Chapter 17: Energy efficiency and renewable energy

Transcription

1 Unit 6: Energy Resources Chapter16: Nonrenewable energy Chapter 17: Energy efficiency and renewable energy

2 Chapter16: Nonrenewable Energy What is nonrenewable energy?

3 "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"

4 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 February 19, 2014

5 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)

6 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%)

7 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 lifetime 2. Subtract amount used (1st law), automatically wasted (2nd law), and unnecessarily wasted

8 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?

9 What has a higher ratio: accessible deposits of oil or deposits that are harder to access?

10 Ne energy ratio February 19, 2014

11 Energy Resources Oil Natural gas Coal Nuclear Energy Fossil fuels

12 February 19, 2014 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

13 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%?

14 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

15 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

16 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 February 19, 2014

17 February 19, 2014 US Oil Offshore drilling (29% oil, 21% natural gas) > hurricanes in Gulf of Mexico Alaska's North Slope (17%, Trans-Alaska Pipeline)

18 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. February 19, 2014

19 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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21 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

22 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 February 19, 2014

23 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

24 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) >

25 Natural Gas: Mixture of gases 50-90% methane (CH4) ethane, propane, butane (chemical formulas?) Hydrogen sulfide February 19, 2014

26 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

27 Unconventional Natural Gas *Higher environmental risk and higher price coal bed methane gas methan hydrate

28 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 February 19, 2014

29 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

30 Supply of natural gas Russia has 31% world supply US only 3% Last years February 19, 2014

31 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

32 Why is coal burned? Generate 62% world electricity Make 75% world steel February 19, 2014

33 TIME February 19, 2014

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36 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)

37 Nuclear energy Nuclear fission chain reaction > Split nuclei of atoms > Heat released > Use heat to produce steam > Steam turns turbine (generator) February 19, 2014

38 Light-water reactors (LWRs) 85% world, 100% US Fuel rods --> Fuel assembly Uranium oxide fuel: 97% Uranium-283, 3% Uranium-235* (enriched)

39 After 3-4 years, spent fuel rods removed *Not as well protected

40 *Takes 10, ,000 years until radioactivity falls to "safe" levels *The more we use, the more that builds up

41 World electiricy produced by nuclear power fall from 17% to 15% from 2005 to Why? Aging reactors not replaced by new ones expensive (what makes them affordable?) malfunctions Public concern of safety Economic feasibility Vulnerability to terrorist attack February 19, 2014

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44 Dirty Bombs Explosive + radioactive material > radioisotopes from hospitals (cobalt-60), industry, laboratories > Removing plutonium from spent fuel rods February 19, 2014

45 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

46 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 longterm radioactive waste storage

47 Breeder nuclear fission generates nuclear fuel: converts nonfissionable Uranium-238 to fissionable plutonium 239 Slow to produce plutonium safety? > liquid sodium coolant February 19, 2014

48 Nuclear fusion? safer? no radioactivity D-T No success yet February 19, 2014