06 fossil

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Fossil Fuels: 

Fossil Fuels Our fantastic flash in the pan

A brief history of fossil fuels: 

A brief history of fossil fuels Here today, gone tomorrow What will our future hold? Will it be back to a simple life? Or will we find new ways to produce all the energy we want? Or will it be somewhere in the middle

Finding Oil: 

Finding Oil Oil is trapped in special (rare) geological structures Most of the oil in the world comes from a few large wells About one in ten exploratory drillings strike oil and this in places know to be oil-rich: get nothing in most of world Q

The Oil Window: 

The Oil Window Organic material must be deposited without decomposing oxygen-poor environment: usually underwater with poor flow Material must spend time buried below 7,500 feet of rock so that molecules are “cracked” into smaller sizes But must not go below 15,000 feet else “cracked” into methane: gas, but no oil So there is a window from 7,500 to 15,000 feet Additional circumstances must be met existence of “caprock” to keep oil from escaping: even a drop per second depletes 20 million barrels per million years source rock must be porous and permeable to allow oil flow

The hydrocarbons: 

The hydrocarbons All fossil fuels are essentially hydrocarbons, except coal, which is mostly just carbon Natural Gas is composed of the lighter hydrocarbons (methane through pentane) Gasoline is hexane (C6) through C12 Lubricants are C16 and up kJ per gram 55 51 50 46 48 48 48 48 48 48

Hydrocarbon Reactions: 

Hydrocarbon Reactions Methane reaction: CH4 + 2O2  CO2 + 2H2O + energy 1 g 4 g 2.75 g 2.25 g 55 kJ Octane reaction: 2C8H18 + 25O2  16CO2 + 18H2O + energy 1 g 3.51 g 3.09 g 1.42 g 48 kJ For every pound of fuel you burn, you get about three times that in CO2 one gallon of gasoline  ~22 pounds of CO2 occupies about 5 cubic meters (1300 gallons) of space Q2

Aside: Carbohydrate Reactions: 

Aside: Carbohydrate Reactions Typical carbohydrate (sugar) has molecular structure like: [CH2O]N, where N is some integer refer to this as “unit block”: C6H12O6 has N=6 Carbohydrate reaction: [CH2O]N + NO2  NCO2 + NH2O + energy 1 g 1.07 g 1.47 g 0.6 g 17 kJ Less energy than hydrocarbons because one oxygen already on board (half-reacted already) For every pound of food you eat, exhale 1.5 lbs CO2 Actually lose weight this way: 0.5 to 1.0 lbs per day in carbon Must account for “borrowed” oxygen mass and not count it

So where does our petroleum go?: 

So where does our petroleum go? Each barrel of crude oil goes into a wide variety of products Most goes into combustibles Some goes to lubricants Some goes to pitch and tar Some makes our plastics 40% of our energy comes from petroleum


Who’s got the crude oil resources?

Let’s get our barrels straight: 

Let’s get our barrels straight An oil barrel (bbl) is 42 gallons, or 159 liters In the U.S., we use about 24 bbl per year per person average person goes through a barrel in 15 days recall: 60 bbl/yr oil equivalent in all forms of energy: oil is 40% of our total energy portfolio That’s 7.2 billion bbl/yr for the U.S. 20 million bbl/day For the world, it’s 25 billion bbl/year 69 million bbl/day

Oil in the World (older data): 

Oil in the World (older data)

Excerpts from current Table 2.2 in book: 

Excerpts from current Table 2.2 in book

Notes on Table 2.2: 

Notes on Table 2.2 Not a single country matching U.S. demand of 20 Mbbl/day Reserves: Non-OPEC proved reserves: 173 Gbbl OPEC reserves: 882 Gbbl Total: 1055 Gbbl To maintain current production of 68 Mbbl/day… this will last 42.5 years means entries in previous table with longer timescales than this would have to step up production, if they can may not be possible to extract oil fast enough for demand Saudi Arabia used to produce at less than 100% capacity, now running full-out

How long will the world oil supply last?: 

How long will the world oil supply last? Not as long as you might think/hope We’ll be spent before the century is done, but we’ll have to scale down oil usage before then (in the next few decades)

How about the U.S. Supply?: 

How about the U.S. Supply? The estimated total U.S. supply is 230–324 billion bbl We’ve used >60% of this, leaving 130 billion barrels Production is already down to 60% of peak At current rate of production, will be exhausted before 2070 If we used only U.S. supply, we’d run out in 18 years!! Q

Discovery must lead production: 

Discovery must lead production There must be a lag between the finding of oil and delivery to market In the U.S., discovery peaked around 1950, production peaked in 1970

Various Estimates of Oil Remaining: 

Various Estimates of Oil Remaining To date, we’ve used about 1000 billion barrels of oil worldwide We seem to have about this much left halfway through resource There will be some future discovery still, but likely small beans ANWR: 5–10 Gbbl  1 years’ worth at U.S. consumption rate In any case, production unlikely to increase appreciably from this point forward will soon fail to pump as fast as today’s demand Q

Worldwide Discovery and Production: 

Worldwide Discovery and Production discovery peaked before 1970; production peak soon to follow

The Hubbert Peak Idea: 

The Hubbert Peak Idea Hitting new oil field must precede assessment of oil capacity Discovery peak (numerical assessment) must follow hits Production peak follows discovery (assessment) Area under three curves the same (total oil resource) Deffeyes estimates that we’ve hit 94%, discovered 82%, and produced 50% as of about 2005

Logistic (“S”) curves: 

Logistic (“S”) curves exponential logistic resource rate of growth time resource time Qmax Qmax Logistic curves result from growth limited by a finite resource: at first exponential, but unable to sustain exponential once resource limits kick in marks half-way point

Rate plot for U.S.: 

Rate plot for U.S. Can plot rate of production (P: annual production) divided by resource (Q: total produced to date) against total resource, Q P/Q is like an interest rate: fractional increase per year A “logistic” or S-curve would follow a straight line sloping down U.S. oil production does so after 1958 When you get to zero P/Q, you’ve hit the end of the resource: no more growth Peak Production; half consumed 1970

Same fit, in rate history plot: 

Same fit, in rate history plot The best-fit line on the previous plot produces a decent fit to the rate history of oil production in the U.S. Supports the peak position well, and implies a total resource of about 225 Gbbl

World Data: 

After 1983, world data follows logistic curve shows us halfway along 2,000 Gbbl at 2005 (now) implies we’re at the peak right about now World Data 2Q

Discouragement of Oil Usage: 

Discouragement of Oil Usage In this country, there is no such thing U.S. taxes on gasoline are 6.5 times lower than in most industrialized countries (about 32 cents per gallon in the U.S.) The Frito Lay attitude: Burn all you want—we’ll pump more Efforts on the part of the U.S. to keep oil prices low have lead to numerous questionable actions on the international scene Q

Natural Gas: 

Natural Gas Extracted as oil-drilling byproduct was once burned off at well head as means of disposal Mostly methane, some ethane, and a little propane, butane 2 times cheaper than electricity per energy content, comparable gasoline per joule this is recent: last time I taught the class (2004), it was 3.5 times cheaper than electricity, 3 times cheaper than gas Well-suited to on-the-spot heat generation: water heaters, furnaces, stoves/ovens, clothes dryers more efficient than using fossil-fuel-generated electricity

Distribution of natural gas: 

Distribution of natural gas Impractical to ship: must route by pipe 1.3 million miles of pipe (250,000 miles of mains)

How much do we use, and where do we get it?: 

How much do we use, and where do we get it? In 2003, we used 21.8 tcf (Tera-cubic feet, or 1012ft3); about 23 QBtu (23% of total) Out of the 21.8 tcf used, 88% was domestic 11.8% from Canada 0.08% from Algeria (shipped in liquefied form) 0.03% from Mexico Have used about 1,100 tcf to date Q

How much do we have left?: 

How much do we have left? Estimated recoverable amount: 871 tcf 40 years at current rate Estimates like this do account for future discoveries present proven reserves provide only 8 years’ worth


Coal Coal is a nasty fuel that we seem to have a lot of Primarily carbon, but some volatiles (CO, CH4) Reaction is essentially C + O2  CO2 + energy Energy content varies depending on quality of coal, ranging from 4–7 Cal/g Highly undesirable because of large amounts of ash, sulphur dioxide, arsenic, and other pollutants Also ugly to remove from the ground

Coal types and composition: 

Coal types and composition Natural Graphite Anthracite Bituminous Bituminous sub- bituminous Lignite Peat Wood fixed carbon ash volatile matter moisture content kJ/g 34 29 35 31 27 25 21 20

Use of Coal: 

Use of Coal 88% of the coal used in the U.S. makes steam for electricity generation 7.7% is used for industry and transportation 3.5% used in steel production 0.6% used for residential and commercial purposes 0.1% used on Halloween for trick-or-treaters

Estimated Worldwide Coal Reserves: 

Estimated Worldwide Coal Reserves

U.S. Coal Production History: 

U.S. Coal Production History

When will coal run out?: 

When will coal run out? We use 109 tonnes of coal per year, so the U.S. supply alone could last as long as 1500 (250) years at current rate Using variable rate model, more like 400–600 (75–100) years especially relevant if oil, gas are gone This assumes global warming doesn’t end up banning the use of coal Environmental concerns over extraction also relevant

Shale Oil: 

Shale Oil Possibly 600–2000 billion barrels of oil in U.S. shale deposits compare to total U.S. oil supply of 230 billion bbl Economically viable portion may only be 80 billion bbl 8 times less energy density than coal lots of waste rock: large-scale disposal problem Maximum rate of extraction may be only 5% of our current rate of oil consumption limited by water availability

Tar Sands: 

Tar Sands Sand impregnated with viscous tar-like sludge Huge deposit in Alberta, Canada 300 billion bbl possibly economically recoverable It takes two tons of sands to create one barrel of oil energy density similar to that of shale oil In 2003, 1 million bbl/day produced 2002 production cost was $20 per barrel, so economically competitive

References and Assignments: 

References and Assignments Hubbert’s Peak: The Impending World Oil Shortage, by Kenneth Deffeyes Beyond Oil, by same author Out of Gas: The end of the Age of Oil, by David Goodstein Read Chapter 2 in book Read Chapter 3 for next lecture HW2 available on website, tough problems: get a start soon! due Thursday 4/19

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