Petroleum, its products, and their engines
Petroleum is one of three major energy resources that collectively comprise the fossil fuels. The others are coal and natural gas. A fossil is a remnant of formerly living organisms preserved in the Earth’s crust; a fuel is a substance that we use as a source of energy. Fossil fuels are energy sources originating from the remains of once-living organisms that have accumulated inside the Earth. Collectively, petroleum, coal and natural gas represent the most important source of energy that we have, for electric power production, transportation, manufacturing, and use in the home. Fossil fuels are very diverse: a colorless gas, a liquid that ranges in
color from a pale yellow to black, and a brown or black solid. But, they have two things in common: First, they are, by deﬁnition, fossils-remains of animals and plants. Second, their major chemical component is carbon. The origin of fossil fuels can be understood by considering how carbon is dispersed throughout nature, represented by the global carbon cycle (Figure 6). The key step, photosynthesis, occurs in green plants. It converts water and carbon dioxide from the atmosphere into sugars, which the plants use as an energy source to produce the other chemicals needed for their life processes. These chemicals will eventually transform into fossil fuels.