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

On the left is an electric vehicle (EV) plugged into a charging station along a tree-lined street. On the right is a note that reads, “This episode is presented in collaboration with the Energy Innovation Summit and the Climate Center.”

Image caption: Electric vehicles (EVs) have the potential to act as a back-up energy source during emergencies. This episode of Climate Break is presented in collaboration with The Energy Innovators Network and The Climate Center. Image credit: Photo by Andrew Roberts on Unsplash.

Script by:  Kam Ostrum  |  Audio by: Jericho Rajninger |  Blurb by: Sia Agarwal

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


Ethan:   I’m Ethan Elkind, and you’re listening to Climate Break. Climate solutions in a hurry. Today’s proposal: using your electric vehicle to power your home and support the electricity grid. Ellie Cohen, CEO of the Climate Center, explains. 

Ms. Cohen:  We can use the capacity in the batteries of EVs to store energy, like solar. When the sun goes down, we can pull from those batteries to keep the power on, to make sure the grid is secure. There are incredible opportunities to use EVs as a way of preventing power outages across the state and reducing pollution from the fossil fuel peaker plants that the state uses and turns on when there’s high demand for electricity.

Ethan: This aggregated battery power can help avoid blackouts caused by extreme weather and surging demand. According to Cohen, EVs in California alone have the capacity to store a massive amount of electricity. 

Ms. Cohen: The state is expecting 8 million EVs to be on the road by 2030 and 15 million by 2035. 15 million would be the equivalent of 150 gigawatts, almost three times the highest-ever electrical demand in the whole state of California.

Ethan: So why isn’t this technology already available?  

Ms. Cohen: I think the auto industry thought that they could make extra money by charging a lot extra for that feature. But our goal is to make sure that everybody can take advantage of it.

Ethan: Cohen is now working to pass California Senate Bill 233, which will require that all new EVs have two-way charging abilities by 2035. To learn more, and to join the Climate Center at their annual California Climate Policy Summit in Sacramento on March 19th, visit

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