GREEN TECH
systems used to convert light into direct current , or DC , power . Photovoltaic systems include small , thin panels of semiconductors called solar or PV cells . A chemical reaction takes place in the solar cells upon exposure to sunlight that generates electrons to produce current . The solar cells are installed on large panels , some of which are designed to track the sunlight throughout the day . Other components of the PV system include one or more batteries , a charge regulator and an inverter which converts DC , to alternative , or AC current . Solar PV has become a rapidly growing industry as cost effectiveness has improved . It offers a
Hydroelectric power clean , inexhaustible source of energy . Although presently the technology is insufficient to meet energy demand , many utilities , organizations and residences use solar PV systems to supplement present energy sources and help reduce costs .
As of 2013 , there were 46,000 operating wind turbines in the United States . Wind energy provides 4.1 percent of the energy produced in the nation . Wind turbines are equipped with blades that rotate as the wind blows . A shaft that connects from the blades to a generator revolves to produce electricity . The primary objection to the technology stems from the fact that they require a large space to generate a significant amount of power .
Canada is the largest producer of hydroelectric power in the world . Its 450 hydroelectric stations produce 62 percent of its energy . In addition , there are presently 1756 hydroelectric power facilities in the United States . Hydroelectric power facilities are typically constructed on large rivers that have a significant drop in elevation . The damn retains large volumes of water in a reservoir . Gravity forces water through an intake near
20 May 2015