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Nonrenewable Energy Chapter 15 Core Case Study: How Long Will Supplies of Conventional Oil Last? Saudi Arabia could supply the world with oil for about 10 years. The Alaska’s North Slope could meet the world oil demand for 6 months. (U.S.: 3 yrs.) Alaska’s Arctic National Wildlife Refuge (ANWR) would meet the world demand for 1-5 months. (U.S.: 7-24 months) Core Case Study: How Long Will Supplies of Conventional Oil Last? We have three options: • Look for more oil • Use or waste less oil • Use other energy sources 15-1 What Major Sources of Energy Do We Use? Concept 15-1A About three-quarters of the world’s commercial energy comes from nonrenewable fossil fuels and the rest comes from nonrenewable nuclear fuel and renewable sources. Concept 15-1B Net energy is the amount of highquality usable energy available from a resource after the amount of energy needed to make it available is subtracted. Fossil Fuels Supply Most of Our Commercial Energy SOURCE : DEPARTMENT OF ENERGY Annual Energy Review 2009 About 82% of global commercial energy comes from nonrenewable fossil fuels with the remainder coming from renewable sources. Commercial Energy Use by Source for the World and the United States Natural Capital: Important Nonrenewable Energy Resources Case Study: A Brief History of Human Energy Use A Brief History of Human Energy Use – p. 372-373 • Muscle power: early humans • Discovery of fire • Agriculture • Use of wind and flowing water • Machines powered by wood, then coal • Internal combustion engine • Nuclear energy • Energy crisis OIL / PETROLEUM 15-2 What Are the Advantages and Disadvantages of Oil? Concept 15-2A Conventional oil is currently abundant, has a high net energy yield, and is relatively inexpensive, but using it causes air and water pollution and releases greenhouse gases to the atmosphere. Concept 15-2B Heavy oils from oil sand and oil shale exist in potentially large supplies but have low net energy yields and higher environmental impacts than conventional oil has. We Depend Heavily on Oil Crude oil (petroleum) is a thick liquid containing hydrocarbons that we extract from underground deposits and separate into products such as gasoline, heating oil and asphalt. Only 35-50% can be economically recovered from a deposit. Science: Refining Crude Oil An oil refinery uses distillation to separate crude oil into it’s components: • Based on boiling points, components are removed at various layers in a giant distillation column. • The components with the lowest boiling points are removed at the top. OPEC Controls Most of the World’s Oil Supplies Twelve OPEC countries have 60% of the world’s proven oil reserves and most of the world’s unproven reserves. • Organization of Petroleum Exporting Countries Rising Oil Prices Global oil production peaked around 2005 Sharp increases in oil prices could threaten the economies of countries that have not shifted to new energy alternatives. Possible effects of steeply rising oil prices: • • • • • • • Higher food prices Airfares higher Reduce energy waste Upgrade of public transportation Smaller more fuel-efficient vehicles Shift to non-carbon energy sources Higher prices for products made with petrochemicals The United States Uses Much More Oil Than It Produces The U.S. – the world’s largest oil user – has only 2.4% of the world’s proven oil reserves. The U.S. uses 24% of worldwide crude oil. The U.S. imports 60% of the oil it uses. Case Study: Oil and the U.S. Arctic National Wildlife Refuge The Arctic National Wildlife Refuge (ANWR) • Not open to oil and gas development • Fragile tundra biome Decrease dependence on foreign oil?? • “Drill baby, drill!” Trade-Offs: Conventional Oil, Advantages and Disadvantages Burning oil for transportation accounts for 43% of global CO2 emissions. About 60% of U.S oil imports go through refineries in hurricaneprone regions of the Gulf Coast. Will Heavy Oil from Oil Sand or Shale Oil Be Viable Options? Heavy and tarlike oils from oil sand and shale oil could supplement conventional oil, but there are environmental problems. • • • • High sulfur content Extracting and processing produces toxic sludge Uses and contaminates larges volumes of water Requires large inputs of energy which reduces net energy Canada has 75% of the world’s oil sand. The Western U.S. has 72% of the world’s shale oil. Trade-Offs: Heavy Oils from Oil Shale and Oil Sand NATURAL GAS 15-3 What Are the Advantages and Disadvantages of Natural Gas? Concept 15-3 Conventional natural gas is more plentiful than oil, has a high net energy yield and a fairly low cost, and has the lowest environmental impact of all fossil fuels. Natural Gas Is a Useful and Clean-Burning Fossil Fuel Natural gas, consisting mostly of methane (CH4), is often found above reservoirs of crude oil. • Coal beds, bubbles of methane trapped under the arctic permafrost and beneath deep-ocean sediments, and landfills are unconventional sources of natural gas. Natural Gas Is a Useful and Clean-Burning Fossil Fuel Russia, Iran, and Qatar have about 3/4 of the world’s reserves of conventional gas, and global reserves should last 62-125 years. Natural Gas Is a Useful and Clean-Burning Fossil Fuel Produces electricity X 2 Fuel burning in a combustion chamber produces hot gases that pass directly through the turbine, which spins a generator to produce electricity. Then these hot gases are used to turn water to steam, which pushes a second turbine producing more electricity. Natural Gas Is a Useful and Clean-Burning Fossil Fuel Natural gas is transported through dense networks of pipelines Liquefied petroleum gas (LPG) • Pressurized tanks used in rural areas Liquefied natural gas (LNG) • Gas is cooled and pressurized in order to ship across the ocean Trade-Offs: Conventional Natural Gas Natural gas is versatile and cleaner-burning fuel, but it releases the greenhouse gases carbon dioxide (when burned) and methane (from leaks) into the troposphere. Some analysts see natural gas as the best fuel to help us make the transition to improved energy efficiency and greater use of renewable energy. COAL 15-4 What Are the Advantages and Disadvantages of Coal? Concept 15-4A Conventional coal is very plentiful and has a high net energy yield and low cost, but it has a very high environmental impact. Concept 15-4B Gaseous and liquid fuels produced from coal could be plentiful, but they have lower net energy yields and higher environmental impacts than conventional coal has. Coal Comes in Several Forms and Is Burned Mostly to Produce Electricity Coal is a solid fossil fuel that is formed in several stages as the buried remains of land plants that lived 300-400 million years ago. Burned in 2100 power plants, generates 40% of the world’s electricity (49% in the U.S.) • Inefficient process that burns coal to boil water which produces steam that turns a turbine Stages in Coal Formation over Millions of Years Science: Coal-Burning Power Plant Coal Is a Plentiful but Dirty Fuel World’s most abundant fossil fuel Coal reserves in the United States, Russia, and China could last hundreds to over a thousand years. In 2005, China and the U.S. accounted for 53% of the global coal consumption By 2025, China is expected to burn TWICE as much as the U.S. Coal Is a Plentiful but Dirty Fuel Environmental costs of burning coal: • Single biggest air polluter in coal-burning countries • • • • • CO2 – one-fourth of the annual global emissions Sulfur released as SO2 (acid rain) Large amount of soot Mercury (Hg) Radioactive materials Environmentalists call for: • Taxation on CO2 production by power plants • Cleaner coal-burning plants Trade-Offs: Coal, Advantages and Disadvantages Coal is the most abundant fossil fuel, but compared to oil and natural gas it is not as versatile, has a high environmental impact, and releases much more CO2 into the troposphere. 15-5 What Are the Advantages and Disadvantages of Nuclear Energy? Concept 15-5 Nuclear power has a low environmental impact and a very low accident risk, but high costs, a low net energy yield, longlived radioactive wastes, vulnerability to sabotage, and the potential for spreading nuclear weapons technology have limited its use.