German engineering major Siemens is working on a project to develop a thermal storage system for wind energy that involves a rock-filled insulated container.

As part of the effort, the company partnered with the Technical University Hamburg Harburg (TUHH) and urban utility company Hamburg Energie.

The team currently operates a test set-up for the storage solution, known as Future Energy Solution (FES) in the Northern German.

The system is designed to convert excess wind power to heat in rock fill. It is then stored and protected with an insulated cover.

When additional power is required, a steam turbine will convert the heat back to electricity.

The project has received research funding from the German Federal Ministry for Economic Affairs and Energy.

The store is currently being tested at temperatures over 600 degrees Celsius.

Siemens said that the team is also assessing ways to make charging and discharging the store particularly efficient.

The current test set-up is designed to test the thermal requirements for the storage process.

Siemens project manager Till Barmeier said: "The technology of our FES store deliberately uses mainly tried and trusted technology.

"Because we are working here with tested thermal components and a series-ready steam turbine, we will be able to offer a practical solution within a few years. Our complete experimental system will be operational in just around 15 months."

The team plans to commence testing of the complete energy conversion in spring 2017.

As part of this effort, the partners are establishing a complete thermal store on the Trimet aluminum smelter site in Hamburg-Altenwerder to the south of the River Elbe.

Siemens said that the full-size FES will store around 36MWh of energy in a container with around 2,000 cubic meters of rock.

The researchers expect the FES to generate around 25% of effectiveness in early development phase with potential for up to 50% in future.

Image: Illustration of the Siemens’ Future Energy Solution project. Photo: courtesy of Siemens.