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Lecture Outlines Chapter 19 Environment: The Science behind the Stories 4th Edition Withgott/Brennan PowerPoint Presentation
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Lecture Outlines Chapter 19 Environment: The Science behind the Stories 4th Edition Withgott/Brennan

Lecture Outlines Chapter 19 Environment: The Science behind the Stories 4th Edition Withgott/Brennan

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Lecture Outlines Chapter 19 Environment: The Science behind the Stories 4th Edition Withgott/Brennan

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  1. Lecture Outlines Chapter 19 Environment:The Science behind the Stories 4th Edition Withgott/Brennan

  2. This lecture will help you understand: • Our energy sources • Coal • Natural gas • Crude oil • Alternative fossil fuels • Environmental impacts of fossil fuels • Political, social, and economic aspects • Conserving energy and enhancing efficiency

  3. Central Case: Oil or wilderness on Alaska’s North Slope? • Alaska’s remote North Slope • A pristine wilderness to some • Untapped oil riches to others • The Arctic National Wildlife Refuge is the focus of intense debate • Should the “1002 Area”be opened to drilling? • Opponents fear that drilling will sacrifice our national heritage • For little gain

  4. The three regions of Alaska’s North Slope • The National Petroleum Reserve–Alaska (NPR–A) • Supposed to remain untapped unless the nation faces an emergency • Open ecologically sensitive areas for drilling in 2006 • Prudhoe Bay consists of state lands that are drilled for oil • Which is transported via the trans-Alaska pipeline to the port of Valdez • The Arctic National Wildlife Refuge (ANWR) • Federal land set aside for wildlife and to preserve pristine ecosystems • It has been called the “Serengeti of North America”

  5. Alaska’s North Slope

  6. We use energy in our homes, machinery, and vehicles and to provide comfort and conveniences Most of our energy comes from the sun Solar, wind, hydroelectric, photosynthesis, biomass Fossil fuels = highly combustible substances from the remains of organisms from past geologic ages A great deal of energy emanates from Earth’s core Geothermal power Immense amounts of energy reside in an atom’s bonds This energy provides us with nuclear power We use a variety of energy sources

  7. Global consumption is at its highest level ever The high-energy content of fossil fuels makes them efficient to burn, ship, and store Electricity = a secondary form of energy that is easy to transfer and apply to a variety of uses Fossil fuels: our dominant source of energy Oil, coal, and natural gas have replaced biomass as our dominant sources of energy

  8. The energy stream of the U.S. is complex The U.S. energy stream is dominated by coal, oil, and natural gas

  9. Renewable energy = supplies will not be depleted by our use Sunlight, geothermal energy, and tidal energy Nonrenewable energy = we will use up Earth’s accessible store in decades to centuries Oil, coal, natural gas, nuclear energy To replenish the fossil fuels we have depleted so far would take millions of years Resources are renewable or nonrenewable

  10. Fossil fuels were formed from organisms that lived 100–500 million years ago Aerobic decomposition = organic material is broken down and recycled in the presence of air Anaerobic decomposition = occurs with little or no air Deep lakes, swamps Produces fossil fuels Fossil fuels are created from fossils

  11. Fossil fuel reserves are unevenly distributed • Some regions have substantial reserves • Whereas others have very few • How long a nation’s reserves will last depends on how much the nation extracts, uses, exports, and imports • Nearly 67% of the world’s proven reserves of crude oil lie in the Middle East • Russia holds the most natural gas • The U.S. possesses more coal than any other country

  12. Developed nations consume lots of energy • People in developed regions consume far more energy than those in developing nations • Using 100 times more energy per person • Energy use in industrialized nations is evenly divided between transportation, industry, and other uses • Developing nations use energy for subsistence activities • Agriculture, food preparation, and home heating • They use manual or animal energy, not fossil fuels

  13. Regions vary greatly in energy consumption • The U.S. has 4.5% of the population but uses 20% of the world’s energy

  14. It takes energy to make energy • We don’t get energy for free • To harness, extract, process, and deliver energy requires substantial inputs of energy • Drilling for oil requires roads, wells, vehicles, storage tanks, pipes, housing, etc. • All this requires energy • Net energy = the difference between energy returned and energy invested • Net energy = energy returned – energy invested

  15. Energy returned on investment (EROI) • Energy returned on investment (EROI) = energy returned/energy invested • Higher ratios mean we receive more energy than we invest • Fossil fuels have high EROI • EROI ratios can change • They decline when we extract the easiest deposits first • We now must work harder to extract the remaining reserves • U.S. oil EROI ratios have gone from 100:1 to 5:1

  16. Coal • The world’s most abundant fossil fuel • Created 300–400 million years ago • Coal = organic matter (woody plant material) • Compressed under very high pressure in swamps to form dense, solid carbon structures • Very little decomposition occurred

  17. Coal is mined using two major methods • Strip mining = for deposits near the surface • Heavy machinery removes huge amounts of earth to expose the coal • Subsurface mining = underground deposits are reached by digging tunnels to follow seams (layers) of coal • Mountaintop removal = entire mountaintops are cut off • Environmentally destructive • Common in the Appalachian Mountains

  18. Coal use has a long history • Cultures have used coal for centuries • Ancient China, Roman Empire, the Hopi nation • Coal helped drive the Industrial Revolution • It fueled furnaces to produce steam • Coal is used to generate electricity • Converting water to steam, which turns a turbine • The U.S. and China are the primary producers and consumers of coal • It provides half the U.S. electrical generating capacity

  19. A typical coal-fired power plant

  20. Coal varies in its qualities • Coal varies in water and carbon content and its amount of potential energy • Peat = organic material that is broken down anaerobically • It is wet, near the surface, and not well compressed • Additional pressure, heat, and time turn peat into coal • Lignite = least compressed • Sub-bituminous and bituminous • Anthracite = most compressed and has the most energy

  21. Coal contains impurities • It has sulfur, mercury, arsenic, and other trace metals • The sulfur content depends on whether coal was formed in salt water or freshwater • Coal in the eastern U.S. is high in sulfur because it was formed in marine sediments • Impurities are emitted when coal is burned • Unless pollution control measures are used • Ways to reduce pollution must be found • The Earth holds enough coal to last a few hundred years

  22. Natural gas burns more cleanly than coal • The fastest growing fossil fuel in use today • 25% of global commercial energy consumption • It is versatile and clean-burning • Emits ½ as much CO2 as coal, ⅔ as much as oil • It is used to generate electricity, heat homes, and cook • Liquefied natural gas (LNG) = gas converted to liquid • Can be shipped but there are risks of explosions • Russia leads the world in production • The U.S. leads the world in use • World supplies are projected to last about 60 more years

  23. Natural gas is formed in two ways • Natural gas = methane (CH4) and other volatile hydrocarbons • Biogenic gas = pure methane created at shallow depths by bacterial anaerobic decomposition of organic matter • “Swamp gas” • Thermogenic gas = methane and other gases arise from compression and heat deep underground • Most of the gas that is extracted commercially • Kerogen = organic matter that results when carbon bonds begin breaking • Source material for natural gas and crude oil

  24. Natural gas is often wasted • Coalbed methane = from coal seams • Leaks to the atmosphere during mining • Contributes to climate change • In remote oil-drilling areas, natural gas is flared (burned off) • In Alaska, gas captured during oil drilling is being reinjected into the ground for future use • Landfills produce biogenic natural gas • Operators are capturing and selling it

  25. Natural gas extraction becomes challenging • The first gas fields simply required an opening • The gas moved upward • Most remaining fields require pumping by horsehead pumps • Most accessible reserves have been depleted • Fracturing pumps high-pressure salt water into rocks to crack them

  26. Offshore drilling on the seafloor • Requires technology to withstand wind, waves, and currents • Produces 1/3 of our oil and 13% of our natural gas • In 2008, Congress lifted a drilling moratorium along U.S. coasts • In 2010, President Obama said vast areas would be opened for drilling • British Petroleum’s Deepwater Horizon exploded • Producing the worst oil spill in U.S. history

  27. Heat and pressure form petroleum • Oil is the world’s most used fuel • Accounts for 35% of world’s energy use • The U.S. uses the most, but China’s and India’s use is increasing • Crude oil (petroleum) = a mixture of hundreds of different types of hydrocarbon molecules • Formed 1.5–3 km (1–2 mi) underground • Dead organic material was buried in marine sediments and transformed by time, heat, and pressure

  28. Petroleum geologists find deposits • Petroleum occurs in isolated deposits • Collecting in porous layers under impermeable layers • Geologists drill cores and survey the ground and air to predict where fossil fuels may lie • Of the 11.6–31.5 billion barrels of oil in the Arctic National Wildlife Refuge, only 4.3–11.8 billion barrels are “technologically recoverable” with current technology

  29. Not all oil can be extracted • Some oil is so hard to extract, it is not worth the cost • As prices rise, economically recoverable amounts approach technically recoverable amounts • Technology limits what can be extracted • Economics determines how much will be extracted • Proven recoverable reserve = the amount of oil (or any other fossil fuel) that is technically and economically feasible to remove under current conditions

  30. We drill to extract oil • Exploratory drilling = small, deep holes to determine whether extraction should be done • Oil is under pressure and often rises to the surface • Drilling reduces pressure, and oil becomes harder to extract • Primary extraction = the initial drilling and pumping of available oil • Secondary extraction = solvents, water, or steam is used to remove additional oil, but it is expensive • We lack the technology to remove every bit of oil • As prices rise, it becomes economical to reopen a well

  31. Primary and secondary oil extraction

  32. Oil refineries create petroleum products • Refining =hydrocarbons are separated into different size classes and are chemically transformed • Creating specialized fuels for many uses

  33. Petroleum products have many uses Petroleum products are central to our lives

  34. We may have depleted half our reserves • We have used up 1.1 trillion barrels of oil • Half our reserves • Reserves-to-production ratio (R/P ratio) = the amount of total remaining reserves divided by the annual rate of production (extraction and processing) • At current levels of production (30 billion barrels/year), we have about 40 years of oil left • We will face a crisis not when we run out of oil, but when the rate of production begins to decline

  35. We are facing an oil shortage • Peak oil = rate of production peaks and then declines • We experience an immediate oil shortage • Production declines once reserves are depleted halfway • This crisis will begin within the next several years • Geologist M. King Hubbard predicted that oil production would peak around 1970 • His prediction was accurate, and U.S. production continues to fall • Hubbard’s peak = the peak in U.S. production

  36. U.S. oil production has already peaked

  37. Global oil production is peaking Discoveries of new oil fields peaked 30 years ago, and we are using more oil than we are discovering

  38. Predicting an exact date for peak oil is hard • We won’t recognize that we have passed peak production until several years have passed • Companies and governments do not disclose their amount of oil supply • Disagreement among geologists about reserves • Some estimates predict greater than expected reserves • Peak production will occur • Our lives will be profoundly affected

  39. The long emergency • “The long emergency”: lacking cheap oil to transport goods, our economies collapse and become localized • Large cities could not be supported without urban agriculture • Fewer petroleum-based fertilizers and pesticides would mean increase in hunger • Suburbs will become the new slums, a crime-ridden landscape littered with the hulls of rusted-out SUVs • More optimistic observers argue that as supplies dwindle, conservation and alternative energies will kick in • We will be saved from major disruptions

  40. Canada is mining oil sands • Oil sands (tar sands) = sand deposits with bitumen • A form of petroleum rich in carbon, poor in hydrogen • Degraded and chemically altered crude oil deposits • Removed by strip mining • Requires special extraction and refining processes • Most is in Venezuela and Alberta

  41. Oil shale is abundant in the U.S. west • Oil shale = sedimentary rock filled with kerogen (organic matter) • Can be burned like coal or baked in the presence of hydrogen (called pyrolysis) to extract liquid petroleum • World’s supplies may equal 600 billion barrels • 40% is in the U.S., mostly on federally owned land in Colorado, Wyoming, and Utah • Low prices for crude oil have kept investors away • But as oil prices increase, oil shale is attracting interest

  42. Methane hydrate shows potential • Methane hydrate (methane ice) = molecules of methane in a crystal lattice of ice molecules • Occurs in arctic locations and under the seafloor • Formed by bacterial decomposition in anaerobic environments or deep thermogenic formation • Immense amounts could be present • From 2 to 20 times the amount of natural gas • We do not know how to extract it safely • Extraction could cause landslides and tsunamis • Releasing large amounts of methane – a greenhouse gas

  43. Alternative fossil fuels have downsides • Their net energy values are low because they are expensive to extract and process • They have low energy returned on investment (EROI) ratios (about 2:1 compared to oil’s 5:1) • Extraction devastates the landscape and pollutes waterways • Oil sands and oils use strip mining and pollute water • Alberta’s oil sands mined 30 years ago still have not recovered • Combustion emits as much greenhouse gases and pollution as oil, coal, and gas

  44. Fossil fuel emissions pollute • Carbon dioxide is released into the air • Driving changes in global climate • Emissions cause severe health problems • Cancer, irritation, poisoning • Technology and legislation can reduce pollution Carbon dioxide is the greatest impact of fossil fuel use

  45. Clean coal technologies • Clean coal technologies = technologies, equipment, and approaches to remove chemical contaminants while generating electricity from coal • Scrubbers chemically convert or remove pollutants • Removing sulfur dioxide or nitrogen oxides • Coal that contains lots of water can be dried • Gasification = coal is converted into cleaner synthesis gas (syngas) • Which can be used to turn a gas or steam turbine • These technologies have reduced pollution • But clean coal is still a dirty way to generate power

  46. Can we capture and store carbon? • Even very clean coal still releases greenhouse gases • Carbon capture and carbon storage (sequestration) • CCS captures CO2 emissions • Then converts it to a liquid and stores it underground or in the ocean • The $1.5 billion FutureGen project will design, construct, and operate a coal-burning power plant for electricity while capturing and storing carbon underground • This technology is still too unproven to depend on • It prolongs our dependence on fossil fuels

  47. Carbon capture and sequestration

  48. Fossil fuels pollute water and air • For 3 months, the Deepwater Horizon’s explosion spilled millions of barrels of oil into the Gulf of Mexico • We have never had to deal with a spill so deep • The Gulf of Mexico suffered many impacts • Countless animals (birds, shrimp, fish, etc.) died • Coastal marsh plants died, leading to erosion • Fisheries were devastated and fishermen lost jobs • Oil from non-point sources enters waterways and aquifers • Alternative fossil fuels worsens the impacts • They use and pollute massive amounts of water

  49. Coal mining devastates natural systems • Acid drainage = chemical runoff from strip mining enters waterways • Sulfuric acid leaches metals from rocks • U.S. regulations require companies to restore strip-mined land, but complete restoration is impossible • Mountaintop removal removes tons of rock and soil • Destroying immense amounts of habitat and creeks • Loosening of regulations in 2002 allowed companies to legally dump debris into valleys and rivers • Regardless of the consequences

  50. Mountaintop removal Mountaintop removal has greater impacts than strip mining