TrolleyImage by kitch via Flickr
What do you get when you pair the latest 21st century energy technologies with with one of the country’s oldest transportation systems?

Viridity Energy, a Philadelphia-area smart grid company, and the Southeastern Pennsylvania Transportation Authority (SEPTA), which has its origins in the early 1900s, when electrified trolleys were the transportation du jour, have teamed up to find out.

Their pilot project will use Viridity Energy's software optimization system to help SEPTA capture and recycle energy generated by trains, trolleys and even electrified buses using the existing regenerative braking capabilities of those transportation systems.

Regenerative braking isn't new. The energy generated by SEPTA's trains is currently captured and fed to the system's third-rail to power other trains.

The innovation here is to store and use the energy through a one megawatt battery array, which should reduce electrical power purchases by 10-20 percent at each location where the batteries are deployed, according to Viridity Energy.

Viridity estimates that one battery will generate $500,000 per year in value. SEPTA hopes to install the technology at all of its electric substations serving trolleys and trains. It may also allow SEPTA to purchase power at night, when rates are low, and potentially provide power to the grid to stabilize regional demand during peak usage events.

The partnership with SEPTA is "a perfect example of how smart grid innovations and advances in technology can effectively be paired with revenue opportunities from competitive energy markets to yield substantial economic, operational and environmental benefits," said Audrey Zibelman, President and CEO of Conshohocken-based Viridity Energy.

For SEPTA, the project is "a foundation for measurable gains in both energy efficiency and voltage stability" in what is one of its busiest corridors, and "a replicable and scalable model for broader system-wide implementation," according to a spokesman.

The partnership received $900,000 in funding from the Commonwealth of Pennsylvania through its 2010 Pennsylvania Energy Development Authority (PEDA) grant program.