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Ebbs and Flows of Energy Systems (EFES)

What was the challenge?

Stored energy from electric vehicles (EVs) can be used to power large buildings – creating new possibilities for the future of smart, renewable energy - thanks to ground-breaking battery research from WMG at the University of Warwick.

Our Energy and Electrical Systems group, in partnership with Jaguar Land Rover, has demonstrated that vehicle-to-grid (V2G) technology can be intelligently utilised to take enough energy from idle EV batteries to be pumped into the grid and power buildings – without damaging the batteries.

What did we do?

We analysed some of the world’s most advanced lithium ion batteries used in commercially available EVs - and created one of the most accurate battery degradation models existing in the public domain. This was used to predict battery capacity and power fade over time, under various ageing acceleration factors - including temperature, state of charge, current and depth of discharge.

Using this validated degradation model, a ‘smart grid’ algorithm was developed, which intelligently calculates how much energy a vehicle requires to carry out daily journeys and, crucially, how much energy can be taken from its battery without negatively affecting it, or even improving its longevity.

What was the impact?

It has previously been thought that extracting energy from EVs with V2G technology causes their lithium ion batteries to degrade more rapidly. However, the research team, led by WMG’s Dr Kotub Uddin (along with collaborators from Jaguar Land Rover) proved that battery degradation is more complex - and this complexity, in operation, can be exploited to improve a battery’s lifetime.

Given that battery degradation is dependent on calendar age, capacity throughput, temperature, state of charge, current and depth of discharge, V2G is an effective tool that can be used to optimise a battery’s conditions such that degradation is minimised. Hence, taking excess energy from an idle EV to power the grid actually keeps the battery healthier for longer.

Dr Uddin commented on the research:

“These findings reinforce the attractiveness of vehicle-to-grid technologies to automotive Original Equipment Manufacturers: not only is vehicle-to-grid an effective solution for grid support – and subsequently a tidy revenue stream - but we have shown that there is a real possibility of extending the lifetime of traction batteries in tandem.
“The results are also appealing to policy makers interested in grid decarbonisation.”

Reference: Kotub Uddin, Tim Jackson, Widanalage D. Widanage, Gael Chouchelamane, Paul A. Jennings, James Marco, On the possibility of extending the lifetime of lithium-ion batteries through optimal V2G facilitated by an integrated vehicle and smart-grid system, Energy (2017), doi: 10.1016/j.energy.2017.04.116

EFES

Find out more about our Energy Systems research group here.