Cooled coal emissions would clean air and lower health and climate-change costs

August 27, 2012, University of Oregon
Russell J. Donnelly, a physicist at the University of Oregon, revisited a cryogenic approach he'd devised in the 1960s to determine its potential effectiveness to remove dangerous emissions from coal-fired electrical plants. Credit: University of Oregon

Refrigerating coal-plant emissions would reduce levels of dangerous chemicals that pour into the air—including carbon dioxide by more than 90 percent—at a cost of 25 percent efficiency, according to a simple math-driven formula designed by a team of University of Oregon physicists.

The computations for such a system, prepared on an electronic spreadsheet, appeared in Physical Review E, a journal of the American Physical Society.

In a separate, unpublished and preliminary economic analysis, the scientists argue that the "energy penalty" would raise by about a quarter but also reap huge societal benefits through subsequent reductions of health-care and climate-change costs associated with burning coal. An energy penalty is the reduction of electricity available for sale to consumers if plants used the same amounts of coal to maintain while using a cryogenic cleanup.

"The cryogenic treatment of flue gasses from pulverized coal plant is possible, and I think affordable, especially with respect to the total societal costs of burning coal," said UO physicist Russell J. Donnelly, whose research team was funded by the U.S. Department of Energy for the work detailed in the published journal article.

"In the U.S., we have about 1,400 electric-generating unit powered by coal, operated at about 600 ," Donnelly said. That energy, he added, is sold at about 5.6 cents per kilowatt-hour, according to a 2006 estimate. "The estimated health costs of burning coal in the U.S. are in the range of $150 billion to $380 billion, including 18,000-46,000 , 540,000 , 13,000 and two million missed work or school days each year."

In their separate economic analysis, Donnelly and UO research assistant Robert E. Hershberger, also a co-author on the journal paper, estimate that implementing large-scale cryogenic systems into coal-fired plants would reduce overall costs to society by 38 percent through the sharp reduction of associated health-care and climate-change costs. Not in the equation, Donnelly said, are the front-end health-care costs involved in coal extraction through mining.

The cryogenic concept is not new. Donnelly experimented briefly in the 1960s with a paper mill in Springfield, Ore., to successfully remove odor-causing gasses filling the area around the plant using cryogenics. Subsequently the National Science Foundation funded a major study to capture sulfur dioxide emissions—a contributor to acid rain—from coal burning plants. The grant included a detailed engineering study by the Bechtel Corp. of San Francisco.

The Bechtel study showed that the cryogenic process would work very well, but noted that large quantities of also would be condensed, a consequence that raised no concerns in 1978. "Today we recognize that carbon dioxide emissions are a leading contributor to climate-warming factors attributed to humans," Donnelly said.

Out came his previously published work on this concept, followed by a rigorous two-year project to recheck and update his thermodynamic calculations and compose "a spreadsheet-accessible" formula for potential use by industry. His earlier work on the cryogenic treatment of emissions and natural gas sources had sparked widespread interest internationally.

While the required cooling machinery would be large—potentially the size of a football stadium—the cost for construction or retrofitting likely would not be dramatically larger than present systems that include scrubbers, which would no longer be necessary, Donnelly said. The new journal article does not address construction costs or the disposal of the captured pollutants, the latter of which would be dependent on engineering and perhaps geological considerations.

According to the Physical Review E paper, carbon dioxide would be captured in its solid phase, then warmed and compressed into a gas that could be moved by pipeline at near ambient temperatures to dedicated storage facilities that could be hundreds of miles away. Other chemicals such as sulfur dioxide, some nitrogen oxides and mercury also would be condensed and safely removed from the exhaust stream of the plants.

Last December the U.S. Environmental Protection Agency issued new mercury and air toxic standards (MATS), calling for the trapping of 41 percent of sulfur dioxide and 90 percent of mercury emissions. A cryogenic system would do better based on the conservatively produced computations by Donnelly's team—capturing at least 98 percent of , virtually 100 percent of mercury and, in addition, 90 percent of carbon dioxide.

"This forward-thinking formula and the preliminary analysis by these researchers offer some exciting possibilities for the electric power industry that could ultimately benefit human health and the environment," said Kimberly Andrews Espy, UO vice president for research and innovation. "Scientists at the University of Oregon are continuing to develop new ideas and advanced materials to foster a sustainable future for our planet and its people."

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5 / 5 (1) Aug 27, 2012
maybe this is the real application for solar and wind power, to generate power for cryogenics or waste-stream cleaning. That way, if the solar/wind stops, we just see a throttling of the waste stream rather than power generation capacity. Or, solar/wind located near fossil plants could be used as power for CO2 sequestration.

It wouldn't be the best solution, but overcomes problems with renewable power availability and with the energy costs to scrub waste streams.
1.6 / 5 (7) Aug 27, 2012
Carbon dioxide is a dangerous chemical?

So is dihyrodgen monoxide. And for about the same reasons.


Liberalism is a philosophy of consolation for western civilization as it commits suicide. - James Burnham.
2.7 / 5 (3) Aug 27, 2012
clean plus coal does not equal cleancoal.

it never will. coal is filthy , always will be. Time to pursue natural gas and natural gas liquids , nuclear energy including thorium reactors, renewables, and a more efficient grid and 'smart' device for lowering transmission lossses , waste and inefficiency.

there is no global warming catastrophe heading our way, there is a catastrophe of dirty soot and coal particulates coming our way, from every developing country in the world --particularly china. If we cannot lead the way by example, we're doomed to choke on smog.
5 / 5 (2) Aug 27, 2012
Carbon dioxide is a dangerous chemical?

So is dihyrodgen monoxide. And for about the same reasons.


No its not toxic but, its commonly believed that its release into the atmosphere has negative effects over time. Not saying I believe (I say believe because I'm not a scientist and haven't seen enough research either way for me to know) in AGW but, don't be purposefully blind.
Liberalism is a philosophy of consolation for western civilization as it commits suicide. - James Burnham.

not rated yet Aug 28, 2012
I'd like to see some numbers regarding total costs and cost of production comparing a 'new' coal plant using this technology vs a NG or nuclear plant.
not rated yet Aug 29, 2012
They explicitly mention leaving out front end health care costs for coal mining, but aren't those large? And don't they go up by 4/3 because the plant efficiency went to 3/4?

I'm not trying to nay-say this seemingly way-cool (oh. pun. sorry.) idea because even if you don't believe CO2 is a problem, getting rid of the extra mercury and sulfur dioxide seems like a pretty darn good idea.

I just hope those front-end coal extraction healthcare costs don't ruin the apparent cost benefit.

Next we can have a policy debate about the best way to inspire private industry to invest in the expensive new technology for the good of the public. Regulations? Tax breaks? Paid for out of Medicare savings? Utility bills? Oh boy!

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