Daimler and enercity are turning a spare parts store into a giant battery

Cooperation partners Daimler AG with its wholly owned subsidiary ACCUMOTIVE and enercity (Stadtwerke Hannover AG) will start work on the construction of a new battery storage facility this year. What makes it particularly special is the fact that this is a spare parts storage facility for electromotive battery systems. Around 3000 of the battery modules, determined for the current smart electric drive vehicle fleet, are being pooled to create a stationary storage facility 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.

2012 saw the launch of the third-generation smart fortwo electric drive and since then it has been convincing customers around the world. The next generation of the electric city car is now at the ready. But what actually happens should the battery become unusable? Automotive manufacturers are of course prepared for this eventuality and have suitable replacements available. In terms of efficient use of resources, partners Daimler, ACCUMOTIVE and enercity are now treading a unique path. Through the “living storage” of replacement batteries, they are creating an attractive 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 stabilisation 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. With their storage capacity, they balance the energy fluctuations with practically no losses – a task that is currently undertaken predominantly by fast-turning turbines at the fossil power plants. The partners will start work on constructing the battery storage facility this year. After completion, grid-connected operation will be possible without interruption. enercity is responsible for marketing the storage facility on the primary balancing power market.

The innovative storage concept has a further decisive advantage. To be usable in the event of a replacement, a battery requires regular cyclising 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 partner companies allows them to avoid this expenditure. The constantly fluctuating balancing power demand from the grid automatically ensures the required cyclising of the batteries. And the highly advanced 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. Rather than having an impact on the ageing process of the systems, this process has the effect of a fountain of youth.

Electromobility plays an important part in achieving the CO2 targets in road transport and makes a major contribution to meeting the international climate protection targets. Here the Daimler AG understanding of sustainability goes way beyond the car product. The measures for environmentally sound and energy-efficient product design take into account the complete product life cycle – from development through production and product use to disposal and reprocessing. Here the efficient use of powerful batteries and their pooling is becoming an increasingly important aspect. With their concept, Daimler, subsidiary ACCUMOTIVE and enercity are creating a new win-win situation and are thus boosting the progress of the energy turnover in exemplary fashion.