Saving energy

The New York Times has an article by Diane Cardwell about a smart idea (for once) out of Philadelphia:

Along Philadelphia’s busy Market-Frankford subway line (photo), the trains behave like those of any transit system, slowing to halt at the platforms and picking up passengers.
But more is happening than meets the eye. In an experimental system that is soon to be more widely adopted, every time the trains pull into certain stations, they recover the kinetic energy as they brake and channel it as electricity to battery banks at one of two substations. The batteries, managed by software, can then use that power to push the trains back out, or to help modulate electricity flows on the grid.
The system is unusual because the batteries are being used for more than just powering the trains, said Gary Fromer, senior vice president for distributed energy at Constellation, the power provider that will own and operate the system for the transportation authority. The electricity savings alone do not justify the battery costs, he said, so it was important to find another source of revenue, which comes from selling energy services to the grid. “If battery storage is going to work,” he said, “most of it needs to look like this.”
It has been so successful that officials at the Southeastern Pennsylvania Transportation Authority, SEPTA, said on that they are expanding to seven more stations. Officials estimate the program has already saved about forty thousand dollars in electricity costs for each substation and brought in revenue of a quarter million dollars a year since it started running in 2012.
“We don’t have to front the money, and we’re reaping both savings and actually money coming back our way,” said Jeffrey D. Knueppel, general manager of the transportation authority. The base technology of the system, known as regenerative braking, was one of the breakthroughs that allowed for the development of hybrid and electric cars like the Prius.
It has been used in locomotives for years, but operators have only recently been finding ways to recycle the energy into electricity to power their fleets. Amtrak, for instance, is replacing its electric locomotives with newer models that allow for recycling all of the regenerated energy as electricity for its system, rather than converting some of it to heat.
And a few places have begun to experiment with different ways to harvest brake power in public transit. In Portland, Oregon, a super-capacitor helps collect and dispense the energy on its light rail system. In Los Angeles, California, transit officials are testing the use of flywheel-based storage on the expanding Metro, part of efforts to reduce costs and increase the options to meet ambitious environmental goals. London, England is exploring the use of regenerated energy for its Underground, as well.
But the Philadelphia program has broader implications. Co-funded with a grant from the Department of Energy, the pilot program began with a proposal from the energy services company Viridity, which is providing the energy market services and software. The banks of lithium ion batteries tie into the regional system operator, PJM, which can send a signal for the batteries to charge or discharge at a given time to regulate how much power is flowing into or out of the grid.
Chad Von Eck, vice president for storage at Viridity, said that the company was talking to several other rail companies about putting in similar systems. “Most major transit agencies in the urban hubs have added this capability over the last ten to fifteen years,” he said. “And so a lot of them are already realizing the value of the core regenerative braking capability.” For those that do not have the system, Von Eck said, the savings are there for the taking. “These traction power systems, these networks, are just really waiting for batteries to be placed next to them to make them more efficient and make them a more valuable asset.”

Rico says it's nice to see technology getting smarter...