Susan S. Van Biersel
Next the unit will take a step back, so to speak, and examine the ways in which fossil fuels, the fuels used to power the engines studied, are formed. Fossil fuels are “organic chemicals created by living organisms millions of years ago and buried in sediments, where high pressures and temperatures concentrated and transformed them into energy-rich compounds”5. Currently, fossil fuels account for the great majority of the world’s energy use. Students will compare and contrast coal (a solid), petroleum (a liquid) and natural gas. We will study the geologic timetable involved in the formation of these fuels. Emphasis will be placed on the fact that due to the extremely long time involved in forming these fuels, they are essentially
nonrenewable
resources. Students will research current reserves of fossil fuels, versus rate of consumption. Location of current reserves will be researched, particularly domestic vs. foreign. It will be noted that fuels are not distributed evenly throughout the world. For example, about 60 percent of known oil supplies are located in a small area in the Middle East. The United States has just 2 percent of the world’s oil supplies, but about 25 percent of the world’s coal supplies6. One startling fact we will look at is, given the current rate of consumption and available reserves, we may “run out of gas” (crude oil reserves will be depleted) in as little as 30-50 years!7
Following the study of fossil fuel formation, the students will explore the different methods by which the fuels are discovered, attained (e.g. mining, drilling), processed, and ultimately put into use. The economic and environmental impacts will be explored. The study of discovery and attainment of petroleum, gas and coal will offer an interesting look at geography and geology on a national and an international level. The lessons on processing and usage will provide a natural progression into the impacts on the economy and environment.
Environmental Impacts of Fossil Fuels
Obtaining energy by burning fossil fuels creates environmental problems of immense global proportions. It produces oxides of carbon, sulfur, and nitrogen, soot and fine-particulate ash. Carbon monoxide (CO), an oxide produced by combustion of all fossil and plant fuels, is converted to carbon dioxide (CO2), which contributes to global warming. Global warming is “an enhancement of the greenhouse effect of the earth’s atmosphere, resulting in an increase of the annual average surface temperature of the earth on the order of 0.5-1 degree Celsius since the middle of the nineteenth century” 8. Most of that warming has occurred within the last two decades. Global warming is caused by the increasing accumulation in the atmosphere of predominately CO2 and other gases [specifically CH4, N2O and chlorofluorocarbons (CFCs)]. Together these are called the “greenhouse gases”. Many scientists regard anthropogenic (human-caused) global climate change to be the most important environmental issue of our times. Since pre-industrial times atmospheric concentrations of CO2, CH4 and N2O have increased by over 31 percent, 151 percent, and 17 percent, respectively. Carbon dioxide is by far the most important cause of anthropogenic climate change, contributing 64 percent of the world’s global warming problemmore than all other greenhouse gases combinedd9.
It is estimated that at the current rate, the average annual surface temperature of the earth could increase 2-3 degrees Celsius by the end of the twenty-first century. This increase is enough to cause significant impact on human habitat and ecological systems. Speculated implications include increasingly severe weather, more sudden temperature swings, droughts, floods, heat waves, wildfires, and thunderstorms. Food and water supplies would be threatened. The world’s glaciers would melt enough to cause sea levels to rise and low-lying areas such and the Mississippi Delta to flood. Tropical regions would expand, allowing insects that carry diseased such as malaria, dengue fever, and the West Nile virus to spread to places like Florida, Georgia or even New York10.
Burning coal also releases sulfur oxides (SOx) to the atmosphere, where they form environmentally injurious compounds. Nitrogen oxides (NOx), mostly NO and NO2, are products of combustion in not only auto engines, but also power plants. The nitrous oxides are the precursors of the photochemical oxidants, ozone and peroxyacetyl nitrate (PAN), which is associated with smog. Water and oxygen in the atmosphere combine with SO2 and NO2 to form sulfuric acid (H2SO4) and nitric acid (HNO3), the main components of acid rainrain with an elevated pH, mostly due to environmental factors such as pollutants in the atmospheree11. The students will study these adverse environmental impacts, and hopefully gain an appreciation of the ways in which their personal lives are affected by them.
Solutions
The final sections of the unit will focus on possible solutions for reducing negative impacts by fossil fuels on the environment, and possible alternative energy sources for the future. As Blatt states in his text, fossil fuels are “ major pollutants and need to be phased out for that reason alone, without even considering the serious economic cost of importing half our needs. We have no choice but to begin the switch to alternative fuels. This is inevitable. As expensive and disruptive as the changeover will be now, it will only be more expensive and just as disruptive later” 12.
Fossil fuels now provide about 79 percent of all commercial energy in the world13. In many of the world’s wealthier countries, much of this energy is consumed by transportation. In the U.S., transportation consumes 30 percent of total energy used, and 63 percent of all petroleum. We also own 40 percent of the world’s cars. In light of these facts, we will spend time during the unit discussing several alternative
transportation
fuels now available. Three alternative fuels we will discuss will include methanol, ethanol (both largely renewable) and propane (nonrenewable). All three of these fuels offer a more environmentally friendly transportation alternative than gasoline.
For more than thirty years, methanol (also known as “wood alcohol”) has been the fuel of choice at the Indianapolis 500. Most methanol-fueled vehicles use M85, a mixture of 85 percent methanol and 15 percent unleaded gasoline. Produced as a liquid, methanol is currently made from natural gas, but it can also be made from a wide range of renewable sources, such as wood or waste paper. Most methanol-powered vehicles are fuel-flexible, meaning they can use 100 percent gasoline if methanol is not available. There are currently more than 15,000 M85 vehicles in operation, primarily in California and New York. Potential environmental advantages offered by methanol compared to gasoline include lower nitrogen oxide emissions, no particulate matter formation, and lower overall volatile organic compound (VOCs) emissions14.
Ethanol-fueled vehicles date back to the 1880s, when Henry Ford designed his popular Model T to operate on either ethanol or gasoline. Ethanol is essentially 100 percent pure grain alcohol, and is produced by fermenting plant sugars. It can be made from corn, potatoes, wood, waste paper, wheat, and brewery waste. More than 90 percent of U.S. ethanol production today comes from corn. Pure ethanol is rarely used for transportation; it is usually mixed with gasoline. The most popular blend for light-duty vehicles is known as E85, which is 85 percent ethanol and 15 percent gasoline. As of March 2002, American automakers were producing a variety of automobiles, light-duty pickup trucks, and minivans known as flexible-fuel vehicles (FFVs). These vehicles can operate on any combination of ethanol and gasoline by automatically sensing the percentage of alcohol in the fuel tank, and adjusting the engine’s parameters accordingly. In January 2002, the U.S. Postal Service (USPS) made the largest purchase of FFVs by a federal government agency, agreeing to buy nearly 23,750 vehicles powered with up to 85 percent ethanol. Compared to conventional gasoline, ethanol produces fewer total toxics, reduces VOC emissions by 15 percent, and particulate emissions by 20 percent15.
Propane (otherwise known as Liquefied Petroleum Gas or LPG) is a byproduct of natural gas processing and petroleum refining. More than 60 million Americans use propane gas for everything from heating and cooling homes and businesses to powering barbecue grills. Propane has been used as a transportation fuel since the 1940s. Today, auto manufacturers offer a variety of light- and medium-duty propane-powered vehicles, primarily used by vehicle fleets. There are more than 350,000 vehicles on our roads today, including taxicabs, police cars, and school buses. Compared with gasoline, propane can lower carbon dioxide, carbon monoxide, and other toxic emissions16.
The “Renewables”
The main
renewable
alternative energy systems include solar and nuclear power, hydroelectric power, biomass energy, wind energy and fuel cells. During this final section of the unit, by way of introduction and exposure, we will touch briefly on each of these energy options. Students will do cursory research on how and to what extent these technologies are in use today, and what the possibilities are for the future. We will narrow our scope, however, to address solar and wind energy in particular.
Solar Power
As one author describes it, the sun is “a giant nuclear furnace in space, constantly bathing our planet with a free energy supply.” Much of the solar energy arriving at the top of the earth’s atmosphere is absorbed or reflected by the atmosphere (more at high latitudes than at the equator). However, the average amount of solar energy reaching the earth’s surface is some 10,000 times all the commercial energy used each year17. Unfortunately, until this century, we have not devised an efficient and cost-effective way in which to capture and convert this tremendous infusion of energy. The encouraging news is that great strides have been made in just the last 25 years toward developing workable ways to utilize this wonderful source of energy. During this section of the unit, we will examine the following:
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- Passive Solar Heating: This is the simplest and oldest use of solar energy, which basically involves the adsorption of solar energy directly into a building in order to reduce the energy required for heating. This method uses natural materials or structures with no moving parts to simply gather and hold heat. An example of adapting this principle is a glass-walled “sunspace” or greenhouse on the south side of a building.
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- Active Solar Heating: Active solar systems generally pump a heat-absorbing medium such as air, water or anti-freeze through a small collector, rather than passively collecting heat in a stationary medium. Active collectors are usually located adjacent to or on top of a building.
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- Solar Thermal Engines: These are an extension of active solar heating, usually using more complex collectors to produce temperatures high enough to drive a steam turbine to produce electric power.
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- Photovoltaic Energy: Photovoltaic cells capture solar energy and convert it directly to electrical current in a solid-state device. The cells do this by separating electrons from their parent atoms and accelerating them across a one-way electrostatic barrier formed by the junction between two different kinds of semiconductors. Photovoltaic cells are already widely in use on a small scale, as they are built into solar-powered calculators, watches, toys, photosensitive switches, and a variety of other consumer products. Photovoltaic (PV) systems are available today that can provide electricity for residential and commercial buildings. A typical PV system consists of solar cells connected electrically to form a module that can measure two to four feet wide and four to six feet long. Many interconnected PV modules are called an array. An array is often mounted on the roof of a building, or on a tracker, which moves to follow the sun.
Wind Power
Man has used wind power for thousands of years for such mechanical tasks as milling grain and pumping water. However, it is the use of wind energy as a pollution-free means of generating electricity on a significant scale that is peaking current interest in the subject. Wind power is one of the fastest-growing renewable energy technologies worldwide. A total of 31,000 MW wind generating capacity had been installed by the end of 2002. This is about four times the capacity that had been installed by the end of 1997, implying an average growth rate of 40% per annum18.
In the 1980s, the United States was a world leader in wind technology, and California hosted 90 percent of all existing wind power generators. However, poor management, technical flaws, and over dependence on subsidies led to bankruptcy of some major corporations. Currently Danish, German, and Japanese wind machines are capturing the rapidly growing world market.
Wind farms are large concentrations of wind generators producing commercial electricity. Construction sites of wind farms include mountain ridges, plains and seacoasts. Offshore wind farms are being installed by Denmark, the United Kingdom and the Netherlands. These countries expect to soon produce up to 20 percent of their electricity with wind. The World Energy Council predicts that wind could account for 200,000 MW of electricity by 2020, depending on how seriously politicians take global warming and how many uneconomical nuclear reactors go offline. One thousand MW meets the energy needs of about 50,000 typical U.S. households19.