Belgium's North Sea minister has revealed the nation's novel solution to preserving excess energy -- build a doughnut-shaped island a few miles of the coast that continually pumps water through its delicious centre.

Apparently the country has so much clean energy, it doesn't know what to do with it, and while that doesn;t appear to sound like a problem on the surface, storing renewable energy is a big problem.

At the moment, excess energy generated by Belgium's wind farms is simply going to waste, reports Reuters. "We have a lot of energy from the wind mills and sometimes it just gets lost because there isn't enough demand for the electricity," a spokeswoman for minister Johan Vande Lanotte said.


Once completed, the island would receive excess energy from the country's wind farms and use it to pump water out of the doughnut hole (its reservoir). When Belgium is in need of an energy top up, the water will be allowed to flow back into the reservoir where it will spin turbines and generate electricity.

The idea does not sound so bizarre when you consider that pumped hydroelectricity reportedly has a storage efficiency of more than 80 percent. There are pumped storage power stations around the world and in Norway mountain reservoirs are being used to pump water uphill using excess energy, before releasing it downhill from a second reservoir to turn a generator and produce energy. "Pumped storage hydroelectricity is a particularly good match for wind power because water pumped into an upper reservoir will stay there for a long time, making up for potentially large gaps in wind generation," explains David Linley in an issue of Nature.

Trouble is, Belgium's coastline is pretty small -- a brief stretch of about 65km -- so there would be no chance of imitating Japan's Okinawa Yanbaru Seawater Pumped Storage Power Station along the Philippine Sea coastline. And Belgium is not the most mountainous place, aside from within the Ardennes forest region. The small country's dense population, along with environmental concerns, would count this region out as a viable location for energy storage. As Linley comments in his overview of renewable energy storage options, "building such storage tends to be expensive and environmentally destructive, and installing high-voltage transmission lines to connect remote storage sites to grids often triggers opposition on environmental grounds."

For the doughnut island to take shape, Belgium's grid operator Elia will need to strengthen its coastal lines, which is happening anyway. Once that's sorted, there's just the small feat of building the island. The village of Wenduine will get a nice addition to its seaside vista, with sand dumped three kilometres off the coast from it to build the storage facility.


There are no concrete plans in motion to begin work on the island, but according to the Reuters report it could take five or more years. Belgium has time, considering it just delayed its nuclear energy phase-out, but if it wants to stay on track to its 2025 deadline this looks like a viable option.

The country had just 1,078 megwatts of wind power connected to the grid in 2011, but the European Wind Energy Association issued a report the same year predicting Belgium would expand capacity to more than 4,000 megawatts by 2020.

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