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ePaper created 2014-06-03, 15:03:20 | version 1.30.01
60 02 MARKET AND INDUSTRY TRENDS SIDEBAR 5. SUSTAINABILITY SPOTLIGHT: WIND ENERGY A decade of surging growth in the wind energy sector has changed the electricity mix in many countries and brought significant environmental benefit. Wind energy displaces fossil fuel extraction and mining activities that have potentially severe ecological impacts. Lifecycle carbon dioxide emissions from wind-generated electricity are around 40 times less per kWh than those from natural gas power and around 80 times less than those from coal, reducing the risk and impact of climate- related threats to humans and ecosystems. Yet the rise of wind power also has raised concerns about negative environmental and social impacts. Many are typical impacts of large-scale infrastructural development and can be understood and addressed as such. Some are unique to wind turbines and are driving focussed research aimed at quantifying, understanding, and mitigating the associated risks. Others remain subjective or yet unsubstantiated by existing evidence or ongoing research. Observed or claimed impacts pertain to visual and aesthetic obstruction, noise generation, land-use impacts, wildlife mortality, discord and dispute within communities, and consumption of raw materials. Offshore wind turbines may produce specific marine impacts, including noise and vibrational impacts on marine life, disturbance of the seabed and marine ecosystems, and impacts on navigational safety and access to shipping lanes and fisheries. Some have suggested that infrasound, electromagnetic interference, noise, shadow flicker, and blade glint from wind turbines may lead to public health effects, although these claims are currently unsupported by statistical or medical evidence. Some of the impacts of wind turbines are being mitigated through technological innovation. The development of turbine blades with thinner trailing edges and more aerodynamic blade tips has resulted in both higher efficiency and less noise generation. As such, the noise generation of modern wind turbines is often inaudible relative to other background noise. In the offshore sector, various techniques are being applied or developed to reduce noise impacts on marine life during construction, including the use of “bubble curtains” to diminish the sound of foundation pile driving. Technical solutions are reducing collisions with birds and bats as well. These include radar or GPS systems that idle turbine blades when large flocks or individual birds are detected. Research is also under way on the use of ultrasonic noise to deter bats from the vicinity of wind turbines. Idling turbines during low wind conditions (when bats are more active) has been shown to significantly reduce bat fatalities. Other areas under investigation include the use of strike detection systems that shut down turbines to prevent further collisions with flocks, the use of more visible turbine shapes and colours, and the use of tower and turbine shapes that prevent nesting.i Studies have shown that land-use impacts of turbines are small in terms of the land surface that is disturbed: typically, less than 0.4 hectares per MW are disturbed permanently, with roughly 1.4 hectares / MW disturbed during construction. Surrounding land can be used for productive purposes such as public parkland, agriculture, or highways. Concerns over the availability of “rare earths” (used in direct-drive turbines) are being actively mitigated by the research on alternative materials, stock piling, and the development of alternative mining reserves.ii Impacts are also being managed through better planning and regulation. Wind farms can alter the appearance of landscapes and horizons substantially; however, these effects can be mitigated or avoided through effective use of environmental impact assessments, thorough public engagement during the development process, and appropriate turbine placement. A variety of best practice guidelines for public engagement have been developed by public and private entities, including wind energy industry associations and organisations. Furthermore, many countries, including Australia, Ireland, South Africa, and the United Kingdom, now require impact assessments, mitigation, or compensation measures. The "Sustainability Spotlight" sidebar is a regular feature of the Global Status Report, focussing on sustainability issues regarding a specific renewable energy technology or related issue. i - Studies on bird and bat collisions indicate that the turbine-related mortality rate of wind turbines is several orders of magnitude lower than other anthropo- genic influences, including hunting by domestic and feral cats, collisions and electrocutions caused by power lines, and collisions with houses, buildings, and vehicles. ii - Rare earth impacts are addressed in “Sidebar 3. Sustainability Spotlight: Rare Earth Minerals and PV Recycling” in GSR 2011. Source: See Endnote 64 for this section.