The greatest source of newly-produced energy in the Universe today is starlight. These large, massive, and incredibly common objects emit tremendous amounts of power through the smallest of processes: the nuclear fusion of subatomic particles. If you happen to be on a planet in orbit around such a star, it can provide you with all the energy necessary to facilitate complex chemical reactions, which is exactly what happens here, on the surface of Earth.
How does this happen? Deep inside the hearts of stars — including in our own Sun’s core — light elements are fused together under extreme conditions into heavier ones. At temperatures over about 4 million kelvin and at densities more than ten times that of solid lead, hydrogen nuclei (single protons) can fuse together in a chain reaction to form helium nuclei (two protons and two neutrons), releasing a tremendous amount of energy in the process.