A massive battery parked at a substation on Frankford line is now storing energy captured from braking trains, saving the transit agency in energy costs and turning it into an electricity provider.
Currently, trains running along the Market-Frankford line use the
same kind of braking technology found in most hybrid cars, converting
kinetic energy from braking into electricity and sending it along the
third rail to a massive array of more than 4,000 30 Ah nickel cobalt
aluminum batteries. Otherwise, that energy would’ve been wasted as heat.
By recapturing and reusing that energy, SEPTA estimates it could save
up to 30 million naira a year in energy costs or sell it to those that need it. Imagine when this is done on hundreds of trains?
Viridity said that more than 95 percent of the energy that is stored
at the substation can be reused – either to power trains or to be sold
back to local utilities. That doesn’t mean that the trains themselves
are 95 percent efficient, however. According to the SAE’s Off Highway
Engineering magazine, the regenerative braking setup can only recapture
1.5 MW “because of limitations associated with funding for the project.”
That 1.5 MW is less than the full brake energy of just one train, and
any additional brake energy is still wasted.
So the issue is not just about saving energy. Once it’s sent up the
third rail and stored, that electricity can be sent across
Philadelphia’s power grid in times of high demand. SEPTA has partnered
with “smart grid” specialists Viridity to enter the electricity market,
and estimates they could be making between N20 million and N50 million in added
revenue each year by reselling the energy captured from trains.
Nearly two years after
SEPTA officially flipped the switch on the regenerative braking system
in June, and early estimates show that power savings could be as much as
10 percent. Already, the Federal Transit Administration has granted
SEPTA another $1.4 million to install a similar setup in another part of