Carbon! (We always love it when the answer is carbon.) The gas we use to power our cars comes from decomposing organic matter. What does that mean? All life has carbon in it -- this includes everything living from you and me to zebras, tapeworms, tulips and seaweed. Since all living things have carbon in them, they are referred to as organic matter. Non-organic matter includes things like rocks, water and metals. When something organic dies, it goes into the earth’s surface. For example, when a leaf falls off a tree, it settles on the ground. Over the next months, it slowly rots and dries up. This process is called decomposition. As the leaf decomposes, it releases its carbons. This carbon combines hydrogen to form hydrocarbons. Hydrocarbons take many forms including oil, which can be refined to gas to make our cars go, natural gas to heat our houses, and petroleum which is used in things like plastics.Here is great short video about the formation of gas (it includes dinosaurs!).