If you’re a typical American, you come home from work and start turning the switches and dials – doing laundry, cooking dinner, watching TV. With so many other people doing the same, the pressure on the electricity grid in residential areas is currently greatest. That demand will only grow as the world turns away from fossil fuels and more people buy induction stoves, heat pumps and electric vehicles.
That’s a challenge for utilities, which are already managing cracking grids in the United States while trying to meet growing energy demand. That’s why they’re now trying to turn electric vehicles from a burden into a blessing. For example, more and more models have ‘vehicle-to-grid’ or V2G capabilities, which means they send power to the grid if necessary. Others are experimenting with what’s called active managed charging, in which algorithms stagger when electric vehicles are charging, instead of them all using energy as soon as their owners plug them in. The idea is that some people will charge later, but still have a full battery when they leave for work in the morning.
A new one report from the Brattle Group, an economic and energy consultancy, conducted for EnergyHub, which is developing such technology, used real-world data from EV owners in Washington State to demonstrate the potential of this approach for both utilities and drivers. They found that an actively managed charging program saves up to $400 per EV each year, and the vehicles were still fully charged in the morning. Utilities also appear to benefit from this, as the redistributed demand in the early evening ensures fewer peaks. That, in turn, would mean a utility could defer costly upgrades — which they need to accommodate increased electrification — saving taxpayers money.
Active managed charging works in conjunction with something called “time of use,” where a utility charges different rates depending on the time of day. Between 4:00 PM and 9:00 PM, when demand is high, rates are also high. But after 9 p.m. they fall. EV owners who wait until later in the evening to charge pay less for the same electricity.
Time-of-use pricing discourages energy use when demand is greatest, easing loads and reducing the amount of electricity utilities must generate. But there’s nothing stopping everyone from plugging in once the cheaper rates kick in at 9 p.m. As electric vehicle adoption grows, that coordination problem could cause another spike in demand. “An electric car on its own can be twice as high as the peak load of an average home,” says Akhilesh Ramakrishnan, managing energy officer at Brattle Group. “You get to the point where they have to be managed differently.”
That’s where active managed charging comes in. Using an app, an EV owner indicates when he needs to charge his car and how much charge his battery needs for that day. (The app also learns over time to predict when a vehicle will unplug.) When they get home at 6 p.m., the owner can plug it in, but the car won’t start charging. Instead, the system waits until a certain point in the night before turning on the juice, leaving enough time to fully charge the car at the designated hour. “If customers don’t believe we’re going to get them there, they’re not going to allow us to effectively monitor their vehicle,” said Freddie Hall, data scientist at EnergyHub.
The average driver travels only 30 miles per day, Hall added, and requires about two hours of charging each night. By actively managing many cars in the neighborhoods, the system can distribute demand more evenly throughout the night: people will leave for work earlier or later than their neighbors, vehicles with larger batteries will take longer to charge, and some will be low on battery while others may need to be refilled.
They all still get the lower prices with time-of-use rates, but they don’t burden the grid by all charging at 9 p.m. “The results are actually very promising in terms of reducing peak loads,” said Jan Kleissl, director of the Center for Energy Research at the University of California, San Diego, who was not involved in the report. “It shows great potential for reducing the cost of electric vehicle charging in general.”
Active managed charging would allow the grid to accommodate twice as many EVs before a utility would need to upgrade the system to handle the additional load, the report said. (And think of all the extra energy demand from… things like data centers.) These costs are inevitably passed on to all taxpayers. But, the report notes, active managed charging could delay these upgrades by as much as a decade. “As EVs grow, if you don’t implement these solutions, there will be many more upgrades, and that will impact everyone,” Ramakrishnan said.
At the same time, electric vehicles could help lower these rates in the long run, thanks to V2G, a separate emerging technology. This allows a utility to rely on electric vehicles stored in garages as an extensive network of backup power. So as demand increases, those vehicles will can send power to the electricity grid for others to useor simply power the house they are in, effectively removing the structure from the grid and reducing demand. (And think of all the fleets of electric vehicles, like school buses, with huge batteries to use as extra power.) With all that backup energy, utilities might not have to build as many expensive battery facilities of their own, projects that don’t leave ratepayers footing the bill.
Active managed charging and V2G could work together, with some batteries running out of charge at 6pm as they provide energy, and being recharged later overnight. But that ballet requires more large-scale experiments. “How are we going to fit this into the discharging and charging of a battery during the night?” Hal said. “Because you want it delivered the next day.”
To reduce greenhouse gas emissions as quickly as possible, the world needs more electric vehicles. Now it’s just a matter of making sure they benefit the grid, rather than burdening it.
This article originally appeared in Grist.
Grist is an independent, nonprofit media organization dedicated to telling stories about climate solutions and an equitable future. More information at Grist.org
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