From the GE website:
The energy that’s generated when you stop a train is substantial. In a conventional train engine, that energy is dissipated as heat and lost to the atmosphere. But we’re working on technologies that can capture and store that energy, using the hybrid dynamic braking system developed by GE’s ecomagination team. This could mean 10% less CO2 emissions and 10% less diesel fuel than a standard locomotive in North America.
GE even manages a ‘Rail Blog‘ to discuss issues related to their products.
