M5BAT: Testing flexible battery storage

Because the fluctuating availability of renewable energies can only be balanced out using energy storage, it is an essential building block for transforming the energy system, thus ensuring security of supply and network stability. Together with project partners Exide Technologies, SMA & RWTH Aachen University, Uniper Energy Storage is currently building a unique, modular battery storage facility in Aachen. The research project analyses the economic and technical aspects of energy storage.

Five Battery Technologies in Comparison

The unique feature of the "M5BAT" storage facility in Aachen, in addition to its storage volume of five megawatts, is its modular design. Five different battery technologies are to be tested and compared to each other in the project. Three battery strings with different lithium-ion technologies will mainly serve as short-term power storage. In addition to this, two lead-acid battery strings using different technologies are to be installed, which will be used both for short and medium discharge times. The direct comparison of these technologies will provide important findings on response time and stability. The hybrid operation can also exploit synergies. The thermal behaviour of the batteries will also be analysed in order to optimise air conditioning of the energy storage facility, thus enabling an additional decrease in energy consumption.

Engine for progress:

  • 5 MW storage facility at medium-voltage level
  • modular operation of 5 different types of battery
  • parallel technical and economic considerations
  • development of an algorithm for electricity grid planning and operation
  • participation in the balancing power market

1 of 4

Photo: Uniper

Model of the soon-to-be-finished storage facility.

Testing Economic Efficiency

In addition to the technological aspects, the economic aspects of the modular storage facility will also be investigated. The battery storage will be certified for the balancing power market, which means Uniper can sell the energy stored there on the electricity market. Various operating strategies will be tested in regard to their economic result for various purposes. The economic and technical results of the project, in particular regarding structure and operation, will be compiled and published in a manual for large-scale batteries in the medium-voltage network. Furthermore, a comparative assessment of the technology and a calculation tool for analysing the complete life cycle costs are to be created. RWTH Aachen has also developed a new tool for the optimisation of electricity grid planning and operation.

An Energy Storage Facility in Aachen

The building for the storage facility is currently under construction in Aachen Rothe Erde. A former office building is being converted for this purpose. Numerous regulations on the construction of such units have not been standardised yet. Therefore, noise and fire protection concepts, for example, must be extensively developed. One big advantage of battery storage facilities is their low space requirement. The storage facility is to be officially commissioned in 2016.


Photo: Uniper

"The power grid of the future will not survive without large-scale battery storage facilities. Our project provides important technical and economic information for a successful operation. Qualifying for KlimaExpo.NRW sends the right signal for our project."

Dr. Christian Folke, Project Manager, Uniper

Partners and sponsors

  • Uniper Energy Storage GmbH
  • E.ON Energy Research Center
  • IAEW der RWTH Aachen
  • Exide Technologies Operations GmbH und Co. KG
  • SMA Solar Technology AG
  • Bundesministerium für Wirtschaft und Energie (BMWi)