They are converting a coal-fired power plant into an energy storage facility by using electric car battery packs. This project will us 1,920 battery modules to store 8.96 MW/9.8 MWh of energy at a shut down coal-fired power plant that was built in 1912 in Elverlingsen.

The energy storage facility is being built to store energy from Germany's numerous renewable energy sources. Solar and wind energy is only produced when there is sun and wind; it is intermittent. The energy storage facility that Mercedes-Benz Energy is building will store the energy so the renewable energy can be used steadily.

Parent company Daimler said:

The large storage plant is therefore a symbol for the transformation in the storage and use of energy - away from fossil electricity grid supply and towards a sustainable extension of the e-mobility value chain that reduces CO2.

Why battery storage?

Solar plants can't produce energy at night or on cloudy days. The energy that was produced during optimal time needs to be stored in a battery to keep and use when solar power isn't producing energy.

Both commercial and residential solar power users use batteries to store their energy. While residences have been using solar battery storage since the 1970s, according to solartribune.com, it is newer for commercial properties.

This is not Germany's first energy storage facility.

The first battery storage was with Entertrag, a wind energy business in Germany. Enel Green Power Germany built a 22MW lithium-ion storage facility that cost $20.4 million.

The plant will be fully operational at the end of 2018. The first 2 MW are now operating.