R. Parthasarathy. University of Oregon

Transcription

1 Physics 161: Physics of Energy and the Environment November 6, 2008 Prof. Raghuveer Parthasarathy

2 Lecture 11: Announcements Reading: Wolfson, Chapter 5 Problem Set 5: Due NEXT Thursday, November 13, 5pm. Midterm Results (at end):

3 Last Lecture: Fossil Fuels Petroleum:liquids and gas from ancient oceanic organic matter. (Typically 50 MJ/kg energy content) Natural gas: mostly methane, CH 4. Crude oil: mixture of hydrocarbons distillation to separate components Coal: decayed plant matter, high C content. Combustion: hydrocarbon + # O 2 # CO 2 + # H 2 O + Energy balance of chemical elements on each side CO 2 an unavoidable product. How much? Depends on hydrocarbon, how much C.

4 Last Lecture: Fossil Fuels Petroleum:liquids and gas from ancient oceanic organic matter. (Typically 50 MJ/kg energy content) Coal: decayed plant matter, high C content. [Q: Why petroleum from decay in oceans, coal from land? A: I m still working on finding a decent explanation of this. The correlation seems wellestablished: petroleum in sedimentary formations, from ocean floors. Chemical mechanism?]

5 Last Lecture: Fossil Fuels Fossil Fuels: What are they? Combustion: What is it? Next Fossil Fuels: How much do we have left? Environmental Impacts

6 Terms: Fossil Fuel Resources Resource: total amount of fuel in ground (discovered + undiscovered; recoverable + not recoverable). Uncertain, but can be estimated. Reserve: fossil fuels that we re reasonably certain exist, and that are recoverable A lot of effort goes into finding, quantifying reserves.

7 World Oil Reserves Oil reserves are distributed very unevenly throughout the globe: data from U.S. Dept. of Energy

8 World Oil Reserves Oil reserves are distributed very unevenly throughout the globe:

9 Here s oil usage! World Oil Usage data from U.S. Dept. of Energy

10 U.S. Oil use The U.S. uses a lot of oil 2/3 of this is for transportation Most of it is imported (red curve): Why? Are we lazy?

11 U.S. Oil use Most U.S. oil is imported

12 U.S. Oil production Domestic oil production has been steadily declining since A finite resource! (And we re nearly done.)

13 U.S. Oil production Domestic oil production has been steadily declining since A finite resource! (And we re nearly done.) We ve used about 60% of the US reserves of oil At the current rate: all gone around 2050 What about global production?

14 World Oil Production World oil production: rapid rise slowing... U.S. Energy Information Administration

15 How much oil is left? Oil: A finite resource. We ll necessarily run out. When? Not known for certain. Estimates...

16 How much oil is left? Reserve Production Ratio a simple ratio based on energy in reserves & rate of energy use. Energy in reserves J (about 1 trillion barrels of oil) Presentrate of use J / year How many years will it take to use this? A. 3 years B. 30 years C. 1/3 of a year (4 months) D. 300 years

17 How much oil is left? Reserve Production Ratio a simple ratio based on energy in reserves & rate of energy use. Energy in reserves J (about 1 trillion barrels of oil) Presentrate of use J / year How many years will it take to use this? A. 3 years B. 30 years C. 1/3 of a year D. 300 years Time = Energy / Power = ( J) / ( J/year) = 3 10 years = 30 years

18 How much oil is left? Reserve Production Ratio a simple ratio based on energy in reserves & rate of energy use. This simple treatment assumes No new discoveries or oil recovery methods Constant rate of consumption Neither assumption is true New oil? Maybe...

19 New Oil Reserves? Geologists try to estimate the likelihood of undiscovered petroleum deposits. Very uncertain. Optimistic estimates: few hundred billion barrels ( 25% of present reserves)

20 New Oil Reserves? What about new sources like the Arctic National Wildlife Refuge? 20 million acre, ecologically remarkable area Contains 5 billion barrels of oil (estimated) Present U.S. Consumption: 7.5 billion barrels per year! So certainly not a long term fix, even ignoring environmental issues Economics: U.S. EIA estimates most probable reduction in crude oil price of $0.75 per barrel in 2025; present cost is $70 per barrel. Drill, baby, drill??

21 Unconventional Oil Sources Unconventional fossil resources: presently difficult & expensive to extract oil from Oil Shale: rock with kerogen, a waxy precursor to petroleum. With lots of $, energy, environmental damage, can process oil shale into petroleum. Tar Sands: sands into which oil has leaked. Lots in Canada. From 2 tons of tar sands can extract 1 barrel of oil.

22 From the text: Extraction of oil from tar sands entails massive environmental degradation.

23 Unconventional Oil Sources Unconventional fossil resources: presently difficult & expensive to extract oil from Future: extraction from unconventional sources may be technologically more feasible, and may be economically appealing as other sources become scarcer and more expensive. Future is now: mining tar sand mining in Canada CO 2 emissions: Note that new sources of oil still produce CO 2 a necessary combustion product!

24 How much oil is left? Reserve Production Ratio a simple ratio based on energy in reserves & rate of energy use. This simple treatment assumes No new discoveries or oil recovery methods Constant rate of consumption Neither assumption is true rate of consumption...

25 ... is rising. Source: U.S. E.I.A. Oil Consumption World:

26 Oil Consumption China: 6.5 million barrels / day (2005) growing at 7.5 % annually exponential growth! Per capita: U.S.: 69 barrels oil / person / year China: 5 barrels oil / person / year As developing nations develop, global oil consumption will increase. Photo: the Tata Nano, designed & built in India as a people s car (2008), costing $2,200. (Before you complain, ask why you deserved to grow up with a car!)

27 Oil Consumption What about domestic consumption: 21 million barrels / day. Increasing over the last decade. We re setting a poor example...

28 Summary: How much oil is left? Reserve Production Ratio 30 years New discoveries, sources: Maybe; hard to estimate Not likely to be huge Rate of consumption likely to increase, not decrease Should you be worried? Excited? Probably yes to both!

29 Natural Gas How much natural gas is left? Estimate: will probably last a few decades more than oil

30 How much coal is left? Coal If present rate of consumption holds, a few hundred years worth. consumption rate will probably increase, as other fuels are depleted. still, less urgent than oil.

31 Coal How much coal is left? If present rate of consumption holds, a few hundred years worth. What dampens our happiness about this? A. Burning coal doesn t release much energy B. Burning coal releases a lot of CO 2. C. Coal is mostly located in politically unstable countries.

32 Coal How much coal is left? If present rate of consumption holds, a few hundred years worth. What dampens our happiness about this? A. Burning coal doesn t release much energy B. Burning coal releases a lot of CO 2. C. Coal is mostly located in politically unstable countries. Actually, the U.S. is the Saudi Arabia of Coal D. Air Pollution from coal is more severe than other fuels E. Mining coal causes considerable environmental damage.