ERTH15 2006 Special Topic: Energy

ERTH15 2006

Traditional Energy Resources

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.

alternative energy resources

Energy, Resources and Fuel

Energy:

Resources:

Fuel:

The steep increase in energy needs

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.

nonrenewable

renewable

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

(show me a figure)

Making an Oil Reserve

three items are required to make an oil reserve:

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?

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Oil Exploration and Production then and now

THEN:

seeps

rock oil

gusher

NOW:

reflection seismic method

crack the oil

Advantages and Disadvantages of Natural Gas

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FOSSIL FUELS: Coal

How does Coal Form?

Coal is formed from plant material:

plants are buried in an oxygen-poor environment (a.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.

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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

seams

Strip mining

underground mining

Charcoal

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%

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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%

References

Earth, 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

ERTH15 2006

Traditional Energy Resources

Energy, Resources and Fuel

The steep increase in energy needs

Sources of Energy in General

FOSSIL FUELS: Oil and Gas

FOSSIL FUELS: Coal

Air Pollution due to the Burning of Fossil Fuels

References