WASHINGTON, DC, US, May 9, 2007.
Government guidance to help communities and developers evaluate and plan windfarms is lacking in the United States, although the use of wind turbines to generate electricity is increasing rapidly.
The report, ‘Environmental Impacts of Wind Energy Projects,’ was prepared by the National Research Council under a mandate from the federal Congress. It assesses environmental benefits and drawbacks of windfarms and estimates that, by 2020, wind will offset 4.5% of the CO2 that otherwise would be emitted by electricity sources.
Currently, federal regulation of wind projects on private land is minimal and, although some states have developed guidelines, most states are relatively inexperienced at planning and regulation, it concludes. Wind capacity in the U.S. quadrupled between 2000 and 2006 but it still generates less than 1% of the country's electricity.
Some national-level policies to enhance the benefits of wind energy and minimise its harms would help guide state and local regulatory efforts, the report says. It analyses the environmental benefits and drawbacks of wind energy, and provides an evaluation guide to aid decision-making but does not examine the impact of offshore windfarms.
A primary benefit of wind is that it releases no carbon dioxide or other air pollutant; electricity generation in the U.S. accounts for 39% of the country’s total CO2 emissions. Wind would not significantly reduce emissions of sulphur dioxide or nitrogen oxides, where current and expected regulations are largely based on cap-and-trade programs and the committee says the degree to which emissions would be further reduced through special provisions to encourage wind (such as set-asides) is uncertain.
Wind facilities can have adverse environmental effects by damaging habitat and killing birds and bats that fly into turbines, the report notes. Among birds, the most frequent turbine fatalities are nocturnal, migrating songbirds, “probably because of their abundance,” but the committee saw no evidence that fatalities from existing windfarms are causing measurable changes in bird populations in the U.S. A possible exception is deaths among eagles and hawks near California’s Altamont Pass, a facility with older and smaller turbines which appear more apt to kill such birds than newer turbines.
Studies to evaluate possible ecological impacts should be conducted prior to choosing sites for wind facilities, and follow-up studies should be conducted to measure actual effects, the report urges. Additional basic research is needed to help assess the short- and long-term impacts of windfarms on species at risk.
A common objection to proposed wind projects is that they will have a negative aesthetic impact, and the report outlines a process to help communities and developers assess a project's likely aesthetic effects with suggestions on ways to minimise them. It also offers questions which will determine if the aesthetic impact might be great enough to render a project unacceptable.
Wind projects can be disruptive because of noise and shadow flicker, and the report recommends that noise surveys be conducted before a project is sited and that processes be set up to respond to noise complaints. Shadow flicker has generally not been a problem at windfarms in North America, and new turbines can be located so that their shadow paths avoid residences, or operations can be halted during times when troublesome flicker occurs.
