环境概论讲RenewableEnergyandConservation.pptVIP

APES: Notes 12 * A solar sunspace can be added to existing homes. APES: Notes 12 * A system of putting the sun’s energy to use in which a series of collectors absorb the solar energy, and pumps or fans distribute the collected heat. Used primarily for heating water. APES: Notes 12 * A means of producing electricity in which the sun’s energy is concentrated by mirrors or lenses onto a fluid-filled pipe; the heated fluid is used to generate electricity. A solar thermal plant in California uses troughs to focus sunlight on a fluid-filled tube. The heated oil is pumped to a water tank where it generates steam used to produce electricity. (For simplicity, arrows show sunlight converging on several points; sunlight actually converges on the pipe throughout its length.) A solar power tower is a solar thermal system with a tall tower surrounded by hundreds of mirrors. The computer-controlled mirrors move to follow the sun, focusing solar radiation on a central receiver at the top of the tower. A liquid is heated, and the heat is used to produce steam for electric generation. Solar thermal energy systems are inherently more efficient than other solar technologies because they concentrate the sun’s energy. APES: Notes 12 * A wafer or thin film of solid state materials, such as silicon or gallium arsenide, that are treated with certain metals so that they generate electricity (a flow of electrons) when solar energy is absorbed. Sunlight excites electrons, which are ejected from silicon atoms. Useful electricity is generated when the ejected electrons flow out of the PV cell through a wire. They can be arranged on large panels that absorb sunlight, even or cloudy or rainy days. APES: Notes 12 * These thin-film solar cells look much like conventional roofing material. They are much cheaper to manufacture and can be incorporated into building materials like shingles, tiles, and window glass. More than 120,000 Japanese homes have installed PV sloar0energy roofing in the