680 likes | 845 Vues
Nonrenewable Energy. Chapter 16. Core Case Study: How Long Will the Oil Party 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 years).
E N D
Nonrenewable Energy Chapter 16
Core Case Study: How Long Will the Oil Party 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 years). • Alaska’s Arctic National Wildlife Refuge would meet the world demand for 1-5 months (U.S.: 7-25 months).
Core Case Study: How Long Will the Oil Party Last? • We have three options: • Look for more oil. • Use or waste less oil. • Use something else. Figure 16-1
TYPES OF ENERGY RESOURCES • About 99% of the energy we use for heat comes from the sun and the other 1% comes mostly from burning fossil fuels. • Solar energy indirectly supports wind power, hydropower, and biomass. • About 76% of the commercial energy we use comes from nonrenewable fossil fuels (oil, natural gas, and coal) with the remainder coming from renewable sources.
TYPES OF ENERGY RESOURCES • Nonrenewable energy resources and geothermal energy in the earth’s crust. Figure 16-2
TYPES OF ENERGY RESOURCES • Commercial energy use by source for the world (left) and the U.S. (right). Figure 16-3
TYPES OF ENERGY RESOURCES • Net energy is the amount of high-quality usable energy available from a resource after subtracting the energy needed to make it available. • Remember the second law of thermodynamics! • Net energy ratio – useful energy produced/energy used to produce it
Net Energy Ratios • The higher the net energy ratio, the greater the net energy available. Ratios < 1 indicate a net energy loss. Figure 16-4
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. • As prices rise, about 10-25% more can be recovered from expensive secondary extraction techniques. • This lowers the net energy yield.
OIL • Refining crude oil: • Based on boiling points, components are removed at various layers in a giant distillation column. • The most volatile components with the lowest boiling points are removed at the top. Figure 16-5
OIL • World’s largest business • Eleven OPEC (Organization of Petroleum Exporting Countries) have 78% of the world’s proven oil reserves and most of the world’s unproven reserves. • An oil reserve is an identified deposit from which crude oil can be extracted profitably at current prices and current technology.
2007 World Proved Reserves After global production peaks and begins a slow decline, oil prices will rise and could threaten the economies of countries that have not shifted to new energy alternatives. Top three oil consuming nations U.S. (60%) China (33%) Japan (100%) Source: U.S Department of Energy, Energy Information Administration
Oil Refining Capabilities Organization for Economic Co-operation and Development (OECD) countries control most oil refining. Supply and demand economics are therefore interrupted by a multi-stage process dictating the supply.
Historic Oil Prices • Source: Lindstrom, Kirk. Inflation adjusted oil prices fall on strong USD. Seeking Alpha. 19 Oct, 2008. Retrieved 26 Mar, 2009 from http://seekingalpha.com/article/100560-inflation-adjusted-oil-prices-fall-on-strong-usd
As Oil Prices Rise… Prices of food and products produced from petrochemicals will rise. People will necessary move down the food chain. Food production may become more localized. More land will be used to produce renewable biomass crops. Air travel and air freight may decline. Re-urbanization
Case Study: U.S. Oil Supplies • The U.S. – the world’s largest oil user – has only 2.9% of the world’s proven oil reserves. • U.S oil production peaked in 1974 (halfway production point). • About 60% of U.S oil imports go through refineries in hurricane-prone regions of the Gulf Coast.
Alaskan Oil Pipeline Carries 2 million barrels a day of crude oil from the Prudhoe Bay oil field 789 miles south to Southern Alaska to be loaded onto tankers destined for refineries. Represents 25% of the U.S. crude oil reserves.
OIL • Burning oil for transportation accounts for 43% of global CO2 emissions. Figure 16-7
CO2 Emissions • CO2 emissions per unit of energy produced for various energy resources. Figure 16-8
Heavy Oils • Heavy and tarlike oils from oil sand and oil shale 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 natural gas which reduces net energy yield. • Deforestation
Oil Sands Bitumen can be extracted Athabascan Oil Sands deposits equal in area to U.S. states of MD and VA. Supply 1/5 of Canadian energy needs. Production costs high ($13/barrel vs. $1-2 for conventional production. 1.8 mt of oil sand = 1 barrel of oil. China invested heavily.
Oil Shales • Oil shales contain a solid combustible mixture of hydrocarbons called kerogen. Figure 16-9
60 minutes video re: Shalieonaires • http://www.cbsnews.com/video/watch/?id=7054210n&tag=contentMain;contentBody
NATURAL GAS • Natural gas consists mostly of methane and other gaseous hydrocarbons. • Conventional natural gas • found above reservoirs of crude oil. • When a natural gas-field is tapped, gasses are liquefied and removed as liquefied petroleum gas (LPG). • Unconventional natural gas • Coal bed methane gas • Methane hydrate • bubbles of methane trapped in ice crystals deep under the arctic permafrost and beneath deep-ocean sediments
NATURAL GAS • 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. Figure 16-11
COAL • 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. Figure 16-12
COAL • Most abundant fossil fuel • Generates 62% of world’s electricity and is used to make 75% of its steel • Anthracite (98% carbon) is most desirable but least common. • Lower grades of coal have increasing traces of sulfur, toxic mercury, and radioactive materials that are released upon burning. • Extraction by subsurface mining, area strip mining, contour strip mining, and mountaintop removal are environmentally damaging.
Waste heat Cooling tower transfers waste heat to atmosphere Coal bunker Turbine Generator Cooling loop Stack Pulverizing mill Condenser Filter Boiler Toxic ash disposal Fig. 16-13, p. 369
COAL • Coal reserves in the United States (27%), Russia (17%), and China (13%) could last hundreds to over a thousand years. • In 2005, China and the U.S. accounted for 53% of the global coal consumption.
COAL • 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. Figure 16-14
COAL Synfuels • Coal can be converted into synthetic natural gas (SNG or syngas) and liquid fuels (such as methanol or synthetic gasoline) that burn cleaner than coal. • Requires mining 50% more coal • Costs are high. • Burning them adds more CO2 to the troposphere than burning coal.
COAL • Since CO2 is not regulated as an air pollutant and costs are high, U.S. coal-burning plants are unlikely to invest in coal gasification. Figure 16-15
Clean Coal Technology Multiple technologies aimed at cleaning coal and containing its emissions • Coal washing • Wet scrubbers (flue gas desulfurization systems) • Low-NOx burners • Electrostatic precipitators • Oxy-fuel combustion • Pre-combustion capture
Clean Coal Technology • Regardless of method, the CO2 must be sequestered – either in a commercially viable product or stored deep underground or in the oceans. 1. CO2 pumped into disused coal fields displaces methane which can be used as fuel2. CO2 can be pumped into and stored safely in saline aquifers3. CO2 pumped into oil fields helps maintain pressure, making extraction easier
NUCLEAR ENERGY • When isotopes of uranium and plutonium undergo controlled nuclear fission, the resulting heat produces steam that spins turbines to generate electricity. • The uranium (V, VI) oxide (U3O8) consists of about 97% nonfissionable uranium-238 and 3% fissionable uranium-235. • The concentration of uranium-235 is increased through an enrichment process.
Small amounts of radioactive gases Uranium fuel input (reactor core) Control rods Containment shell Heat exchanger Turbine Steam Generator Electric power Waste heat Hot coolant Useful energy 25%–30% Hot water output Pump Pump Coolant Pump Pump Waste heat Cool water input Moderator Coolant passage Pressure vessel Shielding Water Condenser Periodic removal and storage of radioactive wastes and spent fuel assemblies Periodic removal and storage of radioactive liquid wastes Water source (river, lake, ocean) Fig. 16-16, p. 372
Nuclear energy There are currently 435 nuclear reactors in the world. Why is nuclear power considered nonrenewable? What are its advantages over coal, oil, and natural gas as an energy source? What are its disadvantages?
Decommissioning of reactor Fuel assemblies Reactor Enrichment of UF6 Fuel fabrication (conversion of enriched UF6 to UO2 and fabrication of fuel assemblies) Temporary storage of spent fuel assemblies underwater or in dry casks Conversion of U3O8 to UF6 Uranium-235 as UF6Plutonium-239 as PuO2 Spent fuel reprocessing Low-level radiation with long half-life Geologic disposal of moderate & high-level radioactive wastes Open fuel cycle today “Closed” end fuel cycle Fig. 16-18, p. 373
Nuclear Fuel Cycle After three or four years in a reactor, spent fuel rods are removed and stored in a deep pool of water contained in a steel-lined concrete container. After spent fuel rods are cooled considerably, they are sometimes moved to dry-storage containers made of steel or concrete. Figure 16-17
Radioactive Waste • Wastes must be safely stored for 10,000 to 240,000 years. • Options: • Bury it deep underground. • Shoot it into space. • Bury it in the Antarctic ice sheet. • Bury it in the deep-ocean floor that is geologically stable. • Change it into harmless or less harmful isotopes.