Weatherwatch: how do we store surplus renewable energy until we need it?
We are able to produce more renewable energy than we can use immediately. Now we must find ways to keep it stored until the demand is high
A milestone was reached for renewable energy in November when more than 100% of Scotland’s electricity demand was met by wind turbines for the first time – enough for nearly six million homes. Scottish weather is powering a revolution. With ever-larger wind turbines being built at sea, and wave and tidal power being developed, the problem will soon be how to use this surplus energy. Some is already exported to England via interconnector cables and in 2020 there will be another running from the Aberdeen area to Norway. But this will not be enough and the race is on to find ways to store cheap energy to sell back to the grid when demand is high.
Large batteries are helping, but another proven method is pump storage. This uses virtually free surplus electricity at night to pump water into upland reservoirs to be used to power turbines during peak periods. Scotland has had these schemes since the 1960s but there is potential for many more and two new ones are proposed to pump water uphill from Loch Ness to reservoirs in the hills.
Using electrolysis to make hydrogen for heating and vehicle fuel is even more ambitious but has huge possibilities. Orkney is leading the way by planning hydrogen driven ferries.