Absolutely. At hydroelectric stations, for example, the power of gravity is harnessed to produce electricity.
Your question is ambiguous. Are you asking why gravity exists or is gravity or more to the point can Gravity/Magnetism be used as an energy source.
Gravity
Generally when water is used as a source of energy it is either the kinetic energy of the flowing water or the potential energy of the water as it changed height that was used as the energy source. In both cases it is gravity that is the ultimate driving force that makes the water move (for kinetic energy) or is the source of the potential energy - which is recovered as the water moves from higher to lower.
Gravitational energy is generally considered a nonrenewable source because it is derived from the position and mass of objects in a gravitational field (such as Earth's gravity). Once this energy is used, it cannot be easily replenished on a human timescale.
the sun is a energy source of light.
Light energy is used . Sun is the source
The source of energy used by mitochondria is ATP.
fule fossile is the most used energy source
The source of energy in stoves is HEAT ENERGY
Not really because the intense gravity field prevents most of the energy escaping.
Carbs! Carbs are an internal source of energy.
Carbs! Carbs are an internal source of energy.