The London subway has started using a new technology that stops wasting vast amounts of energy. The quick bursts of speed and abrupt stops that trains make to get from station to station is an energy-expensive system. With “inverter” technology, the Cloudesley Road substation in London was able to gather that wasted power and feed it back into the system. When trains brake, the motors that move it forward become generators that turn kinetic energy into electrical energy to make the train stop. The “inverter” technology allows that energy to run from the generators to the electrified rails and back into the system, resulting in enough energy to power one of London’s largest stations for two days in the week. Implementing the technology across the entire Tube network would save $9.2 million in energy savings.