Around 3,000 new battery packs, destined for the current smart electric drive vehicle fleet, are being pooled to create the ESS at the enercity site in Herrenhausen. With a storage capacity totalling 15 MWh, the installation is one of the largest in Europe. After completion, the energy storage facility will be marketed on the German primary balancing energy market. The storage facility is already the third major project for Daimler AG in this business sector.

Daimler AG, with its wholly owned subsidiary ACCUMOTIVE, and enercity (Stadtwerke Hannover AG) will begin construction of a new stationary energy storage system (ESS) this year; the facility also functions as a spare parts storage facility for electromotive battery systems.

Daimler launched the third-generation smart fortwo electric drive in 2012; the next generation of the electric city car is now at the ready. Automakers prepare for the eventuality of battery failure, and have suitable replacements available.

Partners Daimler, ACCUMOTIVE and enercity are now forging a unique path in terms of the efficient use of these available, but hitherto unused, resources. Through the “living storage” of the replacement batteries, they are creating a business case that, in this form, can only be achieved together by an automotive manufacturer and a power supply company.

By marketing the storage capacity on the German market for primary balancing power (PRL), the business model makes an important contribution to stabilization of the power grid and to the economic efficiency of electromobility.

In the event of increasing fluctuations in electricity feed-in from renewable energies such as wind and solar energy, such storage facilities help to ensure optimum settling of a mains frequency that has to be kept constant. The ESS can balance the energy fluctuations with practically no losses—a task that is currently undertaken predominantly by fast-turning turbines at the fossil power plants.

enercity is responsible for marketing the storage facility on the primary balancing power market.

Battery health. The innovative storage concept has a further advantage, tha partners point out. To be usable in the event of being needed as a replacement in a vehicle, a battery requires regular cycling during its storage period—i.e. specific charging and discharging for the purpose of preservation. Otherwise it would suffer from deep discharging, which can lead to battery defects.

In addition to the storage costs, the classic and potentially long-term storage of replacement batteries would therefore involve extremely high operating expenditure. The innovative approach adopted by the partners balancing power demand from the grid automatically ensures the required cycling of the batteries.

Further, noted Madeleine Herdlitschka, from Daimler’s R&D Communications, Future Powertrain, the use case in stationary storage for grid balancing is completely different from the use case in a car—e.g., temperature, vibration. “If you use it ‘softly’”, she said, “you don’t have to fear losses.”

The battery management system employed by Daimler subsidiary ACCUMOTIVE ensures that the batteries are always in optimum condition in terms of temperature and charge level so that they meet the high standards required in terms of quality and service life.

Daimler’s stationary storage business. Daimler entered the stationary battery storage business in 2015 with its subsidiary ACCUMOTIVE and has been developing its activities in this sector since then. The company offers solutions for both industrial and private applications. Mercedes-Benz energy storage facilities for private households can be ordered now and will shortly be installed for customers in cooperation with selected sales partners such as energy service provider EnBW or SMA Solar Technology AG.

Just a few weeks ago, Daimler held the ground-breaking ceremony for the world’s largest second-use battery storage facility in Lünen, Westphalia—a joint venture between partners Daimler AG, The Mobility House AG and GETEC. Further major projects are scheduled to start in 2016.