The Future of Cheap Energy: Underground Coal Gasification

Between 2000 and 2010 world energy use increased by 2.6 billion metric tons of oil equivalent per year. Of this increase, a little over half came from coal, and 72% of the coal increase came from China. The vast exploitation of Chinese coal, the cheapest source of electricity in the world, enabled western nations to benefit from both cheaper goods and outsourcing environmental issues, and for China to benefit from increasing goods exports and rising domestic consumption. Substantial doubt has risen, however, about the possible duration of this economic miracle since China now produces 48% of global coal and consumes around 3% of its reserves every year. How long will Chinese coal last?

The reserve limits for coal, for China as well as the rest of the world, can be postponed for several generations if the technology to gasify coal underground can be commercialized. Underground Coal Gasification (UCG) enables the access of deeper coal layers hitherto unavailable through conventional mining. Several modern pilot projects have been successfully completed in recent years and commercial projects are underway. This article gives an overview of present developments, the technology of the process, costs to produce electricity and liquid fuels from the syngas, and discusses environmental concerns. The article is informed by the excellent presentation given at the ASPO 9 presentation given by Marc Mostade, Technical Director of Clean Coal, and advisor to the UCG Association. The slides of that presentation can be downloaded here, and the video is available here.

The History and Present Underground Coal Gasification Activities

The technology of UCG is quite old as it was already developed in the 1920s and 1930s in the former Soviet Union. These activities resulted in several pilot plants and five industrial sized UCG plants in the 1960s, but efforts were abandoned as large natural gas discoveries made the process uneconomical. Today of these only the Yerostigaz plant owned by the Australian Linc Energy in Uzbekistan remains. Several trials were also undertaken in this period in Europe, documented in detail at the website of the UCG Association.

Figure 1 – An overview of UCG trials over time and their depth. Slide from a presentation given at the ASPO 9 Conference by Marc Mostade, Technical Director of Clean Coal, and advisor to the UCG Association.

The technology has gained substantial interest in the last ten years as fossil fuel prices increased and concerns over rising fossil fuel imports in Europe have grown. There are now over 30 pilot projects either operating or in the planning stage in more than 25 countries, including the U.K., Australia, the U.S., South Africa, and China. Of special importance are:

• The 1 km deep 5 MW coal pilot carried out by ENN in China that ran for 26 months. The Chinese government last month signed a 1.5 billion USD commercial partnership with the UK government for commercial development of the technology to be deployed in Inner Mongolia.

• The Swan Hills project supported by the government of Alberta in Canada that should start in 2012 and become operational in 2015. The 300 MW syngas electricity plant is intended to be equipped with a carbon capture and storage facility. The commercial project follows a trial project in the region which successfully gasified coal in-situ at 1.4 km’s of depth.

• The Chinchilla project in Australia operated by Linc Energy which since 2008 was combined with a Gas-to-Liquids plant to produce 20 barrels per day from the UCG syngas. The company is presently finalizing the engineering aspects to begin construction of a 20.000 barrels of oil equivalent per day UCG-GTL plant in 2012. Linc Energy claims it can commercially produce a barrel of oil equivalent at a price of 30 dollars.

The Technology of Underground Coal Gasification

The latest standard of the technology incorporates horizontal directional drilling. To obtain the gas two wells are drilled - an injection well which brings steam and oxygen or air underground to ignite the coal seam and maintain the process, and a production well which pumps out the raw syngas. Previously vertical wells were used which are difficult to connect and limit control over the formation of the underground cavity as they cannot be steered. Today's horizontal wells can be connected using a magnetic target and detector positioned in the tip of the wells. The injection well is retracted along the borehole to gasify the coal which flows to the production well. The process is monitored above ground based on measurements of pressure, temperature, gas flow rates, gas composition at the wells. These are informed by simulations carried out to model the process. The control of the process comes from the injection of the oxidant, as too low or a halting of flows will stop the process.

The produced syngas varies in composition depending on the coal quality and for a standard horizontal two well retractable injection point technique (CRIP) includes hydrogen (11-35%), carbon monoxide (2-16%), methane (1-8%), carbon dioxide (12-28%) and other smaller components. Specific alteration of the gasification system can also result in a variance of the syngas composition. Yang et al. (2008) published about a field test to manufacture hydrogen using a two-stage gasification process with multiple steam injection points to raise the temperature. In the test syngas was succesfully produced with on average 50%+ hydrogen content with a range between 40% to 73%, and both CO and CH4 contents of over 6%.

Figure 2 – The Controlled Retracting Injection Point technique. Slide from a presentation given at the ASPO 9 Conference by Marc Mostade, Technical Director of Clean Coal, and advisor to the UCG Association

The process itself takes place in a coal seam normally saturated with water at hydrostatic pressure. There, several processes take place including evaporation, pyrolysis, steam gasification, CO2 gasification, and direct hydrogenation, depicted in figure 3. To prevent the “reactor” from collapsing the process needs to take place in modules at a specified length, width, and depth, shown in figure 3. Thereby sufficient structural support is created both via the rock between the modules and by the under burden and overburden, similar to a large extent as the pillars created in room-and-pillar wall mining. Since the reactor is dynamic and its physical conditions depend on the type of coal and surrounding rocks these determine the possible size of a “module”.

Figure 3 – Qualitative description of phenomena occurring at the UCG cavity wall. Reproduced from Perkins (2005)

More information about the process can be found in a post written early 2010 by Heading Out at The Oil Drum.

The economics of Underground Coal Gasification

Several estimates have been made of the cost of an electricity plant based on UCG syngas. The main physical variables are the quality of the coal, depth and thickness of the coal seam, linking distance of the injection and production well, distance between the cavities, and sweep efficiency. The calculations based on theoretical and actual operations point to a cost range of 1 to 8 USD per GJ of produced syngas. The main cost variation is the usage of air or enriched oxygen for injection, the thickness of the coal seam, and the depth of drilling. The later two factors determine the number of wells that need to be drilled and their required length. Oxygen-blown gasification is preferred in case of adding Carbon Capture and Storage technology.

• The estimate of Marc Mostade of Clean Coal is a production cost of 2.5 to 4.5 USD per GJ of syngas, based on a 800 meter deep 500 MW thermal size UCG plant and a coal seam of 4 to 6 meters thickness at 800 meters of depth. The difference is caused by the usage of air-blown or oxygen-blown syngas. Information about the variables underlying his calculation can be found in his ASPO 9 presentation.

• Based on the Chinese ENN Pilot a total cost of 0.9 to 1.7 USD cents per cubic meters of syngas was documented, which translates into 1 to 1.9 USD per GJ of syngas assuming a higher heating value of 9 MJ/Nm3

• In 2007, GasTech carried out an analysis of costs based on coal in the US Powder River Basin using air-blown and oxygen-blown gasification. These were estimated at a cost of 1.5 to 2.4 USD per GJ of syngas.

• In 2011, the School of Public and Environmental Affairs of Indiana University calculated the production costs for air-fired syngas via UCG in the state of Indiana in the US at 4.6 to 7.7 USD per GJ of syngas for respectively syngas produced via enriched or air, assuming a coal seam thickness of 2 to 3.5 meters at 200 meters of depth or more.

These cost levels are when averaged equal to or below the present day price of natural gas in the US, EU and Asian markets, as shown in figure 4 below. The lower cost range is on par with today’s coal price on a GJ energy basis.

Figure 4 – Natural Gas Prices, European CIF, UK heren NBP Index, US Henry Hub and Canada Alberta from 1996 to 2010 based on figures from the BP Statistical Review of World Energy, viewed against a rough 1 to 8 USD cents minimum and maximum UCG cost per GJ (in the figure translated into BTUs).

The costs of electricity produced with UCG based syngas were estimated in the study of the University of Indiana and shown to be highly sensitive to seam thickness as shown in Table 1 below. The cost for a seam with 5 meters thickness was estimated at 5.2 to 6.4 USD cents per kWh, and a seam with 2.5 meters thickness at 6.4 to 8.6 USD cents per kWh, the lower and higher value caused by air or oxygen enriched injection. The average cost of electricity production in 2010 in the state of Indiana according to the report was 5.7 cents per kWh, which at present makes exploitation of UCG in Indiana economically difficult since only seams up to 3.5 meters thick are available at depths greater than 200 meters.

Table 1 - Sensitivity analysis of UCG based electricity with and without carbon capture and storage for Indiana. Source: Indiana University

The potential expansion of coal reserves from UCG

There are only preliminary and hence incomplete studies available of how much coal would become available if UCG becomes a commercial technology. The World Energy Council (WEC) estimates that total coal reserves in 2010 amounted to 860 billion including anthracite, bituminous, sub-bituminous and lignite coal. In 2007 the WEC released a coal reserve estimate based on studies from a number of countries including USA, Russia, China, India, South Africa, Australia as well as Europe. These countries and regions combined were estimated to have a potential of 565 billion tonnes of coal accessible by UCG, 52% of today's coal reserves.

These estimates are highly dependent on a number of variables especially the maximum depth of the coal seams extracted using UCG and whether offshore coal is included. For instance, a GasTech study of the Powder River Basin of Wyoming and Montana included only coal reserves at a depth between 152 and 610 meters, and coal seams thicker than 10 meters. In the study it was assumed that deeper extraction below 610 meters and thinner seams would make the process uneconomical. In assuming a 65% recovery factor the study came to 200 billion tons of coal recoverable in the Powder River Basin, a substantially higher figure than the 138 billion estimated for the entire USA by the World Energy Council.

The figures become even more uncertain if also offshore coal comes into the picture which theoretically can be extracted easily with UCG. In the United Kingdom offshore UCG is taking a leap with five conditional licenses granted to Clean Coal Ltd by the UK coal authority in 2009 to investigate the potential for offshore UCG. These could turn into commercial operations by 2014/2015 giving access to 1 billion tons of offshore coal. At this stage the licenses are for relatively shallow offshore sites where the operating plant would be stationed just onshore and directional drilling takes place offshore, but there is no reason for deeper operations not to work unless the cost of the coal becomes too high. If UCG will prove to be economic in a couple of decades a large share of the estimated 3000 billion tons of coal that lie near Norway's coastline could be gasified. After their natural gas reserves are depleted Norway may still remain a gas exporting nation, but then via underground coal gasification.

The problem of carbon dioxide emissions

The major downside to UCG is that by prolonging the age of fossil fuels substantially it would cause human-caused emissions of carbon dioxide in the atmosphere to continue, unless measures are taken to capture greenhouse gasses emitted from UCG syngas combustion. The costs of carbon capture and storage (CCS) from the UCG syngas are expected to be comparable to that of CCS of above ground gasification of coal in an integrated gasification combined cycle or IGCC power plant (Friedmann et al. 2009).

In an earlier post I discussed the IPCC special report on carbon dioxide capture and storage which estimated an additional 0.9 to 2.2 USD cents per kWh of electricity to install CCS at such an IGCC plant. This cost range is similar to an estimate of the University of Indiana that resulted in a cost range of 1.7 to 2.2 USD cents per kWh to add carbon capture and storage to a power plant run with UCG syngas, as shown in table 1 above. The additional costs are plausibly affordable for coal sites with a high seam thickness in comparison to non-CCS based gas power plants, especially in markets with high natural gas electricity costs such as Europe. Therefore, adopting CCS would mean a restriction to use UCG at the most economic sites, reducing but not eliminating the potential adoption of Underground Coal Gasification.

Environmental concerns – groundwater contamination

In contrast to conventional mining, there is no discharge of tailings and sulfur emissions are much reduced as well as the discharge of ash, mercury, and tar because there is no handling of coal involved. There is one important problem that UCG has in comparison to conventional coal mining, which is the hazard of groundwater contamination. Due to a lack of sufficiently high temperatures across the underground cavity, there will be formation of carcinogenic coal tar. In above ground gasification of coal, the temperature can be controlled in the reactor and is kept at high temperatures uniformly to prevent coal tar formation. If the underground cavity pressure is too high it can force some of the syngas and tar into the surrounding formation, thereby contaminating the groundwater. In case of a pilot in Hoe Creek north-eastern Wyoming, groundwater contamination occurred due to the collapse of the cavity roof in which water from a nearby freshwater aquifer mixed with the tar and rock (Bell et al. 2011). Possible suggested solutions are to select coal seams not hydrogeologically connected to surface waters or wells, pumping contaminated water out for surface disposal, re-mediation after gasification, and/or lowering of the gasification pressure were possible:

“Water contamination issues can be reduced by gasifying at slightly less than the hydrostatic pressure. Water will tend to flow into the gasification cavity, flushing flush coal tars into the gasification zone and towards the production well. This strategy has been successfully demonstrated at the Chinchilla test burn in Australia. A low seep rate will provide steam to help gasify the coal. If the pressure is too low, the water flow rate will be excessive; and the heat required to evaporate this excess water will reduce the thermal efficiency of gasification (Bell et al. 2011, p. 107).”

Unfortunately, such measures cannot fully remove all water contamination because when the process is finished, a cavity will fill up with ground water which mixes with remaining tar. This is not that much of a problem as it is a contained spill according to Bell et al (2011) because the unburned coal can absorb compounds from contaminated water and inorganic rocks will buffer inorganic contamination via ion-exchange. That the problem is taken seriously can be understood from problems with the Cougar Energy project in Australia. The project was permanently suspended by the Department of Environment and Resource Management of Queensland in 2011. In March 2010, a well blocked and ruptured at the Cougar site, resulting in the release of chemicals. By May 2010 elevated benzene and toluene levels were measured in two of the Cougar Energy groundwater measurement holes. Platts reports that this amounted to 2 parts per billion of benzene. In a response Cougar has stated it has since tested over 300 water samples which did not show any detection which exceeded drinking water guidelines. Two other UCG companies with projects in Australia, Carbon Energy and Linc Energy, are also under close inspection of the Queensland State Government. Linc Energy was found to fully comply with environmental regulations but Carbon has been charged for two incidents. One of the Carbon Energy incidents related to the spill of process water to a creek; the other related to unauthorized use of process water for irrigation. Neither relate to direct contamination of groundwater, but illustrate the need for government to scrutinize companies on their environmental standards.


The technology of underground coal gasification has been technically proven to work at numerous locations and different depths ranging from several hundred metres up to 1.4 km of depth. So far the economics look promising with costs competitive to natural gas markets and possibly also coal markets. Furthermore, a combination with gas-to-liquids technology would enable the production of fairly cheap synthetic diesel. These possibilities together with the potential to unlock vast new coal seams unavailable via conventional mining make UCG an important technology that could substantially extend the era of cheap energy. There are justified concerns over groundwater contamination that need continuous attention of both companies and regulators. Finally, the technology does not solve the issue of carbon dioxide emissions as it provides only a marginal improvement over standard coal mining, unless implemented together with carbon capture and storage technologies.


Bell, D., Towler, B.F., Fan, M., 2011. Coal Gasification and its Applications. Elsevier

Friedmann et al., 2009. Prospects for underground coal gasification in carbon-costrained world. Energy Procedia 1. p. 4551-4557.

Yang et al., 2008. Field test of large-scale hydrogen manufacturing from underground coal gasification (UCG). International Journal of Hydrogen Energy. 33. p. 1275-1285.

This technology is just another way of kicking the can down the road. The potential environmental downside is horrendous as well. Let's get on with powerdown and adaptation instead.

Yea, nice report on a monstrously bad idea. It's morbidly fascinating to watch how unintelligently and unimaginitively our species is responding to resource decline.

This UCG stuff is like a terminal lung cancer patient cleverly figuring out how to smoke through a hole in their trachea. Tragic, sad, and pathetic.

Well said! I had much the same reaction, also quite sad to see TOD going downhill like this.

The reserve limits for coal, for China as well as the rest of the world, can be postponed for several generations if the technology to gasify coal underground can be commercialized.

No need to read the rest of the article, that statement alone is enough to completely discredit the coal industry shill writing it. Dr. Albert Bartlett would be shaking his head in dis-belief right now. How can people be so numerically illiterate?


@Jerry McManus

As author of the article I have not affiliation whatsoever with the coal industry, your comment is ill mannered and abusive. In addition your reference to numerical illiteracy it is flawed, a calculation of exponential growth as to Albert Bartlett's calculations would show that the quote of mine you cite is correct, given the coal growth rate we have witnessed in the last ten years and the potential reserves that can be added due to UCG. If you would read the article that would become clear.

Non-related is the moral issue that mamba and dan commented on earlier, which is a different debate altogether on whether we can afford to burn and develop the coal in terms of carbon dioxide emissions. My perception is that we can given the relatively cheap cost of UCG versus other possibilities when including carbon capture and storage. There is no reason hence to discount out the technology a-priori. More importantly, given the cheap cost it is likely that this will be developed any case since that's how our economy works, and hence ignoring it a-priori will prove to be stupid ignorance.

I'm interested in discussion on any perspective but prefer some considerate thoughts. I hope that's a general wish for other folks in this venue of discussion and that you can keep that in mind.

Dan and Mamba are clearly ignorant. They do not understand the most basic of economic principles: cost. The tables have been turned. Dan and Mamba accused Jerry of foolishly not addressing consequences; Jerry now accuses Dan and Mamba of not understanding the basic economic principle of our society: Cost. I beg to differ. I suspect Dan and Mamba are fully aware of how choices are being made.

While Dan and Mamba did not spell out the environmental consequences—other than to say they were horrendous--, I think their argument deserves a hearing. Otherwise, we all should rejoice in love canals—they seemed quite profitable at the outset. Maybe there are costs Jerry should really consider. Maybe, just maybe, we will be foolish if we consider only short-term costs?

My comment wasn't ill-mannered or abusive, but it was a strong statement opposed to doing this. It was deleted. That deletion, if intentional, would seem to be a repudiation of my position and a tacit endorsement by the author or moderator for doing it.

If I had said this practice was the best idea since sliced bread, one wonders if it would have been deleted.

Hi Greenish,

I'm sorry to say I missed your comment.

I'm sure it shouldn't have been deleted, considering your track record here as an old timer.

Hi Mac.

Don't be too sure. It was a post saying "this is a bad idea".

The future habitability the earth for humans and currently extant large species may depend on how much CO2 we inject into the air before we stop being able to extract and distribute flammables at current scales; say the next hundred years or so.

That, in turn, will be determined by how much fossil carbon will remain sequestered and out of reach. Ergo, figuring a way and a rationale to get at deep coal beds economically is bad news for the invisible trillion-or-so human lives which might otherwise exist in the future.

It isn't fashionable to treat those people as real, since any fool can see that the odds of their being born goes down by the day.

I reckon it comes off as "environmentalist" even though that word has been rejiggered as much as "conservative" and I no longer use it; by any reasonable definitions I'm both.

I think it's legitimate to consider the people now alive, and their kids and grandkids; which is what most people do. I also consider subsequent generations. It's valid to hope that the people we know don't have terrible lives. But it's also valid, I'd say, to think about the people who live after them, the earth's carrying capacity and their life quality.

There's financial "economics", and there's the off-books cost of turning the future to a fetid hellscape with anoxic, acidic oceans, leading to actual existential risk for our species versus a few centuries of dieoff which are already baked into the cake.

This site is, or was, about "energy and our future", not just energy. I think I see it up there on the masthead still. I was referring to the "our future" part of that, and noting that it would be nice to have one. I just consider "our future" to be that of our descendants for the next million-plus years, not just the years until our kids retire.

If such a forum allows people to say it's a good idea, one would think it would be allowable to say it's a bad idea, which I did. I respect your perspective and realize that you see both sides of it, I'm just using this reply to restate my position.

Burning more & deeper stuff is clearly a bad idea for the future, making the ultimate carrying capacity lower. It may be true that there's nothing we can do to stop it, but that's a pretty poor standard by which to assess a course of action. I think it would be nice to have a planet that might support 1-2 billion humans instead of 10 million humans after the crash/dieoff.

I have a geology degree and used it working in the oil industry, among other things; if I'm an enviro I've come by it honestly. 60 years of life, study and reflection have led to my current opinions. As it happens, I think the fossil fuel thing has been overdone; and that a hypothetical self-aware species would stop looking for new ways to de-sequester carbon.


a hypothetical self-aware species would stop looking for new ways to de-sequester carbon.

Take one ton of politically-mandatory energy demand.  Add one dash anti-nuclearism.  Spread tragically over one commons.  Yields:  disaster.

Censorship abuse appears to be common on TOD, and is worse because it destroys every trace visible not just to the public at large, but to the author of the censored material as well.  Only the editor(s) have access to censored material.  I have been complaining bitterly about this for years, and I have still not received some of my own writings back.

The worst thing seems to be that the Powers That Be have authorized censorship for "tone".  Anyone with experience in on-line forums knows that it is nearly impossible to infer tone accurately from text.  This leads to the use of censorshp in a way which is inherently capricious and abusive.

Yet nothing presents you from saving the material before you post, either. I have rarely seen anything of high value deleted, though in a few cases high noise exchanges with nuggets of gold may have disappeared. Signal to noise is exceptionally high here, though, and that's a good thing. Surely deletion rates of high-value info is a fraction of a percent?

Only a few people seem to chafe under the rules here, and I wonder why do you stay or post if it is so onerous?

Yet nothing presents you from saving the material before you post, either.

When one posts reference- and analysis-heavy replies to a site which claims to hold to the Creative Commons license, one does not expect it to just disappear.  I know I didn't.  Saving things individually is also very tedious.

I have rarely seen anything of high value deleted, though in a few cases high noise exchanges with nuggets of gold may have disappeared.

A large number of comments, including lots of references and calculations representing hours and hours of work, disappeared from a series of threads a couple of years ago.  When I went back to try to incorporate that work into a rebuttal series, I couldn't find it.  I thought I was just losing it in the mass of comments, spread across multiple pages per keypost.

I was wrong.  That work was, for all intents and purposes, stolen from me.  It was gone even from my own comment history, as if it had never existed.  I have received neither an explanation nor a return of my work to me.  I am still outraged by this.

Only a few people seem to chafe under the rules here

You've missed the ones who left in disgust.  I'm here because I'm hard-headed.

It seems as if a few good folks here are suffering from the delusion that this site is primarily about environmentalism;this is patently not so.

This is an energy site, dedicated to educating it's readership about all things energy and ff energy in particular. and it is to be expected that here you will find the news and the facts in respect to whatever is going on in the energy field.

I suppose these well meaning (?) individuals would like to shoot any messenger arriving with bad news.

That is not a recipe for progress on any front.

I personally am ambivalent about this technology, considering the risks;but it might be the means by which we survive and prevent the starvation of hundreds of millions of people;it might allow us to avoid an energy based WWIII.

Just how big an ecological disaster might WWIII be?

Some environmentalists remind me of preachers and Jesus freaks-i know a LOT all three types.

Well, yea -- it isn't an 'environmental' site, but to separate our quest for energy from its effects on the ecosphere is a very deadly form of autism.

Hi Dan,

In principle, I agree wholeheartedly with your comment.

It's just that some of us seem to think that we should have our ears and eyes and pure little hearts sheltered from any news that does not suit thier environmental agenda-and incidentally, I am pretty much in agreement wioth the typical environmentalist's agenda.

I just like to see a little hard headed common sense mixed in with any and all news and reactions to it......

Wishing will not make coal go away-fighting coal is not likely to make it go away either, but a good fight might soften some of the harsh consequences of burning it.

The most successful soldier or or athlete -or environmentalist- is one possessed of a sound and detailed knowledge his opponent.

Shielding our delicate little ears from news of likely developments in the coal industry is sort of like shielding children from hearing dirty words.

We aren't children, we should be able to handle dirty words and bad news in a level headed and rational way.

We ain't ostriches either-at least, not very many of us.;-)

Too many people can't think about systems as systems, or manage to work unintended consequences into their mental models.

I think this comes out most clearly in thinking about nuclear power.  Soi-disant environmentalists tend to be strongly against it, but fail to consider the consequences if their favored alternatives do not yield enough energy soon enough at affordable prices.  The results will include continued operation of the fossil-fired plants which are (so many environmentalists claim) the biggest threats to the environment world-wide.  (The nuclear threat to people is different; Chernobyl is a wildlife haven, not a desert.)

James Lovelock and Patrick Moore have seen the connections, but the global organizations and their membership remain locked in simplistic, self-defeating thinking.

It's very hard to think about everything at once.

For instance, everybody seems to have forgotten about the threat of nuclear war, even though a nuclear winter wouldn't do much good for us and our environment either. Nuclear power's connection to weapons, and their proliferation, is a significant factor: think Iran.

I think disastrous climate change is rather more likely than disastrous nuclear weapons use, but I still have a hard time getting enthusiastic about nuclear power.

As far as wind and solar power go, I think there's little doubt they'd work well. Similarly, it sounds very likely that UCG with CCS would work just fine.

Will we choose wind/solar, or UCG with CCS, instead of plain old dirty coal?? I think we will to some extent, but I'm not optimistic that we'll do so nearly as quickly and strongly as we should.


Nuclear power's connection to weapons, and their proliferation, is a significant factor: think Iran.

Iran is not using nuclear power reactors to make weapons.  Iran is using uranium enrichment; spent LWR fuel is essentially useless to proliferators, as the Pu isotope ratio is all wrong for weapons.  If Iran bought its LWR fuel from Europe or Russia, there would be neglible risk of Iran developing nuclear weaponry.

True. And yet, they're not doing so...

If you want to argue that the NNPT has some glaring defects, I will violently agree with you.

do you foresee any chance of fixing them?

Not my bailiwick.

Where do we have a carbon capture and storage facility that does not leak? Where do we have one of a size and scope that this article suggests that does not leak?

Lots of food for thought here.

It may be that this technology, if it proves to be scalable at a fast enough rate, will extend the so far successful track record of the techno copians and conventional economists who believe that new tech and ingenuity will always save us.

This might prove to be true for several more decades-there is a hxxl of a lot of deep coal out there, and I have no doubt that an industrial economy can run on coal to liquids motor fuels.There is plenty of room for fuel efficiency improvements and lifestyle changes to compensate for the financial costs.

I forsee two major problems however;the first one is that the technology- meaning both underground gasification and ctl - won't scale fast enough to prevent an economic collapse due to the effects of oil depletion and the ELM.

The second one is the one that will put a REAL hurt on us-if it works on the grand scale, ucg will simply allow us to continue bau soo that the coming overshoot crash will be even more violent when it dies arrive.

Of course overshoot includes all the potential and actual ecological and climatic problems associated with ff in general and coal in particular.

So the risk is that we enact the technological fix either too fast, thus perpetuating BAU, or too slow, thus inducing an economic and probably a technological collapse. While I agree with this, I wonder what the chance is that we will get it just right ??. Enough of an impact to induce some long range thinking but not so miuch as to impede our capacity to develop and apply technical fixes.

There are other risks involved, but yes as I see it you have basically got it in a nutshell.

I fear the odds of us getting it "just right " are rather slim;in the continiuum of possibilities, there are likely many, many times as many opportunities to get it wrong as there are to get it right.

However, as Yogi sez, predictin' is hard, specially the future.

There is some possibility that we might avoid a PERMANENT collapse and merely suffer a major dieoff due to resource depletion, pollution , and climate change.

That possibility lies in the fast falling birth rate in most of the world- outright collapse could if we are lucky be confined to the poorer and worst overpopulated areas with the least potential for food self sufficiency.

I am a firm believer in an overshoot collapse, but I don't expect very many people to starve in for instance North America, unless we suffer an outright failure of our govt.I fear anarchy is our potentially biggest problem here, barring WWIII.

Things are going to be very very grim in lots of places though-let's just hope we don't have to fight WWIII in a nuclear armed world.

I don't have any ideas what the odds are, but a hundred years from now there may very well be a billion or two billion people who are living very well and sustainably because they choose to limit thier family size to replacement level or less. Prosperous people have proven themselves to be in favor of small families all thru Western society, and I foresee this trend spreading with prosperity.

My own people , and my part of the country, are mostly evangelical Baptist fundamentalists-the ones who aren't drunks , lawyers, and so forth- and our birth rate is well below replacement- once we get over the demographic hump, our numbers will begin falling fast.Preachers aren't nearly so influential as those who are opposed to religion make them out to be.

Of course there will almost certainly be areas where Malthusian overshoot is occuring and recurring , as it is today in drought stricken Africa.

After being on a journey of discovery for more than 5 years now, I have come to the conclusion that the real problem we face is not resource depletion or polution or economics. The real problem is population. It is good to see that others get it.

I agree with you that the opportunity to get the timing wrong seems much higher than the opportunity to get it right. I believe that this will act over time to de-globalise the world community. There will be places that manage to achieve an orderly transition to a sustaiable population level. But I fear these will be relatively few. At this time it is not possible to identify a single world government that is actively driving such a transition even though it is likely that the forced transition is only a few decades, maybe only a few years away. Maybe Norway is trending in the right direction.

And then there is the danger that those societies that do manage their own transition will become engulfed in the anarchy that spreads from those that don't.

So then this translates into the day to day problems we face. There will be negative environmental impacts from technologies such as CSG, UCG and nuclear power. But will the extra time bought using these technologies provide for a more widespread transition to lower population and the chance that at least some of the world makes it through. Or will we use the extra time to just gain more momentum before we hit the wall ?

Before natural gas became available in the UK 'town gas;' was produced and distributed as a domestic gas supply. This was
gassified coal, presumably similar to UGC in chemical composition. It was incompatible with natural gas (mostly methane) as a domestic gas source, and the transition in the UK involved modifying every gas burner in the country. It is also toxic, and was a convenient method of suicide for decades.

I think UGC will only ever be used for electricity generation or GTL. We will never us it for domestic supply again.

Does the variable chemical composition of the gas produced cause problems designing burners for it in electricity production?

I echo the worries that it will only accelerate climate change.

Its quite possible to gasify coal to methane rather than CO. If we ever went back to gas from coal for domestic use, thats how it would be done. Either the syngas from UCG would be used to manufacture methane, or the coal would be mined and gasified on the surface.

Coal isn't gasified to methane (there's always some CH4 in the product) so much as the stream is "methanated":  CO + 3H2 -> CH4 + H2O

There's a considerable energy loss in methanation, so it's best to avoid unless necessary.

I have been involved in some detail in one of the UCG operations in Australia including trying to configure gas turbines to run on the syngas.

While the low calorific value of the gas does necessitate modifications to the conventional gas turbine burners, there is no doubt it can readily be utilised in this way. The basic design of the turbine is standard off the shelf with special burners fited. The low calorie gas burners have been in use for a number of years in the steel making industry where low calorie gas is extracted from both the coking and blast furnace processes.

It is also possible to utilise the gas turbine compressor to provide some or all of the large quantity of high pressure air required for the underground injection. Unfortunately, conventional turbines are not designed for such large extraction of the gas flow, however, I expect that as this process develops over time, that new versions of turbines will be developed that optimise this idea.

It potentially both a savior, and a disaster. The former because it may allow us to more gracefully over several decades transition away fro FF. The later, because without the proper political controls, it will always be cheaper to skip CCS. Without CCS it will create severe problems for hundreds of years. And if the economics is marginal, CCS will be jetisoned in order to make it competitive with NG. So how do we insure that if it is developed (hard to stop) it will be used with CCS?

I agree, it is primarily for industrial use at or near the production site. Mostly electricty gen, although perhaps cogen and desalination, as well as GTL.

The main difference between 30 years ago, when I reviewed UGC while working on surface gasifiers, seems to be that the sorts of seams being used now, are the sort that it was assumed would be mined. Why are such thick and shallow seams now regarded as being better gasified than mined?

Could you expand on how steam is used to increase temperature in the Yang process? Steam is the normal method (the reaction is endothermic) to reduce temperature in gasifiers and I am puzzled about how they can get the opposite to happen.

hot - Just a guess but maybe two factors. Since the process involves drilling wells that cost is proportional to depth. Perhaps a more important tech problem: drilling thru coal seams is actually fairly difficult. They wash out easily and you tend to lose your drilling mud. Most coal rich regions have multiple layers in the section. Trying to drill down to deeper non-minable coal seams might be impractical. I also suspect the difficulty/costs/environmental issues with surface mining and the dangers/expense of deep mining could be aanother factor.

From the next comment down, looks like its actually the type of coal. I am not convinced that lignite is actually the best fuel, but gasification is a good way of processing poor quality fuels so I can see how large, shallow lignite seams become the preferred prospect over higher quality but thin and deep seams.

Hot Air,

You seem to have a good handle of coal gasification, matbe you can help.

The wording that is used for the type of coal that is most suited, is "reactive" and apparently Lignite falls into this category, maybe you can educate me in what other types of coal would be considered "reactive".

As for seam thickness, it appears 2m to 10m ie approx 6ft to 30ft thick. Ash content up to 40% is also not a problem.

Unless you are trying to do some pretty fancy chemistry, more reactivity is always good.

Coals tend to have reactivities opposite to their fuel content. Lignites will tend to be more reactive than bitumenous coal and anthracite will tend to be the least reactive. Ash tends to have a catalytic effect, but the big advantage for underground rather than surface is that you don't have to find somewhere to dump the ash after gasifying the coal.

With a low quality fuel you have to run the gasification at low temperature, because the fuel wont support higher temperatures, so you need it to be reactive. With a high quality fuel, it can support higher temperature operation, so it doesn't need to be so reactive.

Lignite makes sense, and with a lignite target, it has to be reactive. If you happened to have a lignite that was rather less reactive than typical, it would be bad.

@hot air

>Why are such thick and shallow seams now regarded as being better gasified than mined?<

It is unclear to me what you mean with this statement. To my understanding the idea is to use UCG where conventional mining is not applicable. In case of too deep coal, offshore areas, or where it is not feasible due too environmental/population restrictions.

>Could you expand on how steam is used to increase temperature in the Yang process?<

Here are the details from the paper, if you want to know the reactions and more details you can purchase the paper:

"The two-stage UCG is an underground gasification method of supplying air and steam stage-by-stage. In the first stage,
the air is injected. The combustion (reactions (1), (2), and (3)) in the coal seam is initiated, producing a lot of heat, which is stored in the coal seam and results in the temperature increase in the gasifier in a stepwise way and forms an ideal temperature field, which, in turn, produces air gas containing a large amount of N2.

In the second stage, the steam is injected. The decomposition reaction (5) occurs [15] between the steam and the
incandescent coal seam, producing water gas with a high content of H2. Because the decomposition reaction is an
endothermic reaction, the temperature in the gasifier declines. When the temperature in the gasifier declines to a
sufficient degree, the gasification agent is changed to air, and this is repeated again and again.

The two-stage underground gasification technique is dependent on the size of the gasifier. If the gasifier is small, and
the heat accumulated is not sufficient in the first stage, then, when the steam is injected, the heat will be consumed too quickly, lowering the temperature in the gasifier, and rendering it impossible for the second stage to last long enough to sustain hydrogen production. Therefore, the gasifier in the Woniushan Mine provides good conditions for the use of two-phase UCG to produce hydrogen. (yang et al. 2008 p. 1276)"

The point on depth is already answered. It has to do with what people regard as "coal". Being relatively advanced in years, and not having worked on coal for several decades, I tend to think of "coal" as that solid black stuff which you could buy in sacks from the coal merchant and has now been mostly mined and burnt. When coal is mentioned the soggy brown stuff does not spring to my mind. There are indeed thick deposits of the soggy brown stuff not far underground, which would certainly have been mined if they were the shiny black stuff, but being soggy and brown are still there to be gasified.

The soggy brown stuff near the surface is a reasonable gasification target. I just don't naturally think of that as "coal", but once "lignite" is mentioned, it makes sense to me.

The Yang process looks pretty straightforward too. With the extra context I think its just a clumsy translation from the Chinese.

To me this is a major new source of available energy, it uses a current stranded resource (deep coal), it has minimal disruption to the country side, it controls aquifers much more successfully than Coal Bed Methane, or Coal Seam Gas (name depending on where you live) and recovers 20 time the amount of energy than CBM/CSG from the same coal.

As the CO2 is easily recovered at source it can also be easily disposed of down hole. It has been found that a depleted cavity can actually absorbed more CO2 than it produced while under production. Therefore each depleted cavity will become an available CO2 sink for other forms of carbon capture.

The greatest advantage of the easily captured CO2 is EOR for depleted oilfields. There are numerous situations where UCG usable coal is in the same area as old traditional oilfields. Both Linc Energy and Carbon Energy, both Australian UCG companies are starting operations in the Powder River Basin with this purpose in mind. It has been stated that CO2 from UCG is the cheapest source of CO2 available.

The best coal for UCG is actually Lignite (Brown Coal), ie the cheap stuff nobody else wants to use, and quite often nobody has looked for or worried able it unless it is very shallow and thick. There actually are deep reserves of brown coal along the TX & LA onshore coast. Nobody has been interested until now, but if this resource could be converted to CO2 and used for EOR in all those TX & LA depleted fields, what would be the result. Might not turn the world around but should be a profit for someone.

The syn gas produced in usually high in CO and H2, making it idea for GTL to ultra clean diesel, as well making N2 fertilizers. The excess H2 can be converted to electricity by fuel cells at 50% efficiency or just burn it in a CCGT for a simple guaranteed result.

I do feel we will see more UCG in the near future.

Declaration: I do own some UGC companies. (At least I put my money where my mouth is)

pusher - Interesting. The Lower Colorado River Authority has a couple of lignite burning plants just a couple of hours west of Houston. Don't know much about those reserves but the plants (built on top of the lignite field) have been running for a couple of decades. And the lignite sits right in the middle of billions of bbls of residual oil. And most of those wells have been abandoned.

I might have to think about getting into UCG and use the CO2 for EOR. Win/win so to speak.


That is what I thought, when Linc came up with the idea in Wyoming, so I bought a few more shares. BTW Linc actually bought the GasTech leases that are quoted in the post above.

They are also on the hunt in the US to repeat the idea in other states.

The minimum depth of the coal seam needs to >150m covered by an impermeable layer of rock, there were some failures in the 70's when it was tried at a too shallow depth.

The max depth is > 1000m where Swan Hill Canada is currently doing a project at 1400m, though I believe this ups the cost due to the higher HSP and the pumps required to over come it.

You say that there is minimal disruption to the countryside but what is the risk of getting collapses as coal is burnt out?


This question was answered below - thanks HotAir


Here is a ref from the Linc web site. The Linc web site has a lot of information on how UCG works. It is worth a look around.

Thanks, that explains it quite clearly.


What happens to the sulpher and other contaminants in the coal? It was always the boast of the nuclear industry that they put less radioactivity into the atmosphere than the same amount of electricity production from coal.

Does this process allow the sulphur and heavy metal in the coal to be extracted efficiently?


If the syngas is going to be used for GTL, then the Sulfur must be removed before it enters the FT process.

Sulphur comes out as H2S, which has to be extracted from the gas, converted to sulphur and disposed of. It tends to be a lot easier to extract H2S from the gas prior to combustion than it is to scrub SOx from the flue afterwards, so gasification should produce less sulphur emissions.

H2S is recovered (along with CO2) in amine-type acid-gas scrubbers.  It can be used with CO2 for EOR or re-injected as fuel for gasification.

I heard a rumor of using Microwave technology for subsurface coal gasification from coal. The idea is to place a long horizontal antenna and use the coal bed as a natural wave guide. Don't
have more details.

I question how cheap this energy really is. At the end of the day, this will still be an expensive source of energy - approx. 6 to 10 cents/kWh including CCS according to the range of estimates above. Compare this cost to alternatives, where, unlike fossil fuel sources, fuel is typically free. How much has been spent on R&D for this technology? R&D spent on wind, solar, energy storage and nuclear (where fuel cost is minimal compared to upfront capital costs) has the potential to reduce levelized energy costs well below 6 to 10 cents/kWh as efficiency improves and capital costs fall. UGC, on the other hand, will never get cheaper as it will always entail ongoing expenses to produce fuel working deep underground, which is by definition expensive. With limited resources to spend on R&D, is pursuing UGC really the best allocation? Or is it an attempt by a fossilized industry to get us all to stick our heads in the sand - literally?


In the present the costs of all renewable energy sources is substantially above 6 cents/kWh, except onshore wind on land in some locations. Not accounting for infrastructure and storage requirements. Your are recycling an unproven theory that R&D developments for wind, solar and other energy sources will continue to develop in the future as in the past. This is based on assuming that all past cost decreases were due to R&D which is not the case (a substantial part has been caused by cheaper commodity costs and cheaper labour) and also ignoring factors which will increase costs of these technologies. Mainly the cost of raw material inputs but also electricity/fuel.

The range of the estimates above to which you refer (table 1) is for a specific region, namely Indiana, which is relatively expensive. If you look at a broader spectrum there is a plausible range at the lower cost end shown by the Chinese pilot and the GasTech calculation, which would translate to 4-6 cents/kWh including CCS.

As to attempts by the fossil industries, the motivations of Linc Energy is partially driven by awareness of Peak Oil. I think it's a concern about future energy availability and far from sticking heads in the sand.


The position that R&D has lowered renewable energy costs is not a recycled unproved theory, it is proven fact. The efficiency of both solar and wind has dramatically improved over the past few decades as a result of extensive R&D efforts. You are correct that I didn't mention the increasing scale of the renewable sector, which has also significantly reduced prices recently as production has skyrocketed. As far as commodity and labor prices go, I think you would have a difficult time demonstrating that they have fallen in real terms over the past decade. For example, even in China labor prices have risen in recent years while solar panel prices have fallen.

The graph you posted directly above the table you refer to shows the range of estimates for UCG cost, ranging from approximately $1 to $8 per MMBTU. At the median level of $4.50, the fuel cost alone is 3.6 cents per kWh, excluding capital, O&M and CCS costs. Including an average of 3 cents for CCS as identified in the IPCC report mentioned plus 1.5 cents for capital (assumes $1,000/kW which is also probably low), and we're already at 8.1 cents before O&M. I would view this as a more middle-of-the-road cost estimate for UCG.

UCG seems preferable to mountaintop removal and open pit mining. But why resign ourselves to continued reliance on fossil fuels when we have an opportunity to radically transform our fuel economy and ensure long-term, cheap sources of energy? If you were to compare the amount of money spent on fossil fuel reserve expansion and R&D to the level of spending on the alternatives I think you would find that a remarkable amount has been done in the alternative space at a fraction of the budget of fossil fuels. Coal will only get more expensive as we have to go deeper and deeper to find reserves. That seems like a losing long-term strategy to me.

One excellent alternative that has not yet been mentioned in this post is thorium, which could, with sufficient R&D, provide baseload power at a fraction of the cost of even the cheapest coal plants.


Thanks for the additional input, here's my reply

You are citing me incorrectly, I stated that it is unproven that the developments as in the past will be the same in the future. I did not say that the developments in the past did not improve substantially. At least that's how I see it.

You are ignoring the most important point I made about the costs of input costs (steel, copper, silver, energy) that will increase for renewable energies which will much less affect fossil fuel technologies, because they are less material intensive. The main reasons for the cost increase (absent of Energy) are the need to mine deeper and relative scarcity.

>Including an average of 3 cents for CCS as identified in the IPCC report mentioned plus 1.5 cents for capital (assumes $1,000/kW which is also probably low)<

Where does the 1.5 cents for CCS capital come from above the 3 USD cents per kWh?

>UCG seems preferable to mountaintop removal and open pit mining. But why resign ourselves to continued reliance on fossil fuels when we have an opportunity to radically transform our fuel economy and ensure long-term, cheap sources of energy? If you were to compare the amount of money spent on fossil fuel reserve expansion and R&D to the level of spending on the alternatives I think you would find that a remarkable amount has been done in the alternative space at a fraction of the budget of fossil fuels<

The main reason is A) stock based resource and therefore B) costs. The opposite of your question is: If we can do UCG with CCS cheaper than renewable energy, why would we do renewable energy?.

Thorium is a straw man argument without proof that it is a workable technology, which so far it is not. If you can provide me with a guest post about thorium reactors and their feasibility than that would be welcomed. For instance similar to the UCG post above.

You are ignoring the most important point I made about the costs of input costs (steel, copper, silver, energy) that will increase for renewable energies which will much less affect fossil fuel technologies, because they are less material intensive. The main reasons for the cost increase (absent of Energy) are the need to mine deeper and relative scarcity

I confess I am baffled by this and other statements like it. Quite frankly I absolutely do not believe it is true! I wish someone would point me to data, research or studies that include a whole cost accounting of all the materials and energy that go into the entire supply chain of the technology and machinery that is needed to mine, drill, process, refine, transport etc.. of all the fossil fuels that we use to power our current industrial civilization. Are you claiming as a fact that there is less need for steel, copper, energy, etc. in keeping even some of the basic infrastructure functional? Let alone the building out of new rigs, wells, ships, heavy machinery, etc?

If someone has a credible comparison of what materials are really needed for both alternatives and fossil fuel technologies I'd love to see it. And that's even without getting into paradigm and expectation changes that are already underway.


Your remark is warranted as I made a bold claim and didn't back it up with data. I'm working on an analysis, give me some time. For now

>Are you claiming as a fact that there is less need for steel, copper, energy, etc. in keeping even some of the basic infrastructure functional? <

yes, that's my present expectation.


I similarly think you may mis-cite my argument, which is that scale and technology gains will work to rapidly lower costs - as has been shown in the past - most than offsetting any increase in commodity costs. For example, FSLR discloses that its COGS in 2010 was only 53.8% of revenue, or $0.77/W, including labor, manufacturing overhead, etc. indicating that there is room for further retail cost reduction even in a rising commodity price environment. Despite the rise in raw material costs including silicon in 2010 over 2009, FLSR's cost to manufacture on watt dropped from $0.87 to $0.77 year over year. Further, FSLR states:

"By continuing to improve conversion efficiency and production line throughput, lower material costs, and drive volume scale to further decrease overhead costs, we believe that we can further reduce our manufacturing costs per watt"

This illustrates my point that there are more important factors than raw material costs alone when it comes to the cost of renewable energy.

FMagyar also makes an excellent point regarding the use of commodities in conventional fuels. I think we can all agree that the pipelines, drilling rigs, refineries, heavy machinery, etc. used in conventional production all use far more raw commodities than renewable techs.

>Where does the 1.5 cents for CCS capital come from above the 3 USD cents per kWh?<

This represents the levelized capital cost of the plant required to burn the syngas. The 3 cent CCS charge is incremental to the cost of the facility needed to generate the power. I based this estimate at the low end of capital costs required for a new natural gas-fired plant.

>The opposite of your question is: If we can do UCG with CCS cheaper than renewable energy, why would we do renewable energy?<

Even with CCS, this process still emits a substantial level of carbon - not to mention the significant groundwater contamination issue. As mentioned before, there is little remaining economy of scale to gain in the conventional business, while investing in renewable energy - even if it may be more expensive in some forms now - promises to yield a substantial return to society in the form of lower costs.

>Thorium is a straw man argument without proof that it is a workable technology, which so far it is not. If you can provide me with a guest post about thorium reactors and their feasibility than that would be welcomed. For instance similar to the UCG post above.<

Thorium fuel can be used in conventional reactor technology, and can even be used in combination with spent fuel rods helping to solve the problem of radioactive waste storage. While I am not a nuclear physicist, I would be happy to provide a guest post covering a meta-analysis of the topic. If there are any readers here with greater knowledge of the technical side of the thorium process that would like to collaborate I would be interested in linking up.

By the way, while I differ in opinion with regard to some of your conclusions, I appreciate the post and would like to thank you for your well-written overview of UCG.

I think we can all agree that the pipelines, drilling rigs, refineries, heavy machinery, etc. used in conventional production all use far more raw commodities than renewable techs.

I'm not so sure. Renewable sources of temperature gradients are almost aways more diffuse than conventional, combustion related sources. The ambient solar power flowing around us results in lower temperature differences than can be obtained through combustion. Generally speaking, a shallow temperature gradient requires a large structure for conversion to a more useful mechanical or electric form. Admittedly, this is neither a rigorous or thorough treatment of the entire system. Are you aware of one?

I'm not sure I fully understand your point - but let me give it a shot. Generally when discussing renewable generation we are not working with thermal gradients to generate power. Wind power is mechanical, while photovoltaic solar converts photons directly into electricity (and waste heat). Solar thermal does rely on the temperature gradient, but it concentrates the sun's energy to achieve a significant temperature difference without requiring a large superstructure to convert that energy collected to electricity.


Thanks for your reply.

Wind results from thermal gradients in our environment, as does rain. A few hundred watts per square meter is a very low energy flux, compared to that which can be obtained by burning our currently accessible endowment of fuel, be it uranium or fossil biomass. A relatively large superstructure is required to concentrate solar thermal energy for an 1000 MWe electric power plant, dam, or wind farm. While true that PV does not require a thermal gradient, it does require large swaths of land for the same reason. I don't know which requires less raw material on a per Joule basis, and the EROI analysis I've seen is pretty much all over the map, depending on who is doing the analysis. My point is that an in-depth analysis is not so simple, but this simple, first-order treatment does not favor renewables.

Of course, renewable has the advantage of being, well, renewable. Greater questions remain: Which renewable, and how to build it while making the best use what remains of our endowment of potential energy, or which currently inaccessible potential energy source might we exploit, AND what about all of these hungry people?

Ah, now I see your point better. And yes, I would agree that to capture these low-intensity sources that some sort of larger structure is necessary. I read further up in this comment thread that Rembrandt is working on a full cost accounting of the raw materials. I still believe that despite these super structures, renewables will prove to be less intensive on a raw material basis, particularly when including the materials needed to produce and transport fossil fuels. I look forward to discussing this report as once we have some good data it will be easier to understand the difference. We should probably avoid whichever source has a higher cost impact - the trick will be to properly discern all the true costs.

There are 525,000 operating oil wells in the US, and probably 10M abandoned or dry wells. There are 70,000 abandoned coal mines - shouldn't we include those somehow in space requirement calculations?
Energy density is a common criticism of wind and solar, when in fact wind consumes very little land - perhaps 1/2 acre per 1.6-3MW wind turbine - much less than other forms of generation, when you include fuel mining and the overall footprint of generating plants (nuclear plants can take up more than a square mile). Rooftop solar doesn't consume any land.

18.5 acres per MW!

The Clinton Power Station is located near Clinton, Illinois, USA. The nuclear power station has a General Electric boiling water reactor on a 14,300 acres (57.9 km2) site with an adjacent 5,000 acres (20.2 km2) cooling reservoir, Clinton Lake. Due to inflation and cost overruns, Clinton's final construction cost exceeded $2.6 billion, leading the plant to produce some of the most expensive power in the Midwest. The power station began service on April 24, 1987 and is currently capable of generating 1,043 MW.

To this we of course have to add the land use for mining and refining the uranium yellowcake.


Yes, the volume of mined material should be accounted for in all cases. How much material is mined for the wind turbine components? How does this compare to the amount of material mined for nuclear?

Footprint should be an apples to apples comparison as well. A 450 MWe nuclear plant will run rain, wind or shine, and is way smaller than, to pick a random example, the 25,000 acre 450 MWe capacity (i.e., on a really good hour) Bigelow Canyon Wind Farm. To use capacity as a benchmark, one must include the capacity factor or duty cycle of the power plant. Another factor against renewables. The nuclear power plant itself is small, and if it is on a square mile site, that has more to do with security than anything else. A nuclear site forest can be logged, just as a wind farm can be farmed. Nobody would really want to live in an area bombarded by turbine blade shadows or security guards. Cooling reservoirs shouldn't count, since they can be and often are major bodies of water.

How much material is mined for the wind turbine components? How does this compare to the amount of material mined for nuclear?

Wind turbines require more steel and concrete per average watt of output, for construction. The steel and concrete have standard specifications, so they're cheaper than nuclear construction. More importantly, wind requires no fuel - the lifecycle mining requirements for nuclear are very likely substantially greater than for wind. The land requirements for uranium mining don't occur so much in N. America or Europe, but they're real.

The nuclear power plant itself is small, and if it is on a square mile site, that has more to do with security than anything else. A nuclear site forest can be logged, just as a wind farm can be farmed.

That sounds mighty unrealistic: you can't maintain good security with loggers running around. No, a nuclear plant "consumes" land in a way that wind power does not.

Nobody would really want to live in an area bombarded by turbine blade shadows or security guards.

Farmers would strongly disagree (I assume "security guards" applies to nuclear).

Cooling reservoirs shouldn't count, since they can be and often are major bodies of water.

Of course. That's my point: just as it's silly to say that a nuclear plant's requirement of a body of water means that the plant "consumes" the body of water, it's silly to say that a wind farm "consumes" the land between the turbines.

The bottom line: "density" or "diffuseness" is an unrealistic argument against renewables.


Thanks again for the reply, I am working on an article on the subject (economies of scale, cost decline, input costs for ren. energy) that will be published in the not too distant future. Hope to discuss there further with more data

I looked a bit into thorium reactors after you brought it up, its interesting especially now that China has ventured into Fluid Thorium. The more "conventional" forms of reactors as pursued by India are probably so interesting in my perception (cost, risks, operation difficulties).

I eagerly await your article and look forward to some good data to digest.

Regarding thorium, I would agree that the more promising forms are the more advanced as they could substantially mitigate many of the items that make building a conventional plant so difficult such as large footprint, NIMBY effects due to the fear of meltdown and substantial red tape. While there is more research that needs to be done, the potential payoff is huge. My concern is that we will continue to shun anything even remotely nuclear-related, and/or allow special interests to continue to block research funding, allowing other countries such as China to commercialize a technology that we invented. Do we really want to wean ourselves off of foreign oil only to rely on China for our nuclear tech?

Thorium is a straw man argument without proof that it is a workable technology, which so far it is not.

The MSRE verified the important details of molten-salt fuels, and the final run of the Shoreham reactor proved that over-unity breeding with 233U-Th fuel is possible even with a light-water coolant.  (Lightbridge will soon be selling U-Th fuel assemblies for LWRs.  I doubt they'll breed more than unity, but they will leave lots of 233U in the spent fuel just waiting for molten-salt reactors to take it.)

Much of what you're complaining about originates in politics, not technical issues.  Both the MSR development effort and the IFR were killed by political action, not technical roadblocks; the IFR in particular was killed at a point where it cost more to close (and refund foreign contributions) than it would have cost to run.  This is the sort of thing that happens to real threats to the status quo, not technically impossible initiatives like an all-hydrogen economy.

"... the final run of the Shoreham reactor ..."

ITYM Shippingport. :-)

You are correct.  Brainf**t!

Assuming the following, which I think are reasonable assumptions today:
(1) We aggressively build out wind/solar.
(2) Nuclear is all but dead due to a combination of escalating costs plus Fukishima.
(3) Shale gas isn't going to be cheap/abundant enough to do the job all by itself.
(4) We do CCS with this.
(5) Cheap energy storage doesn't allow wind/solar to become 100% of our use.
It would seem we need some power sources which can be used as a combination od baseline and dispatchable mode, to make up for generation gaps in wind/solar. Gassification plus CCS, if used primarily to balance out the inevitable supply gaps associated with wind/solar, would allow a fairly longterm sustainable energy future.

Used on a large scale, there might be some issues related to the change of the deep underground layers affected. Will the spent coal layers, contract or expand, leading to either subsidence or rising land surfaces? What other problems might ensue from the widescale use of such methods? Even if we do CCS, it won't capture 100% of the CO2, so there is still climate risk even if we do it almost right.

I think that your assumptions are generally reasonable with a few caveats:

>(2) Nuclear is all but dead due to a combination of escalating costs plus Fukashima.<

Politically, possibly so. Changing the politics of nuclear will be essential to lowering costs. However, from a technical perspective the cost of nuclear is falling as it becomes more modular with smaller footprints. Thorium in particular has the potential to be a game changer - but again, progress is frequently blocked by special interests.

>(5) Cheap energy storage doesn't allow wind/solar to become 100% of our use.<

It doesn't need to. Nuclear will continue to represent ~20% of our generation for decades, hydro 7 - 10% and gas at least 20%. The other half could easily be made up from baseload renewables (including geothermal, wave energy and biomass), and a dispatchable combination of intermittent sources and modern natural gas generation. Demand growth is already more than met by current rates of renewable and gas capacity additions, allowing renewables and gas to take market share from coal. As shown in the link, coal use has declined markedly over the past few years (partially due to the economy, granted).

Either way, while UCG appears to be preferable to traditional generation, I don't see it as necessary for our energy future.

I remember some interesting articles by Heading Out, on long wall coal mining. There was a lot of discussion of how the overburden subsides/collapses sequentially all the way up to the surface of the ground. I wonder what is known about how the underground cavities created by UCG develop and collapse.

I note that the need for an impermeable rock layer is mentioned above. How can one be confident of the continued impermeability of a rock layer if it is subjected to massive differential subsidence? I wonder.

Thanks, Rembrandt, for a very interesting article.

Collapse happens, but not all the way up to ground level.

The rubble from the roof occupies more space than it did in the roof. Around 1/3 of a pile of rubble is the space between the rocks. So if you start out with a 1m high cavity and 200m of solid roof over it, you end up with 3m of rubble filled space and 198m of solid roof over it.

If you had a 5m seam with a 3m impermeable layer over it, you could be pretty sure that it wouldn't be impermeable after you burnt the coal out, but a 3m seam with a 20m impermeable layer is a much better bet. Even though about half its thickness will be in a rubble pile there is still an impermeable layer sitting on top of the rubble after the coal is burnt out.

As the saying goes, "You cannot be serious!!" This is a terrible thing to do. Notice how careful the author and the presentation are to not actually say what they are really doing? They are talking about setting these coal seams ON FIRE and collecting the vapors. This is a recipie for environmental disaster. Having grown up in an area where underground mine fires were common, they are very difficult and extremely expensive to control or contain if it gets out of hand.

Hot Air, yes collapse does happen on the surface. I recommend everybody just Google "Centralia mine fire" to see what happens with underground combustion of coal seams.

I visited a similar fire to the Centralia one, near Cransac in France, many years ago. However these are very shallow fires. The jist of this thread is seams that are very deep, maybe a mile down and hardly easy to connect with the surface.


A chamber capped by an impermeable layer with wells drilled into it is easily flooded to quench a flame.  That's not the problem.  Making resource-cheap and pollutant-costly energy is the problem.

Grin, that's what we thought until we tried to do it. You need the coal seam to be deep enough that the thermally induced cracks, as well as the mechanical ones formed when the roof falls into the cavity are contained well below the surface (to prevent air access, which is the big reason that they can't control the fires at Centralia).. One of the big issues in this process is the control of the fire front, and it is why the dual-bore system is likely to prove the best. We worked on solving some of these problems back in the 70's and early 80's. It is relatively easy to drill a horizontal hole in coal with a high=pressure waterjet stream- and by adjusting the pressure you can actually keep it in the coal. (We were asked to look into developing the "round-the-corner" drill for this because of the problem of keeping the drill in the bottom of the seam - a problem with conventional tools at the time).

We found that if you left a hot spot in the coal no larger than a quarter, then if it was left for a day you might as well not have bothered. Mud works better than water.

I would have thought the problem with cracks would be water getting in or gas getting out rather than air getting in.

How much further does thermal cracking actually go? My assumption was that if you were heating up that much overburden, the process would be not be economic.

that's what we thought until we tried to do it.

If the seam underlies an aquifer, that doesn't seem to be a likely problem.  Too much subsidence and it all goes out.

... air access, which is the big reason that they can't control the fires at Centralia

My prescription for that is to dam the valley and flood it, or just dig canals to allow comprehensive flooding of the seam from many points of entry.  That might be too expensive for people to consider, but even dry spots wouldn't matter so long as they were isolated and eventually burned themselves out.


You are confusing fires in coal seams that are uncontrolled which occurred through unknown reasons with much deeper controllable fires. Controllable as combustion requires inputs and these can be controlled. The Centralia mine fire is in no way comparable to a UCG process.That doesn't diminish the impact of what this disaster may have had on the area there, but it certainly doesn't relate to UCG.

Here is an explanation on how the combustion is controlled and commissioned.

The claimed low cost of liquid fuel from UCG doesn't ring true. Using air input it seems the exit gas could consist of ~35% nitrogen. That would be a lot harder to capture than reactive components like H2S. Same goes for excessive raw CO2 levels. Perhaps the Fischer Tropsch processor can cope and unreacted gases are vented afterwards.

A couple of years ago Linc drove a small car around Australia displaying some words like 'clean fuel' or similar. A truck carrying spare fuel followed behind. The term 'clean' was evidently a reference to low sulphur not low well-to-wheels CO2 which I believe to be about double that of oil derived fuels. Let's say it's 5 kg well-to-wheels CO2 per litre of fuel. A carbon tax of 3c per kg of CO2 would add 15c to each litre of fuel. That is not how Australia's carbon tax will work initially but it may turn out that way.

I think it's implausible that the onsite CO2 could be captured and re-injected underground. That means the same sedimentary formation happily gives up one gas in a permeable layer then stores another gas in a less permeable layer. I suspect Linc are biding their time until Australia has a liquid fuels crisis at which point environmental concerns go out the window.

Britain used town gas to operate vehicles during WWII, when petroleum was in short supply.  The product of UCG could probably be used similarly, though modern vehicles would be much harder to convert than ones with carbureted engines.

The UCG operations would have to be local to the point of use.  The heating value of syngas is much lower than NG (very expensive to pump) and nobody would be building a pipeline network during a crisis.


Not sure what the cost figure about UCG you cite. The figure I have heard is 30 dollars per barrel from Linc Energy which is based on their press statements, and doesn't show any calculation behind it whatsoever.

If you have insights as to the costs without a carbon tax that would be interesting. To what extent can it compete with diesel/gasoline?

I seem to recall somewhere that well-to-wheels CO2 for UCG-GTL was 1.7 times that of petro fuels, but I've also seen 2.1 someplace. Maybe it's a commercial secret.

In Australia petrol and diesel are retailing for $1.35 - $1.50 per litre, much of that being fuel excise. It's hard to believe Linc could make liquid fuel for 19c/L since $30 per barrel is 3000c/159L. Since the excise is a kind of pseudo carbon tax it was decided to leave liquid fuels out of the carbon tax system for a few years. Carbon tax starts July 2012 at $23 per tonne of CO2 with 'carbon cops' visiting sites to check on emissions. If I understand it right in 2015 carbon tax will rise to $29 then both the tax and fuel excise are supposed to change over to an auction based trading scheme. If the market can't afford a high final fuel price then the CO2 component could conceivably fall in price. No matter since the CO2 target should be achieved.

If the future belongs to PHEVs and bi-fuel NGVs we'll still need some high priced liquid fuel to get us home from the back blocks. Provided we no longer burned coal to make electricity perhaps we could afford some minor CO2 to make liquid fuels.


Here is some info on UCG being used for power generation and how it compares to other types of power plants, with and without sequestration.
As for the GTL process, I am not sure why you would assume GTL diesel would be so much higher in CO2 well to wheel than traditional crude to diesel. For FT GTL all the CO2 is captured and there easily sequested. If this is combined with Enhanced Oil Recovery (EOR), then there is now a financial advantage instead of a penalty to aid with any compliance issues.

As for CO2 being produced in the plant. The UCG process produces an excess of H2, therefore the CO is fully reacted leaving no excess carbon atoms. The only real source of CO2 from the plant would for heating of the gasses, but crude oil has to be heated to be refined, therefore would have equivalent CO2 produced.

An unstated advantage of UCG-GTL is transport. As most oil being used today comes from just about the furthest distance it could be from any market. UCG coal on the other hand can be found much closer to home markets.

As to 19c per litre claim, I believe this is an OPEX cost only, and does not include the CAPEX.

"If the market can't afford a high final fuel price then the CO2 component could conceivably fall in price."

I think you are being wildly optomistic here. Australia has promised a reduction of 5% in carbon emissions by 2020. Presumably when the market mechanism is put in place then this is the target that will be used as the basis for issuing/auctioning permits. Unfortunately Australia's population, going on current trends, will be 15% higher by 2020. The net result is that we need to achieve a 20% reduction on a per capita basis. This will require a arbon price far higher than $23.

If the scheme remains in place and they stick to the stated taret then I would expect the carbon price to peak above $80 prior to 2020. Such a price will decimate all Australian manufacturing industries. We will become an economy that is completely dependant on mining.

I would expect the carbon price to peak above $80 prior to 2020

As I understand it, after the scheme moves from a fixed-price ($23/T) scheme to a variable-price scheme, there will still be a period of time when the price 'floats' between upper and lower bounds (the upper bound being something like 20% above the estimated price for overseas ETS', or something).

We will become an economy that is completely dependant on mining.

Unless we reduce wages and conditions or re-impose tariffs, local manufacturing is pretty much dead anyway. There is absolutely nothing that Australia can make that China can't make cheaper. Part of the blame for this can be sheeted home to the manufacturing and retail industries, who could have come out in support of the RSPT (which would have put the brakes oh-so-slightly on the miners), but didn't, and now have to contend with not only flat sales, but a strong dollar as well (and a strong currency is the last thing you want when you're trying to sell stuff overseas).

I think it's implausible that the onsite CO2 could be captured and re-injected underground. That means the same sedimentary formation happily gives up one gas in a permeable layer then stores another gas in a less permeable layer.

Academic evidence exists which indicates that UCG cavities are capable of absorbing significant quantities
of CO2. This research also suggests that UCG cavities could absorb up to 400 times more carbon than
traditional CCS methods due to the effect of the UCG process on the surrounding coal seam.


It may seem implausible, but it appears to be true and Linc is putting up the money to prove it.

There's at least three stages of CO2
1) complete combustion underground
2) FT process
3) vehicle tailpipe
On the second if I recall Robert Rapier visited a GTL plant in Malaysia and concluded 30-40% of the heating value of the gas feedstock was consumed in the FT process. That's to create the heat and pressure needed to get short chain molecules to combine into room temperature liquids. For GTL it seems easier to use normal natgas and CSM of which Australia is supposed to have 500 tcf or nearly a billion tonnes. Better still just use the gas as a vehicle fuel and skip the FT step.

The extensive scrubbing steps must take away a lot of the net energy. First there's removal of N2, H2S and excess CO2 created underground. Then there's post-FT surface CO2 which along with the pre-CO2 should be injected back underground. The nearest oil recovery would be some distance away so there may be no market. There's also the local effort needed to drill new wells when a coal seam is spent.

As for w-t-w CO2 this will come under the watchful eye of the carbon cops


I had a look at RR's post on GTL, It did surprise me that it was so high, but we do have some differences. The GTL must first breakdown the bonds in the CH4, before reassembling into long chain hydrocarbons. Once cleaned up the UCG delivers, H2 +CO for recombination and therefore less energy required on surface. I do not have any numbers but there must be a major energy saving.

I doubt they would be buying in Natural gas, as they would have their own produced CH4 and excess H2 to burn if process heat was required, not forgetting the excess heat produced during the FT process.

Sequestration, it may surprise you but many coal fields have adjacent oilfields, as they are both formed in sedimentary basins, so once the oil companies find out there is a ready supply of cheap CO2 available, they will be all over it like a rash. The areas not so lucky, and as I stated before, the used cavity is capable of absorbing up to 400 times the carbon that it produced. Therefore this will be a ready made solution for carbon sequestration of any third party emissions eg local coal fire power stations.

Just so you don't think I am totally against your ideas. I agree we should be doing more to use our Natural Gas for transport. LNG for heavy transport needs support, BOC (EVOL LNG) is currently building a small LNG plant at Chinchilla, for this purpose, shouldn't be to far from finishing as long as they did not get washed away in the floods, to go with there plants in Melbourne and Tassie.

CNG should also be pushed. There is a ready market just waiting. Anybody who has installed LPG is the perfect market for CNG, of course it won't happen overnight. The problem as I see it, is the Government and the Green movement are so focused on Carbon, nobody is seeing the approaching problem of liquid transport fuels. To the point they left out transport fuels in the Carbon tax. Was there anything in the Carbon tax for rail? I don't think so!

I see we are going to be blind sided in the worst possible way.

I am doing my little bit to avoid disaster, or at least have a Plan B to act on, by investing in what I see are viable alternatives.

Nit in the article:

different depths ranging from several hundred kilometres up to 1.4 km of depth.

The highlighted "kilo" is an error.


Thanks, edited in the article.

The best thing about UCG is the ability to filter off the Hydrogen and pass it through high efficiency fuel cells for clean electricity, whilst passing CO2 back into the burnt out coal seams, where research shows that much more CO2 can be stored than was extracted. See details on the following links:

...and the worst thing about UCG is that it's a death sentence for the biosphere.

It's a toss-up, huh?

dan allen, your comment indicates to me that you know nothing about UCG.

UCG gasifies the coal underground. Toxins and ash remain buried underground where that part of the coal has been for thousands of years.

The Syngas that comes to the surface is split into pure gas streams, all of which are used commercially apart from the CO2 which is returned to the burnt out coal seam, where up to 400x more CO2 can be stored than in other CCS systems(saline aquifers for example).

All UCG is now done below the water table, using methods that do not contaminate the water table(Linc have over 10 years with ZERO water contamination).

UCG is done in blocks, leaving supporting pillars between burnt out areas to support the land and prevent subsidence.

There is ZERO impact to the Biosphere.

Please do research properly before commenting, as it is so easy for an expert on UCG (I have been studying UCG for 2.5 years) to spot comments based on no research or understanding of UCG.

Sigh...gas fracking does not contaminate groundwater...leakage from the core of a boiling-water reactor is impossible...deepwater oil blowouts are impossible...UCG can be benign...only $19.95 and it will last a lifetime, call now!!

Come on, man! In 2.5 years you never came across any of the thousands of grim real-life accounts of past applications of energy technology? We're babies paying with machine guns!

Dear sir, I suggest another 0.5 years of research.

dan - "...gas fracking does not contaminate groundwater..." Yep..that's exactly correct. There has never been one documented instance of the frac'ng of a reservoir having ever contaminated groundwater. But there are numerouse documented instances of other oil patch (and many other industries) activites thast have caused ground water and surface contamination. In Texas, PA, NY and every other area on the planet where hydrocarbon extraction has taken place.

Again too much long established tech to go into here but it is physically impossible for those deep fractures to reach the aquifers. Not an opinion...simple earth physics. Maybe you missed the chat a while back: they finally figured out where the frac fluid contamination was coming from: improper and often illegal dumping of produced frac fluids. And a good bit of which was done my local municipal treatment units. Which is why both PA and NY recently had to pass laws to force the locals to stop doing it. Been illegal in Texas for many decades.

C'mon...shit gets spilled, workers don't follow rules, regulatory 'cops' are perpetually underfunded and undermanned, things break...

Bottom line -- fracking pollutes groundwater.

Maybe you missed the effects of the last 150 years of energy acquisition?

dan - Respectfully get off your high horse and stop trying to spin the story.

"*hit gets spilled, workers don't follow rules" - Is that not exactly what I said: "...there are numerous documented instances of other oil patch (and many other industries) activities that have caused ground water and surface contamination."

" missed the effects of the last 150 years of energy acquisition?" No I haven't. Unlike you I've witnessed it firsthand many times so I think I'm a tad more qualified on the subject then you.

"...fracking pollutes groundwater." No it doesn't. Offer one documented case where the frac'ng operation polluted ground water. You can't. Perhaps the conversation is to technical for you to grasp. Again, it's physically impossible for the fractures generated thousands of feet below the fresh water aquifers to have any effect on them. Companies spend $millions trying to get fractures to extend upwards a 100'...and often fail to reach that height. Perhaps you read my post too fast so I'll say again: "the frac fluid contamination was coming from improper and often illegal dumping of produced frac fluids". Whether those nasties came from a frac'd well or some other industrial activity isn't the issue. If these states had the same laws as Texas and La and enforced them as we do very little contamination would have occurred other then true accidental spillage.

Again, the frac'ng of a well cannot pollute the ground water. Improper disposal of those produced frac fluids, OTOH, can create terrible contamination. If you can't appreciate that distinction then I fear we are wasting space on TOD with this discussion.

dan, UCG is the best way to use coal, proven by over 50 years of running it at the Linc Energy Angren power plant. UCG with fuel cells can produce near zero emissions power(99% CCS, no NOx or SOx and no efficiency loss from that) at a capital cost far less than Nuclear, with power generated at a price that is lower than Nuclear.

Do you think that cutting mountain tops off to get to coal is better for the biosphere?
Do you think wind turbines are less impact on the biosphere than UCG?
Do you think solar electric is less impact on the biosphere than UCG?
Do you think Nuclear waste offer less impact on the biosphere than UCG?
Do you think coal and gas power plants, even with 85% CCS, offer less impact on the biosphere than UCG?
Do you think Coal Bed Methane is less impact on the biosphere than UCG?
Do you think Shale Gas is less impact on the biosphere than UCG?

My guess is that you think some or all of the above are correct, in which case you would be wrong.

Take your head out of the sand and smell the syngas!!

"Do you think that cutting mountain tops off to get to coal is better for the biosphere?"

Certainly not. But UCG won't replace MTR either. Surface mining will continue.

UCG is an interesting technology but it seems to me that the impact, both in btu's and environmental (no mining is benign), will be additive. In the end, the article's theme rings true - the fossil fuel age can be extended a while.

For good or ill, it looks likely that this will become economically viable, possible after the shale gas boom runs out?

I did not see much discussion of the gas collection and usage logistics. Is the typical goal to gather and pipeline the gases to existing power plants? Or build a local gas powered electrical plant? Or something else? Such logistics would seem to weigh in on the overall utility and the electrical cost shown. Does the cost include full carbon sequestration?

I am curious as to whether advancements of a similar sort will eventually make keragen in situ gasification possible. Perhaps it is too soon to tell?

I do hope that a full cutover to renewables occurs prior to needing such sources, and I hope these sources are sufficiently expensive to drive such shifts. I'd rather have a soft landing than a hard crash, but first we gotta push forward on the stick before we stall.


It is not economic to transport the syngas over long distance, therefore most of the solution or uses of the gas are local, power station, GTL or N2 fertilizer. There is an option to convert the syngas to CH4, but this requires energy and extra cost. The decision to go ahead with this step would be very market dependent and from knowledge is not in anybodies current plans.

The carbon sequestration is not a big problem as the old cavities can hold up to 400 times the CO2 that it produced, and this will only be required where there is not a market for CO2 for EOR on depleted oilfields.

If you have clean syngas, surely a gas to liquids process, like methanol production, would be much better than syngas to methane.

One of the "problems" I could see for CO2 sequestration, is that many of the coal areas, like central Queensland, Powder River Basin, etc are not really near anywhere that produces lots of CO2. So they sequester whatever arises from the UCG and any GtL type processes they do, but otherwise, where else would CO2 come from?

Somewhere like the NSW Hunter Valley, where you have coal mines and power stations together, would be a different story, but is anyone proposing UCG there?


The CO2 sequestration I am referring to here, is the CO2 produced down hole during combustion, this CO2 is the produced to surface along with the combustion products, H2+CO+CH4, where it is then separated and "disposed of". The target for this CO2 is,
1/ Sell it to an oil company for EOR,
2/ Sequester into a used, decommissioned UCG cavity where it has been found the used cavity can hold up to 400 times amount of CO2 originally produced.

Can you please confirm something for me. This number of 400 times has been quoted several times in the above posts. The number however has been used to two different contexts:
- 400 times the volume of CO2 that can be contained in a conventional geosequestration rock structure
- 400 times the volume of CO2 that results from the ucg extraction and conversion process
I can believe the first of the above but the second claim appears on the surface to be implausible.

“With a potential efficiency of 400 times that of other CCS methods when storing CO2 in UCG cavities, UCG
operations could end up providing the CO2 sinks required in many parts of the world whilst also producing
cleaner energy.
“Ironically, depending on the price that the world ultimately places on carbon, the UCG cavities themselves
may have a comparable assets value to that of the energy produced from them,” Mr Bond said.


You are correct,
- 400 times the volume of CO2 that can be contained in a conventional geosequestration rock structure

Though the point still remains, there is spare capacity in the decommissioned cavities for third parties to deposit there excess CO2 according to this press release.

It also relies on the coal not being gasified. The CO2 is absorbed on the coal which isn't gasified, so if you only gasify 1% you can put the CO2 from that into the 99% that you didn't gasify. If you later decide that actually it would be more profitable to gasify 90% rather than 1%, that "sequestered" CO2 comes back out again.

400 times as much CO2 into a coal seam that has been activated by gasification, compared to a virgin coal seam, is credible. I'd want to see a peer-reviewed paper, rather than a press-release, to check how representative the conditions it was achieved under were, but its not intrinsically impossible.

400 times as much CO2 as is generated by gasification and combustion of the gas, back into the rubble packed void, is fantasy.

pusher - 400X might seem like fantasy to some folks. But from such statement as the area can "absorb" the CO2 are we really taking about molecular absorption or does it just mean 400X the volume can be contained in the depleted area? More specifically (maybe I missed it) are we talking about the volume of CO2 at STP? I would think if we're talking CO2 at the surface it would be. I know you understand the compressibility of any gas. It's a very simple effort to inject 1,000 cu ft of any gas into a small fraction of that volume if you're injecting under sufficient pressure. So I wonder if a large portion of the "400X" is more a function of the new porosity volume of the rubble zone. Given a high enough injection pressure one can put 1,000 cu ft of gas at STP into a pore space of 1 cu ft. Pretty basic physics: the coefficient of isothermal compressibility of any gas is defined as the change in volume per unit volume per unit change in pressure. Thus the 400X offered could be easily achieved. The capability would just a be a function of horse power and frac gradient.


I had got the impression from the company that it was the surfaces left behind by the burning of the coal, that allowed it to absorb the CO2 on the molecular level, now I am not sure it they were referring to the ash or the cracks and fissures left behind in the coal. I seem to remember a certain hydro static pressure was required, which may mean not all sites would be suitable. My understanding, which could be wrong of course, made me think of an acetylene bottle or most likely the coal becomes activated carbon.

I realize this 400% number has peeked people interest. The number is rubbery at the moment as the research is only just being done, this was the theoretical amount. To be me the important take away point from this agreement is that the used cavities will be able to absorb more CO2 than what they produce, and therefore from the company prospective, becomes a salable prospect, which is a win/win for the environment and the company.

Anyway please see the refs below from the EU web site for CO2 injection. These are the people Linc have their contract with. There are many papers with great detail, but I did not see one for UCG. I believe the reason for this is simply Linc is financing them to do the research and write the paper. Happy reading.;jsessionid=5CAFCDE5D194F63188C...

pusher - Way out of my area but the little I know about desorbtion of methane from organic shales like the New Albany: it a very slow process. Why those wells can produce (at a very slow rate) for many decades. Maybe on paper the resid can absorb 400X but I doubt at the injection rate they would have to use it would work very well. But the rubble zone would increase effective porosity way above the orginal. That's why I was guessing it was more of a storage project than an absorption project.

It's a very simple effort to inject 1,000 cu ft of any gas into a small fraction of that volume if you're injecting under sufficient pressure.

No it isn't.  When you get to the point where the electron clouds of the molecules are jamming up against each other, you're against limits where even diamond-anvil presses have difficulty.

Pretty basic physics: the coefficient of isothermal compressibility of any gas is defined as the change in volume per unit volume per unit change in pressure. Thus the 400X offered could be easily achieved.

You're assuming that CO2 can be treated as an ideal gas.  In the pressure-temperature regions of interest, you cannot do that.

As a simple calculation, look at the numbers for lignite.  Its bulk density (dry matter, I assume) is 0.64-0.86, about 39 wt% water, and 31.4% carbon.  The density of carbon is thus 0.20-0.27.

If all the carbon is converted to CO2, the mass is multiplied by 11/3.  This yields 0.73-0.99 kg CO2/liter of coal.  The liquid density of CO2 is 0.77 at 20°C.  When the volume of ash is added, the CO2 is going to take more room than the coal did (though not a whole lot more).  In the case of lignite, removal of the water appears to free up room which can be occupied by other things such as CO2.  Sequestration in the used UCG chamber does look feasible at the borderline.

EP. Thanks for running the numbers. I don't think we can just add the densities as if each subvolume occupies the same volume it would in isolation. It is possible that dissolved within the coal the volume could be smaller than the coal and CO2 separately occupy. But I have no clue how to compute it.

I have another question regarding sequestration:
If we simply took the combusted gases from one of these plants, and tried to inject it into the coal seam, would the CO2 be absorbed? Maybe the whole apparatus trying to concentrate the CO2 with Amines can be avoided? If air is used as the oxygenator, the flue gas is 80% Nitrogen, but if Oxygen is used it should be 98-99% CO2.

It's possible that the minerals left in the ash (or heat-altered rock nearby) will react with carbonic acid to make carbonates which are denser than the original materials, but that's not something I've studied or would bet on as a SWAG.

It makes little sense to try to extract CO2 from stack gases.  Especially if the syngas is H2-rich, whatever's kept to burn in stationary plants ought to be mostly H2 and require no CCS at all.  CO2 in the syngas stream can be extracted in the cleanup and sent directly to EOR or sequestration.  There are also processes to separate CO from dry syngas; combined with scrubbing of acid gases, even an air-blown gasifier would yield mostly N2 and N2 with some CH4.

Clean syngas can be converted from CO to H2 using the water-gas shift.  The CO2 byproduct can be scrubbed and sequestered.  This was, AFAIK, the premise of the carbon-free FutureGen program.

E.P. Thanks for the update. Didn't FutureGen keep getting put off because the price kept going up? Thats why I'm skeptical of this stuff, it must not be easy in practice.

I wasn't following FutureGen closely, so I am not the one to ask.

The underground gasifier may change matters, as may "polygeneration".  If the gas costs $4.50/GJ (the high end of the estimates from Marc Mostade), half of the energy is converted to hydrocarbons at 75% efficiency (6.1 GJ/bbl) and the rest is converted to electricity at 50% efficiency (mix of simple-cycle and combined-cycle gas turbines) which sells at 5¢/kWh, and the hydrocarbons are worth $105/bbl ($2.50/gallon) wholesale, I get this yield from 1 GJ of syngas:

  Product     Fraction     Yield, GJ     Sales, $  
Electric 25.0%  0.250  $3.47 
Fuel 37.5%  0.375  $6.45 
Total     $9.92 

Looks good to me.

if there is one reason, above all others, why this sort of technology is likely to be adopted, it is that virtually none of the world's coal reserves occur in OPEC countries. On the contrary, almost all the large coal reserves are in the industrialised countries that presently consume large amounts of all forms of energy.

Even if there is a price premium for doing the UCG-CTL, there is a certain value in energy independence. The US of A, which is the world's largest oil importer also just happens to have the largest coal reserves. If the technical feasibility is proven up, a national effort to implement this, similar to efforts for building the Interstate Hwy system in the 60's, is not out of the question.

IF, and it is a big if, you ignore the CO2 aspect, which governments seem to do when it suits them, there are a lot of positives to this approach.

There is no question in my mind that our govt will pay lip service to environmental concerns while pushing this technology for all it is worth once the oil import situation gets critical in terms of actual physical oil-it has long since gone critical in economic terms.

Our country and its safety nets , such as they are , would be fairly safe and stable if we were tio quit buying oil and consumer goods from other copuntries.

It doesn't matter which party is in office-I haven't noticed the Dems pulling out of the Middle East.They won't , no matter how large a majority they might have at any given time.

Of course the 'Publicans hardly even pay lip service to the idea .

mac - So your view is that both the D's and R's are selfserving deceivers but the R's don't try to hide it. In fact, tend to pat themselve on the back over it. So one side says "We should really do the right thing" and then they do little or nothing. And the other side says" We don't care if you think we're not doing the right thing. We're gonna do it anyway...just because we can."

Can't argue with you there. You are a wise man...especially when you agree with me. LOL

Ok then. If they can get this rolled out is there any more detailed extrapolation on how this modifiers the "Big Graph" beyond extending cheap energy for a few decades?

I mean what are we looking at here something marginal or a game changer in medium term (next 50 yrs or so)?

doc - "...beyond extending cheap energy for a few decades". Might be economic but I doubt it will ever qualify a "cheap" IMHO.

So your gut feeling is that this sort of mitigation is a symptom of the "big FF squeeze" rather than a way to outflank it?

doc - Me and the rest of the oil patch "Drill, baby, drill" for a living. Aside from making us some $'s and adding some domestic GDP/employment it won't have much of an effect on PO IMHO. I haven't seen anything else yet that will in the short/medium term. Higher FF prices will make some appoaches profitable that were years ago. But, again, I see no game changers on the horizone.

Assuming 1) coal seams with suitable cap rock so ground water is not contaminated
2) Environmental permissions are given.

Are drilling rates and building GTL facilities the primary constraints?

david - I don't have much of a handle on the cost factors but I'll guess the upfront capex is significant. Wells can be drilled relatively fast compared to the construction of the rest of the infrastructure so I don't think it would be much of a factor.

A large capex by itself doesn't make such projects undoable. But the initial large expense has to be recovered in a timely manner to generate an acceptable return on investment. There's probably a good bit uncertainty in the production rate. And when you combine that factor with the uncertainty factor of future NG prices it may be difficult to generate much interest today. Look how overly optimistic assumptions about future NG prices led to a rush to drill thousands of shale gas wells. As Art et al tells the story today you can see how those players got hit with a double whammy: lower recovery than projected AND lower NG prices. One such misstep is difficult to handle. But both factors hitting a company can easily knock that outfit off the board.

Projecting future oil/NG prices has always been extremely critical in large capex projects. With the relatively rapid swing in the world's economies it's going to be difficult for most investors to feel confident they can project future prices out 5 to 10 years with any great confidence. Yet projects like these require such certainty. As I've said many times I'm uncomfortable when the govt tries to inject itself into such enterprises. But if we want whatever added energy security that could come from such projects the govt might have mandate a future price for such project and/or utilize other incentives. It might end up being good for the American consumer but still makes me nervous.

On the price of oil, I can't see OPEC voluntarily increasing production to reduce the price of oil below $100/bbl. They may have pushed their defacto transfer of funds too fast and pushed EU + USA into recession again and be forced to accept a lower $90/bbl. However some indicate that OPEC budgets would have difficulty in handling below $80/bbl. Furthermore, oil sands projects similarly prefer > $80/bbl.

I presume CERA's marginal oil production cost by project type could be used to estimate the probability of oil price dropping as alternate production increases to displace the remaining global conventional and alternative oil production. e.g. see David Murphy Does Peak Oil matter citing 4. CERA. 2008. Ratcheting Down: Oil and the Global Credit Crisis. Cambridge Energy Research Associates.

Presumably, competitive production would drop out after priced dropped to their cost of production. From CERA's curve, it appears that some 5 million bbl/day above conventional growth would be needed to drive competitive costs below about $80/bbl. Then another 10 million bbl/day would be needed to drive competitive costs down to $60/bbl. After that, another 30 million bbl/day would be needed to go below about $55/bbl.
Conversely, Suncor says they can tolerate prices dropping to $50/bbl, and still be profitable. (Is that given existing operations with sunk costs?)

Are these guestimates of future oil prices anywhere close from what you have seen in commercial proposals?

UCG Firms Update on Estimated UCG Project Economics at Zeus Conference
June 06, 2011

At this publisher’s 5th conference on underground coal gasification (UCG), the cost of UCG was discussed. The conference was held in Houston, Tx May 25. A Lawrence Livermore case study dated 2007 cited at the conference estimated a cost of US$1.5-US$1.62/MMBtu for producing raw UCG syngas in the Powder River Basin in the northern United States. According to Rebecca MacDonald, CEO of Laurus Energy Inc., the company has estimated the cost of producing UCG Fischer-Tropsch syncrude at US$27/barrel using assumptions from a 2007 National Energy Technology Laboratory (NETL) study entitled “Baseline Technical and Economic Assessment of a Commercial Scale Fischer‐Tropsch Liquids Facility,” in combination with the company’s proprietary UCG cost data.

Michael Green, Technical Director of Clean Global Energy, estimated the company’s UCG syngas sales price at US$2.63-US$3.16/MMBtu. They have committed to a project in Oklahoma with a floor offtake price of US$2.35/MMBtu starting in 2011. Clean Global Energy presented its estimates that syngas produced from its UCG facilities would generate power at a cost of US$11.00-15.00 per MwH, with a sell price of US$35.00-US$45.00 at a CAPEX of US$1.2 million per Mwh capacity. In a diesel production case, the company estimates a cost of US$22.00-US$25.00 per barrel with a sell price of US$50.00-US$60.00 per barrel and a CAPEX of US$27,000-US$35,000 per capacity barrel.

The Zeus site has a database of over 800 gasification projects worldwide.

Of all the gasification options UCG is the lowest CAPEX, lowest OPEX, lowest risk to the environment, lowest risk to us and other life on earth.

In places with coal at the right depth, UCG will be the power of the future. It's not that far away either, as all they are doing now is perfecting a technology used for decades, so that they get the most energy out, with the minimum impact, at the lowest cost, with a model and method that can be reproduced en masse around the world.

Form World Coal:
Developments, Projects & Interest
In the last few years there has been significant renewed interest in UCG as the technology has moved forward considerably.
China has about 30 projects in different phases of preparation that use underground coal gasification.
India plans to use underground gasification to access an estimated 350 billion tonnes of coal. In 2007 India compiled a 93-page status report on underground coal gasification that highlighted interest from many of the country's biggest companies.
South African companies Sasol and Eskom both have UCG pilot facilities that have been operating for some time, giving valuable information and data.
In Australia, Linc Energy has the Chinchilla site, which first started operating in 2000. Carbon Energy has completed a successful 100 day commercial scale study in Bloodwood Creek in 2008.
Demonstration projects and studies are also currently under way in a number of countries, including the USA, Western and Eastern Europe, Japan, Indonesia, Vietnam, India, Australia and China, with work being carried out by both industry and research establishments

A map of UCG projects here:

Benefits of UCG, environmental and financial:

UCG vs other power production, note its cost is on a par with Nuclear, but the AFC Energy fuel cells will make it much cheaper, add Nuclear waste into the business case and UCG with fuel cells wins hands down:

FuelCell - thanks for your very informative post on UCG costs. On the Clean Global Energy economics, do you know if those the complete CAPEX costs from coal to diesel?
The following abstract looks interesting: Techno-economic evaluation of coal-to-liquids (CTL) plants with carbon capture and sequestration, Hari Chandan Mantripragadaa & Edward S. Rubinb, Energy Policy Vol. 39 #5, May 2011 pp 2808-2816
Any published capex/opex costs on the AFC fuel cells?

Hi David, thanks ;)

They do say 'CAPEX' for each scenario, so I take it that is the complete CAPEX.

AFC Energy fuel cell CAPEX:
"AFC Energy's fuel cell is currently at £300,000 per MW"

Compare that with other technologies. The data on page 8 is in $/kW. At £300,000 per MW, AFC Energy fuel cells are $492/kW, which is lower than anything else on the list! Note the 'other' fuel cells are over 10x the price of AFC Energy ones!

AFC Energy OPEX is very low too, because all they will do is change the low-cost electrodes, maybe the electrolyte every year. Thing is, the electrodes are recyclable, they just clean and re-coat them with catalyst. KOH electrolyte can be cleaned and reused. Other parts are reusable and recyclable too. Servicing is simple, just unplug(they are hot-swap!) a cartridge, plug a new one in, no downtime!. Take the old cartridge to be refurbished. This keeps the system up and the OPEX down. Look how simple it is.

You don't need the level of technology expertise that you do with a turbine to maintain it, just looking at one is scary enough! Imagine the cost difference between the maintenance staff for a turbine vs fuel cell power station, AFC Energy fuel cells will be around 1/3 of the cost I think.
Turbine manual

AFC Energy fuel cells have another hidden bonus. "for a 1,000MW power station they would produce over 2.5bn litres of clean water a year.". This is ultra-pure deionised water which could be sold to several industries, including semiconductor and cosmetics. The value of the water is estimated at 1/3 the value of the electricity.

The water could be used in the UCG or GTL processes, allowing the UCG to operate with zero use of local water. Handy when you see that 4Bn tonnes of coal in the Pedirka Basin, which is a desert!

See pages 6-7 of this for an interesting read:

News today. Now within spitting distance of Linc Energy demonstrating a commercial UCG + Fuel Cell system.

AFC Energy Complete Rigorous HAZOP Study

Guildford, 8 August 2011 – AFC Energy,the world’s leading developer of low cost alkaline fuel cells, is pleased to announce that the hazard and operability (HAZOP) study of its commercial Beta system has now been successfully completed. This significant milestone on AFC Energy’s route to commercialisation will pave the way for future deployment at industrial partner premises.

Areas for improvement highlighted by the study have been incorporated into the Beta System, which is currently being commissioned at the Company’s premises in Dunsfold, Guildford. None of the modifications involved any significant redesign work and the Company is on track with its plans to deploy a Beta System in the field for testing.

Ian Balchin, Deputy Chairman of AFC Energy, commented: “AFC Energy is delighted to have successfully completed this rigorous study. We have found the HAZOP process to be extremely valuable and it takes us another step forward towards deployment and field testing.”

The completion of the HAZOP study and the technical progress of recent months go hand-in-hand with the development of commercial opportunities in a range of markets, including tie-ups with Linc Energy, the John Lewis Partnership, and N2telligence.

That's one reason Inhofe is popular. He mostly says what he does, and vice versa. A bunch of his positions on renewables and climate may be contrary to national and even local views -- but then, nobody does anything on climate or emissions, so what does it matter? On the big stuff, he mostly votes the way the locals want. Like "no" on the recent debt bill.

paleo - And there's the problem with a republic, eh? We all want our representatives to follow our preferences..."he mostly votes the way the locals want". We're all happy when all of "them" see it our way. But when they don't and their elected representative follows their mandate we get very p*ssed. But at least we can bitch about it without getting shot. Unlike in some parts of the world today.

I would be interested to know the EROEI for the proposed UGC schemes.

Where does it fit in on the scale, compared to other, possibly marginal processes?

It will have to go hand in hand with CCS (or EOR), if it is ever to be deemed acceptable interms of CO2 emissions.

I found some neat links to gas-engines running on coal gas from 100 years ago. Not underground gasification - but the chemistry is the same.

From 1913

From 1903 Mond Gas Book


"I found some neat links to gas-engines running on coal gas from 100 years ago. Not underground gasification - but the chemistry is the same."

I think you are wrong here. Coal gas coming from coal beds naturally is almost completely methane and some CO2. This UCG process has a large percentage of N2 plus possibly oxides of nitrogen, plus CO, plus H2S. Thus the combustable portion of the gas and BTU value per cu foot or liter is much smaller tha natural coal bed gas. Therefore, the efficiency of the heat engine that burns the UCG will be much less, besides requiring more energy for CCS and extraction process.

a friend has a company tht sits above an old coal mine. The gases coming from the "wet" mine shafts produce enough energy to provide electrical power and heat (waste from the generators) to his plant in the winter time. I doubt the company could do the same thing using UCG from this old coal mine.

Perhaps this UCG technology could provide energy where countries have deep or hard to reach coal.

I think you are wrong here. Coal gas coming from coal beds naturally is almost completely methane and some CO2.

Actually, he's right. Coal seam gas may be mainly methane, but what he, and these links, are referring to is coal gas made by gasifying solid coal, inside a purpose built gasifier - a common practice in the late 1800's and early 1900's

The most famous, and largest, was the "gas-steam" engine built to power Henry Ford's highland Park factory in 1915. It ran on gasified coal and used the exhaust from the main cylinder to create steam to run a secondary steam cylinder - combined cycle power plant in 1915!

This hybrid engine was one of nine such units that provided DC power to the Ford Motor Company's
Highland Park; each was rated at 6000 horsepower.
Each of the Highland Park machines consisted of two complete engines direct-connected to a
centrally-mounted direct current generator. Each engine was two-cylinder, arranged in tandem. The
gas engine is a two cylinder, double-acting, four cycle producer gas machine with water cooled 42 inch bore cylinders. The stroke is 72 inches. The engine is equipped with breaker-point low tension
ignition. The steam engine is a tandem compound 72" stroke machine with "composite" valvegear:
poppet valves for the 36" bore high pressure cylinder and corliss valves for the 72" bore low pressure
cylinder. A centrally-mounted governor was used to regulate the speed. This controlled the cut-off on
the steam engine side. If speed exceeded the rated 80 RPM, the governor was arranged so that it
would cut off the supply of gas to the gas engine side. Under that rated maximum speed, the speed of
the entire machine was regulated by the steam engine.

A contemporary engineering magazine reported the thermal efficiency at an unprecedented 72.4%.

Certainly a serious engine!

More photos and discussion here;

I cannot help but admire the "get it done" attitude of that era...

I have been reading about the Hojo Motor
Do you think it's worth pursuing as renewable energy source.

AFC fuel cell cost is probably nearer to £1M/MW after including for power conditioning equipment.