Ohnoes! The Germans are taking us back to the stone age!
The energy company of the German city of Hamburg, in cooperation with Siemens Gamesa, will start the construction of a test version of a stone battery this fall.
The stone battery works on the same principle a stone grill uses. Certain types of rock are very good at retaining heat for a long time.
Engineers have now come up with a way to incorporate 2000 cubic meters of basalt gravel into a hill in such a way, that hot air blowers can be used to heat the gravel up to about 600C (1112F), and the heat can be retained up to a week.
Combined with a solar and wind park, the thermal battery's heat can be used to generate electricity when solar and wind input is low, while charging up when there's surplus energy.
Siemens Gamesa says the method is extremely well suited to replace coal plants. Just demolish the coal plant and replace it with a stone battery.
To run a 500MW plant for four hours, a lot of basalt gravel is needed: 111 thousand cubic meters. This *would* fit though, on the premises of your average 500MW coal plant.
Siemens isn't the first company to experiment with stone batteries. The Norwegian company EnergyNest uses a special kind of concrete, which can be stacked as modular blocks. In Abu Dabi their design is used in a water desalination plant.
According to Siemens however, using basalt is much, much cheaper.
And the world right now needs cheap ways to store fickle green energy. Much simpler and cheaper than basalt rock it will probably not get.
https://www.volkskrant.nl/wetenschap/hete-steen-mogelijk-uitkomst-voor-opslag-overtollige-groene-energie~a4509047/