The three sources of energy include,
Solar energy
Wind energy
Water and geothermal.
Energy is termed as the capacity of physical system to do work. It exists as kinetic or mechanical energy, light potential energy, electrical and heat.
Source of energy can be classified as renewable and non-renewable.
The renewable is derived from natural processes which replenished constantly, for example, solar energy, biomass, ocean, hydropower and wind.
The solar energy it is sustainable to mean that it does not run out but it is maintained reason being that sun shines every day.
A good advantage of solar is that it is natural and available in plenty, and non-pollution. Wind energy helps to turn the blades of windmills as it turns shaft to where they are attached.