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24 May 2020 - capebrenton
Reused electric car batteries could help renewable power grid

Chris White foresees a time when warehouses of batteries retired from use in electric vehicles help usher in a future powered by renewable energy.

The PhD candidate in Dalhousie University`s Faculty of Engineering is studying how to best link up these “second-life” batteries, recovered after the electric vehicles they powered are retired, and use them in the grid.

“We want to convert things that run on fossil fuels to run on electricity,” the Vanier Canada Graduate Scholarship winner said in a telephone conversation on Wednesday. “So battery powered electric vehicles instead of gas-powered cars. And electric heating instead of oil and gas furnaces.

“And then we want to convert our electricity systems to run on renewables instead of fossil fuels, so the electricity we`re using for our cars is clean and not coming from coal power plants, for example.”

But the wind doesn`t always blow and sunlight doesn`t always reach solar cells, he said, so that`s where the concept of connecting large batteries to the grid makes sense.

Solar, wind and maki`g new batteries also have problems, he said. He has written a blog for Dalhousie`s Open Think project (https://blogs.dal.ca/openthink/why-less-energy-beats-clean-energy/) exploring those issues, including the fact they require mining for raw materials, in many cases to the detriment of habitat, water sources and communities in vulnerable areas.

“And another problem is that electric vehicle batteries – EV batteries – will eventually end up as waste,” he said on Wednesday. “We`re already producing millions of EVs per year and this will soon be tens of millions per year and every EV has a large lithium ion battery. The biggest ones I`ve seen are about the size of a double mattress.”

The vehicles will reach the end of their usage cycle after eight to 15 years, he said, meaning there will be millions of EV batteries reaching “retirement age” in the next five to 10 years – and more after that.

He said we shouldn`t recycle the batteries right away because it`s too expensive, ineffective, and they should still be able to store between 50 and 80 per cent of the energy compared to a new one.

“A retired battery doesn`t want a funeral right away, it wants to contribute to society while it can,” he said.

“It could, depending on how you use it, last for 10 more years, so if you recycle it right away when it comes out of the car, you`re wasting all that value.”

White said you can give an old battery an easier job in a second life by connecting lots of them to the power grid so we can use more renewable sources.

“You could have hundreds or even thousands of these second-life batteries all linked together and connected to the grid. So we could see these big warehouses full of these batteries popping up all over.”

As part of his PhD research with Dr. Lukas Swan`s Renewable Energy Storage Lab at Dal, White`s been reading the many economic and technical feasibility studies already completed on the subject.

“I`ve been testing a bunch of different used batteries from electric cars: Tesla, Nissan, Chevrolet, a couple of Chinese manufacturers. And I`ve tested them all under different scenarios that we sort of mimic how it would work on the grid, and they can all do the job.”

Part of his research also has to do with testing to see what batteries are best for different jobs on the grid, how long they will last in their second life, and how to make use of batteries from different manufacturers all in one system.

“I think of it as like a hockey team, for example,” White said. “You have some guys that are not the fastest guys in the world, but they`re big and they do their job well. And then you have players that are small, they`re not going to be making the big body checks, but they can go really fast and that`s their job. So the power grid sometimes needs big, heavy batteries to do a job for a long time – stay on the ice for a long time, kind of thing – so, run several hours. And sometimes it needs batteries that can – not run for a long time – but run really quickly.”

He`s figuring out the different strengths and weaknesses of the batteries to develop a control program that could manage a warehouse of different batteries so it would run efficiently.

Of course, even the second-life batteries would eventually reach the end of their lifespans and need to be recycled.

“That means the waste problem will persist unless someone can develop a recycling process that is both effective and economical,” White said. “There are startup companies here in Canada that are making progress on this, and I feel optimistic that engineers will eventually figure out how to recycle batteries sustainably on a global scale. But regardless of recycling, second-life batteries are a no-brainer technology that can thrive economically while advancing sustainable energy during the critical decades ahead.”