Coal seam gas — dirtier than coal, worse than shale

June 3, 2011

In the land of desperate excuses, coal seam gas is king. The new boom industry of the Queensland and New South Wales hinterlands contaminates ground and surface waters, while taking rich farmland out of food production.

But at least, its promoters argue, coal seam gas (CSG) is a weak hitter among sources of greenhouse pollution. When burnt in modern power plants, the story goes, CSG can be as much as 70% “cleaner” than coal.

But that’s just an excuse. New evidence strongly indicates that when the whole greenhouse “footprint” of various fuels is taken into account, CSG is considerably more polluting than coal.

See also:
Thousands spell out opposition to coal seam gas
Protesters confront Qld coal seam gas conference

A peer-reviewed study of a related technology, shale gas production, has provided important insights. Work by engineers in the US state of Wyoming has revealed huge emissions that current CSG practice fails to prevent.

The new study, published in April by US journal Climatic Change, was conducted by a team under Cornell University environmental biologist Robert Howarth. It concludes: “Compared to coal, the footprint of shale gas is at least 20% greater and perhaps more than twice as great on the 20-year horizon.”

Firms developing CSG stress differences between their industry and shale gas extraction.

But the technology that accounts for most of the greenhouse footprint of shale gas — hydraulic fracturing, or “fracking” — is routinely used for CSG as well. And the end product is identical — the powerful greenhouse gas methane (the main component of natural gas).

Shale gas is found trapped in the pores of shale, a relatively tight rock that underlies much of the eastern US.

To free the gas, the shale must be fractured by pumping in a high-pressure mix of water, sand and various (often toxic) chemicals.

This process opens fissures in the shale and allows the gas to flow to the surface — hopefully through the borehole, but at times by way of geological faults that allow it to vent to the atmosphere or end up in water supplies.

CSG, of which Australia has vast resources, is initially bonded within the matrix of coal in underground seams where it is held by the pressure of groundwater. To extract CSG, wells are sunk into the seams and the water is pumped out. With the pressure reduced, gas then begins flowing to the surface.

Coal seams are fairly porous, and in the early days of CSG development fracking was used only occasionally. But expanding fissures in the seams can allow gas to flow much faster and from a wider area, meaning that fewer wells need be sunk.

A February 2011 National Toxics Network briefing paper said fracking will be used in up to 80% of Australian gas wells in the next ten years.

Once fracking has taken place, Howarth and his co-authors explain, a significant amount of the mix of water and chemicals “returns to the surface as flow-back within the first few days to weeks after injection and is accompanied by large quantities of methane … The amount of methane is far more than could be dissolved in the flow-back fluids.”

Additional methane is then emitted as plugs inserted in the well to allow fracking are drilled out. Once the well is in production, methane is routinely vented from pressure-relief valves. Further losses occur from leaks during transport, storage and distribution.

In all, Howarth and his collaborators calculate, methane losses during the several decades that a shale gas well operates are 3.6% to 7.9% of production.

Unlike shale gas, CSG extraction requires water to be pumped from the well throughout its operating life. This “produced water” — generally saline and laced with contaminants — also contains methane, mostly “entrained” as gas bubbles. In Australia, the usual practice is to pipe this water to evaporation ponds.

How much methane reaches the atmosphere this way? Engineers working on CSG technologies in Wyoming have found that the amount lost as entrained gas varies from 2% of total well yield to a mind-blowing 30%.

An improved gas separator, now awaiting patent, is claimed to remove all but 2-3% of the entrained methane from the water. But with a typical well, at present losing 15% of its output as entrained gas, the new equipment would still fail to catch emissions representing about 0.4% of total well yield.

Moreover, the new separator does not remove dissolved methane.

The produced water can be pumped back underground, but this is expensive and is not always convenient.

Otherwise a significant figure, probably about 0.5%, must be added for CSG emissions on top of the figure for shale gas methane emissions of 3.6%-7.9%.

That is supposing the new separator equipment reaches the market, and that energy companies are moved to install it. If not, the evidence from Wyoming suggests, typical losses of CSG methane from borehole to power plant would be at least 18%.

The implications of all this are ominous. Methane is relatively short-lived in the atmosphere. After 20 years it is virtually all gone, oxidised to water and carbon dioxide.

But recent work that explores the interaction between methane and atmospheric aerosols concludes that during those 20 years, methane has a “global warming potential” a staggering 105 times that of an equivalent amount of carbon dioxide.

If methane is burnt to produce a megawatt-hour of electricity, the amount of carbon dioxide that goes up the exhaust flue is indeed less than if the electricity were produced from coal.

But to the combustion emissions, we have to add the warming impact of the methane that escapes from the wells, produced water, fittings and pipelines. Over a 20-year period, a global warming potential of 105 means that leakage of even 1% more than doubles the cost in warming of gas-fired power.

The credible leakage figures for CSG start at about 4%.

And it gets worse. If the CSG is liquefied for export, as a great deal of Australia’s output will be, we need to add on carbon dioxide emissions corresponding to about 20% of the energy value of the methane, to power the liquefaction process.

Account should also be taken of emissions released by other factors listed in a fact sheet on “Purging, boil-back from cryogenic transfers, leakage during LNG transfers, boil-back in transit, powering of LNG ships; and finally, re-gasification before use”.

We have to conclude that CSG extraction and use, as practised in Australia, is much filthier — probably by several times — than either shale gas or coal.

That is not an argument for burning coal, or even for spending the money that could sharply cut CSG’s greenhouse footprint.

Even with best industry practice, CSG is still a fossil fuel. If humanity’s greenhouse dilemma is to be solved, all net carbon emissions must end around mid-century.

That implies a huge expansion of renewable energy, and it is on renewables that the scores of billions of dollars slated for CSG development in Australia should instead be spent.



The photograph attached to this article is not a picture of the well near Dalby that Arrow lost control of two weeks ago as the caption suggests. That well produced a mixture of saline water and natural gas - and at no stage did the well ignite. The photograph appears to be of an oil well fire somewhere in North America. (One needs only to look at the vehicles in the picture to know its not taken in Australia).

How can we have an informed debate about the facts if the side that is supposed to be holding the moral high ground is misrepresenting them?

The erroneous caption has been corrected. But the facts on coal seam gas are impossible to miss in the actual article. Its dirty, dangerous and emissions-intensive. And most of all, we don't need it. We can shift to 100% renewable energy, but that involves stopping the collusion between state and federal governments and the gas industy.

Oil & Gas companies are not subsidised by government whilst most ‘renewable energy’ is. There is only one way to move people from non-renewable energy to renewable energy and that is to make the cost of producing energy via a renewable the same as that from a non-renewable.

People, on the whole, have a warm heart and as a result if the price of non-renewables was only slightly greater than that of renewables then they might do it. BUT that is not the case… renewable power is very expensive. In order to level the playing field the government is about to add $26 (To be confirmed) onto the price of fossil fuels (effectively subsidising renewables). Let’s see what effect that has.

If you seriously want renewable energy to take on non-renewables you have to make it cheaper. In order do to that you have to build on vastly greater scales. The Chinese are building vast numbers of wind-turbines… but you don’t like those because they kill the birds… and they’ve built some truly massive HEP stations… even they don’t like those as they’ve recently admitted it’s doing terrible things to both the rivers and their people… so that leaves solar cells… which are terribly inefficient and take a lot of energy to produce… tidal power… kills the fish and unfortunately Australia has few good locations… maybe solar concentrators (onto molten salt)… this would be great (it even works at night – sort of) but no one want to see massive concrete (dirty word) pads built (1km x 1km each) built across the dessert… god knows why... seems the right place for them.

Going back to those Chinese windmills… even on the scales the Chinese are building them on they are struggling to make them economical against other sources of energy. Still at least they are trying. If I look up wind farm planning applications in Australia I find them mired in controversy by the Greens of all people.

Collusion might be deemed as the CO2 tax which in effect subsidizes the renewable energy market by increasing (dramatically) the price of non-renewables.

I'm not entirely against the CO2 tax but if you're to talk of collusion one should look a little closer to home.

The tax will be a great and much needed boon to the renewables industry but it will have come about by the government aiding ('colluding' if you were to write it up in a negative way) the renewables industry by increasing the cost of non-renewables.

I don't think your figures are correct. I have always read that CH4 has a 'global warming potential' (which is the heat trapping potential compared to CO2) of around 20-25 times that of CO2, not 105 times. This is also the figure according to the US EPA:

Fossil fuel interests get $12 billion a year in federal and state government subsidies, about $11 billion less than renewable energy. See the research by the Australian Conservation Foundation.

Its renewable energy should receive subsidies, not fossil fuels. But even more importantly, government's must commit to a public investment program to roll out renewable energy. One of the biggest problems with the proposed carbon tax is that it will not be enough to subsidise renewable energy, but will give conventional and coal seam gas a big boost.

If you measure the effect of the methane over 100 years as for CO2, you get the US EPA figure. However, this figure masks the fact that the methane oxidises after about 20 years into CO2 and H2O. During that 20 year period, its warming potential is in the range of 70-100 times that of CO2 depending on which source you read.

If we weren't on the cusp of runaway warming this might not be catastrophic, but in the current situation - where the next years and decades are crucial - methane emissions take on a very sharp significance.

More cheerfully, a global restriction of methane emissions would start to have a very definite effect on warming in a fairly short time, unlike CO2 emissions which remain in the air for a very long time.

Ben Courtice

There are many ways oil and gas companies are supported by various government schemes, and many ways that the renewables industry has been under-supported, or let down at the crucial moment. e.g. here.

To suggest that adding to the price of fossil fuels is simply a subsidy to renewable energy is muddled thinking. Companies burning fossil fuels are not currently paying for the consequences of the huge increase in greenhouse gases that their industry causes. A carbon tax, whether or not it is effective, aims to rectify that.

Next you descend into silly straw figures like "you don't like [wind turbines] because they kill the birds." Who said that, or are you just putting words into someone else's mouth to make it easier to make your own weak argument? Solar cells are rapidly getting cheaper, despite being inefficient generators of electricity in some technical measures; soon they are predicted to generate electricity as cheaply as coal.

Solar concentrators with molten salt are a great idea, there you are quite right, but who are the people that don't want to see them built across the desert? And where (and why)do they involve 1km square pads of concrete? Not this one!

Lastly, environmentalists are mostly not trying to stop wind farms; check this.

This is outright deceptive... otherwise known as a lie. You very well know that the VAST majority of your so called subsidies are not deals between the Govt and "fossil fuel", also not even subsidies at all. That "research" is disgraceful and I am extremely surprised that seemingly intelligent people refer to it at all.

There no point in denying it. That's $12 billion of taxpayers money subsidising the fossil fuel industry through various mechanisms. With what we know about the dangers climate change presents, the real disgrace it that public money is helping to create more emissions.

At least Simon has provided some material to back up his case... other than assertions floating in hot air!

Fossil fuel extraction projects need to have a triple bottom line on a national level. All projects need to be ranked nationally on the criteria of life cycle comprehensive nett return based on the triple bottom-line.

The nett life cycle criteria should incorporate a measure like

Actual net addition to National income over lifecycle - ( collatreral damages estimate including rehabilitation cost + estimated irreparable loss of productive capacity for agriculture over 100 years + loss due to reduced lowered ecological and ecotourism and recreational value).

Many projects though having a very large life cycle revenue(i.e $100billion over 20 years deliver relatively small nett return due to the large infrastructure investment to develop the project as well as the large collateral damages estimate.

Done carefully it should be possible to approve only projects that give maximum return with least value.
Many projects would not even have a net positive outcome

The states ability to approve / promote projects to gain royalty is a major problem as it tends to subvert the approval process as each state govt tries to competitively promote projects even though the project may rank relatively poorly in the comprehensive national ranking.

Coal Seam Gas is will be booming. You cant stop it. All this talk about it being dirtier than coal is rubbish. the only problem with it is what to do with the water. But companies such as Origin Energy are finding way to use it, and are the only csg company allowed to pump water back into the condamine river.