Environmental impacts of renewable energy technologies — страница 6

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The impact of very large dams is so great that there is almost no chance that any more will be built in the United States, although large projects continue to be pursued in Canada (the largest at James Bay in Quebec) and in many developing countries. The reservoirs created by such projects frequently inundate large areas of forest, farmland, wildlife habitats, scenic areas, and even towns. In addition, the dams can cause radical changes in river ecosystems both upstream and downstream. Small hydropower plants using reservoirs can cause similar types of damage, though obviously on a smaller scale. Some of the impacts on fish can be mitigated by installing "ladders" or other devices to allow fish to migrate over dams, and by maintaining minimum river-flow rates; screens

can also be installed to keep fish away from turbine blades. In one case, flashing underwater lights placed in the Susquehanna River in Pennsylvania direct night-migrating American shad around turbines at a hydroelectric station. As environmental regulations have become more stringent, developing cost-effective mitigation measures such as these is essential. Despite these efforts, however, hydropower is almost certainly approaching the limit of its potential in the United States. Although existing hydro facilities can be upgraded with more efficient turbines, other plants can be refurbished, and some new small plants can be added, the total capacity and annual generation from hydro will probably not increase by more than 10 to 20 percent and may decline over the long term because

of increased demand on water resources for agriculture and drinking water, declining rainfall (perhaps caused by global warming), and efforts to protect or restore endangered fish and wildlife. Conclusion So, no single solution can meet our society's future energy needs. The solution instead will come from the family of diverse energy technologies that do not deplete our natural resources or destroy our environment. That’s the final decision that the nature imposes. Today mankind’s survival directly depends upon how quickly we can renew the polluting fuel an energy complex we have now with sound and environmentally friendly technologies. Certainly, alternative sources of energy have their own drawbacks, just like everything in the world, but, in fact, they seem minor in

comparison with the hazards posed by conventional sources. Moreover, if talking about the dangers posed by new energy technologies, there is a trend of localization. Really, these have almost no negative global effect, such as air pollution. Moreover, even the minor effects posed by geothermal plants or solar cells can be overseen and prevented if the appropriate measures are taken. So, when using alternatives, we operate a universal tool that can be tuned to suit every purpose. They reduce the terrible impact the human being has had on the environment for the years of his existense, thus drawing nature and technology closer than ever before for the last 2 centuries. Sources "Biomass fuel." DISCovering Science. Gale Research, 1996. Reproduced in Student Resource Center

College Edition. Farmington Hills, Mich.: Gale Group. September, 1999; "Alternative energy sources." U*X*L Science; U*X*L, 1998; Duffield, Wendell A., John H. Sass, and Michael L. Sorey, 1994, Tapping the Earth’s Natural Heat: U.S. Geological Survey Circular 1125; Cool Energy: Renewable Solutions to Environmental Problems, by Michael Brower, MIT Press, 1992; Powerful Solutions: Seven Ways to Switch America to Renewable Electricity, UCS, 1999;