Greener Grids

University of Warwick (UW) researchers have discovered how to use energy stored in electric vehicles to power large buildings without leaving them high and dry. The secret is smart management of vehicle-to-grid technology, which allows both the use of energy sitting in idle vehicle batteries and the improvement of battery life in those vehicles by about 10 percent. The resulting “smart grid” can determine how much power it can use without hurting the batteries, and will only take enough to improve performance and longevity.

For about two years, a research team led by Dr. Kotub Uddin analyzed some of the most advanced lithium ion batteries used around the world in commercially available EVs in order to create what may be the most accurate public domain model of battery degradation that exists today. They gathered data on power fade over time and overall capacity under just about any relevant conditions you can imagine, assessing for state of charge and temperature, as well as the depth and current of discharge. Once the team validated their model, Dr. Uddin used it to develop a smart grid algorithm. The algorithm calculates how much energy EVs need to execute their trips, and how much energy the grid can draw from their batteries — both to render them unharmed, and to improve their staying power.

Image Credit: ChadoNihi/Pixabay

Smart Grid In Action

The team put their algorithm to the test with a practical goal: they wanted to power the building of the large International Digital Laboratory. Their test included powering the building's staff quarters, 100-seat auditorium, meeting rooms, and laboratories, solely with energy drawn from the batteries of parked EVs on the UW campus. The experiment worked, and the team calculated that they were able to power the facility by drawing power from the parked cars — which were about 2.1 percent of all cars on campus.

Even more impressive, however, was that by powering the building using the algorithm, they could reduce capacity and power fade in participant EV batteries by up to 9.1 percent and 12.1 percent, respectively, over the course of a year. In other words, not only does using EV batteries to power buildings not hurt them, it actually helps them—if you do it right.

“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,” Dr. Uddin commented in a press release. “The results are also appealing to policy makers interested in grid decarbonization.”

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