Readings
Revisit Carrying Capacity Definition?
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Limiting factors for carrying capacity Definition Technology Resources
Supply Extraction
First and second laws of thermodynamics Energy cannot be created or destroyed Universe moves toward greater disorder What does this mean in terms of energy use?
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Energy
•Renewable
•Renewable?
•Nonrenewable
Energy to get the resources Energy to get the energy Energy efficiency
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Gever et al., 1991
Gever et al., 1991
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Gever et al., 1991
Energy Efficiency Percentage of energy input that does useful work in an energy conversion system
Table 16.1
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If we would be more energy efficient • allow nonrenewable fuels to last longer • the above would give us time to phase in renewable energy • decreases dependence on oil imports • reduces environmental damage • slows global warming • saves money
US Energy use
DOE/EIA-0384 (2005) July 2006
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DOE/EIA-0384 (2005) July 2006
Current energy in U.S.
• 80% from nonrenewable fossil fuels (oil 39% of total, coal 23%, & natural gas 18.7%) • 8% from nuclear power; • 6% hydropower • 5.39% other
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Energy use
~80 % of the world’s energy comes from
fossil fuels
Oil 40% of the world’s nonsolar energy
World primary energy production 2004 DOE/EIA0384 (2005) July 2006
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Energy production by country and region DOE/EIA-0384 (2005) July 2006
http://www.nationmaster.com/re d/graph/ene_usa_per_perenergy-usage-perperson&b_map=1#
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Electricity in the US 51 % coal 20 % nuclear 17% gas 7% hydro 3 % oil 3% other
Electricity in Nevada ~67% coal 22% natural gas, 16% hydroelectric 10% geothermal
Recent news on 64 MW solar plant near Las Vegas Program to buy back power Generating capacity 6400 MW (6400000 homes)
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Generating electricity
Chemistry of the Environment, Spiro and Stigliani 2003
How to Evaluate Energy Resources? • How much available? Reserves vs Resources • Net energy yield? • Cost to develop, phase in, & use? • Environmental effects of extraction, transport, & use? • Sustainability? • Life Cycle assessment
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Hydrocarbons and the evolution of human culture Energy used to produce good and services Energy use an important component of most
important environmental change “Our own civilization has become heavily dependent on enormous flows of cheap hydrocarbons, partly to compensate for depleted resources…”
Hydrocarbons and the evolution of human culture 4 principle issues associated with oil based
economy Quantity Quality Patterns of exploitation over time Who gets and benefits from Energy return on investment
Pg 321 Quote-
Easter egg analogy Oil -Currently US 17 to 1 (used to be 100:1) Needs to be high
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Reserves identified resources that can be extracted economically at current prices using current mining technology
Energy to get the energy
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Net energy corn ethanol
Milling process Btu/gal Corn production 21,793 Corn transport 1,244 Ethanol conversion 51,343 Ethanol distribution 3,173 Energy losses 5,271 Total energy used 82,824 N et energy value A gallon of ethanol contains 83,961 Btu on a high heat value basis. Energy ratio 1.01
Oil • fossil fuel, produced by the decomposition of deeply buried organic matter from plants & animals • deposits > 500,000 yrs old • crude oil: complex liquid mixture of hydrocarbons, with small amounts of S, O, N impurities; • High quality, compact, easy to transport
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42 US Gallons in a Barrel/ World uses 83 mb/d/ US uses 21 mb/d
World oil reserves 2005 DOE/EIA-0384 (2005) July 2006 Iraq reserves 215 bb = 7 years world Assume reserve of 1000 bb= 33 yrs
Resource versus reserves
US has 21 bbarrels of reserves ~ 3 years
ANWR 10.4 bill barrels (5 may be more
realistic) 611 days or 300 US BLM Alaska 390,000 acres 2 bill barrels
133 days US
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5.1 US
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•Petroleum overview from DOE
66% of our oil is imported
2005 DOE/EIA-0384 (2005) July 2006 Imports
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Extraction & Processing • Extraction: - primary - drill & pump - secondary - inject H2O - tertiary - inject steam or CO2 • transportation to refinery www.adventuresinenergy.org/main.swf • refine to separate by volatility • high: gasoline, aviation fuel - medium: heating oil, diesel - low: grease, wax, asphalt • transport by tanker, truck, pipeline
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2005 DOE/EIA-0384 (2005) July 2006
© Brooks/Cole Publishing Company / ITP
Natural gas EIA-2008
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Natural Gas • fossil fuel • mixture of 50–90% methane (CH4), smaller amounts of ethane (C2H6), propane (C3H8), & butane (C4H10), and hydrogen sulfide (H2S); • propane & butane removed as liquefied petroleum gas (LPG); • typically transported by pipelines • Figure from geotimes/nature conservancy
•US natural gas use Figs 34-47 •World Fig 11.12
World natural gas reserves 2005
© Brooks/Cole Publishing Company / ITP
23tcf/y = 26 years
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Geotimes feb 2008 Unconventional sources Liquified natural gas
Coal bed methane
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General comments Natural gas
• burns hotter, cleaner, & produces less carbon dioxide than other fossil fuels; • transport overseas difficult (LNG); • Quality of work • pollution & environmental degradation • . •90–95% of natural gas in U.S. domestic (~411,000 km = 255,000 miles of pipeline).
Coal fossil fuel, east coast from swamp plants 250350 million year old deposits, western 230 to 70 million years
Fig.19–16
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Extraction by Mining
© Brooks/Cole Publishing Company / ITP
Chemistry of the Environment, Spiro and Stigliani 2003
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2004 DOE/EIA-0384 (2005) July 2006 67 % world reserves top four China- 76% of its energy supply over half in industry-steel and pig iron bi
U.S. 90% goes to electricity 50% countries electricity Australia –largest exporter Japan and other asian countries
76 of China’s energy supply
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General comments
• most abundant fossil fuel -200 yr reserves • major U.S. reserves, 225-300 yrs. at current consumption rates; • high net energy yield; • dirtiest fuel, highest carbon dioxide; • major environmental degradation; • acid rain, largest anthropogenic source of atmospheric mercury
Carbon dioxide emissions (Figure 11.19) Put contemporary C cycle on board
World CO2 emissions from energy consumption 2004
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Carbon sequestration –Elements papers Koonin
Become more efficient Decarbonize the energy supply
Broecker
Capture from power plants and inject CO2 disposal
Recent EST article Loss of efficiency due to added energy to
sequester Carbon Serious proof of concept has not yet begun
Balance of power-warming and electricity
Figure pg 33 Geotimes Aug 2008
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Other fossil fuels Methane hydrates
Other fossil fuels Oil shale Tar sands
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Nuclear Energy-Electricity without Carbon Harness the energy in the nucleus of an atom
using Radioactive isotopes Fission-spit
U235 and Pu 239
Fusion-put together
Hydrogen
Radioactive isotopes 1/2 life U235-->Pb207 1/2life=710 x 10^6 yrs U238-->Pb206 1/2life=4.5 x 10^9 yrs IodineÆ 8 days Ionizing radiation Alpha particles-Helium atom Beta particle-high speed electrons Gamma rays-high energy electromagnetic waves
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Chemistry of the Environment, Spiro and Stigliani 2003
Nuclear Energy • Controlled fission • Chain reaction
© Brooks/Cole Publishing Company / ITP
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Small amounts of Radioactive gases
Uranium fuel input (reactor core)
Containment shell Waste heat
Emergency core Cooling system
Electrical power
Steam
Control rods
Turbine
Heat exchanger Hot coolant
Useful energy 25 to 30%
Generator
Hot water output Condenser
Pump
Pump
Coolant Cool water input Black Moderator
Pump
Water
Waste heat
Coolant passage Pressure vessel Shielding
Periodic removal and storage of radioactive wastes and spent fuel assemblies
Periodic removal and storage of radioactive liquid wastes
Waste Water source heat (river, lake, ocean)
http://www.nrc.gov/reading-Fig. 14.32, p. 346 rm/basic-ref/students/reactors.html
• U.S. has major reserves of uranium; • lower mining impacts than coal-2.2 # of fuel 2000 metric tonnes coal;
2004 DOE/EIA-0384 (2005) July 2006
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World location nuclear power plants
US location nuclear power plants
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Use • ~443 active plants worldwide, 24 under construction ; • no new U.S. power plants ordered since 1978 until this past year; 40% of 105 commercial nuclear power expected to be retired by 2015 & all by 2030; US new advanced passive reactor two being built in Texas • 2007-35 nuclear plants under construction almost all in Asia
Pros and cons Costs 0.07 to 0.025 –gov subsidies 80 years of reserves at current rate of use Breeder reactors 60x more energy from every
kg Nuclear waste Nuclear proliferation Skilled workers Proven, C free, less surface area disruption Lack of capital investment and extremely costly
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What is Nuclear Waste
Nuclear waste: hazardous byproduct resulting from the use and decay of radioactive materials. (energy, defense, medical, research, industry)
Seven Classes: 1.
2. 3. 4. 5. 6. 7.
High-level waste/spent nuclear fuel (2,000 tonnes/year); Transuranic Waste; Low-level Waste; Mill Tailings; Mixed Waste; Orphaned Sources; Naturally-Occurring and Accelerator-Produced Radioactive Materials.
Nuclear Waste Timeline Cont. 1982 – Nuclear Waste Policy Act US Gov responsible for waste began federal characterization studies (goal: 3 sites), limited waste to 70,000 tonnes in first repository, provide legislation for land designation, require public fee for funding (1/10th of $0.01 for every 1 nuclear generated kWh consumed. $16 billion collected 1982 to 2000). 1983 – 9 candidate sites six states. 1986 – 5 sites suitable – 3 recommended to President: 1) Deaf Smith County, Texas; 2) Hanford Site, Washington; 3) Yucca Mountain (12 sites also proposed for 2nd facility). 1987 – National Waste Policy Amendments Act: directs focus at Yucca Mountain – to begin storage 2/1998, solidifies legislation and federal oversight, requires reporting for suitability of 2nd site by 2010.
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Timeline Continued Breaking ground to NRES onsite: 1991 - 1993 – Break ground at site – feasibility studies. 1994 – Civilian Radioactive Waste Management Program Plan: determine suitability by 1997, licensing by 2001. 1997 – Thermal testing of tunnels at Yucca begins. 1998 – Viability Study released, initial waste storage deadline not met. 1999 – First shipments of Transuranic Waste to Waste Isolation Pilot Plant, Carlsbad , NM. 2001 – EPA recommends radiation standards, Nevada files suit against EPA. 2002 – President Bush approves Yucca Mountain recommendation, Governor Guinn vetoes. 2004 –Congress votes to override Guinn veto, U.S. Court of Appeals dismisses EPA’s 10,000 year site standard, licensing process locked up in court. 2005 – Continued legislation, delayed license processing, continued site studies and development.
Nuclear waste “It is unethical to continue to produce
extraordinary toxic waste through processes that benefit our generation when we have no solution to benefit generations to come.” Dan Hirsh- nuclear policy analyst-nonprofit antinuclear group
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Nuclear waste storage Time scale for safety
CEN article-10000-1000000 yrs?
What to do for government liability? Waste currently at 122 sites in 39 states.
Current Storage
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Yucca Mountain located on federal land in a remote area of Nye County in southern Nevada,
about 100 miles northwest of Las Vegas. layers of volcanic rock, called “tuff.” This rock is made of ash that was
deposited by successive eruptions from nearby volcanoes, between 11 and 14 million years ago. These volcanoes have been extinct for millions of years. Extensive scientific studies suggest it is highly unlikely that volcanoes, erosion, or other geologic processes and events would disrupt a repository at Yucca Mountain. By locating the repository in solid rock about 1,000 feet under the surface and on average 1,000 feet above the water table, the waste would be protected from the impacts of earthquakes. There are no known natural resources of commercial value at Yucca Mountain (such as precious metals, minerals, oil, etc.).
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Climate Yucca Mountain is in the desert
southwest. Like any desert, it has a dry climate, receiving less than 7.5 inches of precipitation on average per year. Most of that precipitation runs off the mountain or evaporates. Only about 5% would ever reach repository depth. On average, the water moves only a half an inch per year through the rock. Yucca Mountain's dry climate is an important feature because water is the primary way by which radioactive material could move from a repository.
The repository at Yucca Mountain relies on two methods to prevent radioactive materials from escaping into the environment. These systems act as barriers to the movement of radionuclides (radioactive atoms).
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•
Natural barriers — characteristics of the rocks and the groundwater at Yucca Mountain.
The geology — which limit the ability of water to infiltrate the surface Unsaturated rock layers above the repository level —Unsaturated rock layers below the repository level — which limit transport of radionuclides that might escape from repository tunnels
•The second system includes man-made, or engineered, barriers that give the repository defense-in-depth and added safety margins. The major engineered barriers include the following:
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Shipping Casks
Proposed Routes
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Geotimes- wanted interim storage facility? Yucca mt Delayed to 2020 Interim site
743 million to build 2015 to open
Parting thoughts-Baruch No CO2 Technology is safer
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