An electric generator is a device that converts mechanical energy to electrical energy. So, if we think of a wind turbine, the mechanical energy of the blades turning around, spinning a central axle will cause a mechanical motion that can be transferred into electrical energy via the electric generator.
So, if we expand this knowledge, we can identify many other ways mechanical energy can be converted into electrical energy with:
- turbine with steam, water, or wind
- hand crank
- combustion, reciprocating or piston engine
The rapidly growing field of electromagnetism has spawned many electromagnetic generators, some with technology that has been around since electricity was identified!