Chapter 12 Nonrenewable Energy Resources Nonrenewable Energy Nonrenewable energy resources- fossil fuels (coal, oil, natural gas) and nuclear fuels. Modern society requires large quantities of energy that are generated from the earth’s natural resources. Primary Energy Resources: The fossil fuels(oil, gas, and coal), nuclear energy, falling water, geothermal, and solar energy. Secondary Energy Resources: Those sources which are derived from primary resources such as electricity, fuels from coal, (synthetic natural gas and synthetic gasoline), as well as alcohol fuels. The laws of thermodynamics tell us two things about converting heat energy from steam to work: 1) The conversion of heat to work cannot be 100 % efficient because a portion of the heat is wasted. 2) The efficiency of converting heat to work increases as the heat temperature increases. Btu (British thermal unit) - amount of energy required to raise the temperature of 1 lb of water by 1 ºF. cal (calorie) - the amount of energy required to raise the temperature of 1 g of water by 1 ºC. Commonly, kilocalorie (kcal) is used. 1 Btu = 252 cal = 0.252 kcal 1 Btu = 1055 J (joule) = 1.055 kJ 1 cal = 4.184 J Energy Units and Use Two other units that are often seen are the horsepower and the watt. These are not units of energy, but are units of power. 1 watt (W) = 3.412 Btu / hour 1 horsepower (hp) = 746 W Watt-hour - Another unit of energy used only to describe electrical energy. Usually we use kilowatt-hour (kW-h) since it is larger. quad (Q) - used for describing very large quantities of energy. 1 Q = 1015 Btu Energy Use Commercial energy sources- those that are bought and sold, such as coal, oil and natural gas. Subsistence energy sources- those gathered by individuals for their own use such as wood, charcoal and animal waste. Changes in U.S. Energy Use www.bio.miami.edu/beck/esc101/Chapter14&15.pp t Energy resources removed from the earth’s crust include: oil, natural gas, coal, and uranium www.bio.miami.edu/beck/esc101/Chapter14&15.ppt Process of Energy Use Overall Fuel Efficiency of U.S. Automobiles Electricity Generation Electricity Generation The burning fuel from coal transfers energy to water, which becomes steam. The kinetic energy contained within the steam is transferred to the blades of a turbine, a large device that resembles a fan. As the energy in the steam turns the turbine, the shaft in the center of the turbine turns the generator. This mechanical motion generates energy. Energy Efficiency Most coal burning power plants are about 35% efficient. Cogeneration Cogeneration- using a fuel to generate electricity and to produce heat. Example- If steam is used for industrial purposes or to heat buildings it is diverted to turn a turbine first. This improves the efficiency to as high as 90%. Coal Coal- a solid fuel formed primarily from the remains of trees, ferns, and other plant materials that were preserved 280-360 million years ago. Four types of coal ranked from lesser to greater age, exposure to pressure, and energy content. These four types are: lignite, sub-bituminous, bituminous, and anthracite. The largest coal reserves are in the United States, Russia, China, and India. Coal Lignite: A brownish-black coal of low quality (i.e., low heat content per unit) with high inherent moisture and volatile matter. Energy content is lower 4000 BTU/lb. Subbituminous: Black lignite, is dull black and generally contains 20 to 30 percent moisture Energy content is 8,300 BTU/lb. Bituminous: most common coal is dense and black (often with well-defined bands of bright and dull material). Its moisture content usually is less than 20 percent. Energy content about 10,500 Btu / lb. Anthracite :A hard, black lustrous coal, often referred to as hard coal, containing a high percentage of fixed carbon and a low percentage of volatile matter. Energy content of about 14,000 Btu/lb. www.uvawise.edu/philosophy/Hist%20295/ Powerpoint%5CCoal.ppt Bituminous Subbituminous Lignite Anthracite Advantages and Disadvantages of Coal Advantages Disadvantages Energy-dense Contains impurities Plentiful (300 years of use remaining) Release impurities into air when burned Easy to exploit by surface mining Trace metals like mercury, lead, and arsenic are found in coal Technological demands are small Combustion leads to increased levels of sulfur dioxide and other air pollutants into the atmosphere. Economic costs are low Ash is left behind Easy to handle and transport Carbon is released into the atmosphere which contributes to climate change Needs little refining Major threat to health garnero101.asu.edu/glg101/Lectures/L37.ppt Acid Mine Drainage The impact of mine drainage on a lake after receiving effluent from an abandoned tailings impoundment for over 50 years Relatively fresh tailings in an impoundment. http://www.earth.uwaterloo.ca/services/whaton/s06_amd.html The same tailings impoundment after 7 years of sulfide oxidation. The white spots in Figures A and B are gulls. Petroleum Petroleum- a mixture of hydrocarbons, water, and sulfur that occurs in underground deposits. Oil and gasoline make this ideal for mobile combustion, such as vehicles. Formed from the remains of ocean-dwelling phytoplankton that died 50-150 million years ago. Countries with the most petroleum are Saudi Arabia, Russia, the United States, Iran, China, Canada, and Mexico. Petroleum Oil in U.S. • 2.3% of world reserves • uses nearly 30% of world reserves; • 65% for transportation; • increasing dependence on imports. www.bio.miami.edu/beck/esc101/Chapter14&15.ppt Advantages and Disadvantages of Petroleum Advantages Disadvantages Convenient to transport and use Releases carbon dioxide into atmosphere Relatively energy-dense Possibility of leaks when extracted and transported Cleaner-burning than coal Some water pollution Low Cost with subsidies Releases sulfur, mercury, lead, and arsenic into the atmosphere when burned Ample supply for about 50 years When price is low discourages alternate choices encourages waste Natural Gas Natural gas- exists as a component of petroleum in the ground as well as in gaseous deposits separate from petroleum. Contains 80 to 95 percent methane and 5 to 20 percent ethane, propane, and butane. Sources of Natural Gas •Russia & Kazakhstan - almost 40% of world's supply. •Iran (15%), Qatar (5%), Saudi Arabia (4%), Algeria (4%), United States (3%), Nigeria (3%), Venezuela (3%); •90–95% of natural gas in U.S. domestic (~411,000 km = 255,000 miles of pipeline). www.bio.miami.edu/beck/esc101/Chapter14&15.ppt billion cubic metres Advantages and Disadvantages Natural Gas Advantages Disadvantages Contains fewer impurities and therefore emits almost no sulfur dioxide or particulates When unburned, methane escapes into the atmosphere Emits only 60% as much carbon dioxide as coal Exploration of natural gas has the potential of contaminating groundwater Ample supplies up to 150 years Low cost with huge subsidies Shipped across oceans as highly flammable LNG Other Fossil Fuels Oil sands- slow-flowing, viscous deposits of bitumen mixed with sand, water, and clay. Bitumen (tar or pitch)- a degraded type of petroleum that forms when a petroleum migrates close to the surface, where bacteria metabolize some of the light hydrocarbons and others evaporate. The Hubbert Curve Hubbert curve- a graph that shows the point at which world oil production would reach a maximum and the point at which we would run out of oil. The Future of Fossil Fuel Use If current global use continues, we will run out of conventional oil in less than 40 years. Coal supplies will last for at least 200 years, and probably much longer. • Burning any fossil fuel releases carbon dioxide into the atmosphere and thus promotes global warming. • Comparison of CO2 emitted by fossil fuels and nuclear power. www.bio.miami.edu/beck/esc101/Chapter14&15.ppt Nuclear Energy Fission- a nuclear reaction in which a neutron strikes a relatively large atomic nucleus, which then splits into two or more parts. Nuclear Reactors Nuclear Reactors Fuel rods- the cylindrical tubes that house the nuclear fuel used in a nuclear power plant. Nuclear power plants work by using heat from nuclear fission to heat water. This water produces the steam to turn the turbine, which turns a generator. Control rods- cylindrical devices that can be inserted between the fuel rods to absorb excess neutrons, thus slowing or stopping the fission reaction. Advantages and Disadvantages of Nuclear Energy Advantages Disadvantages No air pollution is produced Possibility of accidents Countries can limit their need for imported oil Disposal of the radioactive waste Emits 1/6 as much pollution as coal High cost even with high subsidies Low environmental impact if no accidents Spreads knowledge for nuclear weapons Low net energy yield Radioactive Waste Radioactive waste- once the nuclear fuel can not produce enough heat to be used in a power plant but it continues to emit radioactivity. This waste must be stored in special, highly secure locations because of the danger to living organisms. Radioactive Waste High-level radioactive waste- the form used in fuel rods. Low-level radioactive waste- the protective clothing, tools, rags, and other items used in routine plant maintenance. Chernobyl • April 26, 1986, reactor explosion (Ukraine) flung radioactive debris into atmosphere • Health ministry reported 3,576 deaths • Green Peace estimates32,000 deaths; • About 400,000 people were forced to leave their homes • ~160,000 sq km (62,00 sq mi) contaminated • > Half million people exposed to dangerous levels of radioactivity • Cost of incident > $358 billion www.bio.miami.edu/beck/esc101/Chapter14&15.ppt Three Mile Island • March 29, 1979, a reactor near Harrisburg, PA lost coolant water because of mechanical and human errors and suffered a partial meltdown • 50,000 people evacuated & another 50,000 fled area • Unknown amounts of radioactive materials released • Partial cleanup & damages cost $1.2 billion • Released radiation increased cancer rates. www.bio.miami.edu/beck/esc101/Chapter14&15.ppt Fusion Nuclear fusion- the reaction that powers the Sun and other stars. This occurs when lighter nuclei are forced together to produce heavier nuclei and heat is released. Fusion is a promising, unlimited source of energy in the future, but so far scientists have had difficulty cotaining the heat that is produced.