energy, sources of: The Search for New Sources of Energy

The environmental consequences of energy production have led many nations in the world to impose stricter guidelines on the production and consumption of energy. Further, the search for new sources of energy and more efficient means of employing energy has accelerated. The development of a viable nuclear fusion reactor is often cited as a possible solution to our energy problems. Presently, nuclear-energy plants use nuclear fission, which requires scarce and expensive fuels and produces potentially dangerous wastes. The fuel problem has been partly helped by the development of breeder reactors, which produce more nuclear fuel than they consume, but the long-term hopes for nuclear energy rest on the development of controlled sources using nuclear fusion rather than fission. The basic fuels for fusion are extremely plentiful (e.g., hydrogen, from water) and the end products are relatively safe. The basic problem, which is expected to take decades to solve, is in containing the fuels at the extremely high temperatures necessary to initiate and sustain nuclear fusion.

Another source of energy is solar energy. The earth receives huge amounts of energy every day from the sun, but the problem has been harnessing this energy so that it is available at the appropriate time and in the appropriate form. For example, solar energy is received only during the daylight hours, but more heat and electricity for lighting are needed at night. Technological advances in photovoltaic cells and in the cost of the their production have made solar energy a more financially competitive source of energy.

Wind energy, which has long been used as a source of mechanical energy for milling and pumping, can also be used to produced electricity. Modern propellerlike wind turbines, often joined together in wind farms, can produce 1.5 MW or more of electricity and can serve as a significant source of electric energy in plains and coastal areas (including offshore locations). Wind turbines have been most extensively used in Europe, but also have been used in many areas in the United States.

Some scientists have suggested using the earth's internal heat as a source of energy. Geothermal energy is released naturally in geysers and volcanoes. In California, some of the state's electricity is generated by the geothermal plant complex known as the Geysers, which has been in production since 1960, and in Iceland, which is geologically very active, roughly 90% of the homes are heated by geothermal energy. Still another possible energy source is tidal energy. A few systems have been set up to harness the energy released in the twice-daily ebb and flow of the ocean's tides, but they have not been widely used, because they cannot operate turbines continuously and because they must be built specifically for each site.

Another direction of research and development is in the search for alternatives to gasoline. Possibilities include methanol, which can be produced from wood, coal, or natural gas; ethanol, an alcohol produced from grain, sugarcane, and other agriculture plants and currently used in some types of U.S. motor fuel (e.g., gasohol and E85, a mixture of 85% ethanol and 15% gasoline); and compressed natural gas, which is much less polluting than gasoline, but all of these contribute to a greater or lesser degree to air pollution and global warming. Hybrid vehicles, which use electric power from batteries in addition to an internal combustion engine, are less polluting, but rely in part on the engine to recharge the batteries. Fully electric vehicles, which are increasingly common, are significantly less polluting if the energy used to charge them is primarily derived from hydroelectric, solar, or wind sources.

Sections in this article:

• Introduction
• The Search for New Sources of Energy
• Environmental Considerations
• Nuclear Energy
• Electrical Energy
• Heat Energy
• Chemical and Mechanical Energy
• Bibliography

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