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Renewable Energy. Section 1- Renewable Energy Today . Renewable Energy. Energy from sources constantly being formed Use needs to be increased. Solar Power. Sun Passive Solar Heating Uses heat from sun directly Large windows face directly into sun N. hemisphere- south windows.
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Renewable Energy Section 1- Renewable Energy Today
Renewable Energy • Energy from sources constantly being formed • Use needs to be increased
Solar Power • Sun • Passive Solar Heating • Uses heat from sun directly • Large windows face directly into sun • N. hemisphere- south windows
Solar Power • Active Solar Heating • Gathered by collectors • Usually mounted on roof • Heats water in collector and transfers throughout home
Solar Power • Photovoltaic Cells- solar cells • Use sun energy to produce a small amt. of electricity • Can be stored in batteries • Efficient and less expensive • Good for developing countries
Wind Power- Cheap and Abundant • Uneven heating from sun causes wind • Wind turbines can convert into electricity • Cheap • Wind Farms- Large arrays of wind turbines • Problem transporting electricity from rural to urban areas
Biomass- Power from Living Things • Biomass fuel- any organic matter used for energy • Ex: Wood, organic trash and manure • Burning can release air pollution • Methane gas from decomposition
Biomass- Power from Living Things • Alcohol- Liquid fuel derived from biomass • Ethanol- from fermenting fruit or agricultural waste; corn is major source • Gasohol- gasoline + ethanol • Less air pollution
Hydroelectricity- Power from Moving Water • 20% of world’s electricity • Dams hold water- reservoir • Released to turn a turbine • Benefits: • Inexpensive • No air pollution • Last longer than power plants • Provide: flood control, drinking water, agriculture, industry, and recreation
Hydroelectricity- Power from Moving Water • Disadvantages: • Disruption of ecosystems; Ex: Salmon • Displacement of people • Farmland below dams less fertile • Future: • Micro-hydropower- Floating turbine in a small stream
Geothermal Energy- Power from the Earth • Energy from heat in the water deposits of the earth’s crust • Geothermal pumps- heated water to turbine and recycle back for reheating • U.S. world’s largest producer • Ex: The Geyser’s in CA-1.7 million houses
Geothermal Heat Pumps- Energy for Homes • 600,000 homes in U.S. • Stable underground temperatures year-round allows for heating and cooling all year • Ground cooler in summer and warmer in winter
Chapter 18- Renewable Energy Section 2- Alternative Energy and Conservation
Alternative Energy • Energy sources that do not use fossil fuels and are still in development • Viable if cost effective and environmental effects are acceptable • Research with gov’t investment
Tide- movement of water caused by gravitational b/w sun, moon and Earth Twice a day, rise and fall Used to generate electricity in France, Russia and Canada France and Britain used over 1000 yrs ago High tides come in, trapped by a dam After low tide, dam opens to allow water to rush out spinning a turbine to generate electricity Cost is high to build and maintain Few siutable locations Tidal Power
Ocean Thermal Energy Conversion • Warm surface water boils sea water at low temp. in a vacuum • Steam spins a turbine to generate electricity • Cold water from deep ocean cool steam back into liquid to be used again • Not cost effective and effects of pumping large amounts of cold water to surface are unknown
Hydrogen- A Future Fuel Source? • Most abundant element in universe can be burned as fuel • No carbon-no pollution! • When burned combines with oxygen to form water vapor and nitrogen oxide • Can split molecules of water or grow plants to produce hydrogen cost effectively
Challenge of Hydrogen Fuel • Takes a lot of energy to produce • Use of fossil fuels to split atoms pollutes • Can use solar or wind power • Can store in tanks and transport in pipes • Could use as it is produced in fuel cells
Fuel Cells • Produces electricity chemically by combining H with O • Can be fueled by anything w/ large amounts of H, such as gasoline, natural gas and alcohol • Could continue to use gasoline stations
Energy Efficiency • Percentage of energy put into a system that does useful work • Energy efficiency = Energy Out X 100 Energy In • First Law of Thermodynamics- Energy in must equal energy out; much lost as heat
Energy Efficiency • Over 40% of commercial energy is wasted • Fuel-wasting vehicles, furnaces, and appliances • Leaky, poorly insulated buildings • Could save by: • Fuel cells instead of internal combustion engines • Increase public transportation • Fluorescent instead of incandescent lights
Hybrid Cars • Small, efficient gasoline engines with also an electric motor for extra power • Convert braking energy into electricity to store in battery • Shut off gas engine to save fuel when sitting • Aerodynamics make less energy for acceleration • Cost a little bit more, but less to refuel and pollute less
Cogeneration • Production of two useful forms of energy from same fuel source • Ex: Waste heat from an industrial furnace can run a steam turbine for electricity • Can supply heat and electricity to multiple buildings • Small units now available in U.S.
Cities and Towns Plug leaks around windows and doors Replace inefficient furnaces Insulate water heaters EX: Osage, Iowa saved over $1 million a year; boosted economy Around the Home $1,200/year per home; lost energy through poor insulation Seal doors and windows (replace w/high efficiency windows) Energy Conservation-Saving Energy
Use less of any resource to save energy Wash clothes in cold water for less energy usage (25% of heat usage) Conservation Tips: Walk or ride a bike on short trips Carpool or use public transportation Drive a fuel-efficient automobile Choose ENERGY STAR* products Recycle and buy recycled products Set computers to sleep mode when not in use Conservation in Daily Life