I think you meant capacitors. Resistors would just dissipate the energy as heat. edit: Thanks for the correction. They do indeed use resistors and just dump th

I think you meant capacitors. Resistors would just dissipate the energy as heat. edit: Thanks for the correction. They do indeed use resistors and just dump the energy as heat. Unfortunate. Hopefully this will change as supercaps continue to improve. Maxwell tech's modules are already used in light rail, and looks like some work towards smaller locomotives in Switzerland here: https://www.osti.gov/etdeweb/servlets/purl/20823697 https://www.osti.gov/etdeweb/servlets/purl/20823697