Almost all the energy sources on Earth are forms of solar energy. The only exception is the geothermal energy. Our common sources of energy include fossil fuels, such as, coal, petroleum, natural gas, etc. Other sources include wood, solar energy, wind energy, etc. Sun's energy can be directly used as solar energy. Wood is a result of plant growth. Plants derive the energy from the process of photosynthesis. In this process, plants use carbon dioxide and water, in presence of sunlight, and generate glucose and oxygen. In this way, sun is the source of wood and other plant components. Animals eat plant and/or each other and thus derive energy from plants, directly or indirectly. Fossil fuels are fossilized form of plants and animals and thus forms of solar energy.Thus, Sun is the source of all energy resources on Earth.
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