By John Parnell
Belgium has proposed building a doughnut-shaped island in the North Sea to store its excess wind energy generated when demand for it is low.
Turbines will be built into the sand island built two miles offshore. Unused wind power would pump water out of the ring to empty the reservoir. When demand increases water will be allowed to re-enter through the turbines, generating electricity in the process.
As part of a broader renewable energy plan, Johan Vande Lanotte Minister of Economy, Consumer Affairs and the North Sea, announced an offshore wind farm sited with a 25 foot high island to make the most of the intermittent power from the wind farm.
“The big advantage is that with such an energy storage depot we can supply wind power at peak times,” said Vande Lanotte. “You can also save electricity produced on land. We intend to examine the possibility of selling electricity to other countries.”
The island will pump water out with unwanted wind power. It will refill through turbines to generate power on demand.
Belgium is downsizing its nuclear energy operations and is looking for new sources of dependable low-carbon energy.
In 2007, an energy island was proposed by the consultancy DNV KEMA with a similar storage system and wind turbines on site as well.
The doughnut proposal would be sited near a conventional offshore wind farm.
Storing so-called “wrong time” electricity would boost the efficiency of renewables and help to make them more competitive with on price with fossil fuels.
Countries with hydro power dams (and plenty of rainfall) can use unwanted renewable energy to pump water back into reservoirs. It can then be released back down into turbines as and when required.
This is the only current large scale feasible solution although hydrogen fuel cells are improving all the time.
A pilot scheme using “liquid air” in the UK offers another option.
CO2 and water vapour are removed before air, mostly the remaining nitrogen, is frozen using the excess electricity.
The power can be cashed in by allowing the liquid nitrogen to warm and expand drastically as it reforms as a gas. This expansion is then used to drive a turbine.