Energy & Air Pollution potx

Energy & Air Pollution Introduction Fossil Fuels: Oil & Gas Fossil Fuels: Coal Nuclear Energy Alternative Energy Resources Air Pollution Summary At the heart of modern society lies an economy driven by energy use. Unfortunately, the same energy that brings us comfort, convenience, and prosperity also brings us pollution, impoverishment, and global warming. Our challenge is to maximize the benefits gained from energy consumption while minimizing the costs incurred. Douglas Foy A fuming smokestack is the perfect symbol of our national dilemma. On the one hand, it means the jobs and products we need. On the other, it means pollution. American Gas Association ad, 1991 2 Introduction • Fossil fuels (oil, gas, coal) makeup most of the energy consumed in the U.S. • Energy use increases with increasing population, land area, and industrial activity and energy use per capita is greatest in large, sparsely populated states. • Fossil fuels are non-renewable resources with limited life span and their combustion contributes to global warming. • Alternative energy sources such as solar and wind power are renewable and hold the promise of a sustainable energy future. U.S. Energy Use Current U.S. energy use is weighted heavily toward fossil fuels (oil, natural gas, and coal) that account for approximately 90% of all energy used in the nation (Fig. 1). Environmental concerns over air pollution and the potential for global warming may encourage wider access to alternative energy sources such as nuclear power and wind or solar energy. Nuclear power accounts for about a fifth of U.S. electricity generation but only 5% of total energy consumption. Alternative energy sources (hydroelectric, wind, solar, geothermal) generate 5% of U.S. energy production but may expand that share in the decades ahead. Energy use within the U.S. varies with population size and character of energy demand (Fig. 2). States with large populations, large land area (greater distances to travel), and Figure 1. U.S. energy consumption per energy type, 1949 to 1995. Graph courtesy of the Energy Information Administration. 3 energy-intensive industries (e.g., oil refining, chemicals), typically use the most energy. Large sparsely populated states such as Wyoming and Alaska rate highly in energy use per person because transportation consumes large volumes of fuel. Fossil fuels form from decayed organic material through a series of chemical reactions that occur gradually over millions of years under specific physical conditions in a select group of rocks. These conditions make it possible to predict where oil and gas may be found but also highlight the fact that fossil fuels are non-renewable resources that will not be replaced once used. Reserves of oil and natural gas will probably be stretched out for another century but we must face the inevitable conclusion that these finite resources will have to be replaced with an alternative form of energy in the next 50 years. The inevitable decrease in the availability of fossil fuels will be felt most acutely in transportation because there is no viable inexpensive replacement for the refined petroleum products that fuel automobiles and airplanes. Coal represents an alternative fossil fuel with a potentially longer life span than either oil or gas but it has the unfortunate distinction of generating more pollution than the other fossil fuels. Furthermore, coal produces more carbon dioxide during combustion than either oil or gas, but all three have been fingered as the primary sources of the greenhouse gas that is the culprit for global warming. Advocates of a nuclear future have seized the potential threat of global warming and the nation's dependence on foreign oil to advance the nuclear cause. Fifty years ago, scientists working in the fledgling U.S. nuclear power industry (Fig. 3) predicted that electricity would be virtually free by the end of the century because of the electrical benevolence of nuclear energy. Today, only 17% of the world’s electricity is generated by nuclear power and that number is unlikely to grow because of concerns about the safety of nuclear reactors and anxiety over how to dispose of highly radioactive waste produced Figure 2. Distribution of U.S. energy use. Energy use at home and industry is typically in the form of electricity generated by burning coal. Transportation is almost exclusively fueled by forms of gasoline refined from petroleum. 4 during power generation. Rarely has a technology shown such early promise only to fall so rapidly from grace. Alternative energy resources (hydroelectric, wind, solar, biomass, geothermal) generate less than 10% of U.S. energy but have few of the drawbacks of fossil fuels or nuclear power and hold promise of a sustainable energy future. A veritable chorus of Pollyannas has sung the praises of alternative energy since the 1970s but their potential remains ambiguous because of uncertainties over the rate of technological development and operating costs. Some of these renewable energy sources have greater potential than others with solar energy and wind power holding the most hope for the future. The industrial air pollution that was once proudly viewed as a by-product of economic growth is now largely a thing of the past. No longer will thousands of people die during a weekend of lethal air pollution as they did in London in 1952. Air pollution is still widespread but its effects are muted, hidden among reports of greater incidence of asthma and other respiratory ailments and studies of acid rain downwind from industrial centers. The burning of fossil fuels represents a major source of air pollutants and cleaner air will therefore be an indirect by-product of any change in energy production in the years ahead. Figure 3. Perry nuclear reactor, 35 miles northwest of Cleveland, Ohio. Lake Erie is on the left of the image. Image courtesy of the Nuclear Regulatory Commission (NRC). Think about it . . . 1. Predict which of the following states consumes the most energy. a) California b) Illinois c) New York d) Texas 2. Examine the partially completed graph found at the end of the chapter that plots gross domestic product (GDP) per capita vs. energy consumption per capita. Label the points that represent where you think the eight named nations would plot on the graph. 3. Draw a time line for energy use before you read any further in this chapter. Label the time line to indicate how energy consumption has changed/will change from 1850 to 2050. Differentiate between domestic and industrial energy sources and transportation energy sources. 5 Fossil Fuels: Oil & Gas • Time and a specific temperature range are necessary for the generation of oil and gas. • As hydrocarbons become mature they progress from heavy oils to light oils to natural gas. • Hydrocarbons become concentrated in sedimentary rocks. • The volume of the world’s oil reserves is approximately 1,070 billion barrels. • The U.S. uses 25% of the world’s oil. • Two-thirds of the world’s oil reserves are located in the Middle East. Fossil fuels form from decayed organic material. Oil, coal, and natural gas are the most common products of this process. Oil and gas form from organic material in microscopic marine organisms, whereas coal forms from the decayed remains of land plants. Tar (oil) sands and oil shale are less common forms of fossil fuels and are less widely used because extraction of oil from these deposits is more expensive than producing other forms of fossil fuels. Generation and Production of Oil and Gas The two principal requirements in the generation of oil and gas (also known as hydrocarbons - chemical compounds of carbon and hydrogen) are time and a specific range of temperature. The steps in the process are: 1. Organic-rich sediments are deposited and gradually buried to greater depths and converted to sedimentary rock (e.g., shale). 2. Chemical reactions occur during burial under conditions of increasing temperature and pressure. The reactions occur at temperatures of 50 to 100 o C, higher temperatures "boil off" the hydrocarbons; lower temperatures are not sufficient to drive the chemical reactions. 3. The reactions change the organic molecules to hydrocarbon molecules. With increasing time (millions of years) the hydrocarbons become more mature changing from heavy oils to lighter oils to natural gas. Fossil fuels are considered 6 non-renewable resources because they are consumed much faster than they can be replaced. Oil and gas migrate upward through fractures and pore spaces in permeable rocks and/or sediments. Some hydrocarbons escape at Earth’s surface through features such as oil seeps. Others collect below the surface in sedimentary rocks when their path is blocked by low-permeability rocks (Fig. 4). Rock structures such as faults and folds may serve to juxtapose permeable and impermeable units. Oil and gas are trapped in the permeable rocks and will migrate upward to lie at the highest elevation in the rock unit. When an oil field is first drilled the oil is driven into the well by pressures within the rocks. This primary recovery will extract about 25% of the oil. Additional oil can be extracted using enhanced recovery techniques that make it easier for the oil to enter the well. Such techniques may include artificially fracturing the rock to create passages for oil migration or pumping wastewaters from drilling operations into nearby wells to drive the oil toward the producing well. Oil Reserves Oil and gas are not distributed uniformly within Earth's crust (Fig. 5). Hydrocarbons are initially formed as organic-rich sediments and the oil and gas subsequently migrate upward, into younger rocks that are also of sedimentary origin. Consequently, oil and gas reserves are generally absent in areas underlain by igneous or metamorphic rocks such as volcanic island chains like Japan or Hawaii. Even in areas where sedimentary rocks are present, they must fall within a specific age range to ensure that the rocks are mature enough to contain hydrocarbons but not so old that oil and gas would have long ago escaped. Oil reserves steadily increased since the first commercial oil well was drilled in Titusville, Pennsylvania, in 1859 but estimates of global reserves have remained relatively uniform Figure 4. Oil and gas will migrate through permeable rocks to the highest available elevation. Examples of traps include folds (left), and faults (right). 7 at around a billion barrels over the last decade. Oil reserves remained stable despite the fact that global population has doubled in the last thirty years. Reserves haven't declined because of: • Exploration of geologic formations in increasingly remote areas of the world, including the seafloor, using an array of new methods that utilize satellites and geophysical instruments to unravel the geology in regions where few rocks are visible. • Improved technology used by oil companies to extract greater volumes of oil through enhanced recovery techniques. • Greater efficiency in energy use as a result of higher fuel prices and stricter pollution standards that caused manufacturers to build more energy-efficient appliances and engines. Further improvements in energy efficiency will continue to delay the inevitable decline in oil reserves. For example, recently introduced combination gas-electric cars can be driven 112 km (70 miles) on a gallon of gas. However, even with the best management and environmental stewardship we must anticipate that a world that continues to rely on oil will see this finite resource decline toward the second half of this century. Known world oil reserves are approximately 1,030 billion barrels (one barrel is equivalent to 42 gallons). These reserves would last for nearly 40 years at current global consumption Figure 5. Locations of principal North American oil fields (left) and other hydrocarbon resources (right). Most oil shales and oil sands are not economically viable now but may play a more significant role in energy production as supplies decrease. 8 rates. The U.S. Geological Survey recently issued a more optimistic estimate that there actually may be double those reserves left to be discovered with a potential life span until the end of this century. The U.S. uses 25% of the world's oil, much more than any other nation, and imports over half of the oil it consumes. Consequently we are vulnerable to disruptions in oil supplies. Current fluctuations in gasoline prices that result from relatively modest changes in supply and demand will become much more exaggerated as the available reserves of oil decline. The future success of the U.S. economy may rely on the state of our political relationships with the relatively few nations that have abundant oil reserves. The majority of the oil and other petroleum products currently imported into the U.S. come from just four nations, Venezuela, Mexico, Canada, and Saudi Arabia. However, as two-thirds of all the world's oil reserves are located in the Middle East (Fig. 6), countries such as Saudi Arabia, Kuwait, Iran, and Iraq may play an increasingly important role in U.S. oil supply in the decades ahead. Figure 6. Distribution of global oil and gas reserves expressed as a percentage of global reserves. Two- thirds of the world’s oil and one-third of all natural gas reserves are located in the Middle East. Russia has 33% of the world's natural gas and Saudi Arabia has 25% of the world's oil. Think about it . . . 1. Use the Venn diagram found at the end of the chapter to compare and contrast the similarities and differences between the characteristics of oil and coal resources. . . . continued on next page 9 Fossil Fuels: Coal • The carbon content and heat content of coal increase with increasing maturity. • The volume of ash residue after burning decreases with increasing coal maturity. • The two principal regions of coal production in the U.S. are the Appalachian basin and the Great Plains. • Sulfur content of coal is lower in the Great Plains and higher in the Appalachian basin. • Air pollution, medical expenses, and landfill fees are external costs of coal use. Coal, the carbon-rich residue of plants, can be classified by rank or carbon content. Coal matures by increasing rank with increasing burial pressure (Fig. 7). 2. Similar organic-rich source rocks are present in two locations. Oil deposits formed in the overlying rocks at the first location but did not form at the second location. Which of the following is the best explanation for this difference? a) The first location was more deeply buried than the second. b) The first location was subjected to lower temperatures than the second. c) The first location contains younger rocks than the second. d) Rocks at the first location had lower permeability than rocks at the second site. Figure 7. Progression of coal rank (maturity) from carbon-poor peat to carbon-rich anthracite. The relative proportion of U.S. coal production by rank is anthracite 2%, bituminous 53%, sub-bituminous 36%, and lignite 9%. 10 Peat is the least-mature form of coal, containing a large volume of fibrous plant matter. With increasing compaction, water is driven out and carbon becomes increasingly concentrated. Both carbon content and the amount of heat released during burning increase with maturity. The carbon content ranges from around 30% in peat to 99% for anthracite. The higher the carbon content, the more heat that is released when the coal is burned. Small amounts of high-carbon coals produce the same heat as large volumes of low-carbon coal. The volume of ash that remains after burning decreases with increasing rank. The ash must be disposed off in a landfill thus increasing expense. Figure 8. Coal- bearing areas of the U.S. Image courtesy of Energy Information Administration. [...]... inversion occurs when cold air lies below warm air Under normal conditions, the temperature of air decreases with increasing altitude A parcel of warm air will rise through the overlying colder air, diluting pollution as it is carried higher in the atmosphere Pollutants become concentrated below a blanket of warm air when cold air lies immediately above the ground surface The cold air remains trapped near... is restricted by location to sites in sparsely populated areas of the West Solar and wind energy represent the greatest potential for technological advances and increasing energy production among renewable energy sources Solar Energy Solar energy accounts for approximately 1% of all U.S energy use Passive solar energy refers to using the heat from sunlight to warm buildings (Fig 25) and was first used... resources 2 The graph located at chapter end compares projected plots of the generation of wind energy vs time (19852025) with nuclear energy capacity vs time (19602000) Make some predictions on the future of wind energy using the evolution of nuclear power as a model 27 Air Pollution • • • • • Toxic air pollution killed thousands in the relatively recent past Industrial emissions are recorded annually... they will increase their share of U.S energy significantly in the future Passive solar energy requires that structures be oriented to receive light and heat from sunlight and active solar energy converts solar radiation to electricity Wind energy accounts for 0.5% of all U.S energy but could generate up to 20% Future energy must come from one of the three principal energy sources currently in use Approximately... standards National air quality is improving despite increases in population, transportation, and economic growth In addition to various health effects, air pollution also causes acid rain and can reduce visibility Air quality diminished in big cities following the Industrial Revolution and declined further as the popularity of the automobile increased during the last century Air pollution at Earth's... sources currently in use Approximately 80% of the nation's current energy needs are supplied by fossil fuels (oil, gas, coal) that carry with them the threat of potential energy shortages as well as associated environmental degradation from air pollution and concerns about global warming Nuclear power supplies less than 10% of total U.S energy and is 21 unlikely to undergo a resurgence any time soon in... proportion of U.S energy from renewable sources from its current level (Fig 19; less than 10%) to at least 30% of total energy use Figure 19 Proportion of U.S energy generated by renewable energy vs fossil fuels and nuclear power Controls on Renewable Energy Unlike fossil fuels, renewable energy must often be used relatively close to where it is generated Transmission lines may conduct electricity up to... (renewable) energy sources (hydroelectric power, biomass) account for the 31 remainder of electricity generation and approximately 10% of all U.S energy consumption 2 What factors influence energy use in different locations? States with large populations, large land area (greater distances to travel), and energy- intensive industries (e.g oil refining, chemicals), typically use the most energy Texas... to generate electricity High-sulfur bituminous coals contribute to air pollution but yield more heat per ton of coal than low sulfur sub-bituminous coal Utility companies must balance the cost of guarding against pollution with the extra cost of transporting more low-grade coals that generate more waste (ash) following combustion Air pollution represents an external cost associated with the combustion... wind energy hold hope for the future as they have few of the drawbacks associated with other energy sources (pollution, safety) However, renewable energy sources will be limited by climate and have little potential for replacing petroleum as the energy source of choice for transportation 11 How is nuclear energy generated? Uranium ore contains is a small fraction of the uranium isotope (U235) The radioactive . Energy & Air Pollution Introduction Fossil Fuels: Oil & Gas Fossil Fuels: Coal Nuclear Energy Alternative Energy Resources Air Pollution Summary At. Alternative energy sources such as solar and wind power are renewable and hold the promise of a sustainable energy future. U.S. Energy Use Current U.S. energy