Dive Brief:

• The German state of North-Rhine Westphalia plans to turn an unused coal mine into a 200 MW pumped hydro storage plant, according to media reports.

• The facility, in the town of Bottrop, would store renewable energy by using wind and solar power to pump water into a storage reservoir that could be released when the wind isn’t blowing or the sun shining.

• The Prosper-Haniel project would be operated by the University of Duisburg-Essen and RAG AG, the German coal company that owns the mine.

Dive Insight:

Germany’s Energiewende calls for the country to be 80% powered by renewable resources by 2050, which includes the closure of all its nuclear power plants and most of its coal-fired plants.

That poses the dual problem of finding a way to ensure that the wind and solar power are able to provide continuous power and bridging the gap left by closed coal mines and power plants.

A pumped hydro plant housed in a retired coal mine could help solve both problems.

The Prosper-Haniel mine, which is scheduled to close in 2018, is deep enough at 1,969 feet to serve as a penstock for the water stored at ground level. The water would fall into a turbine housed near the bottom of the shaft to produce electricity and would be stored in a lower reservoir formed by the 16 miles of horizontal shafts at the mines base.

When electricity prices are cheap or wind or solar plants are producing more electricity than can be consumed, the water would be pumped back to the upper reservoir where it would be stored until needed to produce hydro power again.