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Alternative Energy Sources. Activity 31 Fueling Trade-offs. What is energy?. Energy is the ability to do work. Energy sources are all around us. For example, you are all giving off heat (a form of energy) to the environment. But could this energy be easily or economically harvested?
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Alternative Energy Sources Activity 31 Fueling Trade-offs
What is energy? • Energy is the ability to do work. • Energy sources are all around us. For example, you are all giving off heat (a form of energy) to the environment. But could this energy be easily or economically harvested? • Alternative energy sources are not based on the burning of fossil fuels.
Why bother with alternatives? • Fossil fuels cause pollution that result in environmental pollution and illness. • Burning fossil fuels releases carbon dioxide, a gas tied to global warming. • Fossil fuels that can be harvested economically exist in limited amounts. • Most of the world supply of oil is in the Middle East, a politically unstable region.
Types of alternative energy • Solar • Nuclear • Wind • Hydro (water) or hydroelectric power • Tidal power • Biomass • Geothermal • Hydrogen – fuel cells
Why are fossil fuels accepted by consumers? • They are abundant. • They are low cost. • They are safeto use.
What are two drawbacks to using fossil fuels? • Environmental degradation • They will not always be available.
Alternative energy sources replace… Fossil fuels! www.ngdir.ir/.../nonrewnewables-mm.jpg
Solar Energy • Solar energy uses energy from the sun. • The main expense is collecting, storing and converting the sun’s rays into useful forms of energy. • Environmental impacts/risks are negligible. Solar power is clean and quiet! http://www.astronomy.com/asy/objects/images/sun_full_disk_soho_09_14_1997.jpg
Solar Energy • This is a roof-top solar collector used to heat water that heats the air in the house. • Unless new technology is developed, solar energy can not be used for large-scale industry or transportation. http://www.fsec.ucf.edu/en/publications/html/FSEC-CR-978-97/index.htm
Solar Energy • A photovoltaic cell produces energy when it is exposed to light. • Silicon (from sand) is the material from which a PV cell is made. • The light excites the electrons in the silicon and that produces electricity. http://www.acmegreen.com/page2/page7/files/page7_2.jpg
Solar Energy - PV (photovoltaic) panels http://en.wikipedia.org/wiki/Solar_power
Solar Energy • Small PV cells are used to power solar calculators and emergency roadside phones. • To provide electricity for a satellite, space station, or typical home, the PV cell would have to be as large as 10 square meters! • The high cost of solar power prevents its use on a wide-scale. http://www.abc.net.au http://media.popularmechanics.com
Solar Energy … An Application The CIS Tower, Manchester, England, was clad in PV (photovoltaic) panels at a cost of $11 million. It started feeding electricity to the national grid in November 2005. http://en.wikipedia.org/wiki/Photovoltaics
Nuclear Energy • Two ways that nuclear energy can be produced… • Fission – the breaking apart of atomic nuclei hyperphysics.phy-astr.gsu.edu/hbase/nucene/im...
Nuclear Energy Produces Electricity… • www.comedition.com
Nuclear Energy Fission reactions are used to supply significant amounts of energy for… • Electricity • Heating • Military use encarta.msn.com
Nuclear Energy • Two advantages of nuclear energy: • It produces huge amounts of energy from small amounts of nuclear fuel (uranium and plutonium). • Earth contains enough nuclear fuel to meet all present and future needs. www.pollutionissues.com
Nuclear Energy • Nuclear energy produces wastes in the form of heat and spent (used) fuel – which can remain radioactive for thousands of years. • Disposing of this radioactive spent fuel is a major problem. • One proposed disposal site is Yucca Mountain in Nevada. • www.nrc.gov
Nuclear Energy www.amargosavalley.com
Nuclear Energy Four reasons why nuclear power is not as widely used as it could be… • High cost • Peoples’ fear of exposure to radiation • The threat of a meltdown (nuclear explosion) • The fear that nuclear weapons could be developed using this technology Stable, highly centralized governmental control is necessary for the safe operation of nuclear power. www.answers.com
Nuclear Energy • Two ways that nuclear energy can be produced are fusion and fission. • Fusion – the combining of atomic nuclei – such as in the stars (and sun!) – generates energy http://www.aa.washington.edu
Nuclear Energy – Fusion Reactor www.virtualsciencefair.org
Nuclear Energy – Fusion Reactor • The power produced by a fusion reactor will be converted to electric energy or other goods like hydrogen or desalinised water. Neutrons produced in the D-T fusion process carry 4/5 of the energy. They will be slowed in the blanket where the tritium breeding takes place. Power by a’s goes to the divertor and first wall (FW). • One or two fluids circulate in the blanket and in the divertor/FW to extract the energy and to provide stable operational temperature of the components. The fluids must flow at high velocity (often in conditions of turbulent flow) while structural materials, pipes, junctions must withstand neutron bombardment, corrosion/erosion, high operational temperature, high heat flux. The presence of a magnetic field plays an important role in optimising the flow regime in electrically conducting fluids. Therefore the energy conversion system is a process that requires a trade off analysis among the various solutions. http://www.isfrt-erice.enea.it/Page2.htm
China claims fusion reactor test a success Government hopes fusion provides clean, limitless energy source … • BEIJING - Scientists on Thursday carried out China's first successful test of an experimental fusion reactor, powered by the process that fuels the sun, a research institute spokeswoman said. • China, the United States and other governments are pursuing fusion research in hopes that it could become a clean, potentially limitless energy source. Fusion produces little radioactive waste, unlike fission, which powers conventional nuclear reactors. http://www.msnbc.msn.com/id/15043462/ updated 3:22 p.m. ET, Thurs., Sept. 28, 2006
Nuclear Energy • Fusion reactions are not currently a practical alternative energy source because… • Scientists have not yet been able to initiate a controlled, long-lasting fusion reaction suitable for producing heat and electricity. • Fusion reactions produce intense radiation that bombards all the materials in the reactor – making them intensely radioactive. • Fusion reactors are very expensive to build.
Hydroelectric Power • Four drawbacks to hydroelectric power… • Inability to store energy • Covers large geographic areas • Large initial investment for facilities • Contributes to habitat destruction These drawbacks also apply to wind power. www.worldproutassembly.org
Hydroelectric Power Dams have an advantage over other alternative energy sources in that they provide power on demand. This is the Hoover Dam. • photo.e-khmer.net
Hydroelectric Power • library.thinkquest.org
Hydroelectric Power • Three problems associated with dams include… • Dams can gradually fill with silt which reduces the water stored in the reservoir. • Dams can disrupt the local ecosystems and prevent the migration of some species of fish. • Dams have the potential to break and cause catastrophic floods. This is what is left of the Hadlock dam in the Adirondacks. • thecommunicator.org
Wind power – old to new Wind power has been used to pump water for centuries A modern wind turbine generates electricity
Wind Power • Wind mills act as giant turbines that spins with the energy of the wind and generate electricity. • This only happens when the wind blows! www.eere.energy.gov
Wind Power • Wind power has some of the same disadvantages of hydroelectric power. It must be supplemented with other energy sources because the energy produced cannot be stored. • Wind farms can also be noisy (a giant swooshing sound!), unsightly (modern windmills are HUGE!), and can kill migrating birds. rochsolartech.itcstore.com
Hydroelectric Power home.clara.net • Other forms of hydroelectric power include: • Tidal power – dams or turbines are constructed to capture the energy of incoming or outgoing tides • Wave power – turbines are situated to catch the power of the rising and falling water. • OTEC – Ocean Thermal Energy Conversion. www.logicalscience.com
Biomass • Biomass is organic material that can be “combusted” for energy. • Biomass includes municipal wastes, crop residues, manure, lumber and paper by-products. www.nrcan.gc.ca
Biomass • To be used for energy, biomass can be… • burned directly • gasified into methane and hydrogen (the by-products of which can be used as fertilizer) • fermented into ethanol • anaerobically digested to produce biogas (a mixture containing methane and CO2). sitemaker.umich.edu
Biomass • This is switchgrass, a hardy, fast growing plant that can be used as biomass http://en.wikipedia.org/wiki/Image:Panicum_virgatum.jpg
Biomass – A Power Plant that Uses Cow Manure! • http://www.cbc.ca/gfx/pix/cowpoop_energy050505.jpg greenplanets.blogspot.com
Biomass • Two major drawbacks of biomass energy include… • The use of farm and forest residue prevents the recycling of nutrients back into the ecosystem. • Pollution is generated in the process of converting biomass to energy. • However, once methane is purified from biogas, the nitrogen, phosphorus, and other nutrients can be used as fertilizer. www.ctahr.hawaii.edu
Geothermal Energy Remember, geo means Earth • Geothermal energy is “Earth heat” which is present everywhere beneath the Earth’s surface • The highest temperature and thus the most desirable resources are concentrated in regions of active or geologically young volcanoes. • This is the Old Faithful geyser – atop the supervolcano of Yellowstone! zebu.uoregon.edu/2001/ph162/special/oldfaith.gif
Geothermal Energy … Wells can be drilled down to 6 miles to reach Earth’s thermal energy. www.geothermal.ch/bilder/obp0zjs6.jpg
Geothermal Energy Three major drawbacks to geothermal power include… • Geographic restrictions • The cost of drilling down into hot rocks (as deep as 6 miles!) is very high • The environmental impact of habitat disturbance and the need to dispose of large quantities of noxious gases and very salty water.
Geothermal • The Bjarnarflag Geothermal Station in northeast Iceland • Iceland gets most of its energy for heating in the winter from geothermal sources.
Geothermal Plant in New Zealand… http://www.rise.org.au/info/Tech/geo/index.html
Geysers Geothermal Facility in California … http://www.rise.org.au/info/Tech/geo/index.html
Hydrogen • Hydrogen and oxygen chemically combine to form water and energy in the form of heat. • An advantage of using hydrogen as fuel is that fuel cell reactions produce no pollution. • This reaction can be used to generate electricity using fuel cell technology. • A fuel cell is somewhat similar to a battery but with a fuel cell, chemicals constantly flow into the cell so it never goes dead. As long as there is a flow of chemicals into the cell, the electricity flows out of the cell. • Hydrogen must be in the proper form to be used as a fuel. Most hydrogen used in today’s fuel cells comes from methane
Hydrogen • Current disadvantages of using hydrogen as a fuel… • Currently it is expensive. Large-scale production will reduce its costs • Range is limited with current fuel storage options • Current small distribution channels - California is making some progress • It is extremely flammable – Remember the Hindenberg! • Many improvements are expected as this technology develops
The Hindenberg… wellington.pm.org/.../hindenberg_strict.jpg
Hydrogen Fuel Cells … • A typical hydrogen fuel cell works by channeling hydrogen and oxygen into different sides. • The hydrogen atoms split into protons and electrons (which produce the current). • The hydrogen and oxygen combine at the end of the process to form water. http://en.wikipedia.org/wiki/Image:Fuel_cell_still.gif
Hydrogen • Other materials can also supply the fuel for a fuel cell. • This is a methanol fuel cell • The actual fuel cell stack is the layered cubic structure in the center of the image http://en.wikipedia.org/wiki/Fuel_cell
Hydrogen- Applications …September 2006 - BMW will lease Hydrogen Cars • BMW is going to make a limited number of Hydrogen Series 7 sedans available for lease starting next year. This is the first fleet of hydrogen powered vehicles. • The cars will have tanks for storing liquid hydrogen and gasoline. The BMW Hydrogen 7 will emit only water vapor when burning hydrogen in the combustion engine. • The vehicle has a 260 hp twelve-cylinder engine and will accelerate from 0-62 mph in 9.5 seconds and tops out at 143 mph, according to BMW