How electric vehicles could transform the power grid

More electric vehicles are becoming capable of not only storing energy for driving, but also for powering buildings and the wider grid, thanks to a capability called “bidirectional charging.”

It’s an emerging technology that could keep fridges, lights and the internet on in homes and other buildings during emergencies, eliminating or reducing the impact of most power outages.

Bidirectional charging also has the potential to make the entire power grid greener and more efficient, enabling increased and better use of wind and solar power. Here’s a closer look at the technology.

What is bidirectional charging?

Up until now, most electric vehicles have been designed around a one-way charge, taking energy from the grid to charge their batteries and releasing it only to power the vehicle.

With bidirectional charging, vehicles are also able to discharge power from their batteries, feeding it back into buildings and the grid when plugged in.

Which vehicles have this capability?

The Nissan Leaf and Mitsubishi’s Outlander plug-in hybrid are currently the only consumer models on the Canadian market that have bidirectional charging, according to Nova Scotia Power.

The utility is running a pilot to test the integration of such vehicles into its grid.

But other manufacturers have said their vehicles will have the feature soon, including Ford’s F-150 Lightning pickup truck and all Volkswagen EVs. Some non-consumer vehicles, such as school buses made by the Quebec-based Lion Electric, also support bidirectional charging.

David Landrigan, vice-president of commercial for Nova Scotia Power, predicts it will eventually be the norm for EVs.

“I actually can’t see any electric vehicle not allowing bidirectional charging in the future, just because of the amount of value it brings,” he said.

Why would you want bidirectional charging?

The simplest use of this technology is what’s being marketed by vehicle manufacturers: spare power when you need it most.

“It’s your own personal power plant, automatically powering your house for three days during an outage,” explained Ford’s chief engineer, Linda Zhang, while unveiling the F-150 Lightning.

That could be handy — and even life-saving — as climate change increases the risk of extreme weather.

It could come into play during lengthy blackouts, like the February outage that cut off power and heat to millions of people for days amid a deadly cold snap in the southern U.S., or during rolling blackouts, like the ones in California in recent years, easing the strain of air conditioners on the grid and lessening the risk of wildfires during heat waves.

Sending power from vehicle-to-building is known as V2B.

While it might function similarly to a backup battery, like a Tesla Powerwall, a car battery typically has a much higher capacity: 155 kilowatt-hours (kWh) for the F-150 Lightning, for example, which is more than 10 times greater than a Tesla Powerwall’s 13.5 kWh.

Ford says its all-electric Ford F-150 Lightning pickup truck will be able to power a home from its battery for three days. The battery has more than 10 times the capacity of a Tesla Powerwall. (Rebecca Cook/Retuers)

Can this benefit people besides the vehicle owner?

Yes. For one thing, electric vehicles can be driven to locations where extra power is needed during natural disasters and mass evacuations.

But taking this one step further, feeding power beyond a single building to the grid itself is a concept known as vehicle-to-grid or V2G, which could potentially benefit the whole power system.

“It’s going to give a lot more grid resiliency,” said Landrigan. If a generating unit goes down or a power line falls, he said, “we can use the tremendous power of these batteries for … keeping the power on for everybody.”

Utilities are also trying to incorporate more wind and solar — cleaner but more variable power sources that don’t necessarily generate maximum power when it’s most needed.

Wind and solar made up 10 per cent of the global power mix in 2019, but need to grow to 60 per cent by 2050 to meet the targets of the Paris climate agreement, according to Francisco Boshell, of the International Renewable Energy Agency (IRENA). 

And their variability will require more storage and backup power to manage supply and demand in the system — something electric vehicles could offer through bidirectional charging. 

Wind and solar energy sources don’t necessarily generate maximum power when demand is highest. But electric vehicles could be used to store some of that energy and feed it back to the grid when needed. 

How can vehicles be used for storage and backup power?

The simplest case doesn’t require bidirectional charging at all — just something known as smart charging. Vehicles would be charged when there is lots of power available — when it’s windy or sunny, for example — and not when electricity demand is high. 

Utilities can encourage this through variable pricing, which raises electricity prices when there’s a shortage of power and lowers rates when there’s lots available. 

With bidirectional charging, when vehicles aren’t in use, they can sell power back to the grid. That could benefit everyone when demand is unusually high, such as during heat waves, when the power consumed by air conditioners can break records.

“It would save the utility from having to turn on extra generators or potentially even hitting a brownout situation,” said Wayne Groszko, an applied energy research scientist at Nova Scotia Community College who is collaborating with Nova Scotia Power on its pilot project.

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