Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Remewable Energy
Transcript
Renewable Energy Ch. 18 What is Renewable Energy? • Energy from sources that are constantly being formed. • Many govt. Plan to increase their use of renewable sources • European Union plans to produce 12% of their energy from renewable sources by 2010. List of Renewable Energy • • • • • Solar Energy Wind Power Biomass Hydroelectricity Geothermal Energy Solar Power • Power from the sun – Medium sized star that radiates energy from nuclear fusion reactions in its core – Only small amount of energy produced reaches earth Passive Solar Heating • Uses the sun’s energy to heat something directly • Passive Solar Buildings – Large windows • Face south – Solar energy enters windows and warms house – Nighttime – heat is released slowly – Buildings must be well insulated with thick walls and floors to prevent heat loss – Building oriented according to movement of sun Active Solar Heating • Solar Energy can be gathered by collectors and used to heat water • Mounted on roof • Liquid within collector heated by sun • Liquid then pumped through a heat exchanger – Heats water for building Photovoltaic Cells • A.K.A – Solar cells • Invented over 120 years ago • Run on nonpolluting solar energy – Why don’t they meet all our energy needs? • Produce very little electrical current • Require extended periods of sunlight Wind Power • Energy from sun warms earth’s surface unevenly • Causes air masses to flow in atomosphere – WIND • Wind power converts movement of wind into electrical energy • Fastest growing energy source in the world! Wind Farms • Large arrays of wind turbines • California – Supply 280,000 homes • Scientists estimate that the windiest spots on earth could generate 10 times the energy used worldwide! Biomass • Plant material, manure, and any other organic matter that is used as an energy source AND is considered renewable • List of biomass fuel sources – Methane – Alcohol – algae • When bacteria decompose organic wastes, can produce methane – Can be burned to generate heat – CHINA • More than 6 million households use biogass digesters to ferment manure and produce gas for heating and cooking – USA • Some landfills generate electricity by using methane from decomposing trash Methane Alcohol • Liquid fuels can be derived from biomass – Ethanol comes from frementing fruit or agricultural waste • Corn – major source of ethanol – Gasohol – mixture of ethanol and gas » Produces less pollutants than fossil fuels » Some US states require the use of gasohol Renewable Energy Ch. 18 cont. Hydroelectricity • Energy produced from moving water • Accounts for about 20 % of worlds electricity • Benefits – Dams are inexpensive to operate – No air pollutants – Last much longer than fossil fueled power plants • http://techalive.mtu.ed u/meec/module17/Hyd roelectricity.htm Hydroelectricity • Disadvantages – Changes a rivers flow – Disrupts ecosystems • Salmon fisheries in NW US – Sediments are stuck behind dam • Reduces mineral richness of land below dam Geothermal Energy • Deposits of water in earths crust are heated by energy within the Earth • US is worlds largest producer of geothermal energy – Geyers in CA. Produce electricity for 1.7 million households • http://www.geysers.com/ geothermal_energy_1mb _peak.wmv Geothermal Energy • Geothermal heat pumps – More than 600,000 homes in US are heated and cooled by geothermal heat pumps Alternative Energy • Describes energy sources still under development – Tidal Power – Ocean Thermal Energy Conversion – Hydrogen Tidal Power • Was used over 1000 years ago to power mills in France and Britian • Today – Generates power in France, Russia, Canada Ocean Thermal Energy Conversion • In tropics, temperature difference between surface of ocean (warmed by solar energy) and deep ocean waters can be as much as 24 degrees C. • Use this temp. difference to generate electricity • Warm surface water is used to boil sea water Hydrogen • Most abundant element in the universe • Found in every molecule of living things • Does not contain carbon – No pollutants associated with burning fossil fuels and biomass – Makes water vapor as waste product • Challenge Hydrogen – Takes a lot of energy to produce • Can use electricity from solar cells or wind power to split water molecules to produce Hydrogen • Can be stored in pressurized tanks and transported in pipelines
