Alternative Energy Sources

Other sources of alternative energy, some experimental, are also being explored. Methane gas is generated from the anaerobic breakdown of organic waste in landfills and in wastewater treatment plants; this methane can be collected and used as a gaseous fuel for the generation of electricity. With the cost of garbage disposal rapidly increasing, the burning of organic garbage is becoming a viable option as an energy source. Incinerators doing this are sometimes known as "waste to energy" facilities. Adequate air pollution controls are necessary, however, to prevent the emission of toxic chemicals to the environment—a "landfill in the air" effect.

Fuel cells are another rapidly developing technology. These devices oxidize hydrogen gas, produce electricity, and release only water as a waste product. Experimental vehicles (including buses) and medium-sized generating units are already running using this promising technology. Like electricity itself, however, hydrogen is not an energy source; hydrogen gas (H₂) does not occur naturally on Earth in significant quantities, but must be manufactured using energy from fossil fuel, solar power, or some other source. Fuel cells have the advantage of producing electricity at their point of end-use from a concentrated fuel that does not produce pollution; if their fuel can be produced by nonpolluting means, such as from solar energy,

Although not in the strictest sense an alternative source of energy, conservation is perhaps the most important way of reducing society's dependence on nonrenewable fossil and nuclear fuels. Improving the efficiency of energy usage is an excellent way of meeting energy demands without producing pollution or requiring changes in lifestyle (though lifestyle changes may also ultimately be necessary, as nonrenewable energy stocks decline). If a society needs, for example, to double the number of refrigerators it uses from 10 to 20, it is far cheaper at this time to engineer and manufacture 20 refrigerators with twice the efficiency of the old ones than to manufacture 10 refrigerators of the old type and double the amount of electricity produced. New electric generation facilities of any type are expensive, and all—even alternative types—impose some costs on the environment. Experts have estimated that it is still possible to double the efficiency of electric motors, triple the efficiency of light bulbs, quadruple the efficiency of refrigerators and air conditioners, and quintuple the gasoline mileage of automobiles. Several European and Japanese automobile manufacturers are already marketing hybrid vehicles with extremely high gasoline mileage (40–70 + miles per gallon), and these by no means reflect the upper limit of efficiency possible.