posted by sebastian .
source of energy of oil, coal, natural gas, nuclear, water
What is the earth??
The first three oxidize carbon and hydrogen to make CO2 and H2O and give off heat (energy)
Nuclear (fission, fusion another ball game) takes advantage of the slight loss of mass during nuclear fission which appears as heat energy.
water? You generally have to put energy into it to get the same amount or less out later. For example you can heat it up and make steam, or you can let the sun heat it up and lift it up as vapor to a high place from which it falls over a water wheel.Or you can put electrical energy in to split water into Hydrogen and Oxygen and recombine them later giving heat energy out.