El Hierro July 2016 performance update

During July the hybrid wind-hydro Gorona del Viento (GdV) plant set a new record of 65.9% renewable energy delivered to the El Hierro grid, handily exceeding the previous record of 53.9% achieved in June. This was dominantly a result of a continuation of the sustained northerly winds that began in mid-June. Total renewables generation since full operations began at GdV in June 2015 is now 37.8%, up from 34.6% at the beginning of the month. (Data on GdV plant layout, operation and capacities are given in the September update. Previous posts on GdV are accessible through the El Hierro Portal.)

Figure 1 shows daily mean percent renewables generation since June 27, 2015 (data from Red Eléctrica de España (REE):

Figure 1:  Daily mean percent renewables generation since June 27, 2015.

The Table below updates the monthly grid statistics:

And Figure 2 shows the REE 10-minute generation data for the month:

Figure 2:  10-minute REE grid data for El Hierro, July 2016

There was actually nothing much new during July. Demand fluctuations during higher-wind periods are still being met by switching wind generation between the grid and pumping – i.e. by using the hydro system as a dynamic resistor. This procedure has been used since project startup and seems to have been selected as GdV’s most efficient and stable mode of operation, although it wastes a large amount of wind power. Hydro generation is used to fill the gap when wind generation is deficient, but there’s not that much hydro to go round. The hydro generation on July 25 and 26, for example, accounts for about 50MWh delivered from storage, or about a fifth of GdV’s nominal reservoir capacity. This may be as much as the hydro system can deliver without compromising its demand-balancing capabilities.

Approximately five days of 100% renewables generation was recorded in three separate tests during July, but the conditions that triggered the startup and shutdown of these tests remain unclear. There was also a period of grid instability during July 20 and 21, when three grid malfunctions occurred in the space of about 30 hours. These are shown in more detail in Figure 3 should anyone care to speculate on the causes:

Figure 3:  Period of grid instability showing the three grid failures, July 2016

Figure 4 compares 10-minute wind generation at GdV with three-hourly wind speed readings at El Hierro airport for July. The correlation is not exact, but low-wind periods at the airport again broadly coincide with low output at the GdV wind farm. (Airport wind speeds in July 2016 averaged 7.9m/s compared to the 6.7m/s average during recorded during 2015.) Wind generation during the month was fairly consistently curtailed at between 7 and 7.5 MW when wind power exceeded demand:

Figure 4:  GdV wind output versus El Hierro airport wind speeds

In additional news, a paper on GdV authored by Energy Matters collaborator Hubert Flocard has made it to to the Canary Islands media. Hubert’s paper is based on data from the first 6 months of operation and predicts that GdV will be able to supply only 46% of El Hierro’s electricity demand. There has been no reaction as yet from GdV or the Island Council.

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31 Responses to El Hierro July 2016 performance update

  1. ducdorleans says:

    Roger, buenas dias …

    in the table, aren’t the numbers “total” en “diesel” inversed for past July ?

    gracias por todo y que tiene un buen dia ..


  2. roberthargraves says:

    To me it looks as if wind-to-pumping far exceeds hydro-to-grid. Is the pumped storage efficiency low?

    • Wind-to-pumping certainly exceeds hydro-to-grid but we can’t say by exactly how much because pumping and hydro generation are often conducted at the same time and because REE supplies only one number – the net of the two. The hydro plant, which has a reported overall efficiency of only 60%, supplies minimal power to the grid largely because wasting surplus wind energy via pumping water uphill and letting it flow back down without turning the hydro turbines seems to have been adopted as the best way of using the hydro system to maximize renewables generation. It’s also possible that a shortage of fresh water and/or concerns regarding reservoir stability may enter into the equation, but we can’t confirm this.

  3. SE says:

    The last row of the table (July) needs correcting (Diesel and Total).

  4. Duc and SE. Thanks for picking up on that. The numbers are now in the correct order.

    Duc: No hay de que y que también tenga un buen dia.

  5. Rainer says:

    Roger, please remember to link this post to in the
    Thank you

  6. Kees van der Pool says:

    Hi Roger,

    You wrote:
    “There was also a period of grid instability during July 20 and 21, when three grid malfunctions occurred in the space of about 30 hours. These are shown in more detail in Figure 3 should anyone care to speculate on the causes”.

    Speculation: car into a pylon, lightning, cable meltdown, malfunctioning circuit breaker(s) etc.
    Whatever the cause, the substantial demand drops were handled well between the Llanos Blancos diesel plant and GdV.
    The ‘power balance’ (wind+diesel+hydro less demand+pumping) never deviated more than 0.3MW throughout the three ‘events’. This seems about a normal value, most of the time slightly positive and occasionally negative.


    • Kees: Do you think grid malfunctions 2 and 3 would have happened if malfunction 1 hadn’t? Seems to me they are related, i.e. it took about 30 hours to bring the grid back to complete stability. .

      • Kees van der Pool says:

        I sure think they are related.

        #1 is a double dip, at 2:00am 7/20 the initial event, cascaded into the second dip at 3:10am, the second event a repair @ 3:40pm. The third event at 5:50am 7/21 was maybe another repair in the early morning.
        My WAG: tourist season+rental car+party+navigational error and half the island goes dark. . . . .

        Throughout all three events, the power supply was stable as far as I can tell from the way the system responded, which is fairly impressive.

        I trolled through the on-line newspapers to see if there was any mention of a partial blackout – no luck.

    • Another grid problem at 0840 August 4:

  7. Kees van der Pool says:

    The 8:40 dip in demand from 6.1MW to 4.7MW (-1.4MW) was compensated by increased pumping from 3.1MW to 4.4MW (+1.3MW) :

    D W P/H L balance
    8/4/2016 8:10 1.6 7.6 -3 6.1 0
    8/4/2016 8:20 1.6 7.6 -3.1 6 0.1
    8/4/2016 8:30 1.7 7.8 -3.1 6.1 -0.1
    8/4/2016 8:40 1.6 7.5 -4.4 4.7 0.2
    8/4/2016 8:50 1.7 7.5 -3.5 5.6 0
    8/4/2016 9:00 1.6 6.4 -2 6.1 0.1
    8/4/2016 9:10 1.6 5.5 -1 5.9 0.1
    8/4/2016 9:20 1.6 6.8 -2.3 6.1 0.1
    8/4/2016 9:30 1.4 6.6 -1.9 6 0.2
    8/4/2016 9:40 1.7 7.6 -3.2 6 0.1
    8/4/2016 9:50 1.6 7.6 -3.4 5.7 0
    D=diesel, W=wind, P/H = pumping/hydro, L=load (‘demanda’),
    balance = (diesel+wind) – (load+pumping/hydro)

    Apologies for the formatting.

  8. Rainer says:

    Nobody at El Hierro will be upset by a short blackout.
    People are used to it.
    This small partial blackouts are really normal.

  9. Rainer says:

    The press-release i (we?) waited for:
    1:1 in the local newspapers….

    Some extracts:

    Google-translator: “last July, with 67% coverage of demand,”
    Looks like a little optimistic “calculadora”
    Rogers numbers: 65,9%

    “An example of this is the last record surpassed by the Central, which managed to stay 76 hours continuously contributing 100% of electricity production on the island, just over a week.”
    24×7=76 ????
    Looks like a little creative human “calculadora”.
    No one word why they stopped running REE without diesel….

    Google translator:
    “”Meanwhile, the Central hydro-wind is a system that can cover between 70% and 80% of the annual electricity demand of El Hierro and the known data today point to a good evolution that soon we will reach that average, with significant results environmental, technical and economic “says Sanchez.”
    Looks like a very optimistic human “calculadora” to.

    No further comment, look yourself.

  10. Graeme No.3 says:

    O/T but there is an article in the WeekEnd Australia August 13 (unfortunately paywalled – Sue Neales – The Future of Farming ) about a renewable powered tomato farm Sundrop Farms near Port Augusta.
    It has a 127m solar heat tower with 24,000 mirrors. This generates electricity for the 20 Hectares of greenhouses, as well as the desalination plant and heating for the 200m long greenhouses.
    Presumably it runs at a profit but the article gives 2 figures for the output of 18,200 or 25,000 tonnes of tomatoes per annum. It claims to employ 150 workers (?) and ship to all the capitol cities, which would be very expensive in the case of Darwin and Perth.
    The article claims “in another hi-tech innovation, carbon dioxide levels are elevated in the glasshouses to boost crop production by about 30 per cent”.

    Given that all solar heat plants I have heard of start up in the morning with gas firing, I wonder about its credentials.

  11. Rainer says:

    Eólica -Wind- max Events:
    2016-08-12 22:00: 7.9 MW
    2016-08-13 09:50: 8.1 MW
    2016-08-13 11:10: 8.2 MW

  12. Rainer says:

    2016-08-15 07:20
    Diesel off REE only

  13. Rainer says:

    2016-08-17 05:00
    Diesel on
    Why is another miracle again……

  14. Ilmar Bouwer says:

    Hi Roger Andrews,

    Im wondering from which website did you retrieved your data? From the REE website, i could only find the real time data shown in blocks of 10 minutes. And from ISTAC they only show total production and consumption.

    I would like to see the data from El Hierro from the past 5 years in monthly figures from the production of energy by source. In this case Wind+ Hydro and Diesel generator

    Best regards,


  15. Ilmar Bouwer says:

    Hi Roger Andrews,

    I was wondering from where did you retrieved your data? When i search on the REE website, they show the energy statistics perfectly but only in blocks of 10 minutes. and ISTAC only shows the total production but not divided by source and total consumption,

    I would like to see the energy statistics from the past 5 years of energy production by source in monthly figures. Like how you showed it in your graphs.

    Best regards,

    Ilmar Bouwer

  16. I download the data, a day at a time, from REE, so if you want to go back five years you have a lot of work in front of you. But maybe I can save you the trouble.

    In the first three years generation was 100% diesel
    In the fourth year (GdV’s “test year”) generation was ~90% diesel
    In the fifth year (full operation) generation was 61.6% diesel, as shown in http://euanmearns.com/el-hierro-july-2016-performance-update/

    • Ilmar Bouwer says:

      I was already afraid of that, cause thats the only thing i could find, is data per 10 minutes. Oke thank you. I will look into that.

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