Could EV batteries have a second life as energy storage?

IT’S likely to be years after the lease runs out, but if your customers ever wonder what could happen to their EV’s batteries at the end of their life then wonder no more…

Last month, after having issued more than 30,000 State of Health (SoH) certificates for EV batteries before resale, Arval said that actual EV battery degradation is low, predictable, and far below common misconceptions. For example, at 99,419 miles (160,000 km) or after six years of use, SoH remains above 90%

A large portion of the battery capacity (70-80%) would still be usable even when the vehicles reach the end of their lifespan. Lithium-ion batteries of end-of-life vehicles would have significant capacity remaining for stationary Battery Energy Storage Systems (BESS).

A large and eye-catching use for old EV batteries is demonstrated by Nissan and its Leaf used as backup power for the Johanne Crufy stadium in Amsterdam, Holland. Back in 2023 Jaguar Land Rover announced a collaboration with Wykes Engineering to develop one of the largest energy storage systems in the UK which included 30 second‑life Jaguar I‑PACE batteries

EV vehicle battery as an energy storage at Lempäälä house, Finland

On a smaller scale, the EU-funded TREASoURcE project has tested batteries as energy storage in two locations in Norway and at the Lempäälä House municipal centre in Finland.

Extending the battery lifespan through reuse reduces the need for mining new virgin materials and offers a cost-effective way to support the integration of renewable energy into the electricity grid.

Not all batteries are equal

One of the project’s key technical findings relates to the large differences between batteries. A battery’s suitability for reuse depends on several factors.

It is not worthwhile to scrap batteries if the materials do not have a high value. More typical NMC batteries (nickel-manganese-cobalt) contain valuable metals, which might make materials recycling economically wiser than secondary use as a battery storage unit. Newer LFP batteries (lithium-iron phosphate), however, may be more suitable for reuse, as they do not contain equally valuable materials.

“Reuse is clearly more successful if the original Battery Management System, or BMS, can be used. This is properly successful if the battery’s original manufacturer permits the reuse solution provider to use the BMS”, says Raimo Tengvall, Senior Specialist from the City of Helsinki Innovation Company, Forum Virium Helsinki.

The remaining capacity and internal resistance of the battery must be reliably tested before reuse. The project emphasised the need for standardized testing methods and better availability of battery data, such as charging history.

Key steps in deploying battery storage

During the battery storage experiments in Norway and Finland, the TREASoURcE project learned things that are also suitable for deploying battery energy storage systems based on new batteries.

“A battery as an energy storage unit is best suited for sites with an occasional large power requirement: public events, industrial processes, or even high-power charging for electric vehicles”, Tengvall says.

A used and old battery is naturally more likely to fail and, in the worst case, catch fire, for example, due to thermal runaway. In addition to connection permission from the distribution network company, a rescue plan, and a fire suppression system are required. Furthermore, the battery system must work in conjunction with the property’s potential solar panels and other electricity consumption.

Battery rooms do not yet have their own regulations, so the safety of each site must be assessed separately by experts. Therefore, it may be simpler to implement used battery solutions primarily in outdoor spaces.

Challenges remain

The lessons learned from the TREASoURcE project show that the reuse of EV batteries as energy storage is technically possible, but several obstacles still need to be cleared.

The EU Battery Regulation requires a Digital Product Passport (DPP) starting in 2027, which will contain information on the battery’s origin, service history, and chemistry, among other details. This will significantly ease the evaluation of batteries for reuse. However, such batteries will only begin to become available for reuse in the 2030s–2040s. Additionally, the reasonably affordable prices of new batteries challenge the profitability of reuse, as converting used batteries into energy storage often involves a lot of manual work.

The closed software systems of battery and car manufacturers (OEMs) make it difficult for external operators to assess and control the batteries. Each battery model is different, which prevents automated dismantling and scaling reuse to an industrial scale.

“If processes can be standardised, used electric vehicle batteries could become one part of a flexible energy system—alongside new batteries and other energy storage solutions”, Raimo Tengvall concludes.

Photo by Igor Omilaev on Unsplash