“Our intention is to solve the intermittency of the wind and the sun,” says Siemens Gamesa Renewable Energy (SGRE) chief technology officer Antonio de la Torre. “We are 100% convinced that unless we solve this intermittency we will not be able to provide a sophisticated energy transition.”

The ambitious wind turbine manufacturer has developed a hot-rock thermal energy storage system, which is now being tested at a commercial-scale pilot project in Hamburg, that it believes can be a cornerstone of the energy transition.