Fossil Fuels
Chapter 19
http://www.anwr.org/gallery/pages/03-ANWRtoUSmap.htm
1. Natural Gas
• What it is:
– Mixture of methane (50-90%), heavier hydrocarbons (ethane,
propane, butane) and small amounts of H2S (highly toxic)
• Properties:
– Highly flammable; transportation difficult. Done in pipelines
– Cleanest burning fossil fuel
• Methane is dried, cleansed of H2S, pumped in low
pressure lines nationally.
• Heavier gases are removed as liquefied petroleum gas
(LPG) for use in rural areas.
Natural Gas Distribution
Hydraulic Fracturing
• How:
– Pumping water & chemicals under high
pressure underground to force natural
gas/petroleum to surface
• Problems:
– Possible groundwater contamination
– CH4 released
– Release of Fracking Chemicals
http://en.wikipedia.org/wiki/File:HydroFrac.png
How Much Is There?
• Resource:
– A concentration of
material that is
economically feasible
to extract, now or in
the future.
• Reserve:
– Portion of the resource
that can be extracted
now, economically &
legally.
How Long Will Natural Gas Last?
• At current consumption rate, factoring in
undiscovered reserves, approximately 125
years.
• Including unconventional sources, 200325 years
2. Coal
• What is it:
– Solid fuel formed from
plant matter during
Carboniferous period, 360285 million years ago.
• C content increases,
water content decreases
over time
• Ranked according to
energy content
Type
Energy Content
(megajoules/kg)
Location in
US
1.
Anthracite
30-34
PA
2.
Bituminous
23-34
Appalachia,
Midwest, West
3.
Subbituminous
16-23
West
4.
Lignite
13-16
Gulf Coast,
No. Great
Plains
• Half is acquired through Strip-Mining (Surface Mining)
• Acid Mine Drainage:
• rainfall reacts with exposed rock, reacts with
sulfides, produces sulfuric acid.
• Processed to remove much sulfur before burning
• Uses of Coal:
– converted into synthetic oil or gas.
– Mostly used by power plants to create electricity (60%
of electricity produced).
– Transported by train and coal slurry pipelines (uses
more water).
Open Pit Mining: digging at the surface to extract ore
Coal Surface Mining in Wyoming
http://en.wikipedia.org/wiki/Strip_mining#Strip_mining
Coal Mine in India
http://en.wikipedia.org/wiki/File:182619562_00d6f703b6_b.jpg
Pollution & Coal
• Burning releases mercury into env.
• Takes a great deal of water; expensive, heavy
environmental impact
• Production of NOx and SOx
• Particulate Ash
• Treatment--Scrubbing
– calcium carbonate-rich materials are injected into the gases
produced from burning coal, producing hydrated calcium sulfite
as sludge.
– Disposal issues.
How Long Will Coal Last?
• At current consumption, 225 years. If
usage rises 2%/yr, 65 years.
• Believed to be unidentified reserves
projected to last 900 years.
3. OIL!
• Petroleum (crude oil):
– thick liquid consisting of hundreds of combustible hydrocarbons.
• Impurities
– sulfur, oxygen, nitrogen & other impurities.
• Formation
– decomposition of organic matter (mostly plant)
– extreme pressures & temperatures
– millions of years
• Usually dispersed throughout pores in rocks.
Oil Recover: 3 Stage Process
• Primary:
– Drilling a well, then remove oil that flows into the well.
• Secondary:
– Pumping water under high pressure into a nearby well, forcing
oil out, pump up to surface,
– remove water from oil and reuse the water for recovery.
• Tertiary:
– Use of superheated steam, CO2 or detergent to dissolve oil,
then removed from that.
– Large amounts of energy needed (~1/3 barrel for every barrel
produced)
• Production clip
Fractional Distillation
• Separating the components that make up
crude oil.
• Uses boiling points of the various fractions
64% in the Middle East;
26% in Saudi Arabia alone
Oil Facts
• US uses 30% of crude oil
extracted; 68% for transportation
•
•
•
•
$130.00 per barrel on 6/6/08
$48.92 per barrel 4/22/09
$91.58 per barrel 4/25/13
1 barrel petroleum = 42 gallons
Reserves…
• Production of reserves expected to peak
between 2010 and 2030. Peaked in US in
1975.
• Undiscovered supplies may extend it 2040 years.
Other Sources of Oil
• Oil Shale: fine-grained sedimentary rock containing
kerogen.
– Distilled to form shale oil.
– Potentially recoverable from CO, UT, WY.
– Generally very low grade, takes much energy.
• Tar sand: mixture of clay, sand, water & bitumen (thick,
high sulfur oil).
– Most lie below earth’s surface; those close can be mined.
– Largest deposits in Canada, UT, Venezuela, Colombia, Russia.
Hubbert’s Prediction for Peak Oil Production
http://en.wikipedia.org/wiki/File:Hubbert_peak_oil_plot.svg