A gas turbine–electric locomotive is a type of railway locomotive in which the power is provided by a gas turbine engine. The turbine is connected to an electrical generator which powers the wheels of the train. The electric power is used to make the train move, and the gas turbine is used to provide the energy for the electric generator. It is similar to a diesel-electric locomotive, except that the energy source for the engine is gas (usually natural gas) instead of diesel fuel.