More and more electric vehicles are becoming able not only to store energy for driving, but also to power buildings and the network at large, thanks to a capacity called “two-way charging“.
This is an emerging technology that could keep refrigerators, lights, and the internet on in homes and other buildings in an emergency, eliminating or reducing the impact of most power outages.
Two-way charging also has the potential to make the entire electricity grid greener and more efficient, allowing more and better use of wind and solar energy. Here is an overview of the technology.
What is two-way charging?
Until now, most EVs have been designed around one-way charging, taking energy from the grid to charge their batteries and releasing it only to power the vehicle.
With two-way charging, vehicles can also discharge energy from their batteries, feeding it back into buildings and the grid when plugged in.
What vehicles have this capability?
the Nissan Leaf and Mitsubishi’s Outlander plug-in hybrids are currently the only mainstream models in the Canadian market to have two-way charging, according to Nova Scotia Power.
Utility is running a pilot to test the integration of such vehicles in its network.
But other manufacturers have said their vehicles will soon be equipped with the feature, including Ford’s F-150 Lightning pickup truck and all Volkswagen electric vehicles. Some non-consumer vehicles, such as school buses manufactured by Quebec company Lion Electric, also support two-way charging.
David Landrigan, commercial vice president of Nova Scotia Power, predicts that this will eventually be the standard for electric vehicles.
âIn fact, I don’t see any EVs that allow two-way charging in the future, just because of the value it brings,â he said.
Why would you want two-way charging?
The simplest use of this technology is what is marketed by automakers: saving energy when you need it most.
“It’s your own power plant, which automatically powers your home for three days during an outage,” Ford chief engineer Linda Zhang said at the unveiling of the F-150 Lightning.
It could be practical – and even saving – because climate change increases the risk of extreme weather events.
This could come into play during long outages, like the February blackout that cut power and heating to millions of people for days amid a deadly cold snap in the southern United States, or during continuous failures, like those in California in recent years, reducing the voltage of air conditioners on the network and reducing the risk of forest fires during heat waves.
Sending power from vehicle-to-building is known as V2B.
While it can work the same as 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, this which is more than 10 times greater than 13.5 kWh of Tesla Powerwall.
Can it benefit people other than the vehicle owner?
Yes. On the one hand, electric vehicles can be driven to places where extra power is needed during natural disasters and massive evacuations.
But go further, feed the power beyond a single building to the grid itself is a concept known as network vehicle or V2G, which could potentially benefit the entire electrical system.
âIt’s going to give the network a lot more resiliency,â Landrigan said. If a generator fails or a power line goes down, he said, “we can use the enormous power of these batteries toâ¦ keep the current for everyone.”
Utilities are also trying to incorporate more wind and solar power – cleaner but more variable energy sources that don’t necessarily generate maximum power when it’s needed most.
Wind and solar represented 10% of the global energy mix in 2019, but must reach 60% by 2050 to meet the goals of the Paris climate agreement, according to Francisco Boshell, of the International Agency for renewable energies (IRENA).
And their variability will require more storage and backup power to manage supply and demand in the system, which EVs could offer through two-way charging.
How can vehicles be used for storage and emergency power?
The simplest case doesn’t require a two-way charging at all – just something called smart charging. Vehicles would be charged when there is a lot of electricity available – when it’s windy or sunny, for example – and not when the demand for electricity is high.
Utilities can encourage this by variable pricing, which increases electricity prices when there is a shortage of electricity and decreases the tariffs when there are lots available.
With two-way charging, when vehicles are not in use, they can sell electricity back to the grid. This could benefit everyone when demand is unusually high, such as during heat waves, when the power consumed by air conditioners can break records.
“This would prevent the utility from having to turn on additional generators or even end up in a brownout situation,” said Wayne Groszko, a researcher in applied energy research at Nova Scotia Community College who collaborates with Nova Scotia Power on its pilot project.
WATCH | Renewable energy batteries could potentially change the way NS powers homes:
How much power might be available?
The number of electric vehicles in the world is expected to increase from six million in 2018, to 160 million in 2030, and to more than one billion in 2050, according to IRENA.
This means that “massive electricity storage capacity would be available with all of these batteries on wheels,” Boshell said.
One billion electric vehicles could provide 40 terawatt-hours (tWh) of storage capacity, more than quadruple the nine tWh of storage capacity expected from stationary sources, such as pumped hydropower and grid-scale batteries, d ‘by 2050.
âI think we can call it a game-changing resource,â Landrigan said.
Why have electric vehicles not yet been integrated into the network?
One big reason is that two-way chargers weren’t available, Landrigan said. Some of those being tested in the Nova Scotia Power pilot have not even been certified for general use in Canada.
âThey’re hard to graspâ¦ they’re sort of not at the market stage,â he said.
Another is that charging and discharging a battery degrades it and shortens its lifespan.
A recent study by researchers at the National Research Council of Canada found that under experimental conditions, the battery life of a Nissan Leaf was reduced from 10 years to six years when charged and discharged to help stabilize the battery. network. The process would also reduce the vehicle owner’s electric bill, but only by 10 percent, which is not enough to make up for the reduced battery life.
The researchers predict that improvements in the battery, improvements in charge and discharge conditions, and better compensation or incentives could change the equation.
A recent pilot study of Lion Electric’s New York school buses found that charging and discharging their batteries on the grid once a day had a “very little” impact on degradation, similar to adding an extra route per day, said Patrick Gervais, vice president of communications at the company.
What needs to happen before EVs become part of the network?
There are still a lot of unknowns about how to integrate electric vehicles into the grid, Gervais said. “Nobody really did it.”
This includes programming the load to ensure that there is enough power for the right use – the pipe or the grid – at the right time.
With the Nova Scotia Power pilot project, volunteers allow the utility to control their charging according to certain parameters and to signal if this is causing disruption.
The utility is also interested in the incentives it needs to provide customers – such as specialized tariffs – to allow their battery to be partially controlled by the utility.
While the technology and its regulations both need upgrading, Landrigan said he believes we are “really close” to a future where electric vehicles can be an integral part of a greener network. and more reliable.
“The more we can build the momentum for more and more people to buy electric vehicles and use them to their full potential, the better off we will all be,” he said.