Intersections: Brake Dance


story by Lee Stabert | illustration by J.P. Flexner

Viridity Energy, local pioneers of smart grid technology (featured in Grid’s August Energy Issue), have announced an exciting partnership with SEPTA. The city’s trains already employ regenerative breaking, generating electricity when they come to a stop. Until now, a large portion of that energy was wasted—it could only be transferred if another train happened to be accessing the station at the same time. Viridity will install a storage device at a substation in Kensington, and their software will enable the battery to capture and distribute that energy.

“That’s electricity they won’t need to pull down from PECO,” explains Viridity’s Laurie Actman. “They can also sell it back into the wholesale market. That will fulfill two goals: save them energy and generate revenue.” The partnership recently received a $900,000 grant from the 2010 Pennsylvania Energy Development Authority (PEDA) program.

“As a company, we’ve opened up a new market—making the power infrastructure of transit systems a resource into the grid,” says Actman. “That has all kinds of wonderful benefits, especially because it helps transit systems, which are themselves sustainability assets for cities and regions.”

Viridity’s other flagship project, Drexel’s microgrid, went live in July. It has already helped the university reduce energy expenses by 15-20 percent in participating buildings. And, by selling excess capacity back to the grid at a premium price, they’ve helped the school create an entirely new revenue stream—during five weeks of summer, the three smart grid-enabled buildings generated about $10,000.