SEPTA puts the brakes on energy loss by slowing subway cars

It’s one of the basic tenets learned in high school physics class. The first law of thermodynamics says that energy cannot be created or destroyed; it can only change form.

SEPTA subway cars use a lot of energy, but then cast it off each time one of them stops at a station. Now, the transit agency is about to put that physics lesson to use.

SEPTA is launching a project to build a battery storage network, which will capture and reuse  energy released by braking subway cars. When complete, the network will be one of the nation’s largest customer-sited battery storage systems — the first commercially deployed for a transit operation — and serve as a model for using stored energy to supply power in congested parts of the grid.

“It’ll save us about a million kilowatt hours each year,” explained Erik Johanson, SEPTA’s director of innovation. He shared the details of the project with NewsWorks Tonight’s Dave Heller.