unit 6: energy resources chapter16: nonrenewable energy
TRANSCRIPT
February 19, 2014
Unit 6: Energy Resources
Chapter16: Nonrenewable energy
Chapter 17: Energy efficiency and renewable energy
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Chapter16: Nonrenewable Energy
What is nonrenewable energy?
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"Oil is used to grow most of our food, transport people and goods, and make the most of things we use every day--from plastics to asphalt on roads"
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Known and projected global reserves of oil are expected to be 80% depleted sometimes between 2050 and 2100• End of age of cheap oil• Rising prices = search for new oil
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• Saudi Arabia--largest known crude oil reserve (10 year world supply)
• Alaska--largest reserve in N. America (6 month world supply, 3 year US)
• Alaska's Arctic National Wildlife Refuge (1-5 month world supply, 7-24 month US)
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Types of Energy Resources
Sun (99%)• Nuclear fusion reaction• heats earth• wind• hydropower• biomass
Commercial Energy (1%)• supplement sun • nonrenewable mineral
resources> fossil fuels (76%)> nuclear power
(6%)
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Net Energy: usable amount of high-quality energy available from a given quantity of an energy resource
= (Total Energy) - (Energy to find + extract + process + transport)
Calculated by: 1. Estimating total energy over lifetime2. Subtract amount used (1st law),
automatically wasted (2nd law), and unnecessarily wasted
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Net energy ratio
useful energy produce: energy used to produce
Ex: 20 units of energy produced
5 units of energy used to produce it
ratio=20/5 or 4
If ratio is < 1, what does that mean?
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What has a higher ratio: accessible deposits of oil or deposits that are harder to access?
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Ne energy ratio
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Energy Resources • Oil• Natural gas• Coal• Nuclear Energy
Fossil fuels
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Oil• Petroleum (Crude oil, conventional oil, light oil)• Dispersed in pores/cracks in rock formations (like a
sponge)• Well drilled (up to 6km)
> Why does it get more difficult as it gets deeper?
> Peak production (halfway point), and then production declines
http://en.wikipedia.org/wiki/File:Petroleum.JPG
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Currently, get only 35-50% of oil out of a deposit• heavy crude oil is too expensive/difficult to recover
> as prices rise, can use steam/water to flush well (lowers net energy yield)
> New technology can increase to 75%?
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Refinery• Crude oil heated and distilled• Decreases net energy yield• Accounts for 8% of US energy consumption
Petrochemicals• Organic chemicals• pesticides• plastics• synthetic fibers• paints• medicine
Alternatives? Industrial biotechnology
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OPEC: Organization of Petroleum Exporting Countries• Currently 12 countries• 78% of oil reserves• control supplies and price***• Algeria, Angola (added 2007), Ecuador (suspension
ended 2007), Indonesia (suspended 2009) , Iran, Iraq, Kuwait, Libya, Nigeria, Qatar, Saudi Arabia, United Arab Emirates, Venezuela
Largest consumers: US, China, Japan• Limited domestic supply
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World's oil production to peak with in 5-38 years.• Oil becomes more expensive• Other related consequences:
> increase in food prices + changes in diet> biomass crops?> Air travel and freight level off or decline?> Reduce suburbs
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US Oil• Offshore drilling (29% oil, 21% natural gas)
> hurricanes in Gulf of Mexico• Alaska's North Slope (17%, Trans-Alaska Pipeline)
http://en.wikipedia.org/wiki/File:Trans-Alaska_Pipeline_System_Luca_Galuzzi_2005.jpg
http://en.wikipedia.org/wiki/File:Trans_alaska_international.jpg
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US Oil• Produces 9% but consumes 25% of global oil
production• Only has 2.9% of reserves• "The Hubbert Peak" (Halfway production) reached
in 1974> higher cost to extract dwindling oil supplies> *Need to import more oil.
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US Oil: Issues with importing more oil• Large import of oil: Canada, Mexico, OPEC: Saudi
Arabia, Venezuela, Nigeria• Buying oil = funding terrorism? • Competition for imports (China)
Should the US look for more domestic oil supplies?> efficient?> environmental cost?> is there even any more oil?> Alaska: Arctic National Wildlife Refuge> *Domestic oil will not lower prices--global
market> *Alternatives? Using fuel more efficiently
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Sticky Black Gold: Heavy oil from oil sand and oil shale• Oil sand: mixture of clay, sand, water, and bitumen
> bitumen: thick ,sticky, heavy oil, high S content> extracted with hot water and steam> refined
• Deposits in Canada, Venezuela, Colombia, Russia, Utah
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Oil sand disadvantages• more expensive to produce than conventional oil• disrupts land• produces toxic sludge and waste water• need large input of natural gas (reduce net energy
yield)• destroy environment (boreal forest)
> strip mines> need 1.8 metric tons of oil sand for 1 barrel of
oil
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Oil shales (oil rock)• kerogen• shale oil extracted by heating crushed oil shales
> processed to remove S, N, other impurities
• Deposits in western US (Wyoming, Utah, COlorado)• Global supply estimated to be about 240x larger
than conventional oil• But...
> low grade (energy, water, money)> environmental impact
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Hydraulic Fracturing or Fracking• Mixture of water, sand, and chemicals injected at
high pressure into shale deposits• creates small fracture where oil or natural gas can
flow• Dangerous?
> chemicals> contaminates ground water? (flaming faucets)>
http://exploreshale.org/
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Natural Gas: Mixture of gases• 50-90% methane (CH4)• ethane, propane, butane (chemical formulas?)• Hydrogen sulfide
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Natural gas• Propane and butane liquefied LPG (liquefied
petroleum gas)• Rest of gas dried, remove hydrogen sulfide and
other impurities Pressurized pipeline
• Less CO2 per unit of energy
• *Clean-burning turbines to generate electricity> more efficient
than coal or gas
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Unconventional Natural Gas
*Higher environmental risk and higher price• coal bed methane gas• methan hydrate
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Unconventional Natural Gas• coal bed methane gas
> remove before mining for coal to reduce greenhouse gas
• Can pump aquifers to release> reduce pressure, release, and capture
• Negative impacts> Depletes groundwater > Produces water contaminated with salt and
other minerals> Roads, pipelines, waste water pits
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Unconventional Natural Gas• methane hydrate
> methane trapped in icy, cage-like structures of water
> buried under arctic permafrost and beneath ocean bottom
• Downside> currently too expensive
– technology?> if any is released, contribute to global warming> can cause landslides on continental shelf if
decompose on ocean floor, cause tsunamis
http://geology.com/articles/methane-hydrates/
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Supply of natural gas• Russia has 31% world supply• US only 3%• Last 62-125 years
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Coal• Solid fossil fuel• Mostly C, contains small amounts of S
> released as sulfur dioxide (and then what happens to it...?)
• Burning carbon also releases mercury and radioactive materials
http://teeic.anl.gov/images/photos/EIA_coal_train.jpg
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Why is coal burned?• Generate 62% world electricity• Make 75% world steel
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TIME
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http://www.eia.gov/todayinenergy/images/2011.10.04/CoalProductionPie.png
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Synthetic natural gas (SNG or syngas)• coal gasification or coal liquefaction turns coal into
methanol or synthetic gasoline> Why would you do this?> Gasification results in mixture of CO, H2, and CO2
> Can purify hydrogen to be used in fuel cells> can burn at higher temperatures = less energy lost as
heat> Can be converted to other things (methanol, synthetic
gasoline)
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Nuclear energy• Nuclear fission chain reaction
> Split nuclei of atoms> Heat released> Use heat to produce steam> Steam turns turbine (generator)
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Light-water reactors (LWRs)• 85% world, 100% US• Fuel rods --> Fuel assembly• Uranium oxide fuel: 97% Uranium-283, 3% Uranium-235*
(enriched)
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After 3-4 years, spent fuel rods removed
*Not as well protected
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*Takes 10,000-240,000 years until radioactivity falls to "safe" levels
*The more we use, the more that builds up
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World electiricy produced by nuclear power fall from 17% to 15% from 2005 to 2025. Why?• Aging reactors not replaced by new ones• expensive (what makes them affordable?)• malfunctions• Public concern of safety• Economic feasibility• Vulnerability to terrorist attack
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Dirty Bombs• Explosive + radioactive material
> radioisotopes from hospitals (cobalt-60), industry, laboratories
> Removing plutonium from spent fuel rods
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What to do with a old nuclear power plant?• dismantle and store radioactive material in storage• Physical barrier and set up full-time security, wait, and
then dismantle later• Encase in tomb
• **Cost, security
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New technology• Advanced light-water reactors
> passive safety features> high-temperature gas-cooled reactors (avoid water as
coolant)– *safety?
> Pebble bed modular reactor– No need for core cooling system or containment?
« pebbles of uranium are encased in ceramic: Is it enough/
Problems?• safety• graphite can burn
and release radioactivity
• produce more waste
• expense and hazards of long-term radioactive waste storage
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Breeder nuclear fission• generates nuclear fuel: converts nonfissionable
Uranium-238 to fissionable plutonium 239• Slow to produce plutonium• safety?
> liquid sodium coolant
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Nuclear fusion?• safer? no radioactivity• D-T• No success yet