Over 3 years ago, I blogged about the MTA going green, and ways they can improve the entire transportation system. The very last bullet-point of the latter blog post identified "Kinetic Energy Generators" as a way to capture the wasted energy through turnslides.
Inhabitat.com published an article yesterday about Vycon, a company that plans to integrate a system to capture the kinetic energy of moving trains. The potential energy that can be captured and reused when a train is decelerating is about 4 megawatts, which is approximately the amount of energy required to get a train moving. New York City is one the largest consumers of energy in the world. Implementing these types of systems would drastically affect energy costs and energy waste.