El Hierro – and the water goes round and round ……

In my last post on Gorona del Viento (GdV) I brought comments to a close with the portentous words: “new information that greatly complicates the picture has come to my attention and we are not going to get much farther until this issue is resolved.”

Well, it turns out that this was a bit of an overreaction on my part. The new information in fact confirms what we were thinking all along – that GdV is indeed pumping water uphill and allowing it to flow back down again without passing through the hydro turbines. Here’s a brief review of the evidence:

We begin with the Red Eléctrica de España (REE) “hydro” values. These tell us how much energy has been consumed pumping water up from the Lower to the Upper Reservoir, with negative numbers showing net pumping and positive numbers net hydro generation. Here we will look at the period between February 20 and March 10, 2016. According to the REE data some 720MWh were consumed pumping water up from the Lower to the Upper reservoir over this period, enough to lift roughly 250,000 cu m of water up the hill (Figure 1):

Figure 1: Cumulative pumping from lower to upper reservoir, February 20 to March 10, 2016

So we would expect to see a large increase in the level of the Upper Reservoir over this period, correct?

But we don’t. Here are two images of water levels in the Upper Reservoir taken by Rainer – our man on El Hierro – at 0837 on February 20 and 0902 on March 10. The water levels are essentially the same. There is no sign of the 250,000 cubic meters that according to the REE data were pumped into the Upper Reservoir over this period:

Figure 2: Changes in water level, GdV upper reservoir, February 20 to March 10, 2016. Image credits Rainer.

So where did all the water go?

Well, if it didn’t go up it must have gone back down, and according to the photos Rainer took of the Lower Reservoir on February 20 and March 10 that’s exactly where it went. (Note that the water level increases between February and March in the lower reservoir. Presumably this is because of water added from the Tamaduste desalination plant, which reportedly produces about 1,200 cu m/day, or about 25,000 cu m in 20 days, This fits the increase in water level quite closely.)

Figure 3: Water entering GdV lower reservoir, February 20 and March 10 2016. Image credits Rainer

But there’s a problem here too. Rainer’s images clearly show water flowing down, but according to the REE hydro values water was being pumped up the hill at the time. How to reconcile these contradictions? Here’s how I see it:

1. Water pumped up the hill from the Lower Reservoir does not make it to the Upper Reservoir. As soon as it gets to the Caseta de Válvulas (Valve House, ringed in yellow on the graphic below) it’s sent back down again. (According to the Spanish text the Valve House is where “pumping accumulates surplus energy and functions as a generator”, although I’m not sure exactly what that means).

Figure 3:  GdV schematic showing “Valve House”. Image credit El Mundo

2. The water flowing back downhill is metered only if it generates power in the hydro turbines, but most of it doesn’t, so it doesn’t get counted.

3. We therefore have a semi-continuous flow of water going up the hill to the Valve House and flowing back down again, wasting a lot of power but mostly without generating any.

Why do this? Because experience apparently shows that this is the best – and maybe the only – way of matching GdV generation to El Hierro demand while maintaining grid stability. Pumping is being used to “waste” surplus energy the grid can’t accept.

Here are the demand and generation data for February 20 to March 10 for reference:

Figure 4:  Balancing demand by switching wind between the grid and pumping, February 20 to March 10, 2016

Some concluding observations:

The Upper Reservoir has evidently fallen into disuse, not that it was ever used much to begin with. The Figure 5 images show no appreciable variations in water level since 2013. One speculates that there might be an unresolved water dispute between GdV and the Island’s farmers behind this, but for all the use that’s presently being made of it the Upper Reservoir might as well not be there. Another problem is that if you look carefully you will see that the three images that cover the north end of the reservoir (2, 3 and 5) all show the drain barely covered by water. So how much usable water is there in storage in the Upper Reservoir? Would anyone care to make an estimate? (The upper reservoir contains 385,000 cu m when full).

Figure 5: Date-order images of upper reservoir water levels since March 2013.

A final question is how much water is stored in the Lower Reservoir. This is an even more important point because if pumping is needed to ensure grid stability then it’s a good idea to keep the Lower Reservoir full. But Rainer’s most recent photo, taken on March 17, shows the reservoir only about a third full, i.e. containing roughly 50,000 cu m. Limited water availability may in fact explain why GdV sometimes curtails turbine output at relatively low levels, but more work would be needed to confirm this.

Figure 6: Water level in lower reservoir, March 17 2016, image credit Rainer

Finally, a big danke to Rainer for the images. Keep them coming, Rainer.

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102 Responses to El Hierro – and the water goes round and round ……

  1. Gavin D says:

    Strikes me the problem on El Hierro is not so much energy as water. They’re desperately trying to maintain grid stability with a few buckets of water that they have left.

    • botwid says:

      At this moment (6:22 2016.03.24) moment the contribution from ”Hidráulica is more than 40%.


      Tamaduste desalination plant is located in a village up in the north, 40 km from La Restinga. The Tamaduste plant distributes water in in that village, no more. Of cause the Tamaduste plant will use electricity from GdV.

      • Roger Andrews says:


        At 0620 today El Hierro’s generation mix was as follows:

        Diesel to grid 3.0 MW
        Wind to grid: 1.5 MW
        Hydro to grid: probably 0.0MW
        Wind power curtailed to maintain grid stability: 5.3MW

        REE’s graphs and pie slice diagrams can be misleading.

        Do you have any details on the Tamaduste desal plant?

    • sod says:

      This would be just great. Because then we have an obvious solution: More desalination plants, which can use the power (more or less) on demand and which produce more water from the currently wasted wind electricity.

      While at the same time it would help to bring the currently dysfunctional hydro system to a working state.

  2. botwid says:

    At this moment (6:22 2016.03.24) moment the contribution from ”Hidráulica is more than 40%

  3. Ok. Just to be clear the previous post looked at say from the yellow circle or there about to Valverde via a desal plant. We put this system in the 100 m3/h range so relatively minor.

    We are now looking at the main generating system. What is happening here is water from the lower reservoir is being pumped back up and then being allowed to flow back through a bypass around the turbine.

    Do we know the kW rating of the pumps? Or do you have the height differential so I can get a first guess of the size of these pumps.

    As for a volume estimate of the upper reservoir, I would not care to estimate. You wither need a very detailed drawing (available during construction) or a level meter and a known pumping rate when filling.

  4. Euan Mearns says:

    Roger, this is a fascinating story. It does indeed appear that the upper reservoir may have fallen out of use. The green stagnant water and constant water levels point in this direction. Loading and unloading the crater of a dormant volcano with 385,000 tonnes of water maybe wasn’t such a good idea?

    But if this is the case, where is the small amount of hydro production coming from?

    And is it not normally the case with pumped hydro that the turbines are used in reverse to pump? Water can go up or down. How is it possible in GdV to have water going both ways?

    It should also be pointed out that if the hydro part has failed, this goes down as engineering and not concept failure.

    Thanks for all the pics Rainer, it must be fun climbing up that mountain once a week 😉

    • Greg Kaan says:

      Euan, GdV installed a pumping station separate to the Peltons. The details are in the HydroWorld link in Rainer’s post above.

      I always thought that they were pumping fairly continuous amounts and varying the generation from the Peltons to stabilise and control the grid against the variable wind generation – ie continuous pumping demand and variable generation to produce the net hydro output. But the pictures of the state of the upper reservoir would appear to show that is not the case.

      • Rainer says:

        All time visiting lower storage in the time hydro was plus or minus both station have been working. Working sounds from pelton station AND from pumping station.

        • Greg Kaan says:

          Thanks for the clarification, Rainer.

          So water could be pumped up to the Caseta de Válvulas and then be allowed to flow down to the peltons and the bypass without ever reaching the upper reservoir

        • Roger Andrews says:

          To refresh everyone’s memory, the problem is that REE gives us one number for the SUM of hydro generation and pumping. So when we see minus 1 MW it could mean 1 MW of pumping and no hydro, or 2 MW of pumping and 1 MW of hydro or 1.1 MW of pumping and 0.1MW of hydro etc. etc. Maybe Rainer could get his hearing calibrated so that he can measure MW from the volume of noise 😉

          • Greg Kaan says:

            It’s easier than that, Roger. Rainer merely has to observe if the pumping noise (proxy for rate) is at a constant level in a period where the hydro output level varies

    • Roger Andrews says:

      Loading and unloading the crater of a dormant volcano with 385,000 tonnes of water maybe wasn’t such a good idea?

      It seems that they’ve not even dared to load it up yet. Looking at the rock that probably underlies the reservoir, which I suspect is probably a weak, crumbly and highly permeable collapse breccia, I’m not surprised.

      It should also be pointed out that if the hydro part has failed, this goes down as engineering and not concept failure.

      More of a concept failure I would say. The GdV reservoirs were never anywhere near large enough to sustain the Holy Grail of 100% renewables and the concept of an upper reservoir that was 2.6 times bigger than the lower reservoir never did make sense. I also suspect that there were some people who at the beginning of the project pointed out the engineering problems but who are now employed by someone else.

      • Pedro J. says:

        Roger, from a technical point of view, the project never pretend to be 100% renewable in the first place. I don’t know if you are aware of this paper from 2004

        Technical–economic analysis of wind-powered pumped hydrostorage systems. Part II: model application to the island of El Hierro http://www.sciencedirect.com/science/article/pii/S0038092X04002087

        As you can read in the abstract:

        “The results of the application of the model (developed in Part I) in El Hierro indicate that an annual renewable energy penetration of 68.40% can be achieved.”

        100% renewables is just an slogan. Actually this was pointed by two of the engineers who worked in the project at some point at Diario El Hierro, a local on-line newspaper http://www.diarioelhierro.es/t26496/pag02.asp?Id_registro=151989&BDi=INICIO&Id=26496&Md=7

        • Roger Andrews says:

          Pedro: There are literally dozens of differing pre-project accounts of what GdV was supposed to achieve in the way of percent renewables. The one you cite is one of the least useful because all the technical details are behind a paywall. The one I consider most “official” is this from both GdV and Endesa, published in 2010 after the engineering design was completed and contracts had been issued.

          El objetivo final del proyecto es que el consumo de la isla se cubra con energía procedente de fuentes renovables.

          La filosofía de funcionamiento se basa en el abastecimiento de la demanda eléctrica de la isla con fuentes renovables, garantizando la estabilidad de la red eléctrica; la central de motores diesel solamente entrará en casos excepcionales/emergencia cuando no haya ni viento ni agua suficiente para producir la energía demandada.

          • Pedro J. says:

            ” There are literally dozens of differing pre-project accounts of what GdV was supposed to achieve in the way of percent renewables.”

            But not peer-reviewed like this one, as far as I know.

            “The one you cite is one of the least useful because all the technical details are behind a paywall. ”

            Easy to solve nowadays. Just ask someone with access or give me an email to send to you a copy.

            I just meant that discussing the technical failure of the plant to cover 100% electricity demand of the island is quite out of focus.

          • Roberto: Your second link works.

            This project has now mutated into the Chira-Soria project, which I wrote a post on last year:

            I’ll just restate the conclusions:

            In summary, Chira-Soria emerges as yet another example of an ambitious renewable energy project that has no realistic chance of working simply because no one involved in the planning process seems to have realized – or is willing to admit – that it’s impossible to install the huge amount of energy storage needed to make it work. Moreover, the project is still being justified by the alleged success of the €84 million Gorona del Viento wind-hydro plant on El Hierro, which as will be discussed in the October performance update is beginning to fray at the edges after only four months of operation.

            With Chira-Soria Gran Canaria is heading down the same blind alley as El Hierro, although potentially a far more costly one. Up to €300 million is already allocated for the pumped hydro facility, and expanding existing wind and solar capacity by a factor of ten or more will raise costs to well over a billion – if wind and solar ever expand to that level, that is. Crunch time will come when Chira-Soria comes on line and its storage limitations become apparent. Will wind and solar construction grind to a halt at that point, or will it continue regardless? The only thing we can be certain of is that Gran Canaria’s fossil-fuel plants will be keeping the lights on for a long time yet.

          • The link doesn’t work

        • sod says:

          we had this discussion in an older topic already: (search the page for “100% of the time”)


          I gave this link, to a semi official leaflet, giving 80% as a real number.


          Still a false an optimistic number i think, but much more reasonable than any 100% at 100% of the time claim.

          Roger did also provide a link, but i have not seen any “official” number for the 100% for 100% claim.
          (basically some technical description should say “100% means at least over 99.5% for the average year/month)

          It is obvious, that the 100% have been overstated and that the phrase “towards 100%” often got shortened in a misleading way.

          “I just meant that discussing the technical failure of the plant to cover 100% electricity demand of the island is quite out of focus.”

          To be fair, you should read some of the older posts. Roger makes some rather good points here, showing which percentage is good without “spilling” too much wind output:


        • Greg Kaan says:

          Pedro, the following paper presented for the International Conference on Renewable Energies and Power in March 2015 states the 100% renewables goal at the start of Section 5 and also just before.


          It may well be that engineers (who are tasked with making schemes actually happen) analysed the scheme and pointed out the realistic limits of the proposal but the 100% “slogan” was used to promote the scheme and is all over media reports.

          So judging by this metric becomes appropriate in terms of evaluating the statements made by government departments and lobby groups for other renewables schemes.

          • Pedro J. says:

            Sure Greg. But my point is that trying to explain why the plant is not going to produce 100% electricity demand of the island is absurd from a technical point of view. It was not designed to do so .

          • Pedro J. says:

            Thanks for the link. The references point to the one I linked above and the numbers look similar.

            “After 20 years, in 2031 wind energy will cover 52%, 9% through the hydro discharge and diesel generation will over 39% of the total demand of the island.”

            Nevertheless, the authors seem more optimistic in the conclusions.

  5. Jacob says:

    The question is if the water pumped up goes straight back down into the lower reservoir or it flows into the island’s water supply system – i.e. to water users. The pumping is probably done to elevate desalinated water toward water users in the island. It is possible that they do not have surplus water to use for electricity generation.

    • Roger Andrews says:

      I seem to remember answering this question many times before, but it keeps coming back.

      No, the water pumped up does NOT go into El Hierro’s water supply system. According to REE over 2 million cu m has been pumped up the hill in 8 months of operation. There’s no way this much desalinated water could have been delivered to GdV in the first place and no way it could have been extracted from the upper reservoir through the one tiny existing pipeline that connects the reservoir to the island pipeline network – particularly now that this pipeline has been cut above the upper reservoir water level so that it can no longer extract water from it.

  6. sod says:

    So the system is currently run works like this:

    They are wasting 40& of wind, by curtailing it at 7 MW. As they do today:


    Then they waste another 40%, by pumping it up and letting it flow back again.

    That is a disgrace.

    I have two important points to make:

    1. If i remember correctly, i read somewhere that the hydro turbines are designed to keep spinning at about 3% of max output. That should be about 0.3 MW “wasted” all the time, to keep the turbines spinning. Can anyone do the calculation and figure out how much of those 250000 qm would be lost if they were used like that 24/7?

    2. The people running the system must be aware of all these problems. But they are still very optimistic and just recently declared that El Hierro will have the cheapest power of all islands soon:


    So either they are still missleading everybody or they are testing and have real explanations for the current situation that they can change “soon”.

  7. Sod:

    They are wasting 40(%) of wind, by curtailing it at 7 MW

    Please back up this estimate with numbers.

    Then they waste another 40%, by pumping it up and letting it flow back again.

    40% is about right in this case, but please explain how this 40% is “wasted” when the alternative is sending little or no wind power at all to the grid. Alternatively, please explain how you would send this 40% “wasted” power to the grid without crashing it.

    The people running the system must be aware of all these problems ……… So either they are still missleading everybody or they are testing and have real explanations for the current situation that they can change “soon”.

    How GdV turns out could have a major impact on the way future high-penetration renewables projects are structured, and we are studying it for this reason. We’re not studying it with the intention of exposing the technical staff as a bunch of shysters and incompetents, which I’m sure they aren’t.

    Once more your comments are beginning to creep into moderation territory.

    • sod says:

      “Please back up this estimate with numbers. ”

      I was simply talking about capacity: 11.5MW * 0.6 is 7 MW. So they curtail about 40% of wind.

      it is difficult to assess the output that is curtailed, as the wind power seems to be never used at above 7MW, so we do not have data to judge that.

      But the system should have a pretty high capacity factor (more like offshore than onshore, above 40%, and what we see is obviously not an impressive wind output.

      “40% is about right in this case, but please explain how this 40% is “wasted” when the alternative is sending little or no wind power at all to the grid. Alternatively, please explain how you would send this 40% “wasted” power to the grid without crashing it. ”

      I used the 40% number that botwid brought up above.

      as the data in your article above seems to show, the reservoir is not (or barely used). So i would say that building it must have been the most expensive way of getting rid of “surplus” wind that i can think of.

      There should be a much cheaper possibility, like the resistor on King island.

      i could also understand, if they start “spilling” additional hydro if te upper reservoir is full. But it is not.

      so there must be a better explanation, that we do not know yet.

      And as i wrote above, i think that there is a constant loss of water, basically 3% of the hydro capacity, to keep it spinning (working as a flywheel for grid stabilisation. But i do not think that this explains the all of it.

      “How GdV turns out could have a major impact on the way future high-penetration renewables projects are structured, and we are studying it for this reason. We’re not studying it with the intention of exposing the technical staff as a bunch of shysters and incompetents, which I’m sure they aren’t.”

      Neither do i. In fact, as a supporter of solar/wind i have a high interest in a working system on El Hierro and a high interest of finding out, why it is not working very well.

      • sod

        When I asked you to back up your estimate of 40% curtailment with numbers I was hoping that you would go back and look at some real data instead of winging it, whereupon you would recognize all of the complications you were glossing over. But instead you say this:

        I was simply talking about capacity: 11.5MW * 0.6 is 7 MW. So they curtail about 40% of wind ….

        That would indeed be the case if the turbines pumped out a constant 11.5GW, but unfortunately for GdV they don’t. Here are three plots that summarize real-life conditions:

        The first plot shows 10 minute wind generation in July 2015, the strongest wind month at GdV so far (data from REE). The flat-topped-surfaces show where curtailment occurred and there was obviously a lot of it. But where would the green bars have finished up if there had been no curtailment? The question marks give you a rather a large range of options.

        The second plot shows October, when the wind hardly blew at all (for 204 of the 744 hours in the month the wind farm recorded zero output) and curtailment was effectively nonexistent. How do you figure October into the equation? Well, first you have to ask yourself whether GdV really is as good a wind site as it’s cracked up to be, then you have to go back through every month and estimate how long curtailment lasted for and when you’ve done that you have to pick more green question marks.

        And it will probably all be for naught because you’ve not even gotten to the main complication yet. Plot 3 (July again) is color-coded three ways;

        Green: Wind power sent directly to the grid.

        Yellow: Wind power wasted most likely because it exceeded demand and there was nowhere to store it.

        Purple: Either not enough wind to meet demand, or overenthusiastic curtailment, or grid stability issues, ot all of the above or none of the above.

        But when you look at the plot it’s hard to see a significant curtailment percentage unless you insist on putting all the green question marks at or near the 11.5 MW limit, which would be pointless because the plot shows that you wouldn’t be able to use the power anyway, This is going to be a recurring problem when you have 11.5MW of wind capacity (plus 11.3MW of hydro) to service a 5 MW demand.

  8. djtxyz says:

    Is that DiCaprio’s yacht in the background on the last pic? Maybe he was hooked up to island power the few days hydro generation was running…

  9. Rainer says:


    “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.”

    This study speaks of 1.8 GWh for synchronous compensation.
    This 1,8GWh is per year.

    So we should count with daily amount of compensation of 4 MWh, per hour 0,2 MW.

    I also ask for the reason of real data and this calculation.
    See five possible reasons:
    1. I am miscalculating
    2. Wrong study.
    3. Wrong construction
    4. Testing without publishing kinds of tests
    5. Wrong handling.

    Sorry, but as long as GDV do not publish data i got to tend to case 4 or 5.


  10. Rainer says:

    Back to facts:
    Field-studies-2016-03-24 :

    Pictures can be found under GDV in:

    1. Upper-storage
    look out: that white stuff on the pictures is just foam made by the wind. Pretty strong today.
    It is no incoming water!

    The water-level: looks a little more, approx 1m, in comperation to 17.03.
    Check the wrinkles in the plastic shield. You can see it if you zoom in the pictures.

    The water meter did not move at all.

    2. The valve house:
    The small house nearby the valve house: Could that be a transformation house?
    The tank nearby the valve house? A diesel tank, a gas tank, a pressure tank??? New question.

    In the picture “2016-03-24-13_26x1.JPG” spare tubes in upper right corner.

    3. Lower storage:
    More water than 17.03. Half of the distance between the stone rows. approx 2m???

    Where comes the water from??? The new question.

    One Idea:
    The repair job at the pipes on the road between disel plant and harbour looks ready now. Did they fix the water pipe to the desalination plant in Tamaduste? And now new water comming in?????

    Look pictures Fieldstudies:
    Still it is not enough water to bridge 2 days of demand i think.

    • If this is the picture you mean then it’s the lower reservoir not the upper one and there seems to be rather a lot of water coming out of it:

      • Rainer says:

        To :
        “Look pictures Fieldstudies:
        Speak about the pictures of the Tubes
        Unfortunaly in plastics

    • nukie says:

      @ Rainer, about Valve house, and small building next to it:
      The small building could house a transformer, if it was built for a transformer, the tansformer would be much to big to operate just some valves, but would supply some substantial pumps, which would make sense if water is sent from here further up, along the pipe where the branching plastic pipe with the meter is seen.

      The diesel tank also is too big for a small diesel just supplying emergency power to operate some valves. The size fits to a emergency operation in a similar size than the possible transformer, so for some substantial pumping.

      So my conclusions so far are :
      a) something is wrong with the pelton wheels / their regulation, or their regulation in cooperation with wind. If it would be just he cooperation with wind, still they could keep the upper reservoir full and operate hydro when there is no wind, or so small wind that it can be switched off. So observation fits best with some serios regulation problem of hydropower.

      b) the irrigation system is prepared, but incomplete. Pumping operation would fit with a simulation of irrigation operation.

      c) The limitation of wind at 7MW still makes no sense. It would make sense to test wind output till 11 MW and pumping to 6MW, so 5MW to the grid with 7 MW demand at noon.

  11. Rainer says:

    the picture you show:
    that for shure is the lower storage.
    But: sorry no water is coming out of it it is going into it.

    to point 1:
    i am speaking of all the three pictures of upper storage
    just zoom in and you will see the foam.

    to point 3:
    all 4 pictures of lower storage

  12. Jose says:

    Just to say hello from Canary Islands
    After some time trying to find out what is going on at GdV, I recently came across this blog, where you have built a lot of analysis and discussion, particularly with so little information available. I’m astonished, congratulations.

    Allow me to leave aside the technical discussion. As some of you have stated, the lack of reporting from GdV is unacceptable. Public interest and the budget involved makes it necessary to have much more information that is not currently available.

    On the contrary, you are probably aware that we get a flood of press releases which always go like … everything is going great, and El Hierro will soon be 100% renewable (the Holy Grail), if not yet. That is the public perception.

    Politics plays a relevant role in this issue. That is for certain.
    Pity that a relevant test project which could be most useful for many is turned into a classified file.
    Apologies for the off-topic.

    • Euan Mearns says:

      Hi Jose, I can’t recall if I said already that the site has a good search function top right. Simply enter El Hierro and you get a list of all Roger’s posts. The local press really need to get on to this one.

    • Rainer says:

      Welcome at the blog.
      Your statement is not off-topic. It is the reason i try to look into the thing.
      Asked a lot of times directly GDV. Never got a answer.
      The blocking of any really information is a shame for the GDV project and for El Hierro.
      ——- tranparencia ganar confianza ——–

    • If you are the José I think you are then you are welcome indeed. You might even be able to answer some of my unanswered questions, such as where GdV gets its desalinated water from and why no one on El Hierro has ever thought of geothermal.

      I note, however, that you too feel that the “lack of reporting from GdV is unacceptable”. I will have some words to say on this later.

  13. Rainer says:

    @Greg Kaan
    your comment at 24
    Observation changing sound:

    her one a little older:

    Time approx:
    Today observation:
    11:10 lower storage water level like 8:10. Sound: Pumps and turbines working.
    Sound of pumps first quit same like 9:10, then a little less sound, after checking in front of the pump house same sound like 9:10.
    We should install a sound meter………..”
    The times up there are not very exactly, may vary a few minutes.
    If you check REE Data around this time:

    2016-02-20 11:00 0 0 0 6 0 0 0 -0.6
    2016-02-20 11:10 0 0 0 6.9 0 0 0 -1.4
    2016-02-20 11:20 0 0 0 7.1 0 0 0 -1.3
    there you see in the rigth column the hydro change.
    Checked by sound. Power of pumps did change.

    Installed even a “sound-meter” but just beeing “amateur” in working with sound data.
    Maybe an other try later on.

    No really more knowledge…..

    • Greg Kaan says:

      Rainer, thanks again.
      I was being rather facetious when I used the work “merely” in that previous post. A sound recorder would be best of all so that not only the volume but the spectrum could be analysed.

      Then again GdV could just only provide separate figures for the pumping station consumption and pelton output rather than forcing us to ask you for subjective assessments.

      The issue of phase control is what makes me continue to believe that the peltons and pumps work together in the periods when the system goes 100% renewable. Maintaining frequency and voltage with the wind turbines is one thing (it could be done independently by electronics in each turbine) but what provides the phase that they must synchronise to? The Enercon turbines are supposed to be able to provide some assistance in this area but there needs to be a system reference for them. If the diesels aren’t running, then the peltons would be the only source (that I know of)

    • Ampere says:

      After some Holiday I did take a look at the frequency Data (grid, not audio) from the 25.3.2016, when hydropower produced some output during the day according the RED-Site. Unfortunately, the scale was cut of in Raiuners frequiency charts, so I could not compare the scale to other days.
      But what can be seen are the high frequency amplitudes below 0,15Hz at theat day, and no high amplitudes at 0,3Hz aththough the diesel was present.
      At the 24.3. the o,3Hz peak is present but small, in the moringn the diesel was regulating , in the rest of the day the dieselw as running mostly constant. Maybe the regulation of the diesel was switched off for testing durin g half of 24.3. and 25.3, to learn on the regulation of hydropower.
      At 26.3. the high amplitudes below 0,15Hz are much smaller, but Diesel was running at higher volume, and without 0,3Hz peak.
      27.3. again shows high amplitudes below 0,15Hz, and the diesel running mostly constant while Hydro is swinging from negaitve to positive ooutput serveal times a day.
      At 28.3. there is a lower amplitude below 0,15Hz, and a peak at 0,18Hz, and a higher diesel output at the second half of day, and during the day the hydro swinging a lot from positive to negative output.
      At 18.3. there is no significant incrased amplitude below 0,15Hz, and the well known 0,3Hz of some of the diesel sets is present. When looking at the power output graph, as expecteed, there is only pumping durning the day, and the diesel running constant, at higher output.
      At 15.3. there is no increased amplitude at <0,15Hz, although hydro was running during the day. But it was running with quite constant output, maybe operated manually.
      At 16.3. there is no significant swinging below 0,15Hz, no pumping, but relatively high cahnges of output of hydro power, and very little wind.
      At 18.3. there is wind production, but no hydropower production, moderate high amplitudes below 0,15Hz, no significant (very smal) diesel peaks.
      At 19.3. there is wind production, hydropower production, moderate high amplitudes below 0,15Hz, no significant (very smal) diesel peaks.
      At 20.3.there is wind production, hydropower production with a lot of changes from + to -, high amplitudes below 0,15Hz, no significant (very smal) diesel peaks.

      I did not make a deeper analysis, also since I could not see the scale of the graphs, making things more difficult. It looks on first sight as if frwequency starts swinging when the pelton wheels have to regulate power. (Or if wind and pelton wheels have to ragulate power together)

      But it is maybee not always clearly visble when the pelton wheels work since they are camoflaged by the parallel pumping.

      And obviously somebody is constantly performing tests with the system, maybe they are searching for the source of the <0,15Hz swinging in the requlation software (plural).

      Sice originally the upper reservoir was designed for 500.000m³ storage, it was obviously designed for irrigation purposes, too, although this part also is not in operation by now (although the volume of pumped water clearly shows that from electricity side this would work fine). Water could be pumped from elGolfo via Valverde to the reservoir, why this is not done is unknown.

      • Rainer says:

        Thanks for evaluating the frequency graphs.
        About scale:
        Best thing is to use the python file yourself. Know the daily graphs still hiding details. Then you can zoom in / out make your own scale of the plots and look directly into details.
        Please look in the Readme.txt in the home directory of El_Hierro_Mutatio to get the python file of Damian Schneider.
        Not very comfortable to start -just a Script- but i think it gives a really good look inside the Data.

  14. For those who think that GdV is concealing some dark, dirty secret, here are some data, all obtained from publicly-accessible sources, updated to midnight yesterday. They show the monthly generation mix sent to the El Hierro grid and the monthly percentage of renewables generation since project startup. The data can be recalculated weekly, daily, hourly or even once every ten minutes, although the ten-minute table gets to be about 35,000 lines long:

    I now challenge anyone to find a comparable stand-alone renewables project anywhere in the world where this much information is publicly available. You won’t find one because there isn’t one. And that makes GdV the world’s most transparent renewables project, not the world’s murkiest. (And don’t forget that I live in Mexico, which ranks 95th on the world transparency index. Spain, at number 36, looks good in comparison.)

    What you are all basically complaining about isn’t the lack of information on GdV – you can get a much as you want and more in previous Energy Matters posts (in fact I often wish that some of you would take the trouble to soak some of this information up before posting comments). You’re complaining because you don’t believe a word of what you are told by Juan Pedro Sánchez, the spokesman who represents the Island Council’s two-thirds ownership in Gorona del Viento SA, and who being a politician chooses tame interviewers and “spins” the results to make them appear as good as possible without actually lying. Here a few of the more important quotes from his latest interview with El Diario de El Hierro. The English translations are mine:


    In the street there are still many doubts related to Gorona del Viento. Many doubts that those of us who live on this island would prefer not to have. It’s for this reason we have entered into the bowels (sic) of GdV to learn close-up the answers to the questions that many of you would like ask. To get to know certain aspects of this innovative system we spoke with to the counsellor of GdV, Juan Pedro Sánchez, who having been involved in the project almost since its inititation knows it to perfection.

    Has the final objective been met?

    Yes. The objectives of the first phase of operation have been met. The system is operational and has succeeded in delivering 100% renewables while ensuring grid stability and security of supply. This surpasses the technical challenge associated with the project. This is an important advance because no other isolated system has succeeded in supplying an electric grid solely from clean energy sources. The final objective, as set forth in the “enunciación” (anyone know which “enunciación” this is?) is more complex and distant, but obviously it involves supplying 100% energy year-round, eliminating the dependence on diesel and serving as the support for other branches of the “El Hierro 100% Renewable” strategy such as electric cars and the sustainable production of desalinated water etc. etc.

    Anyone who knows anything about GdV will immediately recognize all this as complete BS but won’t be able to find any outright lies, although there is one incorrect claim.

    As to what might be done about it, Energy Matters would be happy to supply updates of GdV’s performance for publication in a local El Hierro paper if anyone can find one willing to publish them.

    • sod says:

      “As to what might be done about it, Energy Matters would be happy to supply updates of GdV’s performance for publication in a local El Hierro paper if anyone can find one willing to publish them.”

      Is there even a seperate paper on El Hierro?

      It is easy to find a english language list of news for the canaries:


      The islands are very dependent on tourism and the green energy also is a tourism project, so a balanced view will have a higher chance of getting published. But i think that you would be the right person to write such a piece.

      Talking about transparency, i simply think that there should be a project website and it should be possible to interact with the people running the project. In general i think interaction with interested people (even those with critical views) improves big projects in about 99.9% of the time.

    • Rainer says:

      like Kees did wrote in a mail:
      “The frequency graphs are great, the 10min. sample frequency hides all the ‘good stuff’.”

      The frequency meter sample every second and really shows events we never will see with the REE data sampled every 10 minutes.
      One single day will have 86.400 lines of data.
      That is an example of open data!

  15. Rainer says:

    you really did a more than good job over a long time.
    The base of this job are the data from REE and other sources.
    REE respects the “ley de transparencia” de Espania.
    El Cabildo do not respect this law. -I wait for more than a year to get information of another project also
    GDV do not give the data we are working with, GDV do not give answers to questions of you or of myself. GDV do not respect the law. 60% of GDV is owned by the Cabildo.
    Another time the Cabildo do no respect to the law de Espana!
    El Cabildo and GDV destroyed any respect to the administration on El Hierro.
    The respect to the newspapers here was destroyed before.
    It is just a shame!

  16. Greg Kaan says:

    A big thanks for that first link, Roger. EVERYONE should read that thoroughly before making any further comments in this thread.

    Section 4 quite clearly states that the system is design for at least 3 of the peltons to be running if the diesels are offline in order to maintain the grid in event of a 3 phase short circuit at the windfarm,
    Figure 11 shows the modelled grid collapse if only 2 of the peltons are online during this sort of event,

    It also mentions the large inductive loads presented by the pumps (inherent in an induction motor), especially in the short circuit recover situation but there is no discussion about how the reactive power requirement is met during normal operation. I have tried to find out the capabilities of wind turbines in this regard but none of the manufacturers seem to include this in their specifications. The best I could find was a reference in an AEMO document stating that type 3 turbines (doubly-fed asynchronous) had some reactive power capability (about 0.3pu) and type 4 turbines (full conversion) had more (about 0.4pu). It is conceivable that the Enercon wind turbines could provide the reactive power for the pumps in normal operation but not in a short circuit event.

    Sadly, there is no mention of the source of the system reference phase – it could be that the first wind turbine started provides the reference for the others. Offshore windfarms are supposed to be able to black start without an external reference if some turbines have a diesel generator to provide an internal reference.

    BTW Here is the online version

    What stands out in the second article is the relatively short lifespan of the windfarm vs the other system components (plus the admission that the initial goal was 100% renewable electricity with the projected maximum being 75%)

    Finally, here is the AEMO article I used for the wind turbine reactive power capability figures

    • Greg; A number of people have read it and commented, including Kees van der Pool, who’s been very quiet recently (You there Kees?). Unfortunately it doesn’t figure within my limited number of established fields of expertise so I have to rely on someone else to tell me what it means.

      But one thing I have noticed is the lack of any mention of using pumping as a “dynamic resistor” to slough off surplus wind, which now seems to be the key ingredient during high-wind periods. When did they start doing this?(I could probably find out from the REE data if it’s worth the effort.)

      • Greg Kaan says:

        Roger, if you look near the end of section 2, there is a sentence that states what you are looking for

        The pumping station has a double purpose: it has to store the surplus electric energy turning it into potential energy, but it also has to contribute to load-generation equilibrium and to reduce the imbalance when severe contingencies happen

        This, along with phase control, makes the case for having a separate pumping station rather than relying on peltons to perform both operations.

        My statement about people reading the document was aimed at some who have joined the conversation late in course of the whole El Hierro analysis – I include myself in this group.

        • Greg; No implied criticism there – except for the people who have recently joined the conversation without bothering to bring themselves up to speed.

          The sentence is nevertheless very interesting. It implies that the Peltons and pumping are about equally important in maintaining grid stability. Well, I’ve been doing a little more detective work which indicates that the Peltons are actually bit players. Keeping three or four of them spinning may be necessary, but it’s no big deal and wastes no significant amount of energy. The big deal is pumping. I suspect that REE, which calls the shots, has known this all along even if GdV’s consultants haven’t. Here’s the evidence:

          1. GdV actually began life at 11.30am on July 21, 2014 when it delivered 0.2MW of wind power to the El Hierro grid.

          2. There followed 11 months of low-level testing (about which we hear little or nothing) during which small amounts of wind – usually less than a megawatt – were fed into the grid, and we can be sure that REE took copious notes of what happened.

          3. Full operations commenced on June 27 2015, when GdV began to send MW rather than tenths of MW of wind to the grid. How long did it take before REE started to switch wind between pumping and the grid to match generation to demand? They began pretty much immediately, and they’ve been doing it on and off ever since.

          And if my summation is correct it’s back to the drawing board, all you power engineers. You need to be looking not at the Peltons but at why REE is using pumping as a dynamic resistor rather than allowing wind, backed up by all those spinning Peltons, to freely access the grid. Another important point is whether REE isn’t doing it just to meet Spanish island grid regulations. If it turns out to be a legal rather than a technical issue this could make a big difference.

          • Rainer says:

            Roger, or should i say Sherlock?
            That hint to legal reason is a very good one.
            Still looking which delta f is allowed in El Hierro.
            Only found two hints in a study. One speaks about min 48,5HZ, the other of 49,6Hz.
            I understand that the first planing was with 48,5 Hz and the final planing with 49,6Hz. Nothing said about max values.

            “Finally, inertia of 6 seconds and a minimum opening time of the needles of 5 seconds were selected. For the El Hierro project, the minimum frequency value was established at 48.5 Hz.”
            “Later studies of the frequency regulation capability of wind generators showed better behavior when a generator trip occurs, as the frequency drop was limited to 49.6 Hz in spite of the 48.5 Hz obtained simulating the wind generator as a simple negative charge. In this way, the wind generator was requested to change its power (see Figure 1 ). Plimited is the active power setting to the wind generator, and Pavailable is the available power of the wind generator at that precise moment.”

            The Frequency meter shows:
            Start: 2016-03-23T16:05:52+00:00
            1458749152.477 48.92484
            1458749153.498 49.09376
            1458749154.512 49.30095
            End: 2016-03-23T16:05:54+00:00

            and there in Data
            or Daily Graps / 2016-03-23
            or Events / 2016-03-23_16_05-minus-1_1-plus-1_3Hz

            That could have been a test run.

            Still the questions:
            Which limits are legal acording to REE? Think you have a connection to REE. What about this question to REE?
            Which limits are really possible without test runs in “regular” extrem situations?

          • Greg Kaan says:

            Roger, I interpret the sentence as stating that the pumping station provides the variable demand (via switching in and out blocks of 1500kW and 500kW with fine tuning by the variators.

            The peltons would seem to be left as an additional power source (using the “potential energy” stored using the “surplus electric energy”) and standby emergency stabilisers.

            My interpretation, anyway, after looking at the audio files provided by Rainer, even though it blows away my envisaged operation.

            It seems like yet more duplication of effort but perhaps this is an inherent trait of renewable power systems.

    • sod says:

      “A big thanks for that first link, Roger. EVERYONE should read that thoroughly before making any further comments in this thread.

      Section 4 quite clearly states that the system is design for at least 3 of the peltons to be running if the diesels are offline in order to maintain the grid in event of a 3 phase short circuit at the windfarm,”

      The paper is a nice theoretical study, but i think that it has basically no relevancy to tze real problems on El Hierro.

      Check pdf page 8:

      “The critical operating scenario takes place when the highest wind
      generation (11.5 MW) coincides with the lowest demand in the system (2.35 MW) because there are
      less conventional units connected. In this operating situation, the worst disturbance considered is a
      three-phase short circuit in the wind farm busbar. The most relevant point of this scene plot is that the
      system has to withstand the disturbance with no help from conventional synchronous units.”


      so they assume a scenario that does never happen and then conclude, that with 3 spinning turbines it can be handled.

      In the real world, they curtail wind at 7MW all the time. This reduces the problem by 40%. And as they do not use the pumped hydro to produce electricity, they could curtail even more at night.

      So the real problem is much smaller than the one in the analysis, but is still causing much more trouble to them.

      • Greg Kaan says:

        sod, engineers have to plan for the worst case scenarios – saying the study “basically no relevancy to the real problems on El Hierro” is just naive.

        The fact that they appear to be having problems even with the output restricted (as you complain about in other comments) shows just how difficult grid control is without large synchronous generators performing most of the work.

        BTW some of the reduction in capacity may not be simple curtailment. If they are using the Enercon turbines to provide the reactive power for the pump motors, then the active power output of the turbines will be reduced due to the reactive current component – just another possible complication.

        • sod says:

          “The fact that they appear to be having problems even with the output restricted (as you complain about in other comments) shows just how difficult grid control is without large synchronous generators performing most of the work.”

          What b”large synchronous generators” are you thinking about? the diesel spin is not bigger than the hydro spin, is it?

          “f they are using the Enercon turbines to provide the reactive power for the pump motors, then the active power output of the turbines will be reduced due to the reactive current component – just another possible complication.”

          This could have been, but look at the graphs provided by Roger: The output is extremely flat at 7MW.


          • Greg Kaan says:

            “diesel spin is not bigger than the hydro spin”

            sod, please reread the article that describes the system operation and also the pumping sound discussion I had with Rainer and Roger.

            In short, when not running the diesels, the GdV system is designed to only use the peltons for providing additional power and emergency stabilization. For general balancing, the pumping load is varied to match demand with the variations in wind generation (ie the reverse of a “normal” grid). Personally, I think this is a strange operational strategy but I am not there, experiencing the actual difficulties of integration.

            As for the curtailment levels, the low water levels shown in Rainer’s latest pictures would suggest that there isn’t enough water for the peltons to provide additional power if the wind levels fell. Perhaps they are only willing to run without the diesels when the forecast guarantees there will be sustained strong winds. You may find this excessively conservative – I don’t know enough to have an opinion on this.

  17. Gaznotprom says:

    Think the only thing ’emptying’ here is the poor(er) bill/tax/rate payer – who one way or another pays for this…

    And ‘filling’ is well, those who are the net recipients of the above… And a little weapons-grade greenwash for the pontiffs to spout as and when…

    Wish it could work as described, seems like a reasonable idea and sure there’ll be a few who’ll say this would work if only it was up-scaled…

  18. stone100 says:

    I don’t know anything about electrical engineering and so I’m struggling to understand why the synchronisation issue from windfarms etc is so insurmountable at high penetration levels. When electricity is supplied from imports via a HVDC interconnection it gets converted from DC to AC; same thing when battery storage is used in a grid; so why can’t the messy output from a wind farm be converted into good AC by going through such a DC-AC conversion? Wouldn’t the efficiency losses be worth it if the only other option is to curtail most of the wind power? If there needs to be inertia in the system, could flywheels be used?

  19. Rainer says:

    Tech Info:
    REE switched to summer saving time at 01:00 this night:
    2016-03-27 00:40 1.7 0 0 6.4 0 0 0 -3.4
    2016-03-27 00:50 1.6 0 0 6.8 0 0 0 -3.6
    2016-03-27 02:00 1.6 0 0 6.7 0 0 0 -3.9
    2016-03-27 02:10 1.6 0 0 6.8 0 0 0 -4.1

    All Data of the frequency meter Mutatio will stay in UTC timestamps all year long.


    frequency meter:

    Daily data you will find there in directory Data
    To plot your own graphs and find events by yourself just look into the readme,txt.

    • Rainer says:

      To begin with:
      Nead some analiysis:
      In the Fourier Analysis of Wind and Diesel there is a peak at 0.225Hz. Near the value Daedae, the builder of the Mutatio frequency meter, aspect from hydro in wind & hydro situation. And the peak at 0.33Hz from the diesel. My idea is: 0,225Hz peak produced from the Enercon windmills. But never seen again till now. Why not is a new question.

      • Rainer: The data you contribute to the El Hierro threads is invaluable and much appreciated. But instead of posting periodic updates on frequency etc. that really don’t tell us very much it might be better if you could make your data site a little more user-friendly to those who don’t speak German and who aren’t completely computer literate (like me). Then we could access whatever of your data we needed when we needed it. How about it?

        • Rainer says:

          same complain got from Hubert before.
          My answer: Everybody would like to get a baked caked ready to eat.
          Think adapted all german to english till now. If you do not want to understand frequency when there is written frequenz in some old graphs i can not help you. I look for help in interpreting the frequency data. If you can not, no problem, maybe somebody else can. That a forum is for.
          I had not to event own server space when i had space here or at netzsin.us.
          Also made a complete translation of the words in netzsin.us. Can not help if it is not live yet.

  20. Rainer says:

    upper storage:
    ca plus 0.5m water since 2016-03-24.
    water meter: no move at all since watching
    lower storage:
    ca plus 1m water since 2016-03-24
    pumps are working

    • Thanks for the pics Rainer

      The black pipe “connecting” the water meter to the UR is cut off before it reaches the water, so all it can record is water flowing into the UR.

  21. Rainer says:

    2016-03-30 14:32
    Valverde Airport: Gusts 74 km/h
    2016-03-30 14:50 Enercons starting production low level 0.2 MW

    • hfrik says:

      So they have been actively switched off for whatever purpose

      • No they haven’t. Look at the data.

        • hfrik says:

          I looked here: http://www.wetter.de/spanien/wetter-el-hierro-1637441/wetterbericht-aktuell.html Starting speed of the E70 si around 2,5m/s at hub height, so much less at the airport. http://www.windfinder.com/report/hierro
          They should run at >>6MW output since around 17:00 (>10m/s, 20 knots at ground level, >>6MW because 6MW would be reached at 10m hub height at sea level at airport. At 80m hub height on a mountain wins should be stronger), and for sure at 11 MW at 20:00.
          http://www.windenergie-im-binnenland.de/powercurve.php;see similar turbines in xls-data); http://www.thewindpower.net/turbine_de_5_enercon_e70-2300.php

          • Here’s a comparison of EH airport wind speeds with GdV wind generation so far today. Looks like a pretty good fit to me.

            0100: 4m/s, 0.1MW
            0400: 7m/s, 1.3MW
            0700: 5m/s, 0.6MW
            1000: 2m/s, 0.0MW
            1300: 4m/s, 0.1MW
            1600: 9m/s, 1.8MW
            1900: 11m/s, 5.2MW
            2200: 14m/s, 6.7MW

          • nukie says:

            Rogers data fit to 2 of 5 wind turbine being switched off. Data of the day befor looks like even more being switched of. So test program now seems to switch on and of wind turbine, and see how the grid behaves then.
            At 14 MW the output of 3 turbines should be 6,6 MW, of 5 turbines 11 MW.
            Maybe they test operation with non curtailed wind turbines and grid regulation by hydro or diesel now.

          • Rainer says:

            All time looking in wind + REE data also thought that only 3 of 5 E-/0 running. But passed the E-70 often and every time all 5 turning same speed. So other reason we do not really know.

          • Roger Andrews says:

            Curtailment is what you do when you have 11MW of generation, 5MW of demand and nowhere to store the surplus.

          • Rainer says:

            Your statement of curtailments is a possible one.
            What about a line not strong enough for 11MW?
            What about one or two or more E-70 not working fine.
            3 years and more of warranty are gone. The E-70 have been just standing around without any use for a very long time spoiling public money. There is a rumor around here 2 of E-70 are just turning around for tourists….
            Do not put in public here what else is spoiled of public money here in El Hierro. The people of El Hierro know himself. And if you look at the statements of GDV and compare it with facts you might imagine.

  22. nukie says:

    Well, if the do testing with 3 out of 5 turbines, while the other two are fine, just switched of, it would be reasonable to keep them spinning, to have them online within a few seconds at full output in case something happens during testing. So it could be that 2 out of 5 spin idle (pitch regulation), like a pelton wheel with no or minimum water. Since there are some dips in whe wind output, they do not seem to be curtailed at a fix power level, like often before.
    It would be nice to see the results of testing sometimes 🙂

    • Rainer says:

      Good idea!
      The result of testing i, and i think all of us,would like to be published by GDV too.

  23. Acosta Padrón says:

    Me he leído todos los comentarios y veo con asombro que nadie ha mencionado los problemas hidráulicos y estructurales que pueden tener los embalses, sobre todo el superior y que quizás sea la respuesta al por qué no se llena.
    Este embalse superior se ha hecho en una caldera de explosión que se caracteriza por no tener un material bueno para ese tipo de infraestructuras hidráulicas, con experiencias muy desastrosas, realmente catastróficas, en estas mismas islas. En principio hay que decir que el terreno es permeable en toda la isla y por eso los ingenieros que hicieron el proyecto colocaron una impermeabilización a base de lámina delgada de polietileno de alta densidad -HDP- material que desde luego no es el idóneo para soportar deformaciones ni punzonamientos como los que se pueden producir cuando se llenen ambas balsas.
    Por otro lado y refiriéndonos al embalse superior, el material geológico que forma la base es el resultante del relleno con los propios materiales eyectados con la explosión. Este es el terreno donde se apoya la lámina de impermeabilización, es un material granular formado por piedras, arenas y arcilla procedentes del relleno de la boca del cráter tras la explosión y -esto es importante- la alteración de esos fragmentos que se transforman en arcillas. En el caso de una filtración de agua, hecho nada improbable vista la ejecución de la obra y los materiales usados, el agua se infiltrará por el terreno camino del acuífero arrastrando la fracción arcillosa, con lo que ira dejando huecos que provocarán la deformación de la lámina hasta que se produce la rotura.
    Este ha sido el proceso que originó las cuatro roturas que se han producido en el embalse de la Laguna de Barlovento, situado en la vecina isla de La Palma, emplazado también en una caldera de explosión y que ha llevado a la ruina total de la obra.
    En cuanto al embalse inferior tampoco está exento de problemas. Se ha construido en piroclastos básicos y con una altura de embalse próximo a los veinte metros. Este material, muy usado y conocido en Canarias con el nombre de “picón” es una estructura formada por granos que presentan un primer colapso a partir de poco más de 1 kg/cm2. Con estas cargas que desde un punto de vista hidraulico se producen a partir de los diez metros de altura de embalse, el terreno afectado puede asentarse un tercio de su altura. A embalse lleno se ve venir lo que a este ambalse inferior le puede pasar.
    Como ven desde el punto de vista estrictamente hidráulico hay muchos problemas que afectan tanto al diseño de las balsas como a su ejecución. Ni los emplazamientos de los embalses fueron los adecuados, ni el diseño estructural fue el idóneo, ni los materiales que se emplearon fueron los que mejor se adaptarían a los esfuerzos.
    Por último y como respuesta a uno de los comentarios, la energía geotérmica en El Hierro SÍ se ha estudiado, el problema está en que el calor del subsuelo no nace de una roca caliente sino que es una zona difusa de emanación de gases volcánicos. Esta forma de aparecer el calor invalida el posible aprovechamiento geotérmico.

    Below is my English translation of this interesting comment: RA

    • I have read all the comments and see with astonishment that no one has mentioned the hydraulic and structural problems that the reservoirs can have, in particular the upper reservoir, which might explain why they don’t fill it.

      This reservoir is an explosion crater characterized by a lack of the good material needed to build this type of hydraulic structure, with disastrous, really catastrophic, experiences (already recorded elsewhere) in these islands. First it should be noted that the ground is permeable all through the islands and this is where the engineers who built the project placed a thin layer of impermeable high-density polyethylene, a material which is not ideal for resisting deformation or punctures such as those that can occur when both reservoirs are full.

      In addition, and again referring to the upper reservoir, the geologic material that forms the base is the result of the infilling of (the crater) with the same materials that the explosion ejected. This is the material that supports the impermeable liner. It’s a granular material formed by rock, sand and clay. In the case of a water infiltration, which isn’t unlikely having seen the way the work was conducted and the materials used, the water will infiltrate through (permeable layers?) washing out the clay fraction, leaving holes that will initiate deformation of the liner until it ruptures.

      This process is what originated the four ruptures in the Laguna de Barlovento reservoir, situated on the neighboring island of La Palma and also built in an explosion crater, which have led to the complete ruin of the project.

      The lower reservoir is also not problem-free. It’s constructed on basic pyroclastics with a reservoir height of around 20 meters. This material, widely used in the Canaries and known as “picón”, consists of grains that begin to collapse at a little more than 1 kg/cm2. With these pressures, which from the hydraulic standpoint begin at a reservoir level of 10m, the (picón) can support only a third of the reservoir height. You can see what would happen if the reservoir were full.

      From the strictly hydraulic point of view there are many problems that affect both the design of the reservoirs as well as their manner of construction. The reservoir installations were not adequate, the structural design was not ideal, and the materials used were not the best suited to the project.

      Finally, and as a response to one of the comments, geothermal energy on El Hierro has been studied. The problem is that the subsurface heat comes not from hot rock but from a diffuse zone of volcanic gas emanations. The form in which the heat appears invalidates its possible geothermal utilization.

    • Rainer says:

      @Acosta Padron
      “En cuanto al embalse inferior tampoco está exento de problemas”
      We did see but not everybody is a geology educated purson.
      And what thing is build down of this lower storage? The diesel plant of Llanos Blanco. And the pumping station of GdV. All eggs in one basket.

  24. Kees van der Pool says:

    @ Acosta Padron

    The references to the “Laguna de Barlovento” I can find are somewhat ambiguous regarding leaks and refer more to the long term behavior of the ‘PVC-P geomembrane’ installed in 1991/1992:



    You wrote:
    ‘Este ha sido el proceso que originó las cuatro roturas que se han producido en el embalse de la Laguna de Barlovento, situado en la vecina isla de La Palma, emplazado también en una caldera de explosión y que ha llevado a la ruina total de la obra’.

    Does this mean that the Barlovento lake is empty? Also, would the Gorona del Viento upper reservoir, which is much smaller and more recently constructed, already show such displacements and leaks?

    Thank you for your feedback!

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