Powering buildings from EVs improves vehicle battery life
June 20, 0217
Powering buildings from stored energy in electric vehicles (EVs) can extend the life of the vehicle batteries, according to researchers at the Warwick Manufacturing Group (WMG), an academic department at the UK’s University of Warwick.
The stored energy from EVs can be used to power large buildings, creating possibilities for the future of smart, renewable energy.
Kotub Uddin, with colleagues from WMG’s energy and electrical systems group and car maker Jaguar Land Rover, demonstrated that vehicle-to-grid (V2G) technology can be intelligently used to take enough energy from idle EV batteries to be pumped into the grid and power buildings, without damaging the batteries.
This research into the potentials of V2G shows it could actually improve vehicle battery life by around ten per cent over a year.
For two years, Uddin’s team 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 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, Uddin developed a smart grid algorithm, 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.
The researchers used their smart grid algorithm to see if they could power WMG’s International Digital Laboratory – a large, busy building which contains a 100-seater auditorium, two electrical laboratories, teaching laboratories and meeting rooms, and houses approximately 360 staff – with energy from EVs parked on the University of Warwick campus.
They worked out that the number of EVs parked on the campus (around 2.1 per cent of cars, in line with the UK market share of EVs) could spare the energy to power this building and that, in doing so, capacity fade in participant EV batteries would be reduced by up to 9.1 per cent, and power fade by up to 12.1 per cent over a year.
It has previously been thought that extracting energy from EVs with V2G technology causes their lithium ion batteries to degrade more rapidly.
Uddin’s group along with collaborators from Jaguar Land Rover have proved, however, that battery degradation is more complex, and this complexity, in operation, can be exploited to improve a battery’s lifetime.
Given that battery degradation depends 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 reduced. Hence, taking excess energy from an idle electric vehicle to power the grid actually keeps the battery healthier for longer.
“These findings reinforce the attractiveness of vehicle-to-grid technologies to automotive original equipment manufacturers,” said Uddin. “Not only is vehicle-to-grid effective 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.”
The research on the possibility of extending the lifetime of lithium-ion batteries through optimal V2G facilitated by an integrated vehicle and smart-grid system was published in Energy. It was funded by the Engineering & Physical Sciences Research Council (EPSRC) and the WMG centre High Value Manufacturing Catapult, in partnership with Jaguar Land Rover.