Alexander Fleming

Steve Farmer wrote:The diesel power plant provides the power for pumping the water uphill and then the hydro turbines supply the consumers with their grid power. I'm struggling to see how this benefits anybody except the people who got paid to do it?

Glenn Herbert wrote:Where does the diesel power plant come in? The idea was to use the surplus electricity produced by the wind turbines to pump water uphill.

The aim of the project was to do away with using diesel to generate electricity but like I said, the system is not meeting its aims, because they've not been able to replace diesel generation, for the reasons I explained - they have not designed the system with enough wind power - too few wind turbines - (or other renewable generators such as solar). The renewable generator system is under-powered, by a factor of 5.

It's like they took the V8 engine out of a Hummer and replaced it with a V-twin motorcycle engine and were surprised when it didn't go as fast.

Islands Trying To Use 100% Green Energy Failed, Went Back To Diesel

El Hierro, one of the Canary Islands off  North Africa’s coast, replaced its diesel power plant with a hybrid wind power and pumped hydro storage system worth $94 million.

El Hierro was supposed to be the poster child for 100 percent green energy. The island, located in the Spanish Canary Islands, replaced its diesel power plant with a hybrid wind power and pumped hydro storage system worth $94 million in 2014. The system has only been active since June of 2015.

The expensive system, however, provided an unpredictable amount of power and couldn’t even electrify the entire island. For example, during the high-wind period in the summer of 2015 the island got 51.7 percent of its power from the system, but a low-wind period in December saw the system generate a mere 18.5 percent of the island’s electricity. The sheer unpredictability of the system damages the island’s electrical grid and forces the island to rely on the diesel power it was supposed to replace.

The IER analysis estimates that it would take 84 years for El Hierro’s wind and hydropower system to simply payback its capital costs.

Glenn Herbert wrote:Assuming your calculations are correct, what could have caused the developers to so massively underestimate the necessary amount of wind power?

Matching the appropriate amount of wind turbine power with the appropriate amount of pumped-storage to provide on-demand power was innovative engineering for which there was no existing example for the developers to copy, to reverse engineer, to adapt.

The developers were attempting something new, or at least for which there was no engineers' handbook available.

It really required prior computer modelling (or alternatively physical modelling, as they used to do in the days before computers) to confirm that the system design would work, before building it full scale, but the developers either neglected to model it at all, or they made some errors in their modelling.

If the developers had hired the right person to model their proposed design then such errors might have been avoided but they didn't hire the right person.

Glenn Herbert wrote:Are you calculating as if all of the power is supplied to users from pumped storage, or do you account for some percentage to be directly supplied from the wind turbines?

Users get supplied directly from the wind turbines and if they need more, they get the balance from the hydro-powered turbines.

Perhaps you can follow this?

Line graph of power grid and energy store timeline – June, Scotland
Renewables-only Electricity Generation. Wind turbines and pumped-storage hydro. Case study - Scotland.
Power grid & energy storage modelling time line - June. Annual maxima = Peak Demand 6GW. Installed Wind 33GW. Pumped-storage 160GWh.


So at a time when the demand for power (red line) is higher than the wind power available (grey line), the hydro turbines generate power (green line) to provide the balance of power required to meet demand in full.

The Wind-Hydro-Pumped Station of El Hierro

To quote

“The project is aimed at the design, development, construction commissioning of a hydro-wind system able to cover the electrical demand of the island of El Hierro, making this island a territory that is self-supplied in terms of electricity, strictly through renewable energies.”

But the system developed by Gorona del Viento is not meeting its aims. I’ll explain why and what changes are required to the system to get it to work as intended.

Assuming El Hierro peak demand is 7.6MW

Put the 7.6MW peak demand into my recommendation equations

store energy = 1.11 days x 7.6MW = 8.436 MW-days = 202.5 MWh = 729 gigajoules

Assuming the head between the 2 reservoirs to be 655 metres, the volume of reservoir required is

volume = mass / density
volume = energy / (g x head x density)
volume = 729,000,000,000 / (9.81 x 655 x 1000)
volume = 113,500 m3

So the GdV reservoirs seem to be big enough and no change to the reservoirs is required.

Now let’s find the recommended annual maximum wind power.

annual maximum wind power = 5.5 x 7.6MW = 41.8MW

Whereas only 11.5 MW of wind turbine nameplate capacity is installed.

I’m not sure what the annual peak wind power is now (8MW is the maximum MW plotted in figure 4 here) so let’s assume that 8MW is the annual peak wind power now.

Now – needed — factor increase compared to existing
8MW – 41.8MW – 41.8/8 = 5.2 times more wind power needs to be installed, to a total nameplate capacity of 5.2 x 11.5 = 59.8MW

Executive conclusion.

The El Hierro GdV wind turbines are under-powered by a factor of 5 compared to what will be needed for a successful system design to achieve 24/7/52 100% renewable on demand power.

The recommendation is that additional wind turbines be installed to a total capacity of 60MW.

From a comment on the post Modelling of wind and pumped-storage power on the Scottish Scientist blog