If you’re a typical American, you come home from work and start flipping switches and turning knobs—doing laundry, cooking dinner, watching TV. With so many people doing the same thing, the pressure on the electrical grid in residential areas is highest at this time. This demand will only grow as the world moves away from fossil fuels, with more people buying induction stoves, heat pumps, and electric vehicles.
This presents a challenge for utilities, which already operate strained grids across the United States, all while trying to meet surging energy demand. So they are now trying to turn electric vehicles from a burden into a blessing. For example, more and more models feature “vehicle-to-grid,” or V2G, capabilities, meaning they can send power to the grid as needed. Others are experimenting with so-called active managed charging, where algorithms oscillate when charging EVs, rather than all of them consuming power once their owners are plugged in. The idea is that some people will charge later, but still have a full battery when they leave for work in the morning.
new a report From the Brattle Group, an economic and energy consulting firm created for EnergyHub, which is developing such technology, used real-world data from electric vehicle owners in Washington state to demonstrate the potential of this approach, both for utilities and drivers. They found that an active managed charging program saves up to $400 per EV each year, and the vehicles are always still fully charged in the morning. Utilities also appear to benefit, as redistributed demand results in lower spikes in the early evening. This, in turn, means utilities can delay costly improvements — which they need in order to accommodate increased electricity — saving taxpayers money.
Active managed charging works in conjunction with what is called “time of use,” where the tool charges different rates depending on the time of day. Between 4pm and 9pm, when demand is high, prices are also high. But after nine o’clock in the evening they fall. EV owners who wait until later in the evening to collect tolls pay less for the same electricity.
Time-of-use pricing discourages the use of energy when demand is highest, lightening the load and reducing the amount of electricity utilities need to generate. But there’s nothing stopping everyone from signing up once the cheaper prices start at 9pm. As electric vehicle adoption increases, this coordination problem could lead to a new spike in demand. “An electric vehicle alone can be twice the maximum load that a typical home can handle,” said Akhilesh Ramakrishnan, associate energy director at Brattle Group. “It got to the point where they started needing to manage it differently.”
This is where active managed charging comes into play. Using an app, an electric car owner indicates when he needs to charge his car, and how much charge his battery needs throughout the day. (The app also learns over time to predict when to disconnect the car.) When the owner gets home at 6 p.m., he can plug in, but the car won’t start charging. Instead, the system waits until sometime in the night to turn on the juice, leaving enough time to fully charge the car by the designated hour. “If customers don’t believe we’re going to get them there, they won’t let us control their cars effectively,” said Freddie Hall, a data scientist at EnergyHub.
The typical driver only travels 30 miles a day, requiring about two hours of charging each night, Hall added. By actively managing many cars across 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 need more time to charge, and some will be nearly empty while others may need to be recharged.
How electric vehicles can fix the grid and lower your electric bill
They all still get lower prices with time-of-use rates, but they don’t tax the network by charging at 9 p.m. “The results are actually very, very promising in terms of reducing peak loads,” said Jan Klessel, 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 to reduce overall EV charging costs.”
According to the report, active managed charging will allow the grid to accommodate twice as many EVs before utilities begin upgrading the system to handle the additional load. (And consider all the additional energy demand from things like data centers.) These costs are bound to be passed on to all taxpayers. But the report notes that active managed charging could delay those upgrades by up to a decade. “As EVs grow, if you don’t implement these solutions, there will be a lot of upgrades, and that will have price impacts for everyone,” Ramakrishnan said.
Meanwhile, electric vehicles could help reduce these rates in the long term, thanks to V2G, a separate emerging technology. It allows utilities to call on electric vehicles located in garages as a wide network of backup power. So when demand spikes, these vehicles can send power back into the grid for others to use, or just power the house they’re sitting in, essentially removing the structure from the grid and lowering demand. (Think of all the fleets of electric vehicles, like school buses, equipped with huge batteries to use as supplemental power.) With all that backup power, utilities may not need to build as many expensive battery facilities of their own, projects that taxpayers won’t need to foot the bill for.
Active managed charging and V2G can work in concert, with some batteries depleting at 6pm as they save power, then recharging later in the night. But this ballet will require more large-scale experimentation. “How are we going to be able to discharge the battery and charge it overnight?” Hall said. “Because you want him available 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 them benefit from the network rather than taxing it.