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A car is plugged in at a charging point for electric vehicles in London on March 6, 2018.Simon Dawson/Reuters

When you plug in an electric car, you take power – but what if you could give it back?

“I would drive to work, and I would give up 50 per cent of my charge to the building a few days a week and get some money,” says Cara Clairman, founder and CEO of Plug’n Drive, which released a report this month on using electric vehicle (EV) batteries to store electricity for power companies. “They would take your battery down to whatever you’re comfortable with, as long as you have enough to get home.”

Why would power companies want the electricity in your EV? In Ontario, power companies have low demand at night, but they're still producing power from nuclear reactors and hydroelectricity.

“They can’t stop the reactors or the rivers at night; it’s not like Quebec where they pond it up,” Clairman says. “So, we have a lot of surplus on the grid.”

The companies look for ways to store that excess power and use it during the day, so they don’t have to fire up polluting natural-gas plants to meet the extra demand.

"There's a lot of talk about how storage can benefit the system, but they're all based on using a brand new [standalone] battery," Clairman says. "But with EVs, [power companies] get the benefits of battery storage without having to buy these new batteries."

Give and take?

How would it work? EV owners would charge at home at night and then, at work, plug into a bidirectional charger, which can either give power or take it away. That charger would take power from your EV, which the building could use.

Bidirectional chargers cost about $6,000 more than standard chargers, so it makes sense to have them in office buildings instead of at home, Clairman says.

"At home, the value isn't as good," Clairman says, "In a building, a lot of different people can use them."

So, why would you want to give up your charge? Well, the average daily commute in the Greater Toronto Area, for instance, is 36 kilometres. That means the average EV should have 220 kilometres of surplus range.

“The studies show that many of us are not using the full capacity of our batteries, and these batteries are lasting a lot longer than people thought,” Clairman says.

The building would use the power from your car instead of paying high commercial peak rates for power. It would then, basically, give you a cut of the savings. If you plugged in and gave up power every day you’re at work, you could potentially make more than $600 a year, the report says.

As long as you had charged at night, you would be getting back more than you paid to charge, Clairman says. There could be as many as 18,555 EV drivers in Ontario participating in mobile storage programs by 2030, the study says.

If that happens, power from EV batteries could provide as much as 565 megawatts per hour of electricity per day, or enough to power 367,250 homes.

"It should make electricity cheaper for everyone," Clairman says.

There’s another way you could make money. When you’re ready to retire the vehicle, you would sell the battery, and it could be used for energy storage.

"A 10- or 13-year-old battery still has 80 per cent of its storage capacity," Clairman says.

The wrong time?

While there have been pilots to see whether this could work, nobody is doing it in practice yet, Clairman says.

But for this idea to make economic sense, power has to be cheaper at night than it is during the day.

During the pandemic, Ontario has suspended time-of-use pricing and replaced it with a flat rate of 12.8 cents per kilowatt hour.

"We would need the time-of-use prices to come back," Clairman says. "Ontario has gotten rid of them for the time being because everyone is at home."

It's not clear yet whether they will come back, Clairman says.

“The Conservative government was never a huge fan of time-of-use pricing,” Clairman says. “This idea could still work, because in Ontario workplaces pay a different price – but it would work even better if we all had time-of-use pricing.”

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