Rainer Strassburger is back on El Hierro and has downloaded more Gorona del Viento reservoir images on his Cloud site, which is now accessible via the El Hierro portal . Here we take a quick pictorial look at what has changed since he took his last photographs in April. The main changes are a) two flexible pipelines are now delivering water to the Upper Reservoir from the island pipeline network and b) three long graduated poles presumably intended to measure water levels have been installed in the Upper Reservoir, suggesting that GdV may finally be planning to fill it. Otherwise GdV has continued to work with the ~100,000 cu m of water that the reservoirs contained in April.
Figures 1 and 2 compare reservoir level changes between April 13 and December 3 2016. I’ve not made any quantitative measurements but I would judge that the Upper Reservoir has lost maybe 40,000 cu m of water while the Lower Reservoir has gained about 50,000 cu m. In short, there have been no large additions or subtractions of desalinated water since April:
Figure 1: Decrease in water level, Upper Reservoir, April 13 – December 3, 2016 (as of December 3 the UR was effectively empty). There is still no evidence of any water having come down the spillway. As noted in the water goes round and round post it’s believed that water pumped uphill from the Lower Reservoir is diverted downhill again at the pump station below the Upper Reservoir and never makes it to the Upper Reservoir.
Figure 2: Increase in water level, Lower Reservoir, April 13 – December 3, 2016. Water from the Upper Reservoir appears to be coming down the spillway in both images.
Figure 3 now shows the flexible pipeline that was installed at the Upper Reservoir a few years ago with the apparent intention of extracting water and delivering it to the Island capital of Valverde a short distance up the road (blue arrow). I also assumed at the time that the flexible part of the pipeline between the road and the reservoir was a temporary measure and would shortly become permanent.
Figure 3: Pipeline laid from Upper Reservoir to Valverde before project startup. The pipeline is buried under the concrete ditch and heads off north (arrow).
Which goes to show how wrong you can be. The flexible pipeline has been left in place and is now delivering water to the Upper Reservoir, not extracting water from it.
Figure 4: Flexible pipeline balanced on poles and delivering water to the Upper Reservoir (the water can be seen emerging just above the lower row of concrete blocks).
According to Rainer’s images of the flow meter at the location shown in Figure 3 the pipeline delivered 36,414 cubic meters of water to the Upper Reservoir in 17.1 days between December 3 and December 20, representing a rate of 2,134 cubic meters/day. This substantially exceeds the 1,200 cubic meters/day of the Tamaduste desalination plant to the north, the closest to GdV.
Figure 4 also shows another interesting feature – a supported white metal pipe leading from a metal box on the top row of concrete blocks down to the Upper Reservoir outflow, or close to it. Figure 5, which shows an expanded view of the pipe, suggests that it’s a conduit for electric cables and not a water pipe. Exactly what it does is unclear.
Figure 5: Close-up of white metal pipe shown in Figure 4
There’s also activity on the other side of the Upper Reservoir. Figure 6 shows (dimly) a new flexible pipeline that originates somewhere along the road above the Upper Reservoir and brings more water into the reservoir, presumably also from the island pipeline network. It’s impossible to say how much water but it seems reasonable to assume that the capacity of the pipeline would be similar to that of the flexible pipeline shown in Figure 4, i.e. 2,000-2,500 cubic m/day.
Figure 6: Flexible pipeline delivering water on the other side of the Upper Reservoir
Finally comes the most intriguing innovation of all. GdV has installed three long graduated metal poles (Figure 7 dimly shows the graduations) that as far as I can see can have no purpose other than to measure water levels in the Upper Reservoir up to its full capacity. The three pipes cover the vertical intervals between the base of the Upper Reservoir and the “marker levels” defined by the concrete block terraces (Figure 8) and are close to the flexible pipeline and the metal pipe shown in Figures 4 and 5. But why bother to install them unless you plan to fill the reservoir?
Figure 7: Graduated metal pipes showing graduations at one-meter (?) intervals
Figure 8: Graduated metal poles showning relation to concrete block terraces
According to Rainer’s images we now have maybe 4,000-5,000 cubic m/day flowing into the Upper Reservoir plus three metal poles that are apparently designed to measure Upper Reservoir water levels up to full capacity, suggesting that GdV may finally be taking steps to fill the 385,000 cubic meter Upper Reservoir. This raises the following questions:
Is there enough water to do this? According to 2008 data reported on 27 December 2016 (!) El Hierro produced 4.1 million cubic meters of fresh water in 2008 and used only 2.4 million cubic meters, leaving a “reserve of 40%”. Where this 1.7 million cubic meter reserve went isn’t stated, but it’s substantially in excess of the ~350,000 cubic meters that would be needed to fill the Upper Reservoir. So we might tentatively assume that the water is available.
What does GdV get out of it? Since project startup GdV has used an operating system under which water pumped uphill from the Lower Reservoir acts as a dynamic resistor to shed surplus wind power while matching generation to demand and maintaining grid stability, and to handle high-wind periods the 150,000 cubic meter Lower Reservoir must be kept full. (It’s not necessary to leave space in the Upper Reservoir if the water is diverted back down again at the pump house.) But if the Lower Reservoir is full no hydroelectricity can be generated regardless of how much water is in the Upper Reservoir. Maybe the idea is finally to use the Upper Reservoir for fresh water storage, which was its original purpose, and to use surplus wind power to pump water up to the upper reservoir to replace fresh water extraction. But unless GdV finally relents and supplies full details of its future plans I’m just guessing.
And of course it’s always possible that GdV is taking whatever water it can get while it’s there to be had and that the graduated poles have some other purpose.
Will the Upper Reservoir withstand being filled? This comment from an island resident (in Spanish, English translation below) on the “water goes round and round” post suggests that it may not. Certainly some suspicious-looking wrinkles are visible in the Upper Reservoir liner when the sun is in the right direction:
Figure 9: Wrinkles in liner, Upper Reservoir, December 2016
Finally, Figure 10 summarizes the locations of pipelines and other features around the Upper Reservoir for reference purposes:
Figure 10: Layout of pipelines and other features around the Upper Reservoir
A GdV performance update through the end of December 2016 will be published in the New Year.