15 Nonrenewable Energy

Core Case Study: Is the United States Entering a New Oil and Natural Gas Era? Two most widely used natural resources in the U.S. Oil consumption is increasing New extractions from oil shale cause environmental harm Burning oil and natural gas will continue adding greenhouse gases to the atmosphere

5% Nuclear power 8% Natural gas 28% RENEWABLE Coal 22% Hydropower 3% Oil 37% Figure 15-1: Sources of energy used in the United States in 2011. Oil, the most widely used resource, is removed from deposits underground and from deep under the ocean floor in some coastal areas (see photo). NONRENEWABLE 95% Geothermal, solar, wind biomass 2% Fig. 15-1a, p. 374

87% of US energy consumption is from fossil fuels US rate close to unchanged (+/- 1%) but world wide consumption up 15% in last 15 years – why? Figure 15-1: Sources of energy used in the United States in 2011. Oil, the most widely used resource, is removed from deposits underground and from deep under the ocean floor in some coastal areas (see photo). Fig. 15-1b, p. 374

15-1 What is Net Energy and Why Is It Important? Energy resources vary greatly in their net energy yields

Net Energy Is the Only Energy That Really Counts Net energy yield Total amount of useful energy available from a resource minus the energy needed to make the energy available to consumers Energy return on investment Energy obtained per unit energy used to obtain it

Net Energy Is the Only Energy That Really Counts (cont’d.) First law of thermodynamics: It takes high-quality energy to get high-quality energy Pumping oil from ground, refining it, and transporting it Second law of thermodynamics Some high-quality energy is wasted at every step

Some Energy Resources Need Help to Compete in the Marketplace Cannot compete in open markets with alternatives that have higher net energy yields Need subsidies from taxpayers Nuclear power The uranium fuel cycle is costly

15-2 What Are the Advantages and Disadvantages of Oil? Conventional crude oil is abundant and has a medium net energy yield, but using it causes air and water pollution and releases greenhouse gases to the atmosphere Unconventional heavy oil from oil shale rock and tar sands exists in potentially large supplies but has a low net energy yield and a higher environmental impact than conventional oil

We Depend Heavily on Oil Crude oil (petroleum) Peak production – time after which production from a well declines Global peak production for all world oil Crude oil cannot be used as it comes out of the ground Must be refined Petrochemicals – byproducts

Lowest Boiling Point Gases Gasoline Aviation fuel Heating oil Diesel oil Naphtha Figure 15-4: When crude oil is refined, many of its components are removed at various levels of a distillation column, depending on their boiling points. The most volatile components with the lowest boiling points are removed at the top of the column, which can be as tall as a nine-story building. The photo shows an oil refinery in Texas. Grease and wax Heated crude oil Asphalt Furnace Highest Boiling Point Fig. 15-4a, p. 377

Figure 15-4: When crude oil is refined, many of its components are removed at various levels of a distillation column, depending on their boiling points. The most volatile components with the lowest boiling points are removed at the top of the column, which can be as tall as a nine-story building. The photo shows an oil refinery in Texas. Fig. 15-4b, p. 377

Are We Running Out of Conventional Oil? Availability determined by: Demand Technology Rate at which we remove the oil Cost of making oil available Market price Proven oil reserves – available deposits Profitable

Are We Running Out of Conventional Oil? (cont’d.) Unconventional heavy oil Higher environmental cost; production cost Three major options: Live with much higher oil prices Extend oil supplies Use other energy sources

Barrels of oil per year (billions) Projected U. S. oil consumption Barrels of oil per year (billions) Figure 15-5: The amount of conventional light crude oil that might be found in the Arctic National Wildlife Refuge, if developed and extracted over 50 years, is a tiny fraction of the projected U.S. demand for oil. Arctic refuge oil output over 50 years Year Fig. 15-5a, p. 379

Figure 15-5: The amount of conventional light crude oil that might be found in the Arctic National Wildlife Refuge, if developed and extracted over 50 years, is a tiny fraction of the projected U.S. demand for oil. Fig. 15-5b, p. 379

Use of Conventional Oil Has Environmental Costs Land disruption, greenhouse gas emission, air pollution, water pollution, and loss of biodiversity Burning oil accounts for 43% of global CO2 emissions

Trade-Offs Conventional Oil Advantages Disadvantages Ample supply for several decades Water pollution from oil spills and leaks Environmental costs not included in market price Net energy yield is medium but decreasing Releases CO2 and other air pollutants when burned Low land disruption Figure 15-6: Using conventional light oil as an energy resource has advantages and disadvantages. Questions: Which single advantage and which single disadvantage do you think are the most important? Why? Do the advantages of relying on conventional light oil outweigh its disadvantages? Explain. Efficient distribution system Vulnerable to international supply interruptions Fig. 15-6, p. 380

Case Study: Oil Production and Consumption in the United States The U.S.: Produces 9% of the world’s oil and uses 23% of world’s oil Has about 2% of world’s proven oil reserves Imports 52% of its oil Should we look for more oil reserves? Extremely difficult Expensive and financially risky

Heavy Oil From Oil Shale Rock Oil shales contain kerogen After distillation – shale oil 72% of the world’s reserve is in arid areas of western United States Locked up in rock Lack of water needed for extraction and processing Low net energy yield

Figure 15-7: Heavy shale oil (right) can be extracted from oil shale rock (left). Fig. 15-7, p. 381

Heavy Oil from Tar Sands Tar sand contains bitumen Extensive deposits in Canada and Venezuela Oil sands have more oil than in Saudi Arabia Extraction Serious environmental impact before strip- mining Low net energy yield

Figure 15-8: This gooey tar, or bitumen, with the consistency of peanut butter, was extracted from tar sands in Alberta, Canada, to be converted to heavy synthetic oil. Fig. 15-8, p. 381

Heavy Oils from Oil Shale and Tar Sand Trade-Offs Heavy Oils from Oil Shale and Tar Sand Advantages Disadvantages Large potential supplies Low net energy yield Easily transported within and between countries Releases CO2 and other air pollutants when produced and burned Figure 15-10: Using heavy oil from tar sands and from oil shale rock as an energy resource has advantages and disadvantages (Concept 15-2). Questions: Which single advantage and which single disadvantage do you think are the most important? Why? Do the advantages of relying on heavy oil from these sources outweigh the disadvantages? Explain. Efficient distribution system in place Severe land disruption and high water use Fig. 15-10, p. 382

15-3 What Are the Advantages and Disadvantages of Using Natural Gas? Conventional natural gas: Is more plentiful than oil Has a medium net energy yield and a fairly low production cost Is a clean-burning fuel However, producing it has created environmental problems

Natural Gas Is a Useful, Clean-Burning, but Not Problem-Free Fossil Fuel Natural gas – 50-90% methane CH4 Conventional natural gas Liquefied petroleum gas (LPG) Stored in tanks Liquefied natural gas (LNG) Low net energy yield Makes U.S. dependent upon unstable countries like Russia and Iran

Natural Gas Is a Useful, Clean-Burning, but Not Problem-Free Fossil Fuel (cont’d.) The U.S. produces gas conventionally and from shale rock Increasing environmental problems with shale rock extraction GASLAND!

Conventional Natural Gas Trade-Offs Conventional Natural Gas Advantages Disadvantages Ample supplies Low net energy yield for LNG Versatile fuel Production and delivery may emit more CO2 and CH4 per unit of energy produced than coal Medium net energy yield Figure 15-11: Using conventional natural gas as an energy resource has advantages and disadvantages. Questions: Which single advantage and which single disadvantage do you think are the most important? Why? Do you think that the advantages of using conventional natural gas outweigh the disadvantages? Explain. Fracking uses and pollutes large volumes of water Emits less CO2 and other air pollutants than other fossil fuels when burned Potential groundwater pollution from fracking Fig. 15-11, p. 383

Case Study: Natural Gas Production and Fracking in the U.S. Drilling wells; using huge amounts of water, sand, and chemicals; dealing with toxic wastewater; transporting the natural gas Drinking water contaminated with natural gas can catch fire Fracking has several harmful environmental effects

Figure 15-12: Natural gas fizzing from this faucet in a Pennsylvania home can be lit like a natural gas stove burner. This began happening after an energy company drilled a fracking well in the area, but the company denies responsibility. The home owners have to keep their windows open year-round to keep the lethal and explosive gas from building up in the house. Fig. 15-12, p. 384

Figure 15-13: Solutions: Reforms such as these, recommended by several energy analysts, could reduce the harmful impact of shale gas production. Questions: Which three of these steps do you think are the most important ones to take? Explain. Fig. 15-13, p. 385

Unconventional Natural Gas Coal bed methane gas In coal beds near the earth’s surface; in shale beds High environmental impacts of extraction Methane hydrate Trapped in icy water; in permafrost environments; on ocean floor Costs of extraction is currently too high

15-4 What Are the Advantages and Disadvantages of Coal? Conventional coal is plentiful and has a high net energy yield at low costs, but using it results in a very high environmental impact We can produce gaseous and liquid fuels from coal, but they have lower net energy yields and using them would result in higher environmental impacts than those of conventional coal

Coal Is a Plentiful but Dirty Fuel Solid fossil fuel Burned in power plants Generates 42% of the world’s electricity Abundant – world’s largest coal reserves United States Russia China

Coal Is a Plentiful but Dirty Fuel (cont’d.) Environmental costs of burning coal Severe air pollution Sulfur released as SO2 Large amount of soot CO2 Trace amounts of mercury and radioactive materials

And the mines aint little

Link to youtube video of bucket wheel excavator

Bituminous (soft coal) Anthracite (hard coal) Increasing heat and carbon content Increasing moisture content Peat (not a coal) Lignite (brown coal) Bituminous (soft coal) Anthracite (hard coal) Heat Heat Heat Pressure Pressure Pressure Partially decayed plant matter in swamps and bogs; low heat content Low heat content; low sulfur content; limited supplies in most areas Extensively used as a fuel because of its high heat content and large supplies; normally has a high sulfur content Highly desirable fuel because of its high heat content and low sulfur content; supplies are limited in most areas Figure 15-14: Over millions of years, several different types of coal have formed. Peat is a soil material made of moist, partially decomposed organic matter, similar to coal; it is not classified as a coal, although it is used as a fuel. These different major types of coal vary in the amounts of heat, carbon dioxide, and sulfur dioxide released per unit of mass when they are burned. Fig. 15-14, p. 386

Cooling tower transfers waste heat to atmosphere Coal bunker Turbine Generator Cooling loop Stack Pulverizing mill Condenser Filter Figure 15-15: This power plant burns pulverized coal to boil water and produce steam that spins a turbine to produce electricity. The largest coal-burning power plant in the United States, located in Indiana, burns three 100-car trainloads of coal per day. Question: Does the electricity that you use come from a coal-burning power plant? Boiler Ash disposal Fig. 15-15a, p. 387

Figure 15-15: This power plant burns pulverized coal to boil water and produce steam that spins a turbine to produce electricity. The largest coal-burning power plant in the United States, located in Indiana, burns three 100-car trainloads of coal per day. Question: Does the electricity that you use come from a coal-burning power plant? Fig. 15-15b, p. 387

The Clean Coal Campaign Coal companies and energy companies has fought: Classifying carbon dioxide as a pollutant Classifying coal ash as hazardous waste Air pollution standards for emissions The 2008 clean coal campaign Note: there is no such thing as clean coal

Coal-fired electricity 286% Synthetic oil and gas produced from coal 150% Coal 100% Tar sand 92% Oil 86% Natural gas 58% Figure 15-17: CO2 emissions, expressed as percentages of emissions released by burning coal directly, vary with different energy resources. Question: Which of these produces more CO2 emissions per kilogram: burning coal to heat a house, or heating with electricity generated by coal? Nuclear power fuel cycle 17% Geothermal 10% Fig. 15-17, p. 388

Trade-Offs Coal Advantages Disadvantages Severe land disturbance and water pollution Ample supplies in many countries Fine particle and toxic mercury emissions threaten human health Medium to high net energy yield Figure 15-20: Using coal as an energy resource has advantages and disadvantages. Questions: Which single advantage and which single disadvantage do you think are the most important? Why? Do you think that the advantages of using coal as an energy resource outweigh its disadvantages? Explain. Low cost when environmental costs are not included Emits large amounts of CO2 and other air pollutants when produced and burned Fig. 15-20, p. 389

We Can Convert Coal into Gaseous and Liquid Fuels Conversion of solid coal to: Synthetic natural gas (SNG) by coal gasification Methanol or synthetic gasoline by coal liquefaction Synfuels Are there benefits to using these synthetic fuels?

Trade-Offs Synthetic Fuels Advantages Disadvantages Large potential supply in many countries Low to medium net energy yield Requires mining 50% more coal with increased land disturbance, water pollution and water use Vehicle fuel Figure 15-21: The use of synthetic natural gas (SNG) and liquid synfuels produced from coal as energy resources has advantages and disadvantages (Concept 15-2). Questions: Which single advantage and which single disadvantage do you think are the most important? Why? Do you think that the advantages of using synfuels produced from coal as an energy source outweigh the disadvantages? Explain. Lower air pollution than coal Higher CO2 emissions than coal Fig. 15-21, p. 389

15-5 What Are the Advantages and Disadvantages of Using Nuclear Power? Nuclear power has a low environmental impact and a very low accident risk, but its use has been limited by: A low net energy yield, high costs, fear of accidents, and long-lived radioactive wastes Its role in spreading nuclear weapons technology

How Does a Nuclear Fission Reactor Work? Controlled nuclear fission reaction in a reactor Light-water reactors Very inefficient Fueled by uranium ore and packed as pellets in fuel rods and fuel assemblies Control rods absorb neutrons

How Does a Nuclear Fission Reactor Work? (cont’d.) Water is the usual coolant Containment shell around the core for protection Water-filled pools or dry casks for storage of radioactive spent fuel rod assemblies 48

Pump Pump Pump Pump Water source (river, lake, ocean) Small amounts of radioactive gases Uranium fuel input (reactor core) Control rods Containment shell Waste heat Heat exchanger Steam Turbine Generator Hot coolant Useful electrical energy about 25% Hot water output Pump Pump Coolant Figure 15-22: This water-cooled nuclear power plant, with a pressurized water reactor, produces intense heat that is used to convert water to steam, which spins a turbine that generates electricity. Question: How does this plant differ from the coal-burning plant in Figure 15-15? Pump Pump Waste heat Cool water input Moderator Shielding Pressure vessel Coolant passage 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. 15-22a, p. 390

Figure 15-22: This water-cooled nuclear power plant, with a pressurized water reactor, produces intense heat that is used to convert water to steam, which spins a turbine that generates electricity. Question: How does this plant differ from the coal-burning plant in Figure 15-15? Fig. 15-22b, p. 390

What Is the Nuclear Fuel Cycle? Mine the uranium Process the uranium to make the fuel Use it in the reactor Safely store the radioactive waste Decommission the reactor

(conversion of enriched UF6 to UO2 and fabrication of fuel assemblies) 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 UF6 Plutonium-239 as PuO2 Spent fuel reprocessing Low-level radiation with long half-life Figure 15-23: Science. Using nuclear power to produce electricity involves a sequence of steps and technologies that together are called the nuclear fuel cycle. Question: Do you think the market price of nuclear-generated electricity should include all the costs of the nuclear fuel cycle, in keeping with the full-cost pricing principle of sustainability? (See Figure 1-5, p. 9 or back cover.) Explain. Geologic disposal of moderate and high-level radioactive wastes Mining uranium ore (U3O8) Open fuel cycle today Recycling of nuclear fuel Fig. 15-23, p. 392

Trade-Offs Conventional Nuclear Fuel Cycle Advantages Disadvantages Low environmental impact (without accidents) Low net energy yield High overall cost Emits 1/6 as much CO2 as coal Produces long-lived, harmful radioactive wastes Figure 15-24: Using the nuclear power fuel cycle (Figure 15-23) to produce electricity has advantages and disadvantages. Questions: Which single advantage and which single disadvantage do you think are the most important? Why? Do you think that the advantages of using nuclear power outweigh its disadvantages? Explain. Low risk of accidents in modern plants Promotes spread of nuclear weapons Fig. 15-24, p. 392

Storing Radioactive Spent-Fuel Rods Presents Risks Rods must be replaced every three or four years Cooled in water-filled pools Placed in dry casks Must be stored for thousands of years Vulnerable to terrorist attack

Figure 15-25: After 3 or 4 years in a reactor, spent-fuel rods are removed and stored in a deep pool of water contained in a steel-lined concrete basin (left) for cooling. After about 5 years of cooling, the fuel rods can be stored upright on concrete pads (right) in sealed dry-storage casks made of heat-resistant metal alloys and thick concrete. Questions: Would you be willing to live within a block or two of these casks or have them transported through the area where you live in the event that they were transferred to a long-term storage site? Explain. What are the alternatives? Fig. 15-25, p. 393

Dealing with Radioactive Nuclear Wastes Is a Difficult Problem High-level radioactive wastes Must be stored safely for 10,000–240,000 years Where can it be stored? Deep burial: safest and cheapest option Would any method of burial last long enough? There is still no facility Shooting it into space is too dangerous

Dealing with Radioactive Nuclear Wastes Is a Difficult Problem (cont’d Plans in the U.S. to build a repository for high-level radioactive wastes in the Yucca Mountain desert region (Nevada) Many problems including: Cost of $96 billion Rock fractures Earthquake zone Decrease national security

Dealing with Radioactive Nuclear Wastes Is a Difficult Problem (cont’d Dealing with old nuclear power plants: Decommission or retire the power plant Dismantle the plant and safely store the radioactive materials Enclose the plant behind a physical barrier with full-time security until a storage facility has been built Enclose the plant in a tomb Monitor this for thousands of years

Can Nuclear Power Help Reduce Climate Change? Nuclear power plants – no CO2 emission Nuclear fuel cycle – emits CO2 Opposing views on nuclear power Nuclear power advocates Oxford Research Group Need high rate of building new plants, and a storage facility for radioactive wastes

Experts Disagree about the Future of Nuclear Power Proponents of nuclear power: Fund more research and development Pilot-plant testing of potentially cheaper and safer reactors Test breeder fission and nuclear fusion Opponents of nuclear power: Fund rapid development of energy efficient and renewable energy resources

Experts Disagree about the Future of Nuclear Power (cont’d.) New technologies Advanced Light Water Reactors Safer Thorium based reactors Less costly and safer

Figure 15-26: Some critics of nuclear power say that any new generation of nuclear power plants should meet all of these five criteria. Question: Do you agree or disagree with these critics? Explain. Fig. 15-26, p. 395

Case Study: The 2011 Nuclear Power Plant Accident in Japan Triggered by a major offshore earthquake and resulting tsunami Four key human-related factors: No worst-case scenarios Seawalls too short Design flaws Relationship between plant owners and government

Figure 15-27: An explosion in one of the reactors in the Fukushima Daiichi nuclear power plant severely damaged the reactor. Fig. 15-27, p. 396

Is Nuclear Fusion the Answer? Two isotopes fused together to form a heavier nucleus Releases energy Technology is very difficult to develop

Three Big Ideas A key factor to consider in evaluating the long-term usefulness of any energy resource is its net energy yield Conventional oil, natural gas, and coal: Plentiful and have moderate to high net energy yields Use of these fossil fuels, especially coal, has a high environmental impact

Three Big Ideas (cont’d.) The nuclear power fuel cycle has a low environmental impact and a very low accident risk, but limited use because of: High costs A low net energy yield Long-lived radioactive wastes Its role in spreading nuclear weapons technology

Tying It All Together: A New U. S Tying It All Together: A New U.S. Oil and Natural Gas Era and Sustainability Conventional fossil fuels have high net energy yields We cannot recycle energy Recycling materials can help reduce energy needs Relying on a diversity of energy resources Will reduce environmental impacts