Bidirectional Charging: Vehicles as a Portable Battery, with Ellie Cohen

Climate Break

Renewable Energy is The Future

California is no stranger to power outages. In 2019, for example, over 25,000 blackout events were recorded across the state, leaving homeowners and businesses without electricity. In recent years, most blackouts are the result of wildfire, wildfire risk (leading to utility shutdowns), and extreme heat (leading to high electricity usage). When the electricity grid is stressed, California relies primarily on gas-powered peaker plants and diesel generators to keep electricity running. However, the use of peaker plants and diesel generators as the primary backup source is not only costly, but can accelerate the climate crisis through the release of greenhouse gases. Instead of solely relying on fossil fuel-powered plants, the state is beginning to transition to the use of clean energy sources like wind and solar in addition to incorporating the use of more batteries and other energy storage to make the renewable energy transition a reality. One part of the solution is the use of electric vehicle batteries as a power source for homes and businesses.

How Does Bidirectional Charging Work?

Bidirectional charging, which allows the energy stored in a car battery to be sent to various recipients, is key to this transition as it can power one’s home, business, appliance, or alternate vehicle. Also known as vehicle-to-home or two-way charging, this innovation additionally serves as an energy backup during power outages.

Senate Bill 233, authored by state Senator Nancy Skinner, would require that all new manufactured electric vehicles sold in California have bidirectional charging abilities by 2035. Currently, electric and hybrid vehicles account for one in four new car sales in California. By implementing bidirectional charging now, the majority of electric vehicles purchased would thus be able to serve as a backup power source during extreme weather events in the near future.

Energy Wherever, Whenever

Bidirectional charging has many potential benefits. First, smart charging technology allows a car battery to be charged during off-peak hours, providing a potential financial advantage for users. If owners charge their EVs during off hours, and discharge back to the grid during peak hours, they can earn the difference between the two rates. With vehicle-to-grid technology, homeowners can sell energy back to the utility company for redistribution which can be used to power homes, buildings or other EVs.

Second, bidirectional charging serves as a backup power source during outages, with a typical car battery storing enough power for a home for roughly two days. As the number of extreme weather events like wildfires and hurricanes increase in frequency, dual charging through EVs can become a dependable source of power. Further, bidirectional technology can serve as a portable power source, providing energy while on the road.

What are the main challenges?

As bidirectional EV charging technology is still coming to fruition, it is not yet widely available, although the lowest cost EV on the market, the Nissan Leaf, has been bidirectional for a decade. Tesla has said that its vehicles would be bidirectional by model year 2025, General Motors has promised its EVs would be bidirectional by model year 2026. As noted in the Kia/Hyundai advertisement which ran during the 2024 Super Bowl, “vehicle-to-load” is available now and can be used to power a refrigerator or other load during a power outage. Fully utilizing the benefits of integrated “vehicle-to-home” as has been advertised by Ford requires additional costs to upgrade home wiring and may cost more than low-income consumers can afford so high investment requirements may discourage the use of such technology amongst lower income groups.

Who is Ellie Cohen?

Ellie Cohen, CEO of the Climate Center, is a leader in transformative solutions to climate change and environmental degradation. Cohen is currently working with local governments, labor unions, and climate justice advocates to push lawmakers to enact policies such as SB 233 to spearhead the transition to renewable energy powered vehicles.

Further Reading

• LA Times Editorial Board, EVs have big batteries. They should come equipped to power homes and the grid in emergencies (Aug. 13, 2023)
• The Climate Center
• Sierra Club, New analysis of California’s 2022 heat wave confirms gas plants failed to deliver promised power while toxic emissions soared in environmental justice communities (2023).
• Lipman, Electric Vehicle Blackouts (SF Chronicle opinion, Sept. 5, 2023).

For a transcript of this episode, please visit https://climatebreak.org/bidirectional-charging-vehicles-as-a-portable-battery-with-ellie-cohen/