Battery-based local energy storage to back renewable-energy generation

October 20, 2015 // By Graham Prophet
A project in southern Germany is evaluating the deployment of local energy storage to balance the generation and consumption of energy generated from solar and wind 
resources. Contrary to opinions that have stated that today’s battery technology is not adequate for such a task, this design uses available battery chemistries.

The participating bodies are the Technical University of Munich (TUM), Kraftwerke Haag GmbH, VARTA Storage GmbH and the Bavarian Centre for Applied Energy Research (ZAE-Bayern): who collectively observe that in many southern Germany communities roof-mounted solar panels generate more power during peak times than can be locally consumed. At other times residents must draw on electricity from trans-regional grids. Transmission losses and fluctuations in electric power grids can be reduced when renewable energy is stored locally.

The project is called "Energy Neighbor", and the researchers say it could also could also be a grid-independent solution, although initially it is described as a stationary intermediate storage system. The experimental 200 kWh deployment is in the Moosham district of Kirchdorf in Upper Bavaria. Researchers in the EEBatt project (decentral stationary battery storage for efficient use of renewable energy and support grid stability) funded by the Bavarian State Ministry of Economic Affairs developed the “Energy Neighbor”.

With 200 kilowatt-hours of storage capacity and 250 kilowatts (peak deliverable at any time) of electrical power, the storage facility can balance the performance peaks of solar systems with the consumption peaks of connected households. It occupies a standard shipping-container outline. “In our field test we intend to gather insight from actual operation, [to] apply it to the advancement of storage systems,” says Andreas Jossen, project leader and professor for Electrical Storage Technology at the Technical University of Munich.

The eight-ton, fully integrated storage system currently comprises eight racks of 13 battery modules with 192 battery cells each, a battery management system and performance electronics. The EEBatt project is based around lithium-ion technologies; EEBatt uses Lithium Iron Phosphate (LFP) and Lithium Titanate Oxide (LTO) chemistry for the setup. “As required, the system can be extended in 25 kilowatt steps with further racks. With an additional transformer it can even be used as an insular, grid-independent solution,” says Herbert Schein, managing director of VARTA Storage GmbH.