Dams have displaced people, and destroyed wild-life habitat and archeological sites. A dam-burst can be disasterous. When demand rises, some of this water is channeled through a hydro-turbine to generate electricity. Wind Power Wind-farms do not need reservoirs and create no air pollution. Small wind-mills can provide power to individual homes.
Air carries much less energy than water, however, so much more of it is needed to spin rotors.
In either case, construction costs can be high. Even in such sites, turbines often have to be designed with special gearing so that the rotor will turn at a constant speed in spite of variable wind speeds. Some find less technical problems with installations that can turn a scenic ridge or pass into an ugly steel forest, or that can take a toll on birds. Alternative Generation Other types of power plants do not use traditional equipment to produce electricity. Geo-thermal plants replace boilers with the Earth itself.