Risks cited in renewable energy

Solar power and other renewable energy sources present ''environmental risks'' that must be evaluated as the United States begins a major push for alternatives to fossil fuels, the Audubon Society reports.

The environmental group's study, funded by the National Science Foundation, warns that although renewable energy holds great promise for reducing the use of fossil fuels, scientists and citizens alike should be aware of potential hazards.

Renewable energy sources and the hazards they could cause, as cited in the report, include:

* Solar photovoltaic cells: Their manufacture could create shortages of some substances, such as cadmium and gallium, which have a variety of industrial uses. And big centralized banks of solar cells may use up large areas of land.

* Wood-burning and biomass energy production from animal wastes and plants: If improperly managed, these could lead to destruction of forests, increased air pollution, disruption of wildlife habitats, and soil erosion.

* Wind power: Large, modern windmills can cause noise pollution and may interfere with television, radio, and microwave transmissions.

* Hydroelectric power: Damming of rivers can cause siltation and possible stagnation of streams, soil erosion, and loss of available land.

* Geothermal energy: Tapping for water and steam heat deep in the earth may cause earthquakes, release toxic gases, and contribute to water shortages.

* Ocean thermal energy conversion: This makes use of temperature differences between ocean surfaces and deep waters and could use up valuable coastal land, disrupt local marine life cycles and cause weather changes by altering ocean currents.

* Energy conservation: Insulating, caulking, and using storm windows may lead to increased indoor air pollution, as stagnant air stays locked inside.