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Electromotive battery systems as a mass storage unit

electric vehicle battery systems
Efficient dual use : In October 2017, a large-scale stack of electric vehicle battery systems went into operation in Hanover as part of a cooperation partnership between Daimler AG with its wholly-owned subsidiary Mercedes-Benz Energy GmbH and enercity (Stadtwerke Hannover AG). ©_Daimler

The cooperation partners Daimler AG with its hundred-percent subsidiary Mercedes-Benz Energy GmbH and enercity (Stadtwerke Hannover AG) have put one of the biggest battery systems in Europe into operation following a construction phase of around one year. The innovative accumulator fulfils a special purpose: it is a “living replacement parts store” for electromobile battery systems. 1800 of a total of 3240 of the battery modules reserved for the third-generation smart electric drive vehicle fleet were pooled to form a stationary accumulator at the enercity site in Herrenhausen, and prequalified to provide primary control power (PCP) by the transmission system operator (TSO) responsible, TenneT. The system is thus already placing an output of 5 MW at the disposal of the electricity market. The completion of the entire system with a total storage capacity of 17.4 MWh is planned for the first quarter of 2018.

Pooling expertise efficiently

The lithium-ion batteries earmarked for automotive use provide a system service on the German market for primary control power (PCP) before they are used in electric vehicles from Daimler AG. Through “live storage” of the replacement batteries the partners are creating an attractive business case which can only be realised jointly by an automotive manufacturer and an energy supply company in this form.

The partners thus benefit from their respective expertise in the areas of the energy industry, system services, battery development and production plus marketing. The production of the automotive lithium-ion battery systems was taken care of by the hundred-percent Daimler subsidiary Accumotive. The development and production of the battery storage system was carried out by Mercedes-Benz Energy, also a hundred-percent Daimler subsidiary. Both companies are based at the Kamenz site. enercity is responsible for marketing the battery storage power on the control power market.

“Live replacement parts store” for car battery systems as a storage battery for the network

By marketing the storage power on the German market for PCP the business model is making an important contribution towards stabilising the electricity network and at the same time towards the economy of electric mobility. In the event of increasing fluctuations in electricity feed-in from renewable energies such as wind and solar energy, such storage units help to ensure optimum balancing of the grid frequency, which must be constantly stabilised.With their storage capacity they balance the energy fluctuations with virtually no losses – a task which is currently predominantly performed by fast-rotating turbines, rotating masses in large power stations. Around half of the planned system strands is already coupled with the network with an output of 5 MW.

Major contribution towards the energy revolution

The electrification of the drive system is decisive when it comes to sustainable achievement of the CO2 goals in road traffic and thus contributes towards fulfilling the international climate protection goals. Daimler AG’s understanding of sustainability goes way beyond the car as a product in implementing CASE. The measures for environmentally acceptable and energy-efficient product design take into account the complete product life cycle – from development through production and product use to disposal and recycling. The efficient use of powerful accumulators and pooling them is an increasingly important element. enercity plus Daimler with its subsidiaries Accumotive and Mercedes-Benz Energy and their replacement parts storage concept are creating a new kind of win-win situation and thus providing exemplary support for progress in the energy revolution.