Generators

A generator is a device that moves a magnet near a wire to create a flow of electrons. The he action that does this varies, but the general idea is the same. 

Windmill

The turbine blades capture the kinetic energy in the wind. When the blades start to move, they turn a shaft that leads from the rotor to a generator. In the generator, the shaft connects to magnets surrounding a coil wire. When the shaft spins the magnets, this generates the voltage int he wire that electrical current. The generator turns the rotational energy into electricity. 

How Nuclear Power works 

Nuclear plants use the heat generated during nuclear fission, when an atom splits and releases energy. Uranium pellets are submerged in water in a pressure vessel. Control rods can be used to produce or reduce heat. The uranium bundle heats the water and turns it to steam. The steam drives the turbine, which spins a generator and makes power.