Siemens Gamesa has today started operating an electric thermal energy storage system in Hamburg, Germany, that uses volcanic rock.
The pilot project has been developed in partnership with Hamburg Energie and Hamburg University of Technology.
It contains about 1000 tonnes of volcanic rock, which is utilised as the energy storage medium.
Electrical energy is converted into hot air by means of a resistance heater and a blower that heats the rock to 750° Celsius.
During demand peaks, a steam turbine is used for the re-electrification of the stored energy.
The plant can store 130 megawatt-hour of electricity for a week, while storage capacity remains constant throughout the charging cycles.
Siemens Gamesa said the next step would be to use the technology in commercial projects and to scale up the storage capacity and power.
It said the goal is to store energy in the range of several gigawatt hours.
German State Secretary at the Federal Ministry of Economics and Energy Andreas Feicht said: “Decoupling generation and consumption of fluctuating renewable energy via storage is an essential contribution to implementing the energy system transformation.
“We therefore need cost-effective, efficient and scalable energy storage systems.”
Siemens Gamesa chief executive Markus Tacke said: “With the commissioning of our pilot plant, we have reached an important milestone on the way to introducing high-performance energy storage systems.
“Our technology makes it possible to store electricity for many thousands of households at low cost.
“We are thus presenting an elementary building block for the further expansion of renewable energy and the success of the energy transition.”
The technology reduces costs for larger storage capacities to a fraction of the usual level for battery projects, the company said.