Turbine-electric transmission enters a turbine, where it expands down to the exhaust pressure, producing a shaft work output in the process. The exhaust is fed into the power turbine used to power an output shaft for whatever desired application. The power turbine is also connected to the electric generator, which converts mechanical energy into electrical energy. The electric generator driven by the power turbine charges the battery needed in order to drive the motor that supplies compressed air into the combustor. During cruise speed the electric motor does not have to be functioning, only the gas turbine engine is required to continue
Potential energy hydroelectricity. For example, in Dinorwig, Wales, there are two lakes, one at a higher elevation than the other. At times when surplus electricity is not required (and so is comparatively cheap), water is pumped up to the higher lake, thus converting the electrical energy (running the pump) to gravitational potential energy. At times of peak demand for electricity, the water flows back down through electrical generator turbines, converting the potential energy into kinetic energy and then back into electricity. The process is not completely efficient and some of the original energy from the surplus electricity is in fact lost to