Spent EV batteries could make renewable power more reliable

Spent electric car batteries could be used to improve the effectiveness of wind and solar power generation thanks to planned research by several vehicle manufacturers.

Following similar recent moves by Tesla and Nissan, Vauxhall owner General Motors (GM) this week announced that it would be developing a way of reusing batteries from the Chevrolet Volt electric car, in partnership with Swiss energy technology provider ABB.

Rechargeable batteries that can no longer hold enough electricity to power a car could still be used as stationary electric grid storage systems that require less energy to be held per kilogram and so could help maintain a more consistent energy output from intermittent renewable sources.

‘We see a really significant potential for lithium-ion battery technology to fill the need of the utility sector for storage in the long term,’ said Mark DuVall, director of electric transportation for the US Electric Power Research Institute (EPRI), speaking via a conference call for the GM announcement.

‘Storage can do a number of things that the grid is currently being asked to do and one of the most frequently discussed is intermittent renewables,’ he said, noting the degree to which cloud cover can interrupt solar array output. ‘Energy storage can help smooth that out and it can perform a number of grid services.’

As well as providing renewable energy storage, GM and ABB are looking at ways that rechargeable batteries could act as back-up power sources, help supplement demand during peak-time operation and allow customers to store cheaper, off-peak power for use during peak hours.

‘Future smart grids will incorporate a larger proportion of renewable energy sources and will need to supply a vast e-mobility infrastructure – both of which require a range of energy-storage solutions,’ said Bazmi Husain, head of ABB’s smart grids initiative.

GM hopes to have its technology ready within a few years, well before the warranty expiration of the first wave of Volt batteries, which will have lost 30 per cent to 50 per cent of their capacity by that time.

‘For an average customer using the Volt battery over its lifetime, we are projecting the ability to have secondary usage of another five to 10 years,’ said GM’s executive director of electrical systems, Micky Bly. ‘It has extreme capability, almost doubling the life of the cell itself.’

Stationary storage batteries are likely to have different requirements, such as higher operating voltages, than car batteries and may require substantial re-engineering, the EPRI’s senior project manager, Haresh Kamath, told The Engineer.

‘First, we have to do some testing to decide at what point the battery is no longer suitable for a vehicle. We also have to test the used batteries to see what kind of performance and life we can expect in utility applications.

‘There’s quite a bit of work to do, so we have to get started on investigating this problem right now, even though we don’t expect a huge number of used batteries to be available for a few years.’