Caltrain’s Brakes Feed Power Back to the Grid. And Now They’ll Reduce Its Cost

When Caltrain rolled out its electrified fleet last year, the new, more eco-friendly trains also came with the ability to recapture energy as they slow down and return it to the grid.

Now, the agency will start to be compensated for that power, following policy changes from local providers Peninsula Clean Energy and San José Clean Energy announced Wednesday.

Caltrain’s regenerative braking is performing better than officials originally anticipated, returning 23% of the power used by its new electric trains. As a result, the commuter rail line revised down its estimated annual power cost from $19.5 million to $16.5 million. Caltrain’s service runs on 100% renewable energy.

There is no legal requirement for the transit agency to be reimbursed for the energy generated by its trains; until now, Caltrain was providing that power back to the grid free of charge.

“It’s exciting and will bring down costs for Caltrain, compensate the system for the energy it’s giving back to the grid,” said San José Mayor Matt Mahan, who spoke to KQED after a press conference at the city’s Diridon Station.

State lawmakers are considering legislation that would make this a standard model for any public agency, allowing them to be compensated for all the power they return to the grid. AB 1372, a two-year bill by Assemblymember Diane Papan, D-San Mateo, would also identify regenerative braking from electric trains as a renewable electrical generation facility.

Papan introduced the bill in February to fill what she called a “gap in the system.”

“Caltrain was sending clean, renewable energy back to the grid, but it wasn’t getting credit for it,” Papan said. “If this were a rooftop solar situation, we would certainly be getting the credit for what we sent back to grid.”

The bill did not pass this legislative session, but it will be considered next year.

Meanwhile, Peninsula Clean Energy and San José Clean Energy voluntarily changed their policies to allow for a net billing tariff to compensate the transit agency for energy returned to the grid. “I’m delighted about it because it really does give Caltrain the credit that it deserves,” Papan said.

Mahan said that this model points to a more innovative future that extends to people’s homes, “where we have a connected grid with electric vehicles and devices on the grid that can charge two ways.”

He recently installed two batteries at his house, which are capable of storing power and putting it back on the grid. “But the market and the financing structure still is not mature enough,” he said. “That’s a policy innovation that we need.”