hide You are viewing an archived web page, collected at the request of University of Alberta using Archive-It. This page was captured on 18:01:25 Dec 08, 2010, and is part of the HCF Alberta Online Encyclopedia collection. The information on this web page may be out of date. See All versions of this archived page. Loading media information

a b c d e f g h i j k l m n o p q r s t u v w x y z


For more than half a billion years, photosynthesis has made life possible on Earth. Plants absorb solar energy and use it to convert carbon dioxide and water into oxygen and carbohydrates such as sugar, starch and cellulose. These carbohydrates and other organic materials eventually end up on the ground and in stream, lake and sea beds.
As these organic materials become more deeply buried, heat and pressure transform them into solid, liquid or gaseous hydrocarbons known as fossil fuels - coal, crude oil or natural gas. Coal is generally formed from the remains of land-based plants. Oil is typically derived from water-based plants and animals, mainly algae, that have been gently "cooked" for at least one million years at a temperature between 50 and 150 Celsius. Natural gas can be formed from almost any water or land-based organic materials, under a wide variety of temperatures and pressures.