400 likes | 417 Views
Explore the various sources of alternative energy, including solar, wind, and water power, their benefits, and environmental impacts. Learn about solar collectors, photovoltaic technology, wind turbines, and hydroelectric power plants. Discover how these sustainable energy options are transforming the way we generate power and reduce our reliance on fossil fuels.
E N D
Overview • Introduction to Alternative Energy Sources • Solar Energy • Converting Electricity from Renewable Energy into a Fuel for Vehicles • Water Power • Ocean Energy • Wind Power • Biofuels • Geothermal Energy
Introduction to Alternative Energy Sources • Nonrenewable alternative energy • Nuclear • Requires a mineral fuel mined from Earth • Geothermal • Heat is extracted faster than it is replenished • Renewable energy sources • Solar, fresh water, wind, ocean, and biofuels • All derive from the sun’s energy
Solar Energy • 10 weeks of solar energy equivalent to all known fossil fuel reserves • Two types • Passive • Active
Passive Solar Energy • Promotes cooling in hot weather and retaining heat in cold weather • Methods include: • Overhangs that block summer sun but allow winter sun • Walls in buildings that absorbs heat during the day and releases it at night • Deciduous trees as landscaping
Active Solar • Energy systems that require mechanical power • Electric pump circulate air, water or other fluids from solar collectors to a location where heat is stored • Additional pumps move heat to location where energy is converted and used
Solar Collectors • Provide space heating or hot water • Flat Plate Collector • Flat, glass-covered plates over a black background where absorbing fluid is circulated through tubes • Evacuated tube collector • Each tube filled with absorbing fluid pass through a larger tube
Photovoltaic • Converts sunlight directly into electricity • Made from thin layers of semiconductors and a solid-state electronic components with few or no moving parts • World’s faster growing source of energy
Photovoltaic • Off the grid • Emerging as a major contributor to developing countries • Don’t have ability to build a electrical grid • Systems can power lights and televisions in small villages
Solar Thermal Generators • Focus sunlight onto water-holding containers • Traditionally built using solar power towers • Water boils and is used to run conventional steam-driven electrical generators • Built with very large output
Solar Thermal Generators • In newer facility • Mirrors focus solar energy onto pipes with heat-absorbing fluid
Solar Energy and the Environment • Generally low impact • One concern • Variety of metals, glass plastics, and fluids used in the manufacture and use of solar equipment • Production and accidental spills could release toxic materials
Converting Electricity from Renewable Energy to a Fuel that can be Burned and can Power Vehicles • Two choices: • Store electricity in batteries and use electric vehicles • Transfer the energy in the electricity to a gaseous or liquid fuel • Hydrogen
Hydrogen Fuel • Hydrogen as power for fuel cells • Electric current separates water into hydrogen and oxygen • When H recombined with O, electrons flow between positive and negative poles • An electric current • H Can be transported in pipeline • Combustion product is water • Clean fuel
Water Power • A form of stored solar energy • Long history • Waterwheels convert water power to mechanical energy • Today’s hydroelectric power plants • use water stored behind dams • Also produced through the process of pump storage
Small-Scale Systems • Electrical power produced by large dams will not increase • Most dam sites already utilized • Small scale systems have potential in mountainous areas along streams
Water Power and the Environment • Advantages • Water power is clean and efficient power • No burning of fuel, no radioactive waste • Disadvantages • Flood large tracts of land • Block fish migration • Trap sediment that would replenish beaches • Evaporative loss of water from reservoirs
Ocean Energy • High energy in motion of waves, currents and tides in the ocean • Difficult to harness • Storms destructive and water corrosive • Most successful = tidal power • Very few areas w/ the right topography
Tidal Power • Dam built across the entrance to a bay or estuary • Water held in or out of bay until significant difference in level forces water in or out • This runs the turbines • Environmental impacts • Changes hydrology of bay • Restricts passage of fish • Changes habitat for birds and other organisms
Wind Power • Wind produced when differential heating of Earth’s surface create air masses with differing heat contents and densities • Wind energy is the cheapest form of alternative energy • Less than natural gas and coal • Now used in many place including offshore
Wind Power • Problems • Wind highly variable in time, place, and intensity • Wind velocity often increases over hill tops or funneled through a mountain pass
Wind Power and the Environment • Wind energy does have a few disadvantages • Kills birds • Use large areas of land • May degrade area’s scenic resources
Future of Wind Power • Growing at approximately 30% per year • Nearly 10 times the growth rate of oil use • Created thousands of jobs and investment opportunities • Technology producing more efficient wind turbines
Biofuels and Human History • Energy from biomass is the oldest fuel used by humans. • Until end of 19th century major fuel source in the US • 1 billion people in the world still use wood as primary source of energy for heat and cooking • Includes: firewood, cattle dung, peat
Biofuels • Energy recovered from biomass-organic matter • Three groups • Firewood • Organic wastes • Crops grown to be converted into liquid fuels
Biofuels and the Environment • Can pollute the air and degrade the land • World’s forests will decrease if our need for forest products and forest biomass fuel exceeds the productivity of the forests • Combustion of biomass-derived fuel generally release fewer pollutants then combustion of coal/gasoline • But burning urban waste can release heavy metals
Geothermal Energy • Deep earth - high density • Energy from interior of earth • Mined and used to heat buildings and generate electricity • May be considered nonrenewable when rates of extraction are greater than rates of natural replenishment • Shallow earth - low density • Solar energy that has traveled to shallow depths
Geothermal Systems • Areas of high heat flow occur at plate boundaries • Divergent and convergent plate boundaries • Hydrothermal convection- transfers heat from depths to surface • Using steam or hot water
Geothermal • Most groundwater can be considered a source of geothermal energy • Groundwater at a depth of 100m is 13oC or 55oF • In summer heat can be transferred to the cool water • In winter heat can be transferred from the water to the air
Geothermal Energy and the Environment • Problems: • Considerable thermal pollution from hot wastewaters • Water may be saline or highly corrosive • On-site noise • Emissions of gas • Disturbance of land
Future of Geothermal Energy • Geothermal • Could produce 10% of the electricity needed for the western US • Geohydrothermal • Could potentially provide four times that (10% of US total)