Coal

Potential for Coal-to-Liquids Conversion in the United States—Fischer–Tropsch Synthesis

Publication date:
2009-06-09
First published in:
Natural Resources Research
Authors:
T.W. Patzek, G.D. Croft
Abstract:

The United States has the world’s largest coal reserves and Montana the highest potential for mega-mine development. Consequently, a large-scale effort to convert coal to liquids (CTL) has been proposed to create a major source of domestic transportation fuels from coal, and some prominent Montanans want to be at the center of that effort. We calculate that the energy efficiency of the best existing Fischer–Tropsch (FT) process applied to average coal in Montana is less than 1/2 of the corresponding efficiency of an average crude oil refining process. The resulting CO2 emissions are 20 times (2000%) higher for CTL than for conventional petroleum products. One barrel of the FT fuel requires roughly 800 kg of coal and 800 kg of water. The minimum energy cost of subsurface CO2 sequestration would be at least 40% of the FT fuel energy, essentially halving energy efficiency of the process. We argue therefore that CTL conversion is not the most valuable use for the coal, nor will it ever be, as long as it is economical to use natural gas for electric power generation. This finding results from the low efficiency inherent in FT synthesis, and is independent of the monumental FT plant construction costs, mine construction costs, acute lack of water, and the associated environmental impacts for Montana.

Published in: Natural Resources Research, article in press
Available from: SpringerLink

Historical trends in American coal production and a possible future outlook

Publication date:
2009-04-01
First published in:
International Journal of Coal Geology
Authors:
M. Höök, K. Aleklett
Abstract:

The United States has a vast supply of coal, with almost 30% of world reserves (BP, 2008) and more than 1600 Gt (short) as remaining coal resources (Ruppert et al., 2002). The US is also the world’s second largest coal producer after China and annually produces more than twice as much coal as India, the third largest producer (BP, 2008). The reserves are concentrated in a few states, giving them a major influence on future production. Historically many states have also shown a dramatic reduction in recoverable coal volumes and this has been closely investigated. Current recoverable estimates may also be too high, especially if further restrictions are imposed. The average calorific value of US coals has decreased from 29.2 MJ/kg in 1950 to 23.6 MJ/kg in 2007 as U.S. production moved to subbituminous western coals (Annual Energy Review, 2007). This has also been examined in more detail. This study also uses established analysis methods from oil and gas production forecasting, such as Hubbert linearization and logistic curves, to create some possible future outlooks for U.S. coal production. In one case, the production stabilizes at 1400 Mt annually and remains there until the end of the century, provided that Montana dramatically increases coal output. The second case, which ignores mining restrictions, forecasts a maximum production of 2500 Mt annually by the end of the century.

Published in: International Journal of Coal Geology, Volume 78, Issue 3, May 2009, Pages 201-216
Available from: ScienceDirect
also available from: Global Energy Systems

Expert: Coal Reserve Estimates Way Too High

Publication date:
2008-12-19
First published in:
Seeking Alpha
Authors:
Michael Kanellos
Abstract:

Government agencies have estimated that there is about 850 billion to 998 billion tons of coal in the ground that can be economically recoverable.

Not so, says David Rutledge, the Kiyo and Eiko Tomiyasu Professor of Engineering at Caltech, who has done his own estimates and showed them off this week at the American Geophysical Union in San Francisco.

Rutledge estimates that the Earth had only 662 billion tons of recoverable coal in the first place and around 59 percent of the total remains. Thus, the real estimate of existing reserves is closer to 400 billion tons. (The earth, he added, contained the equivalent of 1 trillion tons of oil before the industrial age began.) He came to the conclusion by analyzing production data, similar to how M. King Hubbert in 1956 predicted U.S. oil production would peak in 1970. It peaked in 1971.

That number, to some degree, is good news for the renewable power industry. Nearly 400 tons of coal would be enough to provide electricity for decades. It would also add huge amounts of pollution to the atmosphere. Still, it makes a peak for coal more tangible and realistic and thus can prompt policy makers and investors to take even more interest in things like solar thermal power or nuclear...

Published in: Seeking Alpha, 19 December 2008
Available from: Seeking Alpha

World Coal Reserves Could Be a Fraction of Previous Estimates

Publication date:
2008-12-17
First published in:
Wired Science
Authors:
Alexis Madrigal
Abstract:

A new calculation of the world's coal reserves is much lower than previous estimates. If validated, the new info could have a massive impact on the fate of the planet's climate.

That's because coal is responsible for most of the CO2 emissions that drive climate change. If there were actually less coal available for burning, climate modelers would have to rethink their estimates of the level of emissions that humans will produce.

The new model, created by Dave Rutledge, chair of Caltech's engineering and applied sciences division, suggests that humans will only pull up a total — including all past mining — of 662 billion tons of coal out of the Earth. The best previous estimate, from the World Energy Council, says that the world has almost 850 billion tons of coal still left to be mined.

"Every estimate of the ultimate coal resource has been larger," said ecologist Ken Caldeira of Stanford University, who was not involved with the new study. "But if there's much less coal than we think, that's good news for climate."...

Published in: Wired Science, 17 December 2008
Available from: Wired Science

Thermodynamics and the Economic Process

Publication date:
2008-12-01
First published in:
http://www.vocat.co.uk/
Authors:
John Bryant
Abstract:

This paper develops further a a model of the economic process concerning the application of thermodynamic laws to economics. The paper sets out relationships between economic output and capital, labour, resource and waste stocks, with specific reference to energy, and is backed up by analysis of data of world energy resources and climate change. the paper concludes that both energy resource availability and climate change will have significant, limiting effects on the forward path of economic development.

Published in: Vocat International Ltd
Available from: Vocat International Ltd

Energy Resources

Publication date:
1969-07-03
First published in:
Geothermal Energy
Authors:
M. King Hubbert
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