RWE and Audi create second life EV battery energy storage system
German energy company RWE is piloting a 4.5MWh second life EV battery storage system alongside pumped storage.
The system is comprised of 60 lithium-ion batteries from Audi’s e-tron vehicle development programme and is being tested in providing temporary storage at the pumped hydro plant at the Hengsteysee reservoir, one of the two main reservoirs at Herdecke near Dortmund in west Germany.
The batteries at the end of life in vehicles have a residual capacity of typically more than 80%, opening the way for their use in stationary electricity storage systems. Depending on how they are used, they could still have a remaining service life of up to ten years.
“Powerful battery systems are essential for the energy transition. In Herdecke we are working with Audi to test ways to use decommissioned high voltage batteries from EVs by connecting them together to form stationary storage systems,” explains Roger Miesen, CEO of RWE Generation.
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”Putting such second life batteries to further use is a sustainable alternative to factory new batteries. The experience from this project will help us identify the applications for which we can use battery systems of this nature most cost effectively.”
As the batteries weigh about 700kg each, RWE has built a 160m2 hall for the full system, with installation starting in October 2021 and commissioning in November.
RWE expects to begin marketing the storage capacity of the system early in 2022, initially to help maintain the frequency in the electricity grid. The plan is then to test other marketing methods on a flexible basis.
RWE intends to draw on the insights gained from the Herdecke storage system to build and operate larger storage systems based on EV batteries in the future. This will involve an innovative system in which pairs of modules are connected in series, thus boosting the operating voltage and reducing costs.
With electric vehicle ownership on the increase, the number of batteries available for second life use also will increase.
According to RWE, experts expect the market for second life batteries in Europe to reach 8GWh by 2030 and as much as 76GWh by 2035.
RWE have a number of battery projects under way in the US, Germany and Ireland, including on redox flow batteries and battery storage systems with a virtual connection to hydropower stations. By 2030 the company expects to increase its battery storage capacity from the current level of 600MW to 3GW.
