Dive Brief:

• Siemens plans to begin testing in December of a thermal storage system that combines rocks and steam turbines to provide what it says will be a low-cost form of energy storage. 

• The technology uses electricity to heat rocks that can hold thermal energy to power a conventional steam boiler and turbine.The demonstration project in the Bergedorf borough of Hamburg will employ a 5 MW, 36 MWh storage facility that includes a 1.5 MW steam turbine that can deliver 1.5 MW for up to 24 hours and is scheduled for completion in early 2018.

• Siemens hopes to follow the demonstration project with a 30 MW to 40 MW commercial pilot project in 2019 and eventually develop full scale commercial projects of up to 100 MW that would be able to store up to 48 hours of energy for up to week.

Dive Insight:

Technologies for integrating thermal storage into renewable resources hold great promise, but they can be costly. Spanish researchers have come up with a technology that uses molten silicon to store energy, which they say is the basis for a cheaper and more efficient technology.

Now Siemens is planning on demonstrating and bringing into commercial production a technology that would use excess electricity to heat basalt to 600°C. The heat of the rocks would then be used to produce steam that is used for conventional generation equipment.

Siemens’ Future Energy Solution (FES) project, which has funding from Germany’s Federal Ministry for Economic Affairs and Energy, will use wind turbines to heat the rocks, although any generation source could be used.

Siemens says the technology is scalable with the only practical limit being the space needed to hold and insulated the heated rocks.

Siemens also highlights that its FES project is based on proven technologies and a highly available and cheap storage medium. Costs can be reduced even further by using existing decommissioned equipment such as steam turbines.

"This is a reliable, low-cost solution," Till Barmeier, Siemens project manager, told Greentech Media.

Siemens told GTM that FES can deliver energy at under $111/MWh, which compares favorably with the cost of a gas-fired peaking plant, according to levelized cost figures from Lazard.

"This technology operates on a set of simple principles with off-the-shelf, tried-and-tested technologies that can ... achieve high system efficiencies at relatively low cost," Aris Karcanias, managing director of FTI’s global clean energy practice, told GTM, adding that the technology “still has to prove itself in a market dynamic where electricity storage is becoming increasingly competitive.”