SEPTA to reuse energy created by braking subway cars

The Southeastern Pennsylvania Transportation Authority (SEPTA) yesterday unveiled a plan to reuse energy created by braking subway cars.

The transit agency is partnering with Constellation Energy, which will fund, own and operate an 8.75 megawatt battery storage network that will be deployed at seven SEPTA substations.

The storage network captures energy created during rail-car braking and allows it to be reused to power trains as they accelerate from stations, agency officials said in a press release.

Additionally, the network can provide emergency generation for trains in the event of a power outage, SEPTA officials said.

An expansion of SEPTA's 1.8 megawatt battery storage pilot program completed in 2014, the new network brings the agency's total battery storage capacity to more than 10 megawatts.

The stored energy also is expected to help balance electric load on the PJM Interconnection, which is the regional transmission organization that manages the movement of wholesale electricity in 13 states and the District of Columbia. Viridity Energy will provide energy market services for the project and will bid the batteries into the PJM market as frequency regulation resources to help match generation with demand, SEPTA officials said.

The project is among the first commercially deployed battery storage systems in a transit operation, SEPTA officials said, adding that it requires no upfront capital costs from the agency. The plan will be financed through a 20-year battery services agreement with Constellation.

ABB will provide engineering, procurement, construction and operations services to Constellation for the project, while Saft will provide lithium ion battery technology.

Construction is slated to begin in the second quarter of this year, with estimated commercial operation beginning later in the year.