PHILADELPHIA — For years, subway cars have been able to recycle some of the energy created when they brake, turning it into electricity to help power the train or others running on the rails at the same time.
The problem is it’s a short-term benefit, with much of the energy wasted by the time the train stops braking. Now, transit agencies in Philadelphia and other cities across the country are hoping to harness that lost energy by storing it in batteries and putting it back into the system, something that could potentially save millions in energy costs.
The idea of storing the power is enticing for officials at transit agencies, especially with ridership up and systems expanding. Many systems are becoming overwhelmed and power costs are spiking.
The Metropolitan Transit Agency in New York is in the early stages of storing such power, while agencies in Los Angeles and Washington, D.C., are looking at doing so, too.
Working with a private energy company and a $900,000 grant from the Pennsylvania Energy Development Authority, Philadelphia’s transit agency is setting out on a pilot program along one of its train lines that would use a battery system to store the energy created. That power could be used on the system later or possibly be put back into the grid.
Ultimately, the agency hopes to save up to 10 percent on power costs on a system that takes $22 million a year to power.