2 Crust (make’s up only 1% of earth’s mass) Compositional LayersCrust (make’s up only 1% of earth’s mass)MantleCorePhysical LayersLithosphereIt is a cool, rigid layer that is 15 km to 300 km thick and is divided into huge pieces called tectonic platesAsthenospherethe solid, plastic layer of the mantle beneath the lithosphere.MesosphereOuter CoreEarth’s outer core is a dense liquid layer.Inner Corecenter of the Earth is a dense, solid inner core, which is made up mostly of iron and nickel.
3 Geologic ProcessesA. The earth is made up of a core, mantle, and crust and is constantly changing as a result of processes taking place on and below its surface.Geology is the study of dynamic processes occurring on the earth’s surface and in its interior.
4 GeosphereCrust is soil and rock that floats on a mantle of partly melted and solid rock.The crust is thin and is divided into:continental crust- underlies the continents and continental shelves extending into the ocean (20-70km thick)oceanic crust- underlies the ocean basin and covers about 71% of the earth’s surface. (5-8km thick)Huge volumes of heated and molten rock moving around the earth’s interior form massive solid tectonic plates that move extremely slowly across the earth’s surface.About 12 or so rigid tectonic plates move across the surface of the mantle very slowly. These thick plates compose the lithosphere.Core is intensely hot. It has a solid inner part surrounded by a liquid core of molten or semisolid material.Mantle is a thick, solid zone. It is mostly solid rock, but an area called the asthenosphere is very hot, partly melted rock about the consistency of soft plastic.
5 GeosphereCrustThere are three types of boundaries for lithospheric plates.Divergent plate boundaries, where plates move apart in opposite directions (ex. Oceanic Ridge- magma flows upward when plates diverge)Convergent plate boundaries, where plates are pushed together by internal forces and one plate rides up over the other. A trench generally occurs at the subduction zone. (ex: Marina Trench)Transform fault where plates slide/grind past one another. (ex. San Andres Fault)Tectonic movement of Earth’s continental and oceanic crust is driven by convection currents/cells.-mountains on land and trenches on the ocean floor are created by this movement.-Earthquakes and volcanic action are likely to be found at the plate boundaries.(Supplement 11 pg S43)The plate tectonic theory also helps to explain certain patterns of biological evolution occurred.
6 Minerals, rocks, and the rock cycle Minerals - solid inorganic elements and compounds found in the earth’s crust and can be used as resources.The crust is the source of the nonrenewable resources we use as well as the source of soil.A mineral is an element or inorganic compound that is solid with a regular internal crystalline structure.A mineral resource is a concentration of naturally occurring material in or on the earth’s crust that can be extracted and processed into useful materials at an affordable cost.Examples of mineral resources are fossil fuels (coal, oil, and natural gas), metallic minerals (such as aluminum, iron, and copper), and nonmetallic minerals (such as sand, gravel, and limestone). As they take so long to produce, these components of the earth’s natural capital are classified as nonrenewable mineral resources.Mineral resources can be classified into four major categories:a. Identified resources with a known location, quantity, and qualityb. Reserves are identified resources that can be extracted profitably at current pricesc. Undiscovered reserves are potential supplies of a mineral resource assumed to existd. Other resources are undiscovered resources and identified resources not classified as reserves.Deposits of nonrenewable mineral resources in the earth’s crust vary in their abundance and distribution.1. Iron and aluminum are fairly abundant whereas manganese, chromium, cobalt, and platinum are fairly scarce.2. Massive exports can deplete a countries supply of nonrenewable minerals.3. Three countries (the United States, Canada, and Russia) with only 8% of the world’s population consume about 75% of the world’s most widely used metals.
7 Minerals Continued…Japan has virtually no metal resources and has to rely on resource imports.The United States currently depends on imports of 50% or more of 24 of its 42 most important nonrenewable mineral resources.Experts are concerned about the availability of four strategic metal resources (manganese, cobalt, chromium, and platinum) that are essential for the country’s economic and military strength.A very slow chemical cycle recycles three types of rock found in the earth’s crust. The earth’s crust contains igneous, sedimentary, and metamorphic rocks that are recycled by the rock cycle.1. Rock is a solid combination of one or more minerals.2. An ore is a rock that contains a large enough concentration of a particular mineral (often a metal) that the rock can be mined and processed to extract the desired mineral.3. Igneous rock is formed below or on the earth’s surface when molten rock wells up and hardens. They form the bulk of the earth’s crust.4. Sedimentary rock is formed from small, eroded pieces of rock that are carried to downhill sites. Layers accumulate over time and an increase of weight and pressure plus dissolved minerals bind the sediment particles together to form sedimentary rock.5. Metamorphic rock is produced from preexisting rock that is subjected to high temperatures, high pressures, chemically active fluids, or some combination of these.6. The rock cycle is the interaction of physical and chemical processes that change rock from one type to another. It is the slowest of the earth’s cyclic processes.
8 Rock Cycle Rock- solid combination of one or more minerals. Rock Cycle -A very slow chemical cycle recycles three types of rock found in the earth’s crust. It is the slowest of the earth’s cyclic processesThe earth’s crust containsIgneous rock is formed below or on the earth’s surface when molten rock wells up and hardens. They form the bulk of the earth’s crust.Sedimentary rock is formed from small, eroded pieces of rock that are carried to downhill sites. Layers accumulate over time and an increase of weight and pressure plus dissolved minerals bind the sediment particles together to form sedimentary rock.Metamorphic rock is produced from preexisting rock that is subjected to high temperatures, high pressures, chemically active fluids, or some combination of these.An ore is a rock that contains a large enough concentration of a particular mineral (often a metal) that the rock can be mined and processed to extract the desired mineral.
9 Environmental Effects of Using Mineral Resources The extraction, processing, and use of mineral sources has a large environmental impact. The greatest danger from mineral extraction may be environmental damage from the processes used to get to the end product.In surface mining, the overburden of rock and soil is removed and discarded as spoils. This mining method extracts about 90% of nonfuel mineral and rock deposits and 60% of the coal used in the U.S.1. Higher grade ores are more easily extracted.2. Greater environmental damage comes with extraction of lower grade ores in higher energy costs and greater environmental damage to the land. Contamination of ground water, air, and land due to solid waste pollution.Two types of Minerals extractions techniques:surface mining- Shallow deposits are removedopen-pit mines are large holes dug to remove oresstrip mining is useful and economical for extracting mineral deposits that lie close to the earth’s surface; area strip mining is used where land is relatively flatcontour strip mining is used on hilly or mountainous land where a series o f terraces are cut into the hillmountaintop removal uses explosives, and huge machinery to remove the top of a mountain for the coal seams beneath it. This method causes considerable environmental damage.subsurface mining- removes coal and metal ores deposits that are too deep to be extracted by surface mining techniques.Disturbs less then 1/10 as much land as surface miningMuch of the resource is left in the groundMore dangerousDangers include: cave-ins, explosions, fires, and disease (black-lung)Higher expense
15 Remediation's for mining The Surface Mining Control and Reclamation Act of 1977 (in the U.S.) requires mining companies to restore most surface-mined land.Reclamation efforts are only partially successful.The land is left scarred and the surface is disrupted.Cleanup may cost in the billions.Subsidence from underground mining causes sewer, gas and water systems to break.Mining wastes contain toxins and acid drainage carries to streams and groundwater.Toxic chemicals can also be emitted to the atmosphere.
16 What is done after the mineral is extracted? After waste material is removed from metal ores they are smelted or treated with chemicals to extract the desired metal.Ore has two components: the ore mineral and the waste material called gangue.Removing the gangue from ores produces large piles of solid waste called tailings.Ore is separated from gangue, smelted to obtain the metal, made into products that are used and discarded or recycled.Environmental repercussions:There can be enormous amounts of air and water pollution from these processes.Ex: Cyanide is used to separate about 85% of the world’s gold ore in a process called cyanide heap extraction. Cyanide is extremely toxic.
17 What does the future hold for mineral resource allocation and supply? The future supply of a resource depends on its affordable supply and how rapidly that supply is used. A nonrenewable resource generally becomes economically depleted rather than totally depleted.There are five choices at that point:recycle or reuse existing supplieswaste lessuse lessfind a substituteor do without.
18 Continued…1. Depletion time for a resource depends on how long it takes to use up a certain proportion (usually 80%) at a given rate of use.2. Depletion time is extended by recycling, reusing and reducing consumption of a given resource.3. New discoveries of a resource extend the depletion time also.4. Demand for mineral resources increases at a rapid rate with increased consumption.5. No one knows whether we will run out of a mineral resource.
19 Price and disputeA rising price for a scarce mineral resource can increase supplies and encourage more efficient use.Some economists feel that price effect may no longer apply since industry and government often control the supply, demand, and prices of minerals so that a truly competitive market does not exist.Rather than receiving billions in government subsidies, critics feel that taxing extraction of nonfuel mineral resources would create incentives for more efficient resource use, reduce waste and pollution, and encourage recycling and reuse of these resources.New technologies can increase the mining of low-grade ores at affordable prices, but harmful environmental effects can limit this approach.Limiting factors for low grade ores extractionincreased cost of miningavailability of freshwater that is needed to mine and process some mineralsenvironmental impacts of increased land disruption, waste material, and pollution produced during mining and processingOne way to improve mining is to use microorganisms for in situ mining. However, the process is slow and biological mining may only be feasible with low-grade ores for which conventional techniques are too expensive.Most minerals in seawater and on the deep ocean floor cost too much to extract, and there are squabbles over who owns them.Rich hydrothermal deposits of gold, silver, zinc, and copper are found as sulfide deposits in the deep-ocean floor and around hydrothermal vents.Another potential source from the ocean floor is potato-size manganese nodules that cover about 25-50% of the Pacific Ocean floor.High costs of extraction of both the nodules and hydrothermal ore deposits are prohibitive.
20 Using Mineral Resources More Sustainably Scientists and engineers are developing new types of materials that can serve as substitutes for many metals. This is known as the materials revolution.Development of silicon and ceramics may replace the need for as much metal.Ceramics have many advantages over conventional metals (harder, stronger, lighter, last longer) and do not corrode.Automobiles and planes are being made of plastics and composite materials since they cost less to make, are lower maintenance and can be molded to any shape.Use of plastics has drawbacks; they require the use of oil and other fossil fuels.Nanotechnology is the use of science and engineering at the atomic and molecular level to build materials with specific properties.Buckyballs are soccer-ball shaped forms of carbon that have been engineered.Nanotechnology is a new area that could provide many things in the near future.One concern about nanotechnology is that smaller particles tend to be more reactive and potentially more toxic due to large surface area compared to mass.They can pass through the natural defenses of the body.e. Analysts say we need to carefully investigate its potential harmful aspects and then develop guidelines and regulations to control and guide this new technology.
21 Using Mineral Resources More Sustainably Continued… Recycling valuable and scarce metals saves money and has a lower environmental impact than mining and extracting them from their ores.We can use mineral resources more sustainably by reducing their use and waste and by finding substitutes with fewer harmful environmental effects.Growing signs point to an ecoindustrial revolution taking place over the next fifty years.1. The goal is to make industrial manufacturing processes cleaner and more sustainable by redesigning them to mimic how nature deals with wastes.2. One way is to mimic nature by recycling and reusing most minerals and chemicals instead of disposing of them. Another is to have industries interact through resource exchange webs.3.These industrial forms of biomimicry provide many economic benefits for business and the environment.Ex: In 1975, the 3M company began a Pollution Prevention pays (3P) program. Other companies are also adopting similar pollution and prevention programs. Redesigned equipment and processes to use fewer hazardous raw materials. Sharply reduced waste production and air pollution emissions and saved almost a 1 billion dollars.
22 Types of Energy Resources About ninety-nine percent of the energy we use for heat comes from the sun and the other 1% comes mostly from burning fossil fuels.1. Without the sun’s energy, life on earth wouldn’t exist. The sun is a giant nuclear fusion reactor.2. The sun provides other indirect forms of renewable solar energy such as wind, falling/flowing water and biomass.3. Commercial energy sold in the marketplace makes up the remaining 1% of the energy we use, most from nonrenewable resources.B. About 76% of the commercial energy we use comes from nonrenewable fossil fuels with the remainder coming from renewable sources.1. About 50% of people in developing countries burn wood and charcoal to heat dwellings and cook.2. Most biomass is collected by users and not sold in the marketplace.3. Many people in developing countries face a fuelwood shortage that is getting worse because of unsustainable harvesting of fuelwood.C. Net energy is the amount of high-quality usable energy available from a resource after subtracting the energy needed to make it available for use.1. It takes energy to get energy.2. Net energy available for use is calculated by estimating the total energy available from the resource over its lifetime and the subtracting the amount of energy used (the first law of thermodynamics), automatically wasted (the second law of thermodynamics), and unnecessarily wasted in finding, processing, concentrating, and transporting the useful energy to users.3. Net energy is like your net spendable income-your wages minus taxes and job-related expenses.4. Electricity produced at a nuclear power plant has a low net energy ratio because of the energy consumed in the nuclear fuel cycle.
23 OilCrude oil is a thick liquid containing hydrocarbons that we extract from underground deposits and separate into products such as gasoline, heating oil, and asphalt.Three geological events led to the presence of oil:1. Sediments buried organic material faster than it could decay.2. Sea floors with these sediments were subjected to the right pressure and heat to convert organic material to oil.3. Oil collected in porous limestone or sandstone and was capped by shale or silt to keep it from escaping.
24 Conventional OilOil and natural gas provide us with food grown with the help of hydrocarbon-based fertilizers and pesticides. This type of oil is known as conventional oil or light oil.Oil and natural gas are often found together under a dome. On average, only about 35-50% of the oil in the deposit is recovered.The remaining heavy crude oil is too difficult or expensive to extract.Improved extraction technologies could raise the oil recovery rate to 75%.Crude oil is transported to a refinery where it is broken down into components with different boiling points. This process accounts for about 8% of all U.S. energy consumption.
25 Oil continued…Petrochemicals are oil distillation products that are sued as raw materials in manufacturing pesticides, plastics, synthetic fibers, paints, medicines and other products.Industrial biotechnology is a new field, the goal of which is to use carbohydrates extracted from plants as building block organic chemicals.
26 Organized Petroleum Exporting Countries Eleven OPEC countries-most of them in the Middle East- have 78% of the world’s proven oil reserves and most of the world’s unproven reserves.Countries include: Algeria, Indonesia, Iran, Iraq, Kuwait, Libya, Nigeria, Qatar, Saudi Arabia, the United Arab Emirates, and Venezuela.1. The control of current and future oil reserves is the single greatest source of global economic and political power.2. Saudi Arabia has the largest supply of oil reserves with 25%.3. Oil is the most widely used resource in the world. The U.S. imports about 60% of its oil, followed by China and Japan as the top three oil importing countries.4. Based on different assumptions, geologists expect the world’s oil production to peak within the next 5-38 years and then begin a long decline.Government Owned oil companies in Saudi Arabia and Venezuela control more than 70% of the world’s oil production.
27 Conventional oilConventional oil is a versatile fuel that can last for at least 50 years, but burning it produces air pollution and releases the greenhouse gas carbon dioxide into the atmosphere.1. CO2 release into the atmosphere helps promote climate change through global warming.2. Figure 16-7 lists the advantages and disadvantages of using conventional crude oil as an energy source.3. Figure 16-8 compares the amounts of carbon dioxide emitted per unit of energy in using fossil fuels, nuclear power, and geothermal energy.F.
28 Oil ShaleHeavy and tarlike oils from oil sand and oil shale could supplement conventional oil, but there are environmental problems.1. Bitumen is a thick and sticky heavy oil with a high sulfur content that is found in oil sand and oil tar.2. The extraction and processing of this material uses a great deal of energy, so reduces net energy yield for the oil.3. Use of these oil sands could reduce U.S. dependence on imports from the Middle East.5. This extraction process has severe environmental impacts on land and produces more water pollution, air pollution and more CO2/ unit energy than conventional crude oil.Northeastern Alberta, Canada has about 3/4ths of the world’s oil sand reserves.
29 Oil Shale DepositsOil shale deposits may be another potential source of oil. The material in this shale is kerogen (resembles synthetic crude oil).It is estimated that there are 240 times more global supplies than for conventional oil.At present it cost more to produce than the fuel is worth.
30 Conventional Natural gas Natural gas consists mostly of methane (CH4), is often found above reservoirs of crude oil. Natural gas also contains small amounts of heavier hydrocarbons and a small amount of hydrogen sulfide.1. Conventional natural gas lies above most reservoirs of crude oil.2. Natural gas is sometimes burned off as an unwanted by-product of oil drilling, a waste of an energy source.3. Propane and butane gases are liquefied from a natural gas field and removed as liquefied petroleum gas (LPG) that is stored in pressurized tanks.4. Natural gas provides about 23%of the U.S. energy needs, heating about 53% of U.S. homes and providing about 12% of the country’s electricity.5. The U.S. imports about 20% of its natural gas, and this is expected to rise in the future. Imports come mostly from Canada.6. Natural gas is a versatile fuel that can be burned to heat space and water and to propel vehicles with fairly inexpensive engine modifications.7. Natural gas releases less CO2/ unit energy than burning oil, oil sand, or coal.8. Increasingly, natural gas is used to run medium-sized turbines to produce electricity. They are more energy efficient, cheaper to build, require less time to install, and are easier and cheaper to maintain than coal and nuclear power plants. Rising natural gas prices are impacting the cost advantages of such turbines.
31 Unconventional Natural Gas Coal beds and bubbles of methane trapped in ice crystals deep under the arctic permafrost and beneath deep-ocean sediments are unconventional sources of natural gas.1. Coal bed methane gas is found in coal beds across parts of the United States and Canada.2. Extracting the methane produces huge volumes of water contaminated with salt and other minerals, in addition to causing environmental problems and public backlash.3. Russia and the Middle East could supply more natural gas to the United States in the future.
32 Unconventional Natural Gas Continued… Methane hydrate deposits are another source of unconventional natural gas found in the arctic permafrost and deep beneath the ocean bottom.Extraction techniques are too expensive at present, but are rapidly being developed.Methane hydrates must be kept cold or they release methane into the atmosphere when they reach the surface.
34 Conventional Natural Gas Continued… Russia and Iran have almost half the world’s reserves of conventional natural gas, and global reserves should last years.1. The long-term outlook for natural gas supplies is better than for conventional oil.2. Natural gas use should increase because it is fairly abundant, has lower pollution and CO2 rates/unit of energy compared to other fossil fuels.3. Projections suggest that natural gas should last the world at least 200 years at the present consumption rate and 80 years if usage rates increase 2% per year.4. Shipping of LNG is very expensive and reduces net energy yield.Natural gas is a versatile and clean-burning fuel, but it releases the greenhouse gases carbon dioxide (when burned) and methane (from leaks) into the troposphere.
35 CoalCoal is an abundant energy resource that is burned mostly to produce electricity and steel. Coal is solid fossil fuel formed from land plants that lived between million years ago. It is mostly carbon with small amounts of sulfur and trace amounts of mercury. Burning coal releases SO2, trace amounts of mercury and radioactive materials.1. Coal is burned in power plants to produce 62% of the world’s electricity and three-quarters of the world’s steel.2. In the U.S. coal produces 50% of the electricity, followed by nuclear power (20%), natural gas (17%), renewable energy (10%), and oil (3%).3. Anthracite is the most desirable type of coal because of its high heat content and low sulfur. It is less common than other types of coal.4. Coal is extracted underground in dangerous circumstances (accidents and black lung disease).5. Area strip mining is used to extract coal close to the surface. Scars from this mining are rarely restored after mining is finished.6. In some cases of mountaintop mining, entire mountains have been removed and dumped into the valleys below to expose seams of coal.
37 Coal Continued…Coal reserves in the U.S., Russia, and China could last hundreds to thousands of years.1. Coal is the world’s most abundant fossil fuel.2. The U.S. has 27% of the world’s proven coal reserves. Russia has 17%, China has 13%, India has 10%, and Australia has 9%.3. Coal reserves in the U.S. and in China should last for about 300 years at current consumption rates.4. If coal consumption in the U.S. increases by 4% a year – as the industry projects – the reserves would last only 64 years.
38 Coal continued…C. Coal is the most abundant fossil fuel, but compared to oil and natural gas it is not as versatile, has a much higher environmental impact, and releases much more carbon dioxide into the troposphere.Coal has a severe environmental impact on air, water, and land and over 1/3 of the world’s annual CO2 emissions come from coal.Coal emissions cause thousands of premature deaths, many thousands of cases of respiratory disease, and several billion dollars of property damage a year.
39 Solid Coal to Gaseous and Liquid Fuels Coal can be converted to gaseous and liquid fuels that burn cleaner than coal, but the costs are high and burning them adds more carbon dioxide to the troposphere than burning coal.Coal can be converted into synthetic natural gas (SNG or syngas) by coal gasification or in to liquid fuel by coal liquefaction.These techniques are not possible without huge government subsidies.These procedures require 50% more coal be mined and will add 50% more CO2 emissions to the atmosphere. They also cost more to produce than coal.Coal gasification plants can be designed to remove all carbon dioxide from their emissions.
40 This power plant burns pulverized coal to boil water and produce steam that spins a turbine to produce electricity. The steam is cooled, condensed, and returned to the boiler for reuse. Waste heat can be transferred to the atmosphere or to a nearby source of water. The largest coal-burning power plant in the United States, located in Indiana, burns three 100-car trainloads of coal per day. There are about 600 coal-burning power plants in the United States.
42 Nuclear energyA. When isotopes of uranium and plutonium undergo controlled nuclear fission, the resulting heat produces steam that spins turbines to generate electricity.1. A controlled chain reaction occurs when nuclei of atoms are split. The heat from the reactions used to produce high-pressure steam that spins turbines that generate electricity.2. Light-water reactors (LWRs) produce about 85% of the world’s nuclear-generated electricity.3. The core of a LWR consists of long, thin rods are packed with fuel pellets and each pellet contains energy equivalent to 1 ton of coal or 4 barrels of crude oil. The uranium oxide fuel in each pellet consists of about 97% nonfissionable uranium-238 and 3% fissionable uranium-235.4. Control rods absorb neutron-absorbing materials move in and out of spaces between the fuel assemblies in the core. This regulates the rate of fission and amount of power the reactor produces.5. A moderator (material that slows down neutrons) keeps the reaction going. It may be water, graphite or deuterium.6. A coolant, usually water, circulates through the core to remove heat to keep the components from melting and to produce steam for generating electricity.7. A containment vessel with thick, strong walls surround the reactor as a safety backup. These are usually made of 4-foot reinforced concrete with a steel liner.8. Spent rods are stored on-site in water-filled pools or dry casks with thick steel walls.9. All the safety features make nuclear power plants very expensive to build and maintain.
43 Nuclear Energy Continued… 10. The nuclear fuel cycle includes the mining of uranium, processing it to make a satisfactory fuel, use in the reactor, safe storage of highly radioactive wastes for 10, ,000 years, and dealing with the reactor after its useful life.11. A nuclear power plant must be decommissioned after years of operation. It contains large quantities of radioactivity that must be kept out of the environment.12. A closed nuclear fuel cycle removes fissionable isotopes uranium-235 and plutonium-239 for reuse as nuclear fuel. This is rarely done currently because of high costs and potential use of the materials in nuclear weapons.13. In an open nuclear fuel cycle the isotopes are eventually buried in an underground disposal facility. These wastes must be stored for about 240,000 years.
45 ChernobylThe world’s worst nuclear power plant accident occurred in 1986 in Ukraine.1. On April 26, 1986, a series of explosions at the Chernobyl nuclear plant, blew the roof off a reactor building, the reactor partially melted down, and its graphite moderator caught fire and burned for 10 days.2. The disaster was caused by poor reactor design and human error.3. By 2005, 56 people had died from radiation released by the accident. Many more may still die from cancers such as thyroid cancer and leukemia.4. Some 350,000 people had to abandon their homes because of radiation fallout 400 times greater than that released from the atomic bomb dropped on Hiroshima.5. In many parts of the Ukraine, people still cannot drink the water or eat locally produced food.6. The cost of the accident could eventually run into several hundreds of billions of dollars.7. A major nuclear accident anywhere has effects that reverberate throughout the world.
46 Nuclear Energy Continued…. The nuclear power fuel cycle has a fairly low environmental impact and a very low risk of accident. But costs are high, radioactive wastes must be stored for thousands of years, facilities are vulnerable to terrorist attack, and the spread of nuclear reactor technology gives more countries the knowledge to build nuclear weapons.1. In 1995, the World Bank said nuclear power is too costly and too risky.2. Currently, 60 countries have nuclear weapons or the knowledge to build them.3. Because of built-in safety features, the risk of exposure to radioactivity from nuclear power plants in the United States and other developing countries is extremely low.4. Potassium iodide pills have been given out to people living close to nuclear power plants in France and California.
47 Possible Storage Techniques Scientists disagree about the best methods for long-term storage of high-level radioactive waste.1. Some of the proposed methods are:a. Bury it deep underground.b. Shoot it into space or into the sun. This strategy has been abandoned for now.c. Bury it under the Antarctic ice sheet or the Greenland ice cap. This strategy is prohibited by international law. There is the possibility of heat making the ice sheets unstable.d. Dump it into descending subduction zones in the deep ocean. Wastes might be spewed out by volcanic activity. This method is also prohibited by international law.e. Bury it in thick deposits of mud on the deep-ocean floor in areas that tests show have been geologically stable for 65 million years. Because of corrosion problems this method is also prohibited by international law.f. Change it into harmless, or less harmful, isotopes. There is no way to do this at present.
49 Nuclear FusionNuclear Fusion: After more than 50 years of research and billions of dollars in government subsidies, this technology remains at a laboratory stage.1. Nuclear fusion is a nuclear change in which two isotopes of light elements, such as hydrogen, are forced together at extremely high temperatures until they fuse to form a heavier nucleus, releasing energy in the process.2. This type of energy production has a number of advantages such as no emissions of conventional air pollutants or carbon dioxide.3. There would be no risk of a meltdown or risk from terrorist attack.4. Fusion power could be used to destroy toxic wastes, supply electricity for ordinary use, and decompose water to produce hydrogen gas to run a hydrogen economy by the end of this century.5. Building a fusion reactor would be much more expensive than the cost of a conventional reactor. The U.S., after more than 50 years of research, has spent around $25 billion on nuclear fusion, but none of the approaches so far has produced more energy than it uses.
50 Phase out Nuclear Power? There is disagreement over whether to phase out nuclear power or keep this option open in case other alternatives do not pan out.Some analysts feel that nuclear power should be phased out regarding all or most government subsidies and the money to subsidize and accelerate the development of other promising energy technologies.According to investors and the World Bank analysts, conventional nuclear power simply can’t compete in today’s energy market.Proponents of nuclear power feel that governments should continue funding research and development. They say that we need to keep nuclear options open if various renewable energy options fail to keep up with electricity demands and reduce CO2 emissions to acceptable levels.Opponents say it makes better sense to invest government funds in spurring more rapid development of energy conservation and renewable energy resources.
51 3 Mile IslandThe Three Mile Island Unit 2 (TMI-2) reactor, near Middletown, Pa., partially melted down on March 28, This was the most serious accident in U.S. commercial nuclear power plant operating history, although its small radioactive releases had no detectable health effects on plant workers or the public. Its aftermath brought about sweeping changes involving emergency response planning, reactor operator training, human factors engineering, radiation protection, and many other areas of nuclear power plant operations. It also caused the NRC (Nuclear Regulatory Comission) to tighten and heighten its regulatory oversight. All of these changes significantly enhanced U.S. reactor safety.
52 Energy Efficiency and Renewable Energy Energy efficiency is a measure of the useful energy produced compared to the energy that is converted to low-quality heat energy.1. Energy efficiency can be achieved by using more efficient technologies that are available and are being developed. An example is the use of fluorescent bulbs in place of incandescent bulbs (5% efficient).2. About 84% of all commercial energy used in the U.S. is wasted. About 41% is wasted because of the degradation of energy quality imposed by the 2nd law of thermodynamics.3. About 43% of the energy used in the United States is unnecessarily wasted by such things as motor vehicles, furnaces and living and working in leaky, poorly designed buildings.4. When buying energy consuming items the life cycle cost (initial cost plus lifetime operating costs) is an important factor in making a decision.5. Since the 1980s the U.S. has reduced the amount of energy used/person. Unnecessary energy waste still costs the U.S. about $300 billion/year.6. Four energy devices commonly used waste large amounts of energy: the incandescent light bulb (95% waste), a nuclear power plant (86-92% waste), an internal combustion engine (94% waste), and a coal-burning power plant (66% waste).
53 Net Energy EfficiencyNet energy efficiency is how much useful energy we get from an energy resource after subtracting the energy used and wasted in making the energy available.1. Net energy efficiency includes the efficiency of each step in the process of making energy available for use.2. A comparison of electricity produced by a nuclear power plant and passive solar heating indicates that only about 14% of the initial energy produced is useful compared to 90% for passive solar heat.3. Two general principles for saving energy are:a. keep the number of steps in an energy conversion process as low as possibleb. strive to have the highest possible energy efficiency for each step in an energy conversion process.