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Topic 6 – Alternative Sources of Energy

Topic 6 – Alternative Sources of Energy

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Topic 6 – Alternative Sources of Energy

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  1. Topic 6 – Alternative Sources of Energy A – The Search for Options B – High Intensity Sources C – Low Intensity Sources

  2. A. The Search for Options Emergence of Alternative Sources Fuel Efficiency The Dominance of the Automobile

  3. 1. Emergence of Alternative Sources • Alternative energy • Supplement / replace an energy source with a new source: • The existing energy source judged to be no longer sustainable. • New source judged more convenient than the previous, but comes with its own drawback. • Have always existed: • Wood to coal. • Whale oil to petroleum. • From non-renewable to renewable. • Received increasing attention since the first oil crisis in 1973: • Attention varies with fluctuations in the price of oil. • Since 2005, renewed attention because of a surge in oil prices (e.g. wind, solar).

  4. 1. Emergence of Alternative Sources • Stocks and flows • Stock: Existing capital accumulation. • Flows: The nature and extent of new capital investments. • Fossil fuels stocks • Dominate energy supply markets. • Dominance likely to remain on the years to come. • Alternative energy flows • Receiving a growing quantity of flows. • These will eventually expand the alternative energy stocks.

  5. 1. Global Carbon Dioxide Emissions from Fossil Fuel Burning by Fuel Type, 1900-2009

  6. 1. Average Global Temperature and World Carbon Emissions From Fossil Fuel Burning, 1800-2009

  7. 2. Energy Efficiency • Transportation • Minimize traveling distances (commuting, leisure freight). • Improve fuel economy of vehicles. • Shift from petroleum. • Buildings • Temperature control systems (heating, cooling, ventilation). • Insulation. • Lighting and appliances. • Industry • Product life cycle. • Re-use and recycling. • Improve industrial processes.

  8. 2. Average Gasoline Consumption for New Vehicles, United States, 1972-2009 (in miles per gallon)

  9. 2. Light-Duty Vehicles Sales in the United States, 1975-2008 (in 1,000s)

  10. 2. Vehicle Sales, United States, 1931-2009

  11. 2. Typical Energy Use for a Car

  12. 2. Alternative Sources of Energy for Transportation

  13. B. High Intensity Sources Hydrogen and Fuel Cells Biomass

  14. 1. Hydrogen and Fuel Cells • Hydrogen • Considered to be the cleanest fuel. • Compose 90% of the matter of the universe. • Non polluting (combustion emits only water and heat). • Highest level of energy content. • Almost three times more than methane. • Nuclear fusion • Currently researched but without much success. • It offers unlimited potential. • Not realistically going to be a viable source of energy in the foreseeable future.

  15. 1. Hydrogen and Fuel Cells • Fuel cells • Convert fuel energy (such as hydrogen) to electric energy. • No combustion is involved. • Composed of an anode and a cathode. • Fuel is supplied to the anode. • Oxygen is supplied to the cathode. • Electrons are stripped from a reaction at the anode and attracted to form another reaction at the cathode. Hydrogen Oxygen Fuel Fuel Cell Catalytic conversion Water Electricity

  16. 1. Hydrogen and Fuel Cells • Storage issues • Hydrogen is a highly combustive gas. • Find a way to safely store it, especially in a vehicle. • Delivery issues • Distribution from producers to consumers. • Production and storage facilities. • Structures and methods for transporting hydrogen. • Fueling stations for hydrogen-powered applications.

  17. 1. Hydrogen and Fuel Cells • Hydrogen production • Not naturally occurring; secondary energy resources. • Producing sufficient quantities to satisfy the demand. • Extraction from fossil fuels: • From natural gas. • Steam reforming. • Electrolysis of water: • Electricity from fossil fuels not a environmentally sound alternative. • Electricity from solar or wind energy is a better alternative. • Pyrolysis of the biomass: • Decomposing by heat in an oxygen-reduced atmosphere. Fossil Fuels Steam Reforming Water Electrolysis Biomass Pyrolysis

  18. 1. Hydrogen and Fuel Cells • Main potential uses • Transportation: • Most likely replacement for the internal combustion engine. • Efficiency levels are between 55% and 65%. • Stationary power stations: • Connected to the electric grid; supplemental power and backup. • Grid-independent generator. • Telecommunications: • Reliable power for telecom systems (e.g. cell phone towers, internet servers). • Micro Power: • For consumer electronics (e.g. cell phones and portable computers).

  19. 2. Biomass • Nature • Biomass energy involves the growing of crops for fuel rather than for food. • Crops can be burned directly to release heat or be converted to useable fuels such methane, ethanol, or hydrogen. • Has been around for many millennia. • Not been used as a large-scale energy source: • 14% of all energy used comes from biomass fuels. • 65% of all wood harvested is burned as a fuel. • 2.4 billion people rely on primitive biomass for cooking and heating. • Important only in developing countries. • Asia and Africa: 75% of wood fuels use. • US: 5% comes from biomass sources.

  20. 2. Energy Consumption, Solid biomass (includes fuel wood) 2001

  21. 2. Global Biomass

  22. 2. Biomass • Biofuels • Fuel derived from organic matter. • Development of biomass conversion technologies: • Alcohols (ethanol) and methane the most useful. • First generation biofuels: • Food-based. • Plant materials like corn, starch or sugar from cane. • Second generation biofuels: • Cellulosic based. • Waste materials like plant stalks composed of cellulose. • Requirements for sustainable biomass use • Production of biomass through low input levels: • Labor, fuel, fertilizers and pesticides. • Production of biomass on low value land. • Low energy of conversion into biofuels.

  23. 2. Biomass Energy Sources

  24. 2. Global Ethanol Production, 1975-2009 (million gallons)

  25. 2. Biomass • Potential and drawbacks • Competing with other agricultural products for land. • Could contribute to reducing carbon emissions while providing a cheap source of renewable energy: • Burning biofuels does create carbon emissions. • The burned biomass is that which removed carbon from the atmosphere through photosynthesis. • Does not represent a real increase in atmospheric carbon. • Genetic engineering: • Create plants that more efficiently capture solar energy. • Increasing leaf size and altering leaf orientation with regard to the sun. • Conversion technology research: • Seeking to enhance the efficiency rate of converting biomass into energy. • From the 20-25% range up to 35-45% range. • Would render it more cost-competitive with traditional fuels.

  26. C. Low Intensity Sources Solar Energy Wind Power Geothermal Energy

  27. 1. Solar Energy • Definition • Radiant energy emitted by the sun. • Large amount of solar energy reaching the Earth’s surface. • 10 weeks of solar energy equivalent to all known fossil fuel reserves. • Advantages • Widely available energy source. • Limited environmental footprint. • Limited maintenance. • Affordable. • Drawbacks • Limitations in temporal availability (e.g. night). • Reconversion of existing facilities. • Can be capital intensive for large projects.

  28. 1. Solar Energy Level of insolation (latitude & precipitation) Sun Solar cells Mirrors Concentration Water Evaporation Conversion Steam Turbine Electricity

  29. 1. The Global Solar Energy Balance

  30. 1. Global Solar Energy Potential

  31. 1. Solar Energy • Photovoltaic systems • Semiconductors to convert solar radiation into electricity. • Better suited for limited uses that do not require large amounts of electricity. • Costs have declined substantially: • 9-10 cents per kilowatt-hour. • Compared to about 3-5 cents for coal fired electrical power. • Economies of scale could then be realized in production of the necessary equipment. • Roofs of buildings (e.g. warehouses) suitable locations to effectively install solar panels.

  32. 1. Photovoltaic System

  33. 1. World Photovoltaic Annual Production and Price 1975-2009

  34. 1. Photovoltaic Production by Country or Region, 1995-2009 (Megawatts)

  35. Solar Energy Consumption (Terawatt-hours), 1990-2011

  36. 1. Solar Energy • Solar thermal systems • Parabolic reflectors to focus solar radiation onto water pipes: • Concentrating the sunlight 1000 times. • 212-750F (100-400C), Generating steam that then power turbines. • Require ample, direct, bright sunlight. • Drawback of the solar thermal systems is their dependence on direct sunshine, unlike the photovoltaic cells. • Limitations • Inability to utilize solar energy effectively. • A record of 25% efficiency rate reached in 2008. • Low concentration of the resource. • Need a very decentralized infrastructure to capture energy.

  37. 1. Solar Thermal System

  38. 2. Wind Power Sun Heat Air Pressure differences Major prevalent wind systems Wind Wind mills Site suitability Fans Turbine Electricity

  39. 2. Wind Power • Potential use • Growing efficiency of wind turbines. • 75% of the world’s usage is in Western Europe: • Provided electricity to some 28 million Europeans in 2002. • Germany, Denmark (18%) and the Netherlands. • New windfarms are located at sea along the coast: • The wind blows harder and more steadily. • Does not consume valuable land. • No protests against wind parks marring the landscape. • United States: • The USA could generate 25% of its energy needs from wind power by installing wind farms on just 1.5% of the land. • North Dakota, Kansas, and Texas have enough harnessable wind energy to meet electricity needs for the whole country.

  40. 2. Wind Power • Farms are a good place to implement wind mills: • A quarter of a acre can earn about $2,000 a year in royalties from wind electricity generation. • That same quarter of an acre can only generate $100 worth or corn. • Farmland could simultaneously be used for agriculture and energy generation. • Wind energy could be used to produce hydrogen. • Limitations • Extensive infrastructure and land requirements. • 1980: 40 cents per kwh. • 2001: 3-4 cents per kwh. • Less reliable than other sources of energy. • Inexhaustible energy source that can supply both electricity and fuel.

  41. 2. Evolution of Wind Turbine Technology

  42. 2. World Wind Energy Generating Capacity, 1980-2009 (in megawatts)

  43. 2. Cumulative Installed Wind Power Capacity in Top Ten Countries and the World, 1980-2011 (Megawatts)

  44. 2. Cumulative Installed Offshore Wind Power Capacity by Country, 2009 (Megawatts)

  45. 3. Geothermal Energy • Geothermal plants • 2-4 miles below the earth's surface, rock temperature well above boiling point. • Some areas where the natural heat of the earth’s interior is much closer to the surface and can be more readily tapped. • Closely associated with tectonic activity. • Hydrogeothermal: • Taping the aquifer. • Fracturing the rocks, introducing cold water, and recovering the resulting hot water or steam which could power turbines and produce electricity. • Injection well: • In situations where there is no aquifers (hot dry plants). • Drilling a pipe to about 5,000 meters (16,000 feet). • Injecting a liquid (often water) through the pipe.

  46. 3. World Geothermal Power in Installed Capacity, 1950-2011 (in megawatts)

  47. 3. Geothermal Energy • Geothermal heat pumps • Promising alternative to heating/cooling systems. • Ground below the frost line (about 5 feet) is kept around 55oF year-round. • During winter: • The ground is warmer than the outside. • Heat can be pumped from the ground to the house. • During summer: • The ground is cooler than the outside. • Heat can be pumped from the house to the ground. Winter House 5 feet 55o F Summer House 5 feet 55o F

  48. Renewable sources of energy are also dependent on non-renewable resources • Photovoltaic cells consume non-renewable resources. • Solar-thermal plants consume land and water from aquifers (arid areas). • Geothermal power consumes water from aquifers. • Wind energy consumes land, concrete, steel and rare earths (gearboxes). • All energy supplies require distribution systems (electric wires) that consume land and resources. • The term renewable energy is therefore misleading.