During May Gorona del Viento (GdV), a “hybrid” wind-hydro plant designed ultimately to provide the Canary Island of El Hierro with 100% renewable energy, provided only 25.4% renewable electricity to the El Hierro grid, thereby lowering the average renewables fraction since project startup last June to 32.8%. This was a result of a change in operating procedures that resulted in even lower renewables generation than usual and which is documented in this post. (Details on GdV plant layout, operation and capacities are given in the September update. Previous posts on GdV are accessible through the El Hierro Portal.)
I hadn’t planned to write another update on GdV until the end of June, at which time the plant will have completed one year of full operation (preceded by a full year of testing). However, the change in operating procedures during May (earlier post here) has had a strongly negative impact on the percentage of renewables delivered to the El Hierro grid during the month, and this merits another update.
Figure 1 shows the percentage of diesel and renewable power delivered to the El Hierro grid since full operations began, based on daily averages of 10-minute REE grid data. There’s no sign of a decreasing trend in diesel generation:
Figure 1: Percentage of diesel and renewable power delivered to the El Hierro grid since full operations began, daily averages
The table below summarizes monthly grid statistics since full operations began. Of particular interest is the low renewables percentage for May, which was a fairly high-wind month. This was a result of the change in operating procedures.
Up to this point GdV has balanced generation against demand either by running diesel in baseload mode and following load by switching wind power between the grid and pumping, or by a combination of diesel and wind with occasional contributions from hydro. The two modes of load management are illustrated in the August 2015 generation plot shown in Figure 2, although the reasons for switching from one mode to the other are not clear:
Figure 2: August 2015 generation. The flat spots in diesel generation around 1.6 and 3.1MW show where diesel was use as baseload and wind was used to match demand. Erratic diesel generation shows where diesel, wind and occasional hydro were used to match demand.
In May, however, a different approach was tried. Instead of using diesel as baseload and wind/hydro for load following GdV began to use wind and hydro as baseload and diesel for load-following, This resulted in the monthly generation plot shown in Figure 3. During the first two days of May the project operated in the diesel baseload mode with one short 100% renewables test on May 2:
Figure 3: May 2016 generation, REE 10-minute grid data
On May 3, however, procedures were changed to make wind and hydro the baseload sources. Figure 4 reverses the plotting order so that the change is more obvious. The test – one has to assume this is what it was – continued to May 30, since when operations seem to have returned to “normal”:
Figure 4: May 2016 generation with plotting order changed to show the wind and hydro “baseload” contribution and how diesel was used to follow load.
Both hydro and wind production remained low while the test was in progress, and as shown by the plot of daily average wind speed at El Hierro airport this wasn’t caused by lack of wind. Between May 14 and May 24 the wind blew quite strongly (the average wind speed of 11.3 m/s on May 17 was in fact among the highest recorded at the airport since January 2014). Yet combined wind and hydro averaged only 0.8MW over the test period, with the result being that most of the island’s demand had to be filled by diesel generation.
Another feature of interest is that hydro production on May 3 and from May 16-21 was preceded by uphill pumping of water from the lower to the upper reservoir, suggesting that the upper reservoir was “primed” before the hydro generation began.
How much difference did the change make? The Figure 5 XY plot compares daily wind generation from GdV (including wind used for pumping) against average daily wind speed at the airport for May 2-30 (red) and for the rest of the data since the start of operations (blue). The trend line for the rest of the data is over twice as steep as the May 2-30 trend line, indicating that the operational change cost GdV a lot of renewable energy production. How much? At the average May 2-30 wind speed of 7.0 m/s the trend lines show a difference of over a factor of two. So had GdV proceeded with normal operations the renewables percentage during May could have been as high as 50% instead of the 25% actually generated.
Figure 5: XY plot of GdV wind generation vs. daily average wind speeds at El Hierro Airport 3km away. Red dots show all the data from May 2 to May 30. Blue dots show all other data since project startup.
On other issues, it was recently reported that GdV was paid 12 million euros for its 2015 renewable energy production. With 2015 production totalling 8,700MWh this works out to 1.38 euros/kWh. This stands in stark contrast to the claim that “ El Hierro has the cheapest electricity in the Canaries, thanks to Gorona del Viento”, although with El Hierro consumers presently paying only about 0.25 euros/kWh GdV could afford to give its electricity away and still make a handsome profit.
And who paid GdV this generous sum? GdV’s contract is with the Instituto de Desarrolo y Ahorros Emergeticos, which is a branch of the Spanish Ministry of Industry, Tourism and Trade, so presumably it was the Spanish government. In short, the Spanish taxpayer footed the bill.
And what does GdV plan to do with the money? Seven million dollars of it will swell the coffers of the Island Council, which is the majority shareholder in GdV, and the remaining five million will be spent on “improvements” at GdV instead of being distributed as dividends. Exactly what improvements are planned is not specified, but if they take priority over dividends they are obviously considered important.