Abstract

Coal production is most significant fuel source followed by natural gas and petroleum. Coal is overwhelmingly the most significant energy source used to generate electricity. Increased emphasis had been placed on renewable energy resources, including wood and wood waste; municipal solid waste and refuse-derived fuel; other sources of biomass and waste, eg, agricultural crop wastes, tire-derived fuels, and selected hazardous wastes burned as fuel substitutes in cement kilns; wind and solar energy; geothermal steam and hot water; and other unconventional energy sources. Estimates of the contribution of these energy sources vary. There are vast reserves of coal and lignite in the United States. Environmental considerations were reflected in coal production and consumption statistics, including regional production patterns and economic sector utilization characteristics. Average coal sulfur content and coal ash content declined, clearly reflecting a trend toward utilization of coal that produces less SO₂ and less flyash to capture. U.S. resources and reserves of petroleum and natural gas, including natural gas liquids (NGL), are limited. The United States has experienced a significant decline in oil reserves. Similarly, there was a net reserve loss of dry natural gas. The decrease in petroleum and natural gas reserves has encouraged interest in and discovery and development of unconventional sources of these hydrocarbons. Domestic petroleum, natural gas, and natural gas liquids production has declined at a rate commensurate with the decrease in reserves. Total U.S. oil and gas consumption remains high, and these are the fuels of choice for residential, commercial, industrial, and transportation applications. Nuclear, hydroelectric, and geothermal resources now contribute some 9.8 EJ annually to the U.S. economy. Biomass and waste fuels contributed some 3.7 EJ to the economy. These fuels include wood and wood waste; spent pulping liquor at pulp and paper mills; agricultural materials such as rice hulls, bagasse, cotton gin trash, coffee grounds, and a variety of manures. Other sources of energy worth noting are the extensive wind farms, solar projects, and related emerging unconventional technologies. Attention is being paid to increasing the efficiency of fuel utilization as well as to reducing the formation of airborne emissions ranging form particulates NO_x and SO₂ to the management of air toxics such as HCl and trace metals.

The overwhelming sources of petroleum reserves and supply are in the Middle East. Other significant sources of reserves include Russia, the North Sea, North American countries, and parts of southeast Asia. There are also significant concentrations of coal reserves in Russia and China.

The United States, Poland, South Africa, Australia, India, Germany, and the United Kingdom also produce coal.

Canada obtains some of its energy from the Athabasca tar sands development. Renewable and unconventional energy sources are used more extensively in other parts of the world than in the United States. Biofuels are a significant contributor to certain economies.