The California Energy Commission asked panelists last week if electric vehicles could help in “compound catastrophes,” such as the combination of wildfires and COVID-19 outbreaks that many fear will occur this fall.

Commissioners asked: Will EVs become an effective tool to store renewable power and to discharge it to the grid when needed? Could battery-powered cars be a backup for homeowners who lose electricity during public safety power shutoffs (PSPS), the intentional blackouts now commonly used by investor-owned utilities to prevent wildfires?

The general answer was “maybe,” but only if policymakers and car buyers can be convinced to see EVs as more than just clean transportation.

“There’s a lot that can be done with EVs,” said Ryan Harty, head of connected and environmental business development at American Honda Motor Co. “It’s a very large energy storage resource that’s frankly sitting there for most of the time. If we look at where cars are parked, about half the cars don’t even leave the home in a typical day — so it’s an incredible energy storage resource that’s just waiting to be exploited for the purpose.”

The problem is, EVs aren’t legally allowed, anywhere in the U.S., to connect and discharge to the grid. That will have to change for vehicles to reach their full potential, he said. “The bidirectional capability of EVs opens up the ecosystem of possibilities.”

Customers asked to pay a premium for EVs must understand the cars’ potential to power their homes or perhaps eventually send energy to the grid in exchange for payments or credits, he said.

The discussion of EVs’ role in grid resilience took place in the first of three CEC workshops on the electrification of the transportation sector on Wednesday and Thursday. Two other workshops dealt with topics such as the role of ride hailing and self-driving big rigs in the state’s push toward 100% clean energy by 2045.

The workshops are part of the CEC’s 2020 update to its Integrated Energy Policy Report.

As with a CEC microgrid workshop July 7-9, the EV resilience session was timely because the state’s annual wildfire season is approaching. (See Fearing Wildfires, PG&E to Cut Power to 800,000.)

Microgrids for resilience are taking hold, but the use of EVs to help in disasters and blackouts remains a more remote solution.

‘100% Energy Security’

At the University of California, Davis, Honda built an experimental “smart home” in 2014 and has been using it to test the capabilities of EVs. In 2016, it began using a vehicle to provide power to the home (vehicle to home, or V2H) and, in 2018, installed technology that allowed an EV to charge and discharge to the local grid (vehicle to grid, or V2G).

A Honda report showed cars are typically parked at home or work, serving little purpose 96% of the time. The automaker intends to change that, Harty said.

“We want to improve the value of this product, not just to the customer but to society, by taking advantage of the fact that it’s there for the purpose of doing other things,” he said.

At the experimental house in Davis, the Honda EV stores 20 kWh of electricity from the home’s rooftop solar array to help power heating and cooling, cooking and hot water heating, he said. A stationary battery provides 10 kWh of additional storage.

“The home can completely isolate from the grid in the case of [an outage],” Harty said. It is “still able to charge the car … and balance itself as a microgrid, providing 100% energy security both for living and for transportation to the customer.”

He said the UC Davis research builds on resilience efforts in Japan after the 2011 earthquake and tsunami that caused three reactors to melt down at the Fukushima Daiichi nuclear power plant.

Battery Degradation

A main argument against using EVs to power homes or the grid is that repeated charging and discharging of batteries causes them to degrade more quickly. Commissioner Patty Monahan asked the resilience panel about that objection.

“Part of the reason that the automakers are not investing in this technology is … the degradation,” Monahan said. “The battery is the most expensive part of the vehicle. This is going to cause some degradation.”

Harty and others said their experiences have shown that degradation wasn’t as serious as critics suggested and could be minimized.

“We’ve studied it in depth,” Harty said. “We’ve published a couple of papers in Society of Automotive Engineers journals on the modes of battery degradation and how it relates to V2G usage.

“A couple of things the battery really hates: It really hates sitting at a very high state of charge for a long time. The battery really hates being cycled from high state of charge to low state of charge, and it hates high temperatures.”

Avoiding cycling the battery “top to bottom” repeatedly is especially important, he said.

“If you just pick a nice healthy window that you’ve established through testing of the middle of the [state-of-charge] range of the battery, and you cycle within that range, then you essentially don’t affect the long-term degradation of the battery,” Harty said.

Occasionally running a car battery to zero to power a home — for instance, to preserve food during a blackout — is OK, he said.

“It’s just like customers driving to zero range on the car,” he said. “The car’s designed to do that a certain number of times in its life.”

Panelist Bjoern Christensen, who heads Northern California advisory firm next-dimension, was formerly chief strategy officer with Nuvve, a leader in V2G technology.

Nuvve has used 10 Nissan Leaf EVs for frequency regulation in Denmark since 2016, with 240,000 hours of vehicle operation in a “very demanding application,” Christensen said. Frequency regulation in Scandinavia is relatively inflexible and must be constantly monitored and adjusted, he said.

The EV batteries have handled the task without undue damage, he said.

“We’ve been measuring the battery state of health over those four years now, and we have found no degradation that is not in line with what Nissan research has predicted,” he said. “We were very surprised that we didn’t see a lot of battery degradation. It’s something … we don’t have any problems with right now for a practical application.”