LAST MODIFIED: May 30, 2013

POSTED: November 26, 2011

• Preface
Energy resources are obviously becoming an increasingly complex and politically charged topic. Energy production, consumption, related global warming and ways out of the dilemma can hardly be covered in a single lecture. I therefore offer this material as additional info material for the interested students. Also check out the supplement that provides links relevant to opening the area near the Arctic National Wildlife Refuge for oil exploration/production.
Also check out additional material on alternative energy resources.

• Energy, Resources and Fuel

Energy: Capacity to do work, to cause change in a system.
Resources: Items that can be employed for a useful purpose.
Fuel: energy resource that consists of matter that stores energy in a usable form (e.g. wood, oil)

• The steep increase in energy needs

By the end of the seventeenth century, energy resource needs began to outpace the supplies available at the Earth's surface (e.g. wood). Since the industrial revolution, different energy resources have been used over the past 150 years to accommodate our needs. While coal, wind and flowing water were used extensively at the beginning of the nineteenth century, hydrocarbons (oil and natural gas) now account for more than 50% of the world's energy usage (60% in the U.S). Nuclear energy has been provided since the 1950ies. While nuclear energy was initially hailed as the ideal alternative energy resource, people now recognize a significant waste disposal problem.
According to the textbook an American today uses more than 110 times the amount of energy needed by a prehistoric hunter-gatherer.

• Sources of Energy in General

• Energy directly form the sun: electromagnetic radiation produced during solar fusion; solar energy can be converted to electricity (through photo-voltaic solar panels) or be used to heat water or a house (through solar collectors). To date, we cannot do controlled fusion on Earth to create economically meaningful amounts of energy. Uncontrolled fusion processes happen in H-bombs.
• Energy directly from gravity/tides: the moon (and to a lesser extent the sun) causes tides on Earth due to gravitational pull. The daily incoming and outgoing tides in some bays or estuaries are used to drive turbines (e.g. France and Canada).
• Combined solar and gravitational energy: Wind drives sails, wind mills and wind turbines. Wind is created when heated air rises (cool air sinks) and stirs the atmosphere. Water condenses in cooling air eventually causing rain to fall. Water at the Earth's surface flows and drives turbines and water wheels.
• Photosynthesis: The chlorophyll in plants uses light to produce sugar as an energy resource. Plants use CO₂ in the process and produce O₂. Burning plant material uses up O₂ and creates CO₂, H₂O, C (soot), other gases and heat.
• Chemical reactions: some inorganic chemical compounds burn to produce light and heat (e.g. dynamite).
• Fossil fuels: oil and coal are made of organisms that lived a long time ago. Burning fossil fuels has the same effects as burning plants.
• Nuclear fission: atoms of radioactive elements spontaneously split to create energy. Nuclear reactors can be found in nuclear power plants, submarines and spacecrafts.
• Earth's internal heat: The Earth's cooling and radioactive decay of some elements produce heat near the surface. Water is heated underground and can be used as hot water directly or to produce steam and drive turbines.
The most widely used energy resources are fossil fuels (oil, gas, coal), nuclear power (nuclear fission) and moving water. The first two are nonrenewable energy resources, while moving water, wind and Earth's internal heat are renewable energy resource.
Consumption of Energy in the U.S., 1997

Energy Resource	Fraction 1997	Fraction 2002
Petroleum	41%	41%
Natural Gas	24%	22%
Coal	22%	24%
Nuclear	7%	9%
Hydroelectric	5%	3%
others	1%	1%

NB: numbers may vary, depending on the reference. Some references list the contribution of "nuclear energy" as high as 20% but the fraction is probably going down (see below). Also, a distinction has to be made between production and consumption (e.g. the U.S. imports a significant amount of electricity from Canada).

• FOSSIL FUELS: Oil and Gas

For reasons of economics and convenience, industrialized societies today rely primarily on oil and natural gas for their energy needs. Oil and gas are hydrocarbons, ring or chainlike molecules of C and H, and are organic chemicals. Hydrocarbons have varying viscosity and the volatility depends on the molecule size.
• How Do Oil and Gas Form?
• the primary source are dead algae and plankton
• dead organisms sink and settle on lake, lagoon or ocean bottom
• with clay in quiet environment (no rivers!) to create muddy ooze
• oxygen-poor water (anaerobic environment) so that material does not decay quickly
• lithification to black organic shale (eventually being the source rock for oil)
• at rising T (100^oC) organic material transforms to kerogen (waxy molecules)
• kerogen turns into a mixture of tar, oil and gas, where the shale is now called oil shale
• at T>160^oC, any remaining oil breaks down to form gas and at T>250^o the remaining organic matter transforms into graphite
• The Oil Window
The oil window (show me a figure) is the range of temperature conditions and depth at which hydrocarbons form. In regions with a geothermal gradient of 25^oC per km, oil occurs only at depths of less that about 6.5 km. Gas can be found at greater depths. The length of hydrocarbon chains decreases with increasing depth.
• Making an Oil Reserve
three items are required to make an oil reserve:
• source rock
• reservoir rock
• oil trap
• seal rock
Oil traps are very important because they accumulate oil so to make production economically feasible (extracting oil directly from oil shale is too expensive!)

Possible oil traps:
• anticline traps
• salt-dome traps (salt is less dense than surrounding rock and rises in diapirs)
• fault traps
• stratigraphic traps
• Where Are the Largest Oil Fields?
Oil can be found in sedimentary deposits. Large oil fields can be found in the Canadian Arctic Ocean, Gulf of Mexico, North Sea, Kara Sea/Northern Russia and the Persian Gulf (largest oil fields). Huge natural gas reserves can be found in Siberia (1/3 of the world's reserves).show me the map¹.
Two oil reserves that are very important U.S. domestic resources are the Gulf of Mexico and off-shore Alaska. The latter currently provides 20% of U.S. domestic oil and there are plans to expand oil production into the Arctic National Wildlife Refuge ( see more).

With 7 Mio barrels per day (1 barrel = 42 Gallons), the U.S. is the largest consumer worldwide, using about 25% of the produced oil (and contributing 25% of the world's CO₂ production). In the 1970ies, when the U.S. oil production passed its peak, the U.S. lost its position as largest producer. U.S. oil reserves now account for only 4% of the world's reserves. So the U.S. must now import more than 50% of its used oil.
• Oil Exploration and Production then and now
THEN: Until the first half of the 19th century, the only available oil came from seeps as rock oil. Oil was used in lamps, to grease wheels and for medical purposes.
In 1859, drilling and pumping oil (from a depth of 21.2 m) started in Titusville, Pennsylvania. The first oil find in Texas was in 1900 in Spindletop. Spindletop became the first gusher in January 1901 and produced oil at a rate (75,000 barrels per day) never seen before. John D. Rockefeller established the Standard Oil Company which monopolized production, transport and the processing of oil.

NOW: The Supreme court eventually broke down the monopoly into smaller companies including Exxon, Chevron, Mobil, Sohio, Amoco, Arco and Conoco.
Wildcatters (people searching for oil) first searched randomly then more systematically (source rock and most reservoir and seal rocks are sedimentary rocks!) using geologic maps.
Nowadays, oil companies use the reflection seismic method to find oil reservoirs. Vibrating trucks or explosives are used to generate seismic waves that travel through the ground. They reflect off internal interfaces (boundaries of buried layers) and show up as enhanced signals at a seismic receiver along a line. The waveforms at a line of seismic receivers can tell us about the geometry of the buried layers. This is a very expensive method but not as expensive as drilling a possibly "dry" hole (a hole costs $10 Mio!).
Simply pumping the oil out of the ground retrieves only 30% of the oil in the reservoir rock. Secondary recovery techniques (e.g. force oil to migrate to a well by pumping steam into the ground) produce up to 50% more oil (i.e. more than 50% is left in the ground!). Crude oil goes into distillation columns in refineries to crack the oil by heating it. The residue (heavier molecules) goes into the plastic industry.
• Advantages and Disadvantages of Natural Gas
More abundant than oil; volatile, short-chain hydrocarbons (methane, ethane, propane, butane). Gas burns more cleanly than oil. Burning gas produces only CO₂ (the least amount of C of all fossil fuels) and water, while burning oil produces more complex organic pollutants. Gas transportation requires expensive high-pressure pipelines and containers making gas less attractive as energy source than oil. A current gas tank for cars needs to be refilled faster than a gasoline tank and is therefore only attractive for city traffic. However, note that natural gas has recently been introduced as fuel for motor vehicles (e.g. San Diego Public Transportation).

• FOSSIL FUELS: Coal

Mostly elemental Carbon mixed with minor amounts of organic chemicals, quartz and clay. Coal forms from plant material (wood, stems, leaves) in swamps and adjacent forests. Most coal was formed in the late Carboniferous and Permian Periods (320-245 Mio years ago) when the continents were locked together to form Pangaea. Coal was formed in equatorial Pangaea, so most coal-bearing areas of today were located in relatively warmer climate belt than today though global temperatures in the Carboniferous were relatively low.

Coal is the most polluting fossil fuel but reserves will last 3 times as long as the oil reserves (300 years). The U.S. burn 1 Billion tons of coal per year, mostly at electrical power plants that generate ~23% of U.S. electricity.
• How does Coal Form?
Coal is formed from plant material:
• plants are buried in an oxygen-poor environment (e.g. stagnant water)
• compaction and partial decay leads to peat which can already serve as energy source.
• peat buried beneath 4-10km of sediments (i.e. in a sedimentary basin)
• loss of water due to pressure and heating. Accelerates destruction of plant fibers and creation of coal minerals.
• changes in sea level can bring an originally coastal environment inlands (transgression)
• The Classification of Coal
The decayed and transformed matter is considered "coal" when more than 70% of it is Carbon. Low-grade coal contains significant amounts of sulfur which makes burning coal environmentally problematic.


Coal is classified by increasing amounts of (burnable) Carbon and, at the same time, decreasing amounts of H₂O, H₂, N₂ and S.
• Peat: 50% C (C stands for Carbon here)
• Lignite: from peat (soft dark-brown coal) (70% carbon)
• Bituminous Coal: from lignite at higher T (100-200^oC) (85% C)
• Anthracite Coal: from bituminous coal at even higher T (200-300^oC); formed at 8-10 km depth (95% C)
• Graphite: at even higher T and P (beneath mountain belts) where rock undergoes metamorphism during which all elements except Carbon leave the coal. The Carbon transforms to Graphite (i.e. coal cannot exist as a metamorphic rock!).
• Where are the Largest Coal Reserves?
Unfortunately, anthracite coal, the highest-grade coal that burns most efficiently and cleanly is the rarest. In the US, it is found at two places in Pennsylvania and Arizona. In general, coal deposits can be found in fluvial and deltaic sedimentary rocks on the continental platforms. More than half of the world's coal can be found in the United States and Former Soviet Union.
The Global Distribution of Coal Reserves

Country	Fraction
United States	28%
Former Soviet Union	26%
China	11%
Western Europe	10%
Australia	10%
Eastern Europe	6%
other	9%

• Finding and Mining Coal
Geologists look for strata that developed in tropical near-coastal, shallow-marine environment. Coal reserves build seams and can be mined when 1-3m thick or more. Coal is found in great quantities in the U.S. and Canadian Rocky Mtns, Appalachian and Midwestern U.S.. The mining technique depends on the depth of the coal reserve. Strip mining (an open pit) is most economic but leaves scars in the landscape. In underground mining miners dig shafts to get to the coal. This becomes dangerous when mine gases develop causing explosions and when mines collapse. Miners develop black-lung disease when particles wedge into lung pockets cutting off the oxygen supply.
Charcoal is not a fossil fuel and has nothing to do with the coal just described (though it is an air pollutant just like coal). Charcoal is made by burning plant and animal matter in a kiln (oxygen-poor environment) and it burns more efficiently than wood.

• Air Pollution due to the Burning of Fossil Fuels

Primary Pollutants from Burning Fossil Fuels

Pollutant	Fraction
Carbon Monoxide	49.1%
Sulfur Oxides	16.4%
Nitrogen Oxides	14.8%
Volatile Organics	13.6%
Particulates	6.0%

NB: the greenhouse gas CO₂ is not considered a pollutant and is therefore not included in this table! CO₂ in the atmosphere has increased from 290 ppm in 1850 to 370 ppm in 2000.
Sources of the Primary Pollutants

Process	Fraction
Transportation	46.2%
Stationary Source Fuel Combustion	27.3%
Industrial Processes	15.0%
Miscellaneous	9.0%
Solid Waste Disposal	2.5%

The pollution per car was even greater before catalytic converters were introduced in the 1970ies (see more).

• References

• ¹Earth, Portrait of a Planet, 2001. Stephen Marshak, Norton & Company Ltd., New York, ISBN: 0-393-97423-5
• Environmental Chemistry, 2000. Colin Baird, Freeman and Company, New York, ISBN: 0-7167-3135-3
• Hubbert's Peak, 2001. Kenneth S. Deffeyes, Princeton University Press, Princeton, ISBN: 0-691-09086-6
• Earth, An Introduction to Physical Geology, 1999. E.J. Tarbuck and F.K. Lutgens, Prentice Hall, Upper Saddle River, N.J., ISBN: 0-13-974122-4
• Earth's Dynamic Systems, 2001. W.K. Hamblin and E.H. Christiansen, Prentice Hall, Upper Saddle River, N.J., ISBN: 0-13-018371-7
• Physics, 1998. J.D. Cutnell and K.W. Johnson, John Wiley and Sons, New York, ISBN: 0-471-19768-8
• Physical Geology: Earth Revealed, 2005. D. McGeary, C.C. PLummer, D.H. Carlson, McGraw Hill, New York, ISBN: 007-282696-7
• http://en.wikipedia.org