Natural gas: 32% of our energy source, can be used like other fuels, gas consisting of mainly methane CH4. Found alone in coal mines/ oil deposits, most efficient energy source and burns cleanest, produces less C02. \n \n Coal: 11% of our energy source, burned to generate electricity, strip mining (layers for coal) underground mining (tunnels) Cheap, widespread, abundant. Lasts 115 yrs/ 472 bil tons reserved. Environmentally costly, toxic drainage runoff, burning it releases air pollution. Mining is dangerous. \n \n Oil (Petroleum): 37% of our energy source, forms pools under Earth's surface, made up of chains of carbon and hydrogen bonded together. Hydrocarbon chains, lipids) Crude oil is separated into diff components, boiling. US top producer.