Here's an unusual way to upgrade a subway system: add a giant battery.
Viridity Energy said Monday that it has been awarded a $900,000 grant by the Pennsylvania Energy Development Authority to build a system that will capture the energy from Philadelphia subwayas they brake to enter a station.
The regenerative braking system will collect energy in a large battery installed along the busy Market-Frankford Line. The stored energy will be used to power trains when they leave the station and to earn money from energy sold back to the grid.
"Essentially we're creating … Read more