Other mines may follow, as the area needs more industrial-scale storage to double its share of renewables
The Prosper-Haniel hard coal mine in the German state of North-Rhine Westphalia will be turned into a giant battery that stores excess solar and wind energy. This 600m deep mine has been in use since 1974, but after its closure in 2018 it will be transformed to a 200 MW pumped-storage hydroelectric reservoir, able to power more than 400,000 homes. People working at the site will remain employed and will continue to play a key role in providing power for the country, said state governor Hannelore Kraft. She also mentioned that other mines may follow, as the state needs more industrial-scale storage in order to double the share of renewables in its power mix to 30% by 2025. North-Rhine Westphalia, Germany’s most populous state, generates a third of the nation’s power and is home to power generation utilities like RWE AG, E.ON, Steag GmbH, Uniper SE and Innogy SE.
How it will work
Conventional pumped storage plants operate with an upper reservoir on a hill and a lower reservoir in the valley, exploiting the height difference between the two to store energy during periods of oversupply and release it again when required. Following the same principle, the reservoirs in the case of the mine will be built on the surface and an underground cavern respectively. When needed to compensate intermittent wind and solar power, 1 million m3 of water could be allowed to flow downwards through around 26km of shafts. The water would power turbines and generate electricity, and it could be pumped back up again during periods of low demand.
Researchers from various German universities (including that of Duisburg-Essen), together with private engineering companies, the government and the mine owner RAG AG are working on the project, while RAG may also become an investor.
Photo: University of Duisburg-Essen
Source: The Independent