Most of the energy on Earth comes originally from the Sun. How is energy created? Nuclear fusion in the Sun's core converts hydrogen into helium and other substances. During the fusion process matter is converted to energy in the form of heat and light. Energy and matter have multiple forms and can be changed from one form to another. When you turn on a light, you are converting electrical energy into heat and light energy. This electrical energy comes from a power plant where it was converted from other sources such as water, oil and gas, nuclear, solar or wind energy.