Can V2G Improve EV Battery Life?

According to a recent press release from Warwick University:

Researchers discover that by intelligently managing vehicle-to-grid technology, energy from idle vehicle batteries can be pumped back into the grid – and this would improve vehicle battery life by around 10%.

That will come as a surprise to many people! Let’s dig deeper to discover what “intelligently managing V2G technology” means in this context. According to the press release once again:

Dr Kotub Uddin, with colleagues from WMG’s Energy and Electrical Systems group and 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.

This new research into the potentials of V2G shows that it could actually improve vehicle battery life by around ten percent over a year.

For two years, Dr 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, Dr 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, 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% 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%, and power fade by up to 12.1% over a year.

This is all still just a trifle vague, so let’s dig deeper still. Dr Uddin and his colleagues have written a learned journal article on the subject at hand, and fortunately for our purposes it’s open access! According to the conclusions to the paper:

The smart-grid algorithm was used to investigate a case study of the electricity demand for the University of Warwick IDL building. Simulation results suggest that the smart-grid formulation is able to reduce the EVs’ battery pack capacity fade by up to 9.1% and power fade by up to 12.1% within the context of the grid topology considered or if the EV is charged to 100% daily. In comparison, if the EV is charged only when the battery is close to depletion, the smart grid optimisation was able to reduce capacity fade by 4.4% and power fade by 9.5%. In conclusion, we show that an EV connected to this smart-grid system can accommodate the demand of the power network with an increased share of clean renewable energy, but more profoundly that the smart grid is able to extend the life of the EV battery beyond the case in which there is no V2G.

I cannot help but think that the opinion of many battery degradation sceptics won’t readily be swayed by “simulation results” based on a “degradation model”, validated or not.

One thought on “Can V2G Improve EV Battery Life?

  1. More on this controversial topic has recently been published in Energy Policy, in a joint paper by Kotub Uddin together with Matthieu Dubarry and Mark B. Glick from the Hawaii Natural Energy Institute who recently published an apparently contradictory paper.

    An Energy Policy press release sums up the new paper as follows:

    Two recent studies, one by Dr. Kotub Uddin at the University of Warwick in the UK and the other by Dr. Matthieu Dubarry at the Hawaii Natural Energy Institute, seem contradictory, with one suggesting that V2G degrades car batteries and the other that it improves battery life. But the two scientists worked together to look at how their studies overlap, showing that they actually come to the same conclusion.

    “Although both our papers seem contradictory, they are actually complimentary,” said Dr. Dubarry. “V2G is not going to be easy, but, if done properly, it has a chance to make a difference for both utilities and electric vehicle owners. We need more research to understand the process better and benefit from the technology.”

    The two authors agreed that in order to be economically viable, V2G has to be optimized between the requirements of the car owner, the utilities and the capability of the grid. In other words, the needs of the different people and systems involved have to be balanced. The question then became ‘can this technology be profitable?’

    The previous studies had different approaches to answering this question: Dr. Dubarry showed that using today’s V2G technology can be detrimental to the car battery, while Dr. Uddin found a smarter grid would make the process economically viable, and even improve the battery. In the new paper, they critiqued each other’s work and found shared conclusions. With improvements to the system, V2G could actually improve electric car battery life and be profitable for everyone involved.

    Interesting stuff indeed!

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