By Hudson Sangree

LOS ANGELES — If millions of electric vehicle owners charge their cars at work in the future, it will absorb the abundant solar power produced during the day in California. But if they charge at home immediately after work, it could strain the ability of the grid to meet peak demand, according to a study commissioned by the U.S. Department of Energy.

“Early-morning charging is beneficial for [California’s] duck curve, [but] coming home and plugging in for California is really detrimental,” Michael Kintner-Meyer, a staff scientist with the Pacific Northwest National Laboratory (PNNL), told this year’s audience at Infocast’s EVs and the Grid forum. Kintner-Meyer reported the preliminary results of the study he led, which will be published in the next three months.

In addition to the effect of EVs on the grid, the conference delved into the prospect of self-driving cars eventually becoming the norm.

As General Motors CEO Mary Barra likes to say, “‘The industry will see more change in the next five years than in the previous 50,’” Jamie Hall, GM’s director of advanced vehicle and infrastructure policy, said in his keynote address. “Our vision of the future is zero crashes, zero emissions and zero congestion.”

Self-driving Cars Face Hurdles

In a panel on autonomous vehicles, panelists said technological and regulatory hurdles mean the vehicles won’t be sold to consumers for at least 20 years.

A big challenge is teaching the computerized cars to drive more like humans.

Jonathan Riehl, a transportation engineer at the University of Wisconsin-Madison, said problems occur when self-driving cars enter the mix with human drivers. An autonomous vehicle programmed to follow traffic laws will slow at a yellow light, while a human will typically speed up, leading to rear-end crashes, he said.

The solution, he said, is trying to get autonomous vehicles “to drive a little more aggressively.”

Panelists also said it will be important for self-driving vehicles to be able to communicate with each other about road conditions and to be connected through communications infrastructure so that they’re able to anticipate hazards.

Gregory Winfree, director of the Texas A&M Transportation Institute and former assistant secretary of the U.S. Department of Transportation, said autonomous vehicles can only see so far ahead, just like human drivers. Self-driving cars wouldn’t know if a boulder fell in the roadway on the other side of a blind curve, or if black ice suddenly formed, unless they were connected through infrastructure to other vehicles and information sources, he said.

Creating that infrastructure will be needed before self-driving cars can become an accepted part of the transportation mix, panelists said.

Charging at Work

When EVs charge was a major topic at the forum.

Lincoln Bleveans, assistant general manager at Burbank Water and Power, said he was driving to the conference hotel on the notoriously congested Interstate 405 and wondering what the carbon footprint of the thousands of slow-moving vehicles must be. EVs could help lessen pollution, but only if there are adequate charging stations for drivers at their workplaces, he said.

The city of Burbank sees about 100,000 commuters leave for jobs elsewhere each morning, while 200,000 workers pour in, mainly by car, he said. They park all day at the movie and animation studios of the Walt Disney Co., NBCUniversal and Nickelodeon, among others.

The city is working with those employers to install hundreds of chargers so that workers can fuel up their vehicles while electricity is cheap, because of low demand and ample solar power, from dawn to dusk. The middle of the day is the “belly of the duck” in California’s so-called “duck curve,” when demand is low but the supply of solar power soars. The economics of the situation should help speed the transition from fossil fuels to renewable energy, but only if employees can plug in at work, he said.

Impact on the Grid

In his presentation, Kintner-Meyer said getting workplaces to install chargers, and encouraging workers to charge their EVs during the day, is key to ensuring resource reliability in the future.

DOE asked his team to examine if the grid was ready for a rapid expansion of EVs, especially in the West, where they already have a strong foothold. NERC reliability assessments extend 10 years in advance, so the study could only project data that far into the future, he said.

The PNNL team examined the balancing authority areas in the Western Interconnection, with the assumption that light-duty EVs would increase nationally from roughly 1.3 million today to an “optimistic” forecast of nearly 24 million a decade from now. They superimposed the forecasted load from EV growth onto the native load anticipated by the Western Electricity Coordinating Council for 2028.

Researchers ran different scenarios of charging patterns, including one in which drivers charged primarily at work during daylight hours and another in which drivers charged their cars during peak demand hours after work. Another scenario anticipated that drivers would charge at home late at night and in the early morning hours to take advantage of lower electricity costs during off-peak times.

They also considered the expected growth in solar generation, with California reaching a projected 40 GW in the next 10 years. Natural gas generation will also play a large part in charging EVs, the study suggested.

Under all the scenarios, Kintner-Meyer said, there were no expected electricity shortages, assuming normal conditions with all transmission lines in service.

“We don’t anticipate major resource adequacy issues,” he said.

However, if conditions change — with wildfires burning under power lines or widespread heat waves, for instance — problems could arise, he said. Congestion at transmission bottlenecks, such as the California-Oregon Intertie or the Path 15 transmission line linking Northern and Southern California, could also upset the balance, he said.

There would be insufficient resources if the number of EVs rose to between 30 million and 37 million, the study found.

The problem isn’t a lack of generation, but the ability to move electricity where it’s needed.

“It’s the transmission system,” Kitner-Meyer said. To head off shortfalls, “either you open that up [the congestion points], or you put more generation into the respective balancing areas,” he said.