Just what qualifies as a renewable energy source remains a source of debate. Should hydro dams, such as China's massive Three Gorges dam, that alter natural river flows, block fish, hold back silt, and drown towns and villages qualify as renewable? How about a plant that burns biomass as fuel but the fuel is shipped from around the world or comes from conversion of native landscape to agriculture? Other plants capture out gassing from landfills or harness the energy in tides, waves, wind or solar power. While these fuel sources seem renewable, in that the fuel is a natural phenomena, the structures used to harness this energy or the conversion of landscapes to build them may have impacts that cause permanent change to energy flows or landscapes.
These questions are complicated and require rationale analysis. For example, wind turbines, as explained by Environmental Engineer Dr. Somnath Baidya Roy, from the department of civil and environmental engineering at Duke University may impact regional and local meteorological conditions by reducing wind speeds and increasing drying conditions. However, improvements in rotor blade design can reduce the turbulence causing these impacts while increasing the efficiency of the turbine. This improvement may not address the issue of bird and bat deaths associated with turbines and wind farms however. The bird article reports on the numbers of both small birds and raptors killed at one of the oldest wind farms in the country, while the bat article linked to explains how advanced radar technology, along with automatic start up and shut down of turbines, could mitigate many of these deaths.
So when you hear the words "renewable energy" remember to think carefully about the fuel, conversion, and impact of whatever type of plant is under discussion. Look through the slide show covering different energy sources in locations around the world and comment back with your thoughts, questions, or analysis.
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