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Sunny California Imagines Its Electric Cars as Mobile Power Grid

Jan. 10, 2020, 11:01 AM

Imagine using an electric vehicle to get around town, but also to store energy during surplus times and give it back to the grid when needed.

Spurred by charging infrastructure, manufacturers of electric vehicles, and a goal of 5 million zero-emission vehicles on the road by 2030, California is eyeing additional uses for this type of clean energy.

“The future of the vehicle isn’t just to move people from Point A to B, but it’s actually going to be a resource,” said Rey Gonzalez, a senior mechanical engineer at California Energy Commission. “It’s going to integrate itself at home as well as the workplace.”

The state energy commission has funded $30 million in projects since 2015 looking at vehicle-to-grid integration, including bidirectional batteries. A 2019-2020 clean transportation investment plan allocates another $30 million for zero-emission vehicles and infrastructure, including grid integration efforts.

Wireless charging and robotic charging, where a human need not be present, are among the technologies the state said it wanted to support in the coming year, according to an updated plan released Dec. 16.

In places like California, where utilities are cutting power to avoid sparking wildfires and nearly half of the nation’s zero-emission cars are located, energy on wheels could also help during blackouts.

‘Mobile Battery’

“The mobile battery really wants to mimic a static, stationary battery,” said Gonzalez, who is the commission’s lead for transportation research. “That’s where we can take the value and look at it from a grid perspective.”

Electric vehicles’ internal battery capacity varies widely, propelling cars from 30 miles to as far as 200 miles depending on the model. As these vehicles increase in popularity, they could become a powerful source of energy for the entire electric grid—if the timing is right.

On sunny days, California can have a surplus of energy from solar generation, making it an ideal time to charge at both home and work. But people often charge their cars during typical peak demand, such as at night when they are home from the office.

If electric vehicle batteries could charge during the sunny day when there is a surplus, they could help reduce demand at peak hours later in the day.

Unanswered Questions

Still in early stages, the idea of a car as a mobile battery comes with tremendous opportunity but also many challenges, said Gil Tal, director of the Plug-in Hybrid & Electric Vehicle Research Center at the University of California, Davis.

“You need a lot of cars before it will make sense, and there’s still a lot of questions about how to make it happen,” Tal said.

Chief among the questions are who will manage the charging, how to account for consumer credits or rebates for giving back energy, and any harm to batteries from the additional burden. The state, researchers, manufacturers, and others are looking into these issues.

Nissan Leaf as Battery Storage

The Nissan Leaf is the only car on the market capable of delivering power to a home, building, or the grid, with the proper converters. The Leaf gained popularity as a power provider in Japan after the devastating 2011 earthquake and tsunami, said Aditya Jairaj, Nissan North America’s director of electric vehicle sales.

More than 133,000 Nissan Leafs have been sold in the U.S., though connecting the batteries for other uses hasn’t been a large focus for the company until recently.

“The capability needs to be converted into execution,” Jairaj said. “It’s a step-by-step process.”

Last year, Nissan North America launched a pilot program to use the Leaf to partially power its headquarters in Tennessee and a design center in San Diego.

“There is a lot of interest in the technology,” said Scott Brierley, Nissan North America’s manager of electric vehicle infrastructure. “We want to make sure the car lasts and meets our customer’s needs.”

2014 Air Force Pilot

In 2014, the California Energy Commission was part of a pilot project at Los Angeles Air Force Base that replaced gasoline-powered vehicles with electric ones, including 29 bidirectional vehicles that fed into the local grid. That group included 13 Leafs.

The project proved that a fleet could be aggregated to support the grid, Gonzalez said.

But the program was complicated and costly. Special software had to be developed, vehicles purchased, fleet use guidelines established, agreements to enter the open energy market finalized, and proper infrastructure put in place. Testing also took 18 months longer than planned, according to a project report.

The project showed the vehicles could be linked into a microgrid, but questions arose about whether the cost was worth the benefit. The fleet was too small to take advantage of peak pricing surges. And the estimated summer revenue the fleet generated selling electricity to the grid was $2,200.

The state is focusing on ensuring first, that using the electric vehicles for additional energy storage won’t affect the life of the batteries. A more robust project will have to look at the potential of vehicle-to-grid integration, Gonzalez said.

A pilot project about how vehicle batteries can integrate with microgrids is underway.

Quintuple the Number

As of Oct. 7, the latest data available, 1.35 million electric cars had been sold in the U.S. over the years, with 655,000 of those in California, according to the nonprofit Veloz, which is working to increase the number of emission-free cars on the roads.

California wants to more than quintuple that figure, to 5 million electric vehicles on the road by 2030, as part of its plan to cut greenhouse gas emissions by 40% over 1990 levels.

Making sure those additional vehicles don’t burden the electric grid is top of mind at the Energy Commission.

“We could be causing peaker plants to come on” to handle the burden, Gonzalez said, referring to power plants that kick in only in times of high demand.

“We want to see that deployment, but we would like it to grow where it doesn’t create other impacts along the way,” such as energy demands for charging, he said about integrating electric vehicles into the grid.

Offsetting Vehicle Costs

Experts say the burgeoning electric vehicle market is like solar a decade ago: a bit pricey, but catching on and working its way into the mainstream.

Before electric vehicles can serve as mobile energy, the industry and regulators need to figure out the best way to manage charging to suit the needs of drivers and the grid, according to Tal, from the University of California, Davis.

That includes guaranteeing certain levels of charging, not making options too complicated, and setting prices to encourage off-peak use.

The first step is having “time-of-use rates that encourage charging at times that are best for the grid,” said Sara Rafalson, director of market development for EVgo, the largest fast-charging network in the U.S.

Using electric car batteries for more than just driving could eventually reduce fuel and energy costs at home and work if people get credits for trading energy.

“Anything that can bring down the cost of EVs is viewed as something worth pursuing,” said Mark Higgins, chief operating officer for Strategen, a Berkeley, Calif., consulting and management firm focused on decarbonizing the grid. “If you are using the system efficiently and charging overnight and not creating a need for new infrastructure, that’s a good deal for everybody.”

Strategen is incorporating a 501(c)6 trade group called the Vehicle Grid Integration Council, which will include electric vehicle service providers and auto manufacturers to look at questions like this.

“I don’t know of much that is commercially available,” Higgins said of connecting cars to the grid. “In a year I think there will be.”

To contact the reporter on this story: Emily C. Dooley at

To contact the editors responsible for this story: Gregory Henderson at; Renee Schoof at; Anna Yukhananov at