climate change
24 Sep 2008
Why "Clean Coal" Is an Oxymoron
Professor Ian Lowe's simple guide to why coal will always be a dirty fuel
The carbon dioxide produced when coal is burnt — mainly to generate electricity — is the single biggest contribution to climate change. "Clean coal" is an immediate contradiction.
Coal is a very dirty fuel for two fundamental reasons.
Firstly, because coal always contains a range of impurities, burning it produces a cocktail of gases, like oxides of sulphur and nitrogen, as well as soot, ash and heavy metals, even some radioactivity.
Secondly, coal is mostly carbon, so burning coal gives carbon dioxide, the most important greenhouse gas. Oil and natural gas contain significant amounts of hydrogen, which burns to produce water. As a result, those fuels produce less carbon dioxide per unit of energy.
Brown coal has a third problem: as it is mostly water, most of the energy produced by burning it is used to evaporate the water. It thus gives even less useful energy for every kilogram of carbon dioxide released.
So how can this dirty fuel be cleaned up? Kevin Rudd's interest in so-called "clean coal" projects focuses on carbon capture and storage. This involves capturing the carbon dioxide from burning coal, compressing it into a liquid, and injecting that liquid into rock layers deep underground. Carbon capture does nothing to reduce other forms of pollution, so talk of "clean coal" is the height of chutzpah — and highly misleading.
Because air is nearly 80 per cent nitrogen and only about 20 per cent oxygen, carbon dioxide accounts for only a small fraction of the exhaust gases from a power station. Separating it from the other gases is a complex and expensive process which consumes large amounts of energy. Some propose burning coal in pure oxygen rather than air, so the exhaust stream would be mainly carbon dioxide. That would simplify separating tcarbon dioxide, but it would be expensive and energy-intensive to produce enough oxygen to burn bulk quantities of coal.
Compressing the gas into a liquid is technically feasible, but it also requires significant amounts of energy. The liquid carbon dioxide would then have to be transported to sites where the rocks are judged suitable for storage. The World Energy Council has estimated that the carbon dioxide from the world's power stations would, if compressed to liquid for transport, be comparable in volume to the entire global oil and gas industry. While there are some sites that look suitable for long-term storage, it has not yet been shown that they will be secure for geological time; obviously, we cannot afford to have the gas leak out into the air. There may be some sites secure enough and close enough to power stations for a few demonstration projects, but it is moonshine to talk of applying this treatment to all future power stations.
Even if all the technical problems can be solved, the extra energy required for the process will mean that carbon dioxide released per unit of energy will only be reduced by about 70 per cent. We need to go much further than this by 2050 to stabilise the global climate, so it makes much more sense to invest in genuinely clean forms of energy like wind, solar and geothermal.
There are no credible estimates of the possible cost of carbon capture and storage, but industry sources talk openly about it adding 50 per cent to the price of coal-fired power. Studies of the prospective renewable supply systems indicate they can achieve greater reductions at lower cost — and much faster.
Even if everything were to work as well as the clean coal optimists hope, it will be many years before the technology is credible. The most that can be claimed is that "clean coal" will perhaps slow the growth of greenhouse pollution after 2020. Climate science is now saying we face an emergency and need to cut emissions significantly before then. Carbon capture is still an unproven technology and even if it can be made to work it will do too little, too slowly and at too high a cost.
So why is it being taken seriously?
There is no simple answer to this question. Coal companies want to stay in business, and have an obvious commercial interest in claims that allow them to keep burning coal.
At the 2020 Summit earlier this year, I argued that while there remain differences of opinion about the feasibility of "clean coal", surely we could all now agree that it is irresponsible to build old-fashioned coal fired power stations? A few delegates, mainly from the industry, objected and so Senator Penny Wong had to report that there was no consensus for the position I advocated. I was shocked to find that there are still people in the coal industry who think it acceptable to plan projects that will belch out millions of tonnes of carbon dioxide.
As well as those in business, some unionists representing coal workers — and some ALP politicians close to those unions — support "clean coal". The companies think it is only acceptable to keep the Earth habitable if profits are not reduced; the labour interests think it is be acceptable if no jobs are lost.
To be fair, jobs are at stake. The coal industry, domestic and export, employs more than 25,000 people. But that figure needs to be put into perspective. During John Howard's tenure as PM 150,000 manufacturing jobs disappeared. Those workers were absorbed in other fields of employment. Expanding clean energy supply and efficient use will create far more jobs than the coal industry now provides. Training and other forms of assistance will help the workforce move into these new jobs.
Some technocrats hope for a big technical fix to the problem of climate change. So they are attracted to grand technical delusions like "clean coal" or nuclear power, rather than accepting the wisdom of applying simpler technologies like wind turbines, solar cells or improved efficiency.
The final challenge to formulating good energy policy is the level of political support required, including both public endorsements and huge allocations of funds. Even politicians who accept that climate change is a real and urgent problem are reluctant to propose the changes we need. They cling to the old myths: business can go on as usual, further growth is tolerable, some claim even that growth should be encouraged.
I criticised the Howard government for pursuing the ridiculous distraction of nuclear power, rather than responding to climate change. The equally bizarre notion of "clean coal" is now playing a similar role for the Rudd Government and State governments along the eastern seaboard: it is a simulated response, aimed at appeasing the public concern about climate change without antagonising business, unions or those troglodytes in Parliament who still can't see the problem.
This is the real danger of the "clean coal" bandwagon. It is frittering away the time and resources that we should be using to re-structure our energy supply and use.
The Rudd Government should trust us and engage the community in developing a concerted response strategy, as was done in Sweden. We need that sort of participative process to produce a politically sustainable strategy to slow climate change. Unless we achieve that, we all face a very bleak future.
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I think we need to make it clear that coal is the new tobacco, only worse: it kills other people, not the ones who consume it.
We also need to start getting real with our language: people like the corporate hacks Dr Lowe mentions are evil. They clearly hate their own grandchildren and don’t give a fig about people dying right now from extreme weather events and rising sea levels caused by rapid climate change.
I think we need to make it absolutely clear that coal is NOT the new tobacco, and that presently, Ian Lowe just doesn’t comprehensively know what he is talking about.
Most of the CO2 produced by the mining of coal and by far the major fraction of anthropogenic CO2 emissions is created by coal burned in coal-fired power stations.
It is actually relatively easy to scrub CO2 from power station emissions using saline and poor quality waste waters e.g. those used now to cool the exhaust gases, recirculated through solar ponds or vertical towers carrying a high population of algae (which absorb dissolved CO2 and bicarbonate from the water).
Recent trials show that algae do not even need particularly high light levels to grow in abundance (marine algae in particular having evolved to tolerate low light levels). Therefore power station exhaust gases can be effectively scrubbed of CO2 in structures looking more or less like multi-story carparks.
If the exhaust gases have already had most dust removed by electrostatic precipitators or baghouses then the residual fine dust does not need to be removed - indeed the residual dust provides the nutrient phosphorus and silica required by the algae. Similarly NOx and SOx do not need to be removed from the exhaust gases either, these also being absorbed in thr water and thereby providing essential nutrients assimilated by the algae.
It can be shown that 1 m^3 of a pumpable 70% slurry of algal cells in water contains as much carbon as 1 m^ 3 of liquid CO2. The viscosity of a 70% slurry of algal cells in water can also be further reduced by breaking (‘lysing’) the cells with cheap enzymes.
Such a carbon-rich (algae-rich) liquid stream can be pumped into old coal mine workings, saline aquifers or even onto the sea floor for safe storage/disposal. A side stream can also be used for creating biodiesel as some species of algae contain up to 74% esterifiable oil.
On the grounds of cost, ease and simplicity of the technology, the ability to implement this technology sooner rather than later, and it’s relevance in the imminence of Peak Oil, this is the likely future of clean coal technology, especially in places like China and India. Trials of this technology are already occurring in various countries and are especially likely to accelerate in the US under an Obama presidency.
I strongly urge Ian to do his homework on, and then promote this rational approach to what is the inexorable utilization of the world’s thermal coal resources.
So ecoeng, there would still be a huge volume of liquid to dispose of. Pumping any concoction into the sea doesn’t sound too good to me.
Not really.
It is not possible to concentrate the carbon content of CO2 any more than what is it. The density of liquid CO2 at 20 deg. C and 57.3 bar is 1.03. Thus every m^3 of liquid CO2 weighs 1030 kg and contains (12.011/44.011) x 1030 = 281 kg carbon.
Conversely, a pumpable 70% slurry of algal cells in water (produced for example by hydrocycloning) also weighs about 1030 kg but of that 70%, about 40% is carbon as the chemical composition of algal cells is about CH2O i.e. 12/30 = 40% carbon. 40% of 50% i.e. 0.4 x 0.7 x 1030 = 288 kg of carbon.
Only 30% of that 1030 kg is water.
So we would be using about 309 kg water to safely dispose of about 288 kg carbon. Comparable amounts of water are evaporated into the atmosphere via cooling towers for every kg carbon combusted in coal-fired power stations.
As you may also be aware, billions of tonnes of dead algal cells from the surfaces of the oceans rain down onto the bottom of the oceans all the time and are incorporated naturally into marine sediments. What is the difference to that which I outline above?
True environmentalism can never be based on a naive ignorance of that which actually occurs out there in the real world.
Hi Ian,
There are clearly lots of risks with CCS re its efficacy, potential timeframe for development, environmental impacts etc., but, if it could be made to work, might it not have some role as a limited transitional strategy in China while renewables are rapidly brought online?
A recent post at Larvatus Prodeo suggests that a small-scale plant is now working in eastern Germany. Might not similar technology be used in the phase-out period for fossil fuels to reduce the emissions from legacy coal-fired plants in China (and possibly elsewhere)? What about the application of CCS to gas on a similar basis?
Obviously there are big questions to be answered by such a plan, but if the technology is at all workable, and its further development were entirely funded by the coal industry as the party most responsible for the related emissions, might that not proceed on a parallel track to massive public investment dedicated to renewables?
If there is no role for CCS in China especially, what then is the game plan? I’d be happy if we could shut down all coal-fired plants tomorrow with zero compensation to the coal industry (given appropriate measures to support the workers), but China might well want to hang onto the plants they’ve got and those shortly to come online. If CCS can at all mitigate those emissions, it might be possible to build the case for renewables through their growing deployment and significance within the Chinese energy suppy - in short, CCS as a phase-out strategy, not a licence to preserve our profitable but environmentally disastrous coal markets.
Darren Lewin-Hill
http://northcote-independent.blogspot.com
Sorry to introduce some basic chemistry mate. Though I would like to believe that an elegant theory like this marine sequestration idea could solve the problem.
First of all: 1. CO2 does’ nt have a liquid state. It sublimates from gas to solid at -77.5C.
The idea that some algal bloom, however artificially controlled will mop up CO2 is fanciful to say the least.
It is even less likely to work than geo sequestration would.
2. A compound of carbon and water (CH2O)Aq, in an aqueous environment is about as stable as is H2O2 (hydrogen peroxide) is in the environment, not very, it forms what are called free radicals in our bodies.
More likely the CO2 mopped up by the algae will turn into h2co3, carbonic acid, and guess what, it bubbles up as CO2 like fizzy drinks do.
So Rowena’s gut feeling is probably right on this one.
I’m as sorry about it too .
I really wish there was a cheap and simple solution to the problem of Carbon pollution from coal.
(iq145), smart (!)
Thanks for elaborating, ecoeng. I am no expert but it sounds more efficient and sustainable than having to condense, transport and permanently store cities-ful of liquid CO2, and provided there would be no toxic byproducts accumulating beyond safe thresholds in the environment.
revilo
Go back and check ALL your ‘science’ mate, it’s all (laughably) wrong.
Liquid (supercritical) CO2 has only been known about for some 150 odd years!
That in fact is the form proposed to pipe CO2 from (conventional) chemical scrubbing along pipelines to geosequestration reservoirs.
Photoautotrophic cyanobacteria (formerly known as photosynthetic blue-green algae) absorb CO2 in the form of dissolved CO2 and bicarbonate (HCO3-) and excrete (respire) oxygen (O2).
Hello, this is precisely why today we have an atmosphere comprised of 21% O2 (given that cyanobacteria only evolved about 2.8 billion years ago) and you now have the (wasted?) privilege of today being an O2-breathing life form.
Sheesh - and in the age of Google too! You should be ashamed.
revilo
Just one more thing.
The average chemical composition of algal protoplasm is the long-known ‘Redfield’ composition after it’s discoverer (about 40 years ago I guess). This formula is (CH2O)106(NH3)16(H3PO4) with thus a total molecular weight of 3553.238.
I simple approximated this to (CH2O)106 with a total molecular weight of 3182.754.
Therefore, assuming the composition of algae is CH2O for carbon content calculation purposes is a legitimate approximation, giving the carbon content of algal biomass to a precision of about 90% (which is sufficient as all algae don’t have precisely the Redfield composition).
So much for Revilo’s comment:
"I really wish there was a cheap and simple solution to the problem of Carbon pollution from coal.
(iq145), smart (!)"
Little bit of hyperbole going on there regarding the ‘iq145’ bit, methinks.
He probably won’t condescend to read any of these comments but if he did Ian might notice that the (NH3)16(H3PO4) part of the algal biomass expresses the nitrogen and phosphorus content of algae which can be derived from the fine dust and NOx in the power station exhaust gases.
However I have already listened to Ian on a number of occasions and therefore expect only silence in response to my comments above…….
After all, what did Marie Antoinette say upon hearing about the abysmal plight of France’s poor - let them eat cake? Lowe is just another one of those numerous 1st world environmental ‘gurus’ who have never actually had the ‘pleasure’ of watching a skeletal dirt poor family in a 3rd world country attempt to cook a small amount of corn meal over a tiny, choking fire fuelled by bits of burning plastic and shreds of tyre rubber.
Hi Ecoeng,
Can you please provide some links that verify your suggestion that Photoautotrophic cyanobacteria can be (and has been) used in the controlled manner you have suggested?
Anything for the ‘non-specialist’ would be preferable.
Cheers!
KL Bedford
I do not know about the proposals above but I do know that solar works. We have 28 solar panels on our roof which generate nearly 4kWh at noon into the grid. we have had solar water heating for the last 15 years and it works and we have solar pool heating that heats the pool to 28 degrees C so we are sure of these technologies. Hot rocks has now been shown to work and it employs known technologies. CO2 sequestratoion by any means has to be seen to work on a large scale before we can ignore the known technologies that do work and make use of our generous allowance of sunshine. I am sure these technolgies will be vastly improved if some of thecleancoal technology money is spent on them.
Hi Bob, Rowena
Here you go:
http://www.pigswillfly.com.au/?p=1744
Dear eco-pigswillfly-eng.I have read a few of your cross grained rants before.
Dear boy,kick back,relax,go out for a round of golf but make sure you take the buggy.We don’t want you having a heart attack from the walking,now do we.
If Ian Lowe had bothered to investigate Atomised Refined Coal (ARC) and recent evidence on manmade global warming, he would not have written this article.
ARC is a process that refines coal before it is burned using hydrogen fluoride - a process developed and demonstrated by Bob Lloyd, an Australian engineer, during the previous oil "crisis" in the 1980’s and now under further development b y Intertech north of Sydney. The refining produces byproducts such as silicon, titanium and alumina that have commercial value. The refined coal can be burned in modern gas turbines, thus increasing the efficiency of coal fired power generation by 30%.
The world temperatures peaked in 1998 and the world has cooled since 2002. recently the cooling has been quite rapid. At the same time, CO2 went up 4%. None of the computer models predicted the cooling. Therefore they have NO credibility. There is no other evidence that CO2 causes warming. If it did, temperatures would have risen, not fallen, over the last 10 years.
Dear Thirra. I have read a few of your cross-eyed wanks before.
To reverse the compliment (as is you’re want) stick it up your Arrith…….dear boy.
Similar comments to thos posted to Milne’s article.
And what if the computer models are wrong (and so far they are, look at www.trac.org.au/images/temps.gif) then we have just wasted $100m. At least investing $100m in renewable technology research is a double bet. When it finally dawns on the community that they have been conned by a less than a dozen or so climatologists who program the computer models we will still have technology for when the oil and coal run out.
But like most things Lowe comments on it only serves to show his ignorance of the science involved i.e. "Because air is nearly 80 per cent nitrogen and only about 20 per cent oxygen, carbon dioxide accounts for only a small fraction of the exhaust gases from a power station. Separating it from the other gases is a complex and expensive process which consumes large amounts of energy.. But then it’s not really about science is it Ian, rather it’s about the ideological agenda of the basket weaving mentality.
DDT Chumley
Ecoeng thanks for the link. However I still concur with icedvolvo that investing in renewables is a double bet win.
Even though CO2 sequestration using algae looks feasible, it does not solve the problem of the fossilised CO2 that has been released.
To lock that away permanently we need the numerous organisms such as Foraminifera that develop calcium carbonate exoskeletons as well.
A broad spectrum of research needs to be done which not only looks at providing clean fuels for the future, but also reduces the amount of energy necessary to maintain modern lifestyles.
For example internal combustion engines are very inefficient and wasteful and should not be used to provided direct automotive power. The aXcess car is a good example of what could be rapidly (and cheaply) achieved with a bit of government support.
http://www.onlineopinion.com.au/view.asp?article=7586&page=0 and
http://www.orbeng.com.au/orbital/investorinformation/news/300399.htm
If we can stop using fossil fuels for energy before destroying the planet’s biodiversity, then the removal of CO2 from the atmosphere will be done by the already existing bio-geological processes.