Local Storage for Renewable Energy

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Transmission losses and fluctuations in electric power grids can be reduced when renewable energy is stored locally. Researchers at the Technical University of Munich (TUM), Kraftwerke Haag GmbH, VARTA Storage GmbH and the Bavarian Center for Applied Energy Research (ZAE-Bayern) have thus developed a stationary intermediate storage system: the Energy Neighbor. It was taken online today by the Bavarian State Minister of Economic Affairs, Ilse Aigner, in the Moosham district of Kirchdorf in Upper Bavaria.

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.

Researchers of 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 have thus developed the “Energy Neighbor,” a stationary battery storage system. Energy Neighbor stores locally generated electric power on-site for local consumption.

Bavaria’s Minister of Economic Affairs and Energy, Ilse Aigner: “Further development of storage technologies is an important element of the energy transition. Energy Neighbor increases the local consumption of generated power, reduces the load on the grid and facilitates the expansion of renewable energy production capacity. Bavaria is moving ahead in this project with its exemplary fostering of research.”

Balancing production and consumption

With its 200 kilowatt-hours of storage capacity and 250 kilowatts of electrical power, the storage facility can balance the performance peaks of solar systems with the consumption peaks of connected households. “In our field test we intend to gather insight from actual operation apply it to the advancement of storage systems,” says Andreas Jossen, project leader and professor for Energy 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. “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.

Long lifetime

Among its greatest strengths is Energy Neighbor’s long lifecycle. The lifetime of the individual cells lies well over 10,000 complete cycles. “A special temperature management system that keeps the battery cells in an optimal working range whenever possible was developed to extend the lifetime,” says Dr. Andreas Hauer, Director Energy Storage at the Center for Applied Energy Research.

“Many local power transformers are at their limit with the currently installed solar capacity,” says Dr. Ulrich Schwarz, managing director of Kraftwerke Haag GmbH. “We expect to gain important insight on how this kind of storage will affect the stability the low-voltage grid.”

The Bavarian Ministry of Economic Affairs and Media, Energy and Technology funds the Technical University of Munich within the EEbatt project with approximately 30 million euro. In addition to the scientists from 13 professorships of TUM, Kraftwerke Haag GmbH, VARTA Storage GmbH and the Bavarian Center for Applied Energy Research are involved as subcontractors.