a large production of these types of energy which use turbines with inertia which also provide stability to the grid one can certainly introduce a small fraction of wind or solar.

      I suspect that Kodak island production is dominated by hydro. Fine for them then. Are data such as those provided by REE for El-Hierro available for Kodak island ?

      The point of El Hierro is that the hydro plant is meant to generate the stability to compensate the instability generated by the wind turbines.That it can’t do.

      The lack of rain on El Hierro is not a problem really. To compensate evaporation in the two reservoirs it is enough to inject about 160m3/day well below the capacity of the desalination plants on the island (about 9000m3/day).

      The real point is that according to the contract GdV signed with the Spanish government it has no incentive to produce electric energy. For its 2015 operation GdV will be paid 7M€ out of which only 0.118M€ correspond to the electricity produced although in the last six months GdV produced 30% of the demand. GdV is not paid for the electricity it produces.

      Reading the contract is the key to understanding why GdV is managed as it is. I suspect the terms of the contract were chosen by ENDESA to make sure that it would not lose money. taking into account that there will be money lost in the operation of the diesel-plant which have to be maintained in a state of readiness 100 % of the time.

    • Take a look at Kodak island. They upgraded and old hydro facility and add 6 GE 1.5MW wind turbines. Since 2014 they have been routinely generating 99% of there power from renewables.

      This is not hard to do when 82% of the power comes from the hydro plant. (And it’s Kodiak, not Kodak).

      Also Costa Rica has also achieved 99% renewable using hydro, wind, and geothermal energy.

      Also not hard to do when 83% of the renewable energy comes from hydro and geothermal.

      Perhaps they are in a drought and don”t have enough water to run the storage system at design capacity.
      GdV uses desalinated sea water. As far as I know the sea is still there.

  16. steven F says:

    “GdV uses desalinated sea water. As far as I know the sea is still there.”

    The desalination plant has an output of 3 million gallons a day. The lower reservoir has a capacity of about 40 million gallons. The upper reservoir is about 5 times the capacity of lower reservoir.

    Most of Desalination plant output goes to drinking and irrigation. The little that is left goes into storage. The Desalination plant would need months to fill the lower reservoir enough to allow energy to be stored. The Desalination plant is also consuming about 20% of the power output.


    • Flocard says:

      As I wrote before, once the reservoirs of Gorona del Viento are filled if no water is sent for irrigation there is only a need to compensate evaporation which according to the documents published by the El-Hierro water council calculation amounts to about 160 m3/day. well below the capacity of the desalination plants of the island. Water is not a problem.
      Your calculation only corresponds to the first step and probably explains why it took almost a full year before one could see something coming out of Gorona del Viento. it does not explain what could be witnessed in the last six months.

    • Here is a Google street view dated July 2012 of the pipeline that carries desal water to GdV being installed:

      How much water could a pipeline that large deliver? I would think quite a lot.

      • sod says:

        Those pipelines are tiny. they look like the gas pipelines that we currently get put along our street.

        I have been hiking a lot this year and i have been to several water plants a storage lakes. A relevant water pipeline would have 3 to 8 times that diameter.


        The look is also very different, to withstand the pressure.

        • Flocard says:

          Don’t you think that the dimensions of the pipes shown by Roger can very well be sufficient to compensate the evaporation, which is typically of 600M3/day, that is less than 8l/s ? Indeed that is the only amount required when GdV is operating.

          Do not forget that filling the reservoirs is done only once. It is clearly stated in the contract signed with the Spanish state (or at least it is reimbursed only once in this contract). It is said that the consortium will only get 135 000 € for that operation. To overfill the lower reservoir over a year (which is probably what happened from June 2014 to June 2015 takes a daily flow rate also of the order of 500m3/day

          In an old post Roger has given the dimensions of the pipes circulating water within GdV their diameters are 0.8m for the up-going pipe connected to a 6 MW pump and 1m.for the downgoing pipe.


        • Roger Andrews says:

          If that’s a ten-inch pipeline it has a maximum flow capacity of close to 200 l/s according to http://www.engineeringtoolbox.com/steel-pipes-flow-capacities-d_640.html

          I was hoping a hydraulic engineer might drop by and give us a professional opinion.

  17. Rainer says:

    Thank you for your knowledgeable blog. You ask the same questions as we here on the island. It simply lacks transparency.
    Perhaps another reason the loss of water in storage. It is a big problem to keep the water storage in the Canaries close.

    I am during wintertime en El Hierro and would like to send an picture of the Rockfall into the waterstorage.

    Please give me an e-mail contact.
    Thank you


    • Hola Rainer, and welcome to Energy Matters:

      Yes, we would very much like to see a photo of the rockfall into the water storage. If you could send it in a recognized format I could bring it up here on the blog. I’ve sent you my email address so you can send it directly to me if you prefer. Any recent pictures you might have of reservoir water levels would also be very helpful.

      The rockfall, which I don’t think was reported anywhere, adds to the list of things we don’t know about GdV, and we would appreciate any other information you could supply from your perspective as an island resident. I look forward to hearing back from you.

  18. Rainer says:

    Thank you for your knowledgeable blog. They ask the same questions as we here on the island. It simply lacks transparency.
    Maybe another reason the loss of water in storage.
    It is a big problem to keep the water storage in the Canaries close.

    I would love to send a picture of the stone shock. Please send me an e-Mai address.

  19. Emilio Hernández says:

    Quite interesting to read about Gorona and the entire project people living outside El Hierro because it is another point of view on a project that begins to raise questions , to me at least you do, live on the island , I know the project from the first day and I would like to know some things, like how much energy is spent on pumping water .
    I read the local press not ready to talk about a 100 % No , I am a local journalist , and every day we know a little more and is increasingly obvious that this will not happen , the full 100 %

    • Flocard says:

      Dear Mr. Fernandez
      Would it be possible to get in touch directly with you: my e-address is

      • Euan Mearns says:

        This is an interesting development. Among all the controversial topics we cover where diverse opinions abound, the role of the media in adopting an extreme view is often not helpful in bringing clarity to the debate. The media tends to brainwash public into particular beliefs that when repeated often enough become truths.

        In my opinion there are not nearly enough professionals willing to stick their head above the parapet and say, “hey wait a minute, this is not how I see things or how things actually are”.

        • Roger Andrews says:

          The problem isn’t so much a brainwashed public. It’s brainwashed politicians:

          The Board of the Island Water Council has approved the construction of the Chira-Soria hydroelectric project, to be operated by the Spanish Electricity Network (REE). The proposal, which was initially passed in 2011, is to complete the project within four years from the start of its construction, which will allow Gran Canaria to gain up to 70% of its energy needs through renewable energies. The basic premise is to use these two massive reservoirs to store potential energy by pumping water from one to the other using renewable energy as a primary source. Once the energy is stored it can be released from the higher reservoir generating power on demand, much in the same way as is now in operation on the island of El Hierro which last year became the world’s first island capable of carbon neutral energy production.


          • Euan Mearns says:

            Keep on the case Roger. Mini traffic spike on El Hierro today. Don’t know how that happens. I guess the Canaries have a local daily newspaper. Send a letter in Spanish and publish it here in Spanish and English. It takes an hour to write a 300 word letter. Find the Editor and email – job done!

    • Roger Andrews says:

      Rainer: Thank you. This article is interesting:


      So is the photo it contains.

      Could you find out on which day the picture was taken?

      The latest approach seems to be to present GdV’s poor performance as a victory:

      Si bien las previsiones iniciales eran cautas, y se pensaba en una integración paulatina de energía renovable en red, llegando, durante los primeros meses, a alcanzar cuotas del 30% de abastecimiento de demanda con fuentes limpias, la Central Hidroeólica superó las expectativas y ya durante los meses de julio y agosto se situó en valores medios del 49 y 55% de cobertura mensual de la demanda eléctrica de El Hierro, llegando a frecuentes puntas superiores al 80%, algo hasta ahora impensable en sistemas aislados, caracterizados por la vulnerabilidad de sus redes.

      “If the initial projections were cautious, contemplating as they did a gradual integration of renewable energy into the grid, the success of GdV in the first months in supplying 30% of demand with clean energy exceeded expectations, and during July and August average monthly values of 49 and 55% were achieved, sometimes reaching levels of above 80%, until now something unthinkable in isolated systems characterized by the vulnerablity of their grids.”

      • Jose A. says:

        The photo is from before the inauguration, it is in the photo reel of this 2014 article:


        • Roger Andrews says:

          Thanks Jose. That answers that question.

          • Bernard Durand says:

            Roger, you did a great job for El-Hierro. You have also looked on the Case of Eigg in Scotland. Why not to spend some time on the case of Samso in Denmark, and Utsira in Norway? This would make it possible to constitute a file, with a summary for media and politicians, entitled” 4 attempts for going 100% renewable electricity, four failures”, or something like that.

          • Euan Mearns says:

            Are there data available? Given that Norway as a whole is basically 100% hydro, it would be failure indeed if Utsira failed.

          • Roger Andrews says:

            I have a number of stand-alone island renewable projects on my evaluation short list, including Kodiak Island, Bonaire, Galapagos, Tokelau, Fair Isle and King Island, Tasmania. King Island, which reportedly powered itself with a combination of wind and storage for 33 continuous days last year, is the most interesting. The problem is the lack of published grid data for these projects. I’ve written to Hydro Tasmania requesting data for King Island but have yet to receive a reply.

            Samso is not a stand alone system because it’s connected to the mainland with a cable that supplies power to the island when the wind doesn’t blow. But Utsira looks interesting. I’ll add it to the list.

  20. Bernard Durand says:

    Roger, for Samso, it is very useful to demonstrate with real data that it is not a self-alone system, and just a wind turbines plant with excess capacity regarding the population of the island and selling power to make money from subsidies, just because it is one of the most quoted in the media,green blogs and journals as a self-alone system. Samso is regularly celebrated at the french TV as a miracle.
    For Utsira I asked to a Norwegian friend if he could find the right person at Statoil. I hope there is one.

    • Bernard: I can find no recent articles on the Utsira plant. Is it still running?

      • Bernard Durand says:

        Roger, it was stopped in 2011 I believe, 4 years after starting the project; It is very difficult to find serious information on the web. Therefore I am trying to approach Statoil via a friend.
        Did you find those 2 :Handrigan, J.P., 2013 : Case study n°1 : Hydro : From Utsira to Future Energy Solutions ; Memorial University of Newfoundland-Marine Institute, 14 April 14, 2013.
        4- IPHE Renewable Hydrogen Report 2011: Utsira Wind Power and Hydrogen Plant, Utsira Island, Norway, March 2011
        May be could you join Pr. Handrigan?

        • Thanks Bernard. Yes, I have the references. Utsira is a particularly interesting case study because it used hydrogen storage to smooth out wind fluctuations. I guess it was shut down because of cost.

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  22. Edward Greisch says:

    Reference “SPP WITF Wind Integration Study” Prepared By:
    Charles River Associates [CRA], 200 Clarendon Street T-33 Boston, Massachusetts 02116
    Date: January 4, 2010 CRA Project No. D14422


    Wind power is so intermittent that even in the US, adding wind to the grid causes overloads that destroy transformers, power lines and other expensive things. You can’t blame the electric company for not wanting to destroy its infrastructure and equipment by using wind power. The replacement infrastructure has to be a lot bigger and stronger than the original to withstand what wind power does. Things like big transformers are generally not immediately available. They are built on order. If the designers did not know all of this in the first place, they underdesigned the system. Trying to use wind and solar power on a grid is foolish. If you don’t want to use fossil fuels, the only option is nuclear.

    There is never enough energy storage to make wind and solar work.

  23. Edward Greisch says:

    Correction: There is almost never enough energy storage avalable.

  24. Rainer says:

    GDV is running stand alone without diesel since 31.01.2016 5:30 local time until????
    That proofs that the Diesel are not necessary for stabilizing the Grid. Stabilizing is possible with pumping ore with Hydro power generation. Why it was not done earlier, that is the question.

  25. Rainer says:

    Here you will get always realtime data.

  26. Rainer says:

    Realtime wind Airport Valverde -update manuel only -:
    Now 12 Hours without diesel
    of course:
    This 12 hours only proofs the no need of diesel at the fact of stabilizing the red.
    This winter on the Island was all together like a summer with nearly no wind at all.
    I myself as Tourist liked it anyway.
    We will see what will happen next.

    • sod says:

      Thanks for all the updates.

      I agree with the analysis in the original post above. To run on 100% renewables, they will need plenty of time with wind covering 100% of demand alone.

      If they can not do that, it will not work over any extended period of time.

      Is there a huge jump between 11:50 and 12:10 from wind to hydro or am i still looking at false numbers?

      • According to REE the diesel plant was off between 5.40 and 21.40. Sixteen hours exactly, and press announcements prepared beforehand …..

        The abrupt change from wind to hydro around 12.00 duplicates what happened during the 2-hour period of 100% RE generation on August 9 last year. I suspect it had to do with grid stability but don’t know for sure.

        GdV underwent a year of pre-production testing between late June 2014 and late June 20i5. Since then it’s supposedly been in full operation.

  27. Emilio Hernández says:

    We have in El Hierro today, and in GdV the correct wind to work at 100%

    • Rainer says:

      Dear Senor Hernadez,
      it looks like you and i are living in two different galaxis. On El Hierro i stay right now it is not the correct wind since exactly 12:00. Only with the help of hydropower it was possible to work without diesel.
      But anyway i am lucky that you setting your point here in this blog.
      Are you a member of staff of Gorona del Viento?

      • Euan Mearns says:

        So how long did they run 100% wind+hydro? I see they have the diesels back on doing most of the work Monday morning.

        • Rainer says:

          Like Roger said and i saw also::
          According to REE the diesel plant was off between 5.40 and 21.40. Sixteen hours exactly, and press announcements prepared beforehand

  28. Emilio Hernández says:

    When I talk about the Central Hidroéolica (Gorona del Viento its the company – Cabildo – Gobierno de Canarias – Unelco Endesa are the owners, Cabildo 66 % after the capital
    capital increase, pay this month 3M €, the second part of the 6 M €, so GdV get money to pay)
    when I speak of the wind and the conditions they were talking about perfect to move the turbines and pumping water, the plant is a combination of water and wind, yesterday in valverde there were ideal wind conditions reach that 100%, and Im not member of Gorona or Cabildo, Im local journalist, that´s all. And if you ask me about that 100%, its an exceptional situation.


  29. Rainer says:

    Dear Senor Hernandez,
    No doubt, 16 hour without diesel was really yesterday made by GDV.
    It proofed that GDV can deliver a net by its own. That is something, but it was build to make this job.
    That is something but not a 100% without diesel.
    100% without diesel is all year long without diesel. In the first 6 Month of production it was poor 30,x %.
    The aim and the promise of GDV to the people of ElHierro is 100% all year long.
    Then there was yesterday the promise to make 10MW with the 5 windmills.
    It was only 6,5 MW
    It looks like only 3 windmills are working.
    You as journalist can do us a BIG favor because our questions never get answers from GDV:
    Ask GDV if all windmills are working.
    ASK GDV to publish all data so we do not only have the database of REE.
    We miss data of the wind exactly at GDV, data of the 5 single windmills, data of the Upper and lower storage, data of the water GDV gets from the Consejo de Aqua.
    Transparenzia produce confidencia.
    Data really would help.
    Todo el Mundo ver a El Hierro

    • Emilio Hernández says:

      Yo ask me about windmills, today at 10:45 local time (GMT) the 5 windmills were working at the same time

      • Rainer says:

        Hello Snr Hernandez,
        i do not have any doubt that the windmills are turning around. I can see it myself when driving to airport or harbour.
        I still doubt that all 5 windmills are working with all possible power. Caused off lack of data of GDV we only can be shure when is good wind. The maximum possible Power of the 5 Mills is 11,5 MW.
        The maximum produced is 7 MW in February 2016 and 7,5 MW in August 2015. At least one time 10MW we need for the proof. Of course only possible if we will have nearly 15 m/s wind.

  30. Rainer says:

    here a surprise:
    there is a newspaper en El Hierro which have a little other information then the others:

  31. Emilio Hernández says:

    There are so many questions about this proyect, the first. 100% at 100% of time?? the answer is clear: No, without any doubt.
    the answers, the good ones , take time to answer because its important to be well informed.

    But I can answer you one, some times i take the Goronas´s press releases

    • Euan Mearns says:

      I’ve added a graphic link in the right margin to the Live El Hierro grid. The diesels are back in control tonight. Maybe I should change the image? Any suggestions?

      I’m sure Roger is working on this. but it will be interesting to see the proportion of wind and hydro in the 100% period. Hydro provides synchronous supply, wind not. Electrical engineering associates tell me that wind needs “a lot” of synchronous supply for it to operate on a grid. But perhaps a small island grid is different.

      • Rainer says:

        To see the 100%:
        Just change the date down on the page and play around with the cursor on the graph to change time

    • Rainer says:

      Thank you very much for cooperation.
      Every answer will help

  32. Rainer says:

    Maybe of interest for right margin to:
    German Power mix, luckily more wind right now than en El Hierro -over 50% regenerative power right now

    • sod says:

      It is much easier to integrate 30% in a grid with many outside connection than to get close to 100% on an Island. We had significantly stormy weather here in Germany over the last few days.

      The obvious problem of El Hierro is, that many days should be 100% (+!!!) wind.

      The huge jumps from wind to hydro show some serious problem.

      There is just too little wind power in their system and they obviously need it to spread out more. The obvious advice would also be to add plenty of solar PV to the mix, just to get a more diverse system.

      The most important information that we need now is this: Do they simply have too little wind power or is this mainly a grid stability problem (and extra wind would not help with that)?

      • Rainer says:

        With the hydrosystem de Gorona del Viento is possible to pump and at the same time run the hydraulic generators (2 pipes). That is called Hydrailic shortcircuit and can be used for stabilizing the net.
        But we only have the summery of hydraulic energy data.
        Of course you need wind. And all wind generators really producing power, what i doubt

      • Euan Mearns says:

        They need more wind capacity and they need A LOT more storage. But hey price is not object. The people will pay.

    • Euan Mearns says:

      Done – and quite artistic too 🙂

  33. Rainer says:

    Here the last comments of Gorona Del Viento o should we say the good weather sunday plant (18 hours 100% on sundays).
    Here en El Hierro it really is another world with other timelines we can imagine.
    Years to late, 1 year testing time. 7 month production time which now is unnamed to testing time. I still have hope that the plant will be optimezed this year, or am I a hopeless optimist?
    But anyway here the link:

  34. Rainer says:

    The actual information of Roger now in another place
    The same comment ther is, of course nonesense

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