How is energy stored in fossilized plant and animal matter?

Energy in fossilized plant and animal matter is stored in the form of chemical bonds within organic compounds. Over millions of years, heat and pressure transform these remains into fossil fuels, such as coal, oil, and natural gas. The energy originally captured from sunlight through photosynthesis in plants or consumed by animals is released when these fossil fuels are burned, converting the stored chemical energy into usable energy.