Siemens Gamesa launches revolutionary thermal storage pilot

Hot-rock plant in Hamburg could be first step towards making wind and solar dispatchable

Siemens Gamesa has begun operation of its revolutionary hot-rock thermal energy-storage system, which has the potential to cost-effectively store gigawatt hours (GWh) of renewable energy for up to two weeks with minimal losses.

Systems such as this may one day resolve the problem of the variability of wind and solar and enable near-baseload renewable-energy output.

The ETES (electric thermal energy storage) pilot plant in Hamburg, Germany — at the site of a decommissioned conventional power plant — converts electrical energy into hot air using a resistance heater and a blower to hear about 1,000 tonnes of volcanic rock to 750°C. When required, the facility converts the stored thermal energy back into electricity using a steam turbine. Due to efficient insulation, the heat can be stored for a week or longer — at a fraction of the costs of battery storage. Siemens Gamesa says the pilot plant can store up to 130MWh for a week, which will be sold on the market by local utility Hamburg Energie.

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“The aim of the pilot plant is to deliver system evidence of the storage on the grid and to test the heat storage extensively,” said Siemens Gamesa in a statement. “In a next step, Siemens Gamesa plans to use its storage technology in commercial projects and scale up the storage capacity and power. The goal is to store energy in the range of several GWh in the near future. One GWh is the equivalent to the daily electricity consumption of around 50,000 households.”

The system uses 80% off-the-shelf components and existing power-generation and transmission facilities at decommissioned conventional power plants, thus keeping costs very low.

“Decoupling generation and consumption of fluctuating renewable energy via storage is an essential contribution to implementing the energy system transformation," said Andreas Feicht, state secretary at Germany’s ministry of economics and energy. "We therefore need cost-effective, efficient and scalable energy storage systems.”

Siemens Gamesa chief executive Markus Tacke added: “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.”

"We are presenting an elementary building block for the further expansion of renewable energy"

The technology is the brainchild of wind industry pioneer Henrik Stiesdal, who came up with the idea almost ten years ago when he was chief technology officer at Siemens Wind Power, which merged with Spanish turbine maker Gamesa to form Siemens Gamesa in 2017.

Stiesdal is developing his own modular version of the technology — to be used at wind and solar farm sites — via his own eponymous company, Stiesdal AS.

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