by Emil Morhardt

Light rail systems, like hybrid electric vehicles, use their electric engines to generate electricity when they are slowing down, a process called regenerative braking. In hybrid electric vehicles, the energy usually gets stored in lithium-ion batteries, which work well because they are comparatively light weight and not overly bulky. If neither of these were constraints, then flywheels or supercapacitors would be a better choice because they can deliver power faster and they take much longer to wear out. Of the two, flywheels are lighter, less bulky, cost less, and have longer lives according to a study by the UK Rail and Safety Standards board (Kadim 2009). If they are installed alongside the tracks rather than on the trains, weight and bulk are not very important but cost and lifetimes still favor flywheels. Continue reading →