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Cryogenic treatment could cut coal-fired power plant emissions by 90%


August 27, 2012

Cooling the emissions from coal-fired power plants would significantly reduce the levels of dangerous chemicals entering the atmosphere (Photo: Shutterstock)

Cooling the emissions from coal-fired power plants would significantly reduce the levels of dangerous chemicals entering the atmosphere (Photo: Shutterstock)

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A team of physicists from the University of Oregon (UO) has calculated that cooling the emissions from coal-fired power plants would result in a reduction of the levels of dangerous chemicals entering the atmosphere, including CO2, by 90 percent. While cryogenic treatment would also see a 25 percent drop in efficiency, and therefore result in electricity costs increasing around a quarter, the researchers believe these would be offset by benefits to society, such as reductions in health-care and climate-change costs.

Previous studies, including one conducted in the 1970s by the Bechtel Corp. of San Francisco, have shown that cryogenic treatment of flue gases from coal-fired power plants can work. While the Bechtel study was looking at its effectiveness in capturing sulfur dioxide emissions, it also noted that large quantities of CO2 would also be condensed – something that didn’t warrant much attention back in the 70s but is of tremendous interest now.

Building on previous research he carried out in the 1960s into using cryogenic treatment technology as a way to remove odor-causing gases being emitted from a paper mill in Springfield, Oregon, UO physicist Russell J. Donnelly and his team have now composed a math-driven formula on an electronic spreadsheet that could be used by industry to weigh up the potential benefits of the technology.

UO physicist Russell J. Donnelly

The team’s paper says that CO2 condensed and captured as a solid would then be warmed and compressed into a gas that could be delivered via pipeline at near ambient temperatures to dedicated storage facilities that could be located hundreds of miles away. Additionally, other chemicals including sulfur dioxide, some nitrogen oxides and mercury would also be condensed so they could be safely removed from the gases emitted by the power plants.

The team’s calculations show that a cryogenic system would capture at least 90 percent on CO2, 98 percent of sulfur dioxide, and virtually 100 percent of mercury emissions. This is more than the capturing of 41 percent of sulfur dioxide and 90 percent of mercury emissions called for by the new mercury and air toxic standards (MATS) issued by the EPA in December 2011.

The team’s formula doesn’t take into account the cost of construction or retrofitting of the cooling machinery to existing power plants, which would be much larger than existing systems that use scrubbers – potentially as large as a football stadium. Nor does it take into account the cost of disposing of the captured pollutants. However, Donnelly thinks such systems are affordable, “especially with respect to the total societal costs of burning coal.”

“In the U.S., we have about 1,400 electric-generating unit(s) powered by coal, operated at about 600 power plants," Donnelly said. “That energy, he added, is sold at about 5.6 cents per kilowatt-hour, according to a 2006 Congressional Budget Office 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 premature deaths, 540,000 asthma attacks, 13,000 emergency room visits and two million missed work or school days each year."

A separate, unpublished and preliminary economic analysis carried out by the team estimates that implementing large-scale cryogenic systems into coal-fired plants would see an overall reduction in costs to society of 38 percent through a sharp cut in associated health-care and climate-change costs.

The team’s paper appears in the journal Physical Review E.

Source: University of Oregon

About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag. All articles by Darren Quick

So it will be "delivered via pipeline at near ambient temperatures to dedicated storage facilities that could be located hundreds of miles away". Okay, then what? Storing CO2 is like hiding the problem under the carpet...

Steven Senatori

DO IT. I hereby reduce the military budget and allocate the funds to this project to save the health and lives of the very people that my military are supposed to be defending.


So... you have to burn 25% more coal to achieve the same output... that including the costs of commissioning and storage of the condensed gases would easily raise the cost of power for the end user up to 100%... And ok, sulphur dioxide and mercury are surely dangerous and it's worth trying to control them, but CO2, that is now "the enemy", is a natural byproduct even of our breathing http://en.wikipedia.org/wiki/Breathing and it's not really proven that it can affect our climate. Are we really willing to pay the price of such a system? More than a scientific study I see someone that smelt a business in re-proposing old theories in a period when media attention for the mighty CO2 is high.

Giolli Joker

It's like trying to look for a solution that doesn't have a problem? CO² is not now or has ever been a pollutant! We don't have to much of it and what ever amount we generate is a tiny fraction of what occurs naturally, the earth has seen MUCH higher CO² levels in it's history and those time have been beneficial over all to the progress of man. Cut pollutants I agree with but this hiding and prevention of CO² is a colossal wast of money and will be our down fall.


No deal. CO2 isn't poisonous any more than oxygen is. Just ask a tree. Keeping smoke out of the air is great, but I'm not willing to pay 25% more for my electricity. Smoke washes out eventually.

Clay Jones

Except they already by making O2 and using that to gasify coal, the byproducts are H2, CO and CO2, no N2 so by compressing to liquidfy the CO2, allowing it to be shipped to here needed for oil well recovery, etc or just stored underground is more eff than this proposal. Look up TECO Electric for details among many others now. TECO's been running 15-20 yrs now.

The the H2/CO also called syn gas, is easily cleaned of sulfur, radioactive metals, mercury, etc that make coal kill so many, 30k/yr and hospitalize 200k/yr in the US.

Far less expensive, polluting to the consumers is make their own power. PV is now at $1/wt, $1k/kw retail and wind at $2k/kw. An eff home needs just 2-3kw plus 1kw for each extra person above 1. Sadly few wind generators are available at such prices except Axial Flux wind generators.

Well shopped renewable energy for many pays off in 2-4 yrs and then almost free for 20-50 yrs afterward. Most RE is less complicated than a moped and really little reason to cost too much.


A football-stadium-sized cryogenic tunnel? Running liquid nitrogen maybe? I sure would like to see some end-to-end numbers here on the total cost.

Bruce H. Anderson

Yes, anything to keep using coal! Heaven forbid they we should move away from coal, oil and natural gas to clean, abundant, renewable wind water and sunlight. Was this idea backed by the coal industry?

Jerry Peavy

Did you know that most large greenhouses use CO2 generators? If there is too much CO2 already, why are they making more of their own? Because it helps the plants to grow better.


It amazes me that anyone even considers such gyrations when if we would simply ramp up the existing alternatives to burning coal (you all know what they are) we could have inexpensive electricity, avoid the exigent "societal costs" and save the coal for better uses.

But wait, that might make sense.....

Edward Kerr

The average life expectancy is over 70 years. We're no longer extending life, we are extending feebleness. Stop prolonging the inevitable, accept your mortality and focus on improving our lives rather than simply extending it. Close all power plants and replace them with nuclear. Save the oil and natural gas to power autos and trucks. Ice core samples from the arctics show that current temps directly correlate to a 150 yr cycle so stop fussing about global warming. Geesh!


Test then produce for coal fired plants in the Eastern US area.

Stephen Russell

For goodness sakes, no one is saying co2 is poisonous but Giolli Joker, there are numerous scientific studies that prove co2 causes greenhouse warming. There are further studies, published in scientific journals and peer reviewed that show co2 is almost certainly the primary reason we have global warming and that it is our excess production that is causing it. To say we breath out co2 and therefore it is not a problem is stupid if you even think about it for a moment. A coal powerplant is digging up carbon that has been out of the system for millions of years and dumping it at a great rate into the atmosphere. The carbon I exhale is carbon I have previously consumed or inhaled ie: no net change. The idea is to burn coal, get the benefit of electricity and then put back what we don't want: the carbon dioxide, sulphur and mercury. Yes it will cost more than not doing it but you may as well say it isn't worth putting your kitchen scraps in the bin (or garden) because it is more expensive than just chucking them on the floor. Do you want your kitchen and house to be filled with rubbish? Use your brain for once.


Naturally I have no more knowledge than anyone else about whether this particular smokestack cooling plan might prove useful. But that question is not what strikes me here. What I notice is a key difficulty which we usually ignore: there is no economic benefit to be gained from the survival of the human species.

That is to say, the future well-being of humankind does not offer any material benefit to those alive today. If we want to help future humans have decent lives, we can only use non-economic motives to change how our technological systems work.

But non-economic benefits are difficult or impossible to "sell" (the problem is evident in the necessary vocabulary). Right now in the U.S., many politicians make extravagant disclaimers about their non-interest in asking anyone to pay for benefits which might accidentally flow to anyone else.

And these are living persons they want to disown, here and now, so forget helping people of the future!

According to such calculations, no one has any rational reason to care what happens to any other current or future person. This sadly human reaction seems, somehow, simultaneously inexplicable and utterly routine.

That is the unresolved question at the root of all the endless arguments about climate change, saving the oceans, protecting endangered species, preserving the ozone layer and so forth.

As long as we cannot reach consensus on what -- if anything -- future human survival and quality of life are worth to those of us alive today, we can hardly expect to make substantive progress in deciding whether to adopt specific techniques.


@ Scion From the page I previously linked : "The permanent gases in gas we exhale are roughly 4% to 5% more carbon dioxide and 4% to 5% less oxygen than was inhaled. This expired air typically composed of:

78% nitrogen 13.6% - 16% Oxygen 4% - 5.3% Carbon dioxide 1% Argon and other gases

[...] Oxygen is used by the body for cellular respiration and other uses, and carbon dioxide is a product of these processes."

Regarding the effetcs of CO2 on global warming there are thousands of studies that WANT to prove that man generated CO2 affects the global temperature, yet none of them gave a real scientific proof. Most of the planets in the solar system seems to get warmer and warmer in recent years... damn humans with their power plants and cars! :-)

Giolli Joker

This might be a way to scrub coal smoke in a more cost effective way than conventional scrubbers. Stop thinking of sulfur dioxide, mercury and such as pollutants they are industrial chemicals for which companies pay good money.

Any time you have a thermal differential you can tap it to produce electricity, or mechanical energy. The cold "refined" industrial chemicals can be used as a heat sink to cool the cold side of a thermocouple or sterling cycle engine, the C02 presumably dry ice sealed into a tank and then warmed as part of the heat sink can drive a turbine during peak loads. At the same time we must not forget the boiled off cryogenic coolant will also expand greatly.


Goodness, there are still lots of clueless, blinkered sceptics about, even after the most hard-headed of them have given up: http://www.nytimes.com/2012/07/30/opinion/the-conversion-of-a-climate-change-skeptic.html

I quite agree with Ralph. If we go with those that still haven't figured it out, we could skip all this intermediate nonsense and follow their strategy to its logical conclusion: just build power stations that burn children directly.


Giolli Joker said: "there are thousands of studies that WANT to prove that man generated CO2 affects the global temperature, yet none of them gave a real scientific proof."

That you describe it like that suggests you don't know what a null hypothesis is, and thus don't know what a scientific proof is. I've already linked to an article about the BEST study - that is a fair example, though it didn't say anything new, merely confirming many other studies. What was significant about it is that it was done by a confirmed and very vocal CC sceptic, financed by about the biggest anti-AGW company in the world (Koch), set out expressly to try and discredit the available data and conclusions, and yet it found: a) Warming is taking place. b) CO2 is the principal cause. c) Human activity is the source of the CO2. I don't know how much clearer you want it to be. I guess we could just keep burning stuff faster until we get a 3° rise, drown a few major cities and kill a few billion people. Would that convince you? Unfortunately it would be too late to do anything by then.

If the whole world switched to nuclear, we'd be out of uranium in a few years. Wind, wave and solar are still nowhere near good enough to replace everything (though they are getting there - if only they could have even 10% of the ridiculous subsidies oil and coal get). Coal is still by far the cheapest in direct costs, but also has the worst enviromental impact of any energy source we have - that's why energy companies in the US have to provide free face masks to anyone living with 200 miles of a coal-fired power station. This development is good on balance - it reduces overall emissions, and it buys time to develop alternatives in coal-heavy markets like the US and China.


Even if AGW is real a point I am not willing to concede the is no evidence that it will be a net bad. The northern latitudes of Europe, Asia, and north America are very fertile but the yield is low because of cold weather and the current high yield farm land is not going to loose fertility because it is warmer even if the type of crops has to be changed.

If you do want to lower C02 production choose an option that can provide the power for the same standard of living. If you believe in AGW and that it is a disaster support Nuclear energy.


This is absolutely pointless. We already know how to turn coal emissions into Portland cement. This sequesters the emissions and also could reduce or eliminate the emissions of cement making. These are the two largest produces of greenhouse gasses taken car of in one sweep. You solve a problem and get a inexpensive product out of it. You cant beat that.


re; Synchro

Reread http://www.gizmag.com/uranium-seawater/23826/ we are in no danger of running out of nuclear fuel within the next 200 years even ignoring the option of using Thorium as the fuel.

It could provide the energy necessary to build the orbital solar power plants that combined with an orbital tower and superconductors could power the whole of technological civilization. It would take the green fascists getting out of the way though.


I don't know for sure how our existing coal plants are built and configured but I would take a guess to say that some combined cycle process is occurring in most upgraded and new coal fired plants. However, I'd take another shot and say most if not all combined cycle systems are used to directly generate electricity instead of using that work for more efficient secondary work. For instance, a secondary cycle driven by an efficient medium such as ammonia/water cooling systems may be used to derive more cooling per BTU than heat to electricity / electricity to cooling process. Perhaps in the near future, we will see debates on using this type of work between using secondary cycles to reduce the amount of cryo coolant necessary and reducing the amount of energy required to create it. Part of this type of debate may also hinge on how necessary rapid cooling may be needed to separate the mercury, CO2 and other byproducts from each other.

Gary Richardson

When I was at school in Scotland (50 years ago) I remember an illustration in a science book which showed a cartoon of telephones, chairs and other thinks going up in smoke from the chimney of a coal-fired power plant. The point was that burning a rich chemical feedstock like coal just to get heat was very wasteful. Maybe we should look at the process of using coal cleanly in the same way we look at refining oil, that is, a long and complex process which can be tuned to produce a number of products and energy output depending on requirements and the nature and quality of the coal used.

Doug MacLeod

hey slowburn come down here to the sw of australia and tell the drought-stricken (again) farmers how much better their life will be when global temperatures rise another degree.


If they still insist that this is needed , they do not have to burn more coal. It will have an initial cost however that impacts on their profits but sustainable . Coal Factories Produce enormous amount of Heat that is usually wasted to nothing . Using heat to generate power that can be used to cool down the exhaust is possible ; several methods exist , using steam generators or using high grade Peltier pumps ( Semiconductors that generate electricity from heat similar to those in your car /portable 12 V cooler ) . Hopefully , need some engineering skills and an initial investment but I hope they do not go crazy and burn extra 25% coal to do this ....

jaison Sibley
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