New research: natural gas will cook the planet

Residents of St Peters and Sydney rally against plans for coal seam gas mining. December 2010. Photo: Peter Boyle
Saturday, April 2, 2011

If there were an Olympics for climate amorality, Australia’s capitalists would be hauling in the medals.

Just consider this quote from Queensland coal baron Clive Palmer in the December 15 Australian: “The Galilee Basin overall has got 100 billion tonnes of thermal coal, so it’s a great reservoir for Queensland in the future, so you’d be crazy not to develop it.”

And it’s not just coal, but any greenhouse-polluting fuel that can be can be dug or drilled from the landscape or seabed. Take Australia’s natural gas industry, poised now for a vast expansion.

More than a dozen liquefied natural gas projects, The Australian said on March 10, are under construction or proposed, representing more than $200 billion of investment.

Woodside Petroleum chief executive Don Voelte, quoted in the same article, said Australia is ready to emerge as a “global superpower” of the liquefied natural gas (LNG) industry, leapfrogging key rivals.

“Within five years,” federal resources and energy Minister Martin Ferguson crowed to Channel 9 News on February 28, “we expect to climb further up the ladder with exports exceeding 50 million tonnes … only Qatar will be exporting more.”

The Australian Bureau of Agricultural and Resource Economics (ABARE), last year predicted that Australia’s natural gas production would quadruple by 2030.

Clean and Green?

But why, you might ask, should natural gas be a problem? After all, we’re told it’s clean and green. When we extract and export it, aren’t we doing the climate a favour?

Compared with coal, natural gas (which in its refined form is almost all methane) undoubtedly burns cleanly.

Unlike coal, it contains no toxic mercury, arsenic or other heavy metals. There is no radioactive uranium or radium.

Per unit of energy, burning natural gas releases less than a third of the nitrogen oxides that result from coal combustion, about 1% of the sulphur dioxide, and next to no fine particles such as soot.

True, natural gas is a fossil fuel, and when burnt adds heat-trapping carbon dioxide (CO2) to the atmosphere. But compared with coal, the quantities are modest.

Mark Diesendorf, in his book Greenhouse Solutions with Sustainable Energy, says producing a megawatt-hour of electricity in the most modern gas-fired power plants results in the direct release of less than 400 kilograms of CO2, compared with about 800 kilograms for an up-to-date plant burning black coal.

So if coal-fired plants are shut down, and new gas-fired ones built in their place, aren’t we on a winner?

The trouble here is that even at half the emissions intensity of coal, gas-fired power would still cook the Earth, just taking a while longer to do it.

Leading US climate scientist James Hansen explains that preserving a planet similar to the one on which civilisation developed will require ending all net greenhouse emissions by about mid-century.

But might new natural gas power plants still serve as an energy bridge, a transitional measure keeping emissions down until genuinely clean renewable energy can be introduced?

This was suggested in the 2009 Commonwealth Senate Inquiry into Australia’s greenhouse future. Anyone who urges this course, though, should prepare for the mother of all political battles against gas industry investors.

Beyond Zero Emissions’ Matthew Wright said in a March 8 post to the Grassroots Climate Oz email list: “To those who think we’ll build gas plants and run them for 10-20 years a modern gas plant … is a very efficiently manufactured piece of machinery. With proper operations and maintenance practice it should last for 60-plus years.

“Even if the bank loan is paid off after 15 years, you have some company … sitting on an asset that if it was built from scratch would cost say $2 billion. This company … would be happy to spend $100 million in order to defend that asset.”

The gas that gets away

The essential problem, though, lies elsewhere.

To be burnt in a power station, natural gas has first to be extracted and transported. If this broader picture is considered, natural gas ceases to be particularly “clean” in greenhouse terms even when compared with coal. In fact, it can be downright filthy.

The trouble is the gas that gets away, leaking into the atmosphere without being burnt.

Methane in the atmosphere readily oxidises into CO2, and after 20 years is almost all gone. But as long as it lasts, it is very effective at trapping heat.

Over a twenty-year period, the United Nations Intergovernmental Panel on Climate Change has reported, releases of methane warm the atmosphere at 72 times the rate of CO2.

And that’s not all: research at NASA’s Goddard Institute for Space Studies, published in October 2009 in the journal Science, shows that methane in the atmosphere holds back the formation of sulphate aerosol particles that would otherwise reflect heat back into space.

Add in this effect, and the 20-year global warming potential of methane comes to about 105 times that of CO2.



Still, what’s so dangerous about a gas that vanishes from the atmosphere after 20 years, when CO2 keeps warming the Earth for centuries?

The problem is that the fate of our climate will not be decided over centuries, but within the next few decades.

Current warming is pressing hard against “tipping points” which, if crossed, would cause a huge release of carbon now locked away in forms such as tropical forests or Arctic peat.

A further big slug of hyper-warming methane could push global temperatures past the point where these natural “carbon sinks” would give way, and vast amounts of greenhouse gases, including methane, would flood into the atmosphere.

Leakage

Environmentalists have known for decades that leakage of natural gas from distribution systems can be very large.

A 1990 Earth Resources Research report estimated that from 5.3% to 10.8% of the gas flowing through Britain’s system was lost, mainly from pre-1950s cast-iron pipes.

In the US, industry spokespeople nevertheless continued to insist that the problem was trivial, citing figures for leakage as low as a few tenths of 1%.

Then Robert Howarth, a professor of ecology at Cornell University in the US, began collecting evidence. Before long he had established that leakage was much greater than had been made out.

With new technology allowing a rapid spread in the drilling of gas-bearing shale rocks in the US, the amounts of methane lost from wells and pipes could only multiply.

Howarth’s initial estimate put real leakage in the US gas industry at about 1.5% of the total gas consumed.

Burning natural gas for electricity adds about 400 kilograms of CO2 a megawatt-hour to the atmosphere. Howarth’s research implied the carbon footprint of natural gas was close to double this level over a 20-year period.

Recognising that the problem was urgent, Howarth took the unusual step, in April 2010, of releasing his preliminary findings rather than waiting for peer review and journal publication.

In a striking new model of scientific research, the problem of natural gas leakage came to be explored collaboratively via the internet.

People with hands-on experience of gas infrastructure contributed their insights. Even the estimate of 1.5% leakage, it became clear, was too low.

Meanwhile, others pointed out that the comparison with coal was not simple — coalmines emit methane too.

In November 2010, the US Environmental Protection Agency (EPA) released data that firmly debunked earlier low estimates of leakage in the US gas industry.

Crunching the new numbers, analyst David Lewis on the Energy Collective website came up with a most likely figure for the losses of about 3.2%.

Carbon footprints

As indicated by the EPA’s data, leakage occurs all along the chain of natural gas production, processing and distribution.

By far the worst losses are at the production end, either as an unavoidable accompaniment to gas drilling or from sloppy industry practice.

In January 2011, Howarth published an update of his work, with its focus on the booming area of US shale-gas production.

He concluded that about 3.6% to 7.9% of the methane from the shale-gas industry “escapes to the atmosphere in venting and leaks”. For gas from conventional wells, he put leakage at 2.8% to 3.8%.

If we assume 3.2% leakage, where does this put the “carbon footprint” of electricity from conventional natural gas?

Using the global warming potential figure for methane of 72 times CO2 over 20 years, the footprint becomes 1322 kilograms of Co2 equivalent per megawatt-hour.

If we use the more recent global warming potential figure of 105 times, the footprint is 1744 kilograms.

To this should be added the indirect emissions from sources such as diesel fuel for the rigs and trucks, and from the production of equipment and gas infrastructure.

Howarth estimates these indirect emissions are at least one-third of the 400-odd kilograms of CO2 emitted from burning natural gas alone.

The total natural gas footprint then reaches a figure close to 1900 kilograms a megawatt-hour.

In his January update, Howarth provides his own “footprint” calculations for a range of fossil fuels, expressed in grams of carbon (as CO2 equivalent) per million joules (MJ) of energy over a 20-year period.

His figure for the footprint of conventional gas is 25-50 grams of carbon per MJ; for surface-mined coal, 27; for deep-mined coal, 32; and for shale gas, 35-62.

This indicates that the climate change impact of gas from conventional wells is, at best, roughly similar to black coal. Most likely, is a good deal worse.

Shale gas, meanwhile, is a greenhouse monstrosity. “Compared to coal,” Howarth says, “the footprint of shale gas is 1.3 to 2.1-fold greater on the 20-year time frame.”

Here, Howarth uses the figure for the global warming potential of methane of 72 times carbon dioxide. But if NASA’s figure of 105 proves more accurate, the message for the shale gas industry will be still more daunting.

Coal seam gas

Australia has abundant gas shales, mainly in the Great Artesian Basin. But these are unlikely to be exploited soon, since most resource economists say exploiting the country’s vast reserves of coal-seam gas will yield greater profits.

Coal-seam gas is planned as the basis for a huge new LNG export hub at the port of Gladstone in Queensland.

Extracting coal-seam gas involves sinking bores into coal deposits and pumping out the groundwater they contain. Gas from the pores and fissures of the coal can then be drawn off.

No figures seem to have been gathered for gas leakage from coal-seam wells, but there are reasons to think the rate is similar to the 3.6% to 7.9% calculated by Howarth for shale gas.

As with shale gas, extracting coal-seam gas requires wells to be sunk in mind-bending numbers — a projected 30,000 in Queensland alone.

Gas is routinely vented during drilling operations, and accidental leakage is inevitable from the vast array of pipelines and wellhead installations.

Coal seam gas production also requires using large amounts of energy to pump water.

Liquefying gas for export consumes about 20% of its energy content, so the emissions footprint of electricity from coal-seam LNG could well reach the staggering sum of more than two tonnes of CO2 equivalent per megawatt-hour.

We may conclude that Australian capitalism’s gift of “clean” natural gas to the world energy market will be just like Australia’s coal exports — a huge dose of poison for the global environment and for the human civilisation that depends on it.

Phasing out gas?

If climate catastrophe is to be avoided, the boom in natural gas drilling will have to cease. Does this also imply the phasing out of existing gas use?

As has been seen, most of the leakage from the natural gas industry occurs during the production phase. The worst of these losses are associated with drilling and equipment installation.

Once infrastructure is operating, losses are much less, and they can be cut further if pipelines are upgraded and maintenance is rigorous.

In theory, this would suggest that gas from existing wells might serve as a legitimate transition fuel for electricity generation.

Relatively small gas-turbine generating plants can provide a back up for wind and solar energy, smoothing out their irregular nature. From a standstill, gas-turbine generating equipment can be brought into full operation in less than 30 minutes.

But as Beyond Zero Emissions explains, molten-salt heat storage facilities attached to concentrating solar thermal power plants can serve this function better, and do not emit greenhouse gases.

Facilities of this type are already operating in Spain, and the technology is expected to become fully commercial in the next few years.

Much better than looking to the gas industry, Howarth argues, would be to move rapidly toward an economy based on renewable energy.

Recent studies, he notes, “indicate the US and the world could rely 100% on such green energy sources within 20 years if we dedicate ourselves to that course”.

It is to renewables, not gas or other fossil fuels, that the billions of dollars now slated for energy investment in Australia should be directed.

Tags: environmental Comment and Analysis

Comments

Stop whinging about the problem and get on with the solution. Get us a solar thermal plant. Message to government: Carbon tax is a waste of time and effort, and though you seem to think so, constructing something (for instance a solar thermal pilot plant rather than a useless NBN) isn't actually that hard. Once you have it, make all of the economics for its construction, operation and maintenance public information. Legislate against coal fired power in Australia. Fund the program not by taxing the Australian public, but by taxing coal exports- a far smaller tax will thus be required.

Perth having endured a sustained drought would logically be a hot-bed of resistance to anything that could affect the Perth Basin's artesian water quality...

As Australian Worldwide Energy ASX: AWE plans to drill Western Australia's first shale gas exploration well next month, the state's Mines and Petroleum Minister Norman Moore has said shale gas could help create a new industry and provide greater certainty for existing businesses in Western Australia.

The state's first shale gas well, the Woodada Deep-1 well, is located in the onshore Perth Basin, about 100 km north of Lancelin, near Eneabba., right on top of the aquifer. Ironically at one of the aquifer's least saline areas.

According to Govt. sources: "Potential bore yields are very large, ranging up to 20 000 kL/day. The major bore fields supply Perth and Geraldton (from Allanooka), and mineral sands operations at Eneabba and Cooljarloo. The aquifer is also used for Eneabba and Badgingarra town water supply, and for farm water supply. There is currently minor horticultural use, and there is significant development potential of the aquifer." http://www.fish.wa.gov.au/docs/pub/A...h_basin.php?00

AWE estimates that the middle interval of one of these shale intervals (the Carynginia Shale) alone holds a gross Gas in Place of 13-20 trillion cubic feet (Tcf).

AWE now holds a position in approximately 1 million gross acres of prospective Shale Gas acreage in the Perth Basin (620,000 net acres), with high levels of equity in the majority of the permits and licenses.

One of the major complications of shale gas extraction is said to be ground water and aquifer contamination... from what I have read the jury is still out. There is a vast amount of commentary surrounding the issue mainly emanating from the USA, much of it ill-informed and inflammatory.

Perhaps it would be timely for an Australian assessment to be widely circulated... in the meantime is this a classic battle looming... Gas independence for Perth versus potential water quality degradation?

In our small corner of the world in Garfield County, Colorado, USA (journeyoftheforsaken.com) we've been crushed by the comprehensive destruction of aggressive natural gas development for nearly a decade. In the beginning (and still), the gas was touted as the "bridge fuel" to the future. Well guess what? Now, leaking wells, fractured hydro-geology and even new wells that are indefinatly venting methane to the atmosphere are pumping methane and associated hydrocarbons like butane, propane and benzene into the groundwater and air in unmeasured quantities. In the ten years (and still drilling like mad dogs) that this industry has been encouraged to run amok by regulators and fat subsidies, we could have developed and begun to fully tansition to REAL bridge options like solar and algae. So, I have to ask, if natural gas (the new oil) is a bridge fuel, just how damn long is this bridge, and frankly, where does it lead. You know what? Maybe I don't really want to head down this road. Bridges are pretty narrow, and we may not have an opportunity to turn around.

The *extremely* dangerous molten salt heat storage systems (the salt catches fire if exposed to the air) cannot handle a full 24 hour day. They lose heat through out the evening and while taking it past the evening peak are as good as dead even before midnight. And the costs...so...

if good solar thermal concentration is good for rated capacity for 6 hours (maybe)...on a, say, "100MW" plant, if took away enough power for, say 50MWs of power after sun set (way before actually) the plant is no longer a "100MW plant" it's only a 50MW plant. With figures on production hard to come by for those Spanish plants, some estimate that the cost of running one's developed country on this is about 3 times that of nuclear energy. And all that liquid sodium...

There is no truth to the claim that concentrating solar thermal plants with salt storage are "as good as dead before midnight". Beyond Zero Emissions summarises the benefits and cost trajectory of the technology in Australia are here http://media.beyondzeroemissions.org/ZCA2020_Stationary_Energy_Synopsis_...

As for the so called extreme danger of this commercially available, zero carbon technology ... that's laughable. The *danger* of heating salt to store heat is negligible. The danger of climate change is real and is upon us.

"Stop whinging about the problem and get on with the solution. Get us a solar thermal plant."

I shouldn't have to point this out, but, this here is the website of a newspaper. The role of the newspaper is to report. Reporting, lobbying and activism work together to get results (such as getting a solar thermal plant). Rest assured that there are plenty of us, including GLW writers, "getting on with the solution", perhaps you'd care to join us.

The carbon footprint of natural gas stations presented in this article (and therefore the whole surmise of the conclusion that gas is just as bad as coal in terms of GHG emissions) appears to be completely incorrect.

Given the large amount of controversy surrounding coal seam methane, this kind of disinformation is going to cause some misguided confusion, and it would be good to see some further explanation, justification or retraction from the author surrounding their huge carbon footprints for gas power stations, because doing some basic calculations it appears they are wildly wrong. Just before posting this I realised that someone had posted a comment similar on another of Renfrey's article on this same issue back in May 2010! So its very dissapointing that the author is still parroting this misinformation and hasn't actually had their assumptions checked by someone with more understanding.

It looks like the article has wrongly calculated the gas power station's footprint by multiplying the stated Diesendorf's figure of 400kg CO2-e/MWh electricity for a gas power station, by the change in methane global warming potential (GWP) facto, from 21 to 74 i.e. a 3.43 multiplier, giving a footprint of 1371 kg CO2-e/MWh.

This doesn't make any sense because the majority of the methane is burnt in the gas power station, and so only the fugitive emissions should be multiplied by this 3.43 figure. Natural gas power stations don't emit natural gas out of their stacks, rather they emit mostly CO2.

The gas power station footprint is 400 kg CO2-e/MWh electricity produced or 111kg CO2-e/GJ of electricity produced. Gas power stations are generally 60% efficient and so 1.67 GJ of gas would produce 1GJ of electricity, or 6GJ of gas input would produce one MWh of electricity output with associated emissions of 400 kg CO2-e.

If we are losing a massive 10% of our gas through fugitive losses all along the supply chain (which is a worst case assumption, given that Howarth suggests what, 3.5%?), then we are losing 0.6GJ of gas for every MWh of electricity produced. Using the National Greenhouse Accounts (NGA) factor of 32.7 kg CO2-e for every GJ of gas lost to the atmosphere, we have the fugitive emissions contributing 19.6kg CO2-e for every MWh of electricity produced at the electricity station. If you use a Global Warming Potential (GWP) of 72 (which will be the agreed upon factor from 2013 I believe), they would contribute 67.3 kg CO2-e, and if you used the article’s 105 GWP for methane, fugitive emissions would contribute 98.1 kg CO2-e for every MWh of electricity produced at the station.

This then makes the gas power station footprint either 419.6 CO2-e/MWh, or 467.3 kg CO2-e/MWh or at most 498.1 kg CO2/MWh which is still 60% of the coal power station’s 800 kg CO2-e/MWh and vastly different than the 1300 kg CO2-e/MWh or 2000 kg CO2-e/MWh that this article suggests!!

And we haven’t even calculated any change in the coal emissions due to methane global warming potential changes for the emissions released from coal mining!!

This is all based on the National Greenhouse Accounts (NGA) Factors. Table 17 for natural gas composition factor (currently 0.0326T/GJ of gas lost and therefore 0.112T/GJ using a GWP of 74 & 0.16T/GJ using a GWP of 105). The whole Howarth new emissions factor for leakage of gas being 25-50 g CO-2/MJ is 0.025T/GJ to 0.05T/GJ of gas lost is actually not high at all but closer to what everyone uses currently to account for emissions from lost gas!

It doesn’t appear from this perspective that the greenhouse gas emissions of a gas power station are anywhere near as bad as coal, which is what everyone thought all along...no matter how much we step up this industry, it is better than coal.

Nick

If the coolant were liquid sodium, as I think nuclear "breeder" reactors use for coolant, then solar thermal power plants would indeed be dangerous. That's why they don't use sodium. They use a salt. Sodium is a element of some salts, but not the one proposed by BZE - Potassium Nitrate, a common fertilizer. It doesn't burn on exposure to air, as any farmer will tell you.

Also, the idea that a tank of thousands of litres of molten salt at 500°C and above will just cool down in six hours is preposterous. That heat will last a long time; the only thing that significantly reduces it (over a day or two) is using it up to generate electricity.

The whole plan needs a huge program of energy efficiency to cut the demand for power at the same time as we replace fossil fuel power with safe renewable energy. It can work, the only real conflict is with the mining and petrochemical multinationals.
BCC

For all Nick's indignant scorn ("inaccurate calculations"), I didn't simply multiply Diesendorf's carbon footprint figure by the 20-year global warming potential for methane. Here's how my figures were derived.

A certain quantity of natural gas (basically methane), sufficient to produce 1 MWh of electricity, is fed into a modern gas-fired power plant and burnt. As well as the electricity it produces a quantity, X kgs, of CO2.

X is thus the conventionally-calculated footprint, in kgs of CO2, of 1 MWh of gas-fired electricity.

But in the course of extracting the natural gas and and bringing it to the power plant, a certain proportion, say 1%, leaks to the atmosphere. Because methane is a powerful greenhouse gas (global warming potential 72 times CO2 over 20 years), the warming impact of this leaked gas over the next two decades is not 1% of X, but 72%.

Consequently, the carbon footprint of our MWh of electricity becomes X + 72X/100 kgs of CO2-e.

Realists that we are, we accept that the actual leakage rate is much more than 1% - say Y%. The footprint then becomes X + 72XY/100 kgs. Insert the values for X and Y that I noted, and you get my figures for the footprints of natural gas in various contexts.

This method isn't completely accurate, since over 20 years a certain proportion (not all that much) of the CO2 "X" will be absorbed by the oceans and biosphere. But it's precise enough to be very scary.

Go figure!

For all Nick's indignant scorn ("inaccurate calculations"), I didn't simply multiply Diesendorf's carbon footprint figure by the 20-year global warming potential for methane. Here's how my figures were derived.

A certain quantity of natural gas (basically methane), sufficient to produce 1 MWh of electricity, is fed into a modern gas-fired power plant and burnt. As well as the electricity it produces a quantity, X kgs, of CO2.

X is thus the conventionally-calculated footprint, in kgs of CO2, of 1 MWh of gas-fired electricity.

But in the course of extracting the natural gas and and bringing it to the power plant, a certain proportion, say 1%, leaks to the atmosphere. Because methane is a powerful greenhouse gas (global warming potential 72 times CO2 over 20 years), the warming impact of this leaked gas over the next two decades is not 1% of X, but 72%.

Consequently, the carbon footprint of our MWh of electricity becomes X + 72X/100 kgs of CO2-e.

Realists that we are, we accept that the actual leakage rate is much more than 1% - say Y%. The footprint then becomes X + 72XY/100 kgs. Insert the values for X and Y that I noted, and you get my figures for the footprints of natural gas in various contexts.

This method isn't completely accurate, since over 20 years a certain proportion (not all that much) of the CO2 "X" will be absorbed by the oceans and biosphere. But it's precise enough to be very scary.

Go figure!

Renfrey Clarke

Methane (CH4) (about 85% of natural gas) is 105 times worse than CO2 as a greenhouse gas on a 20 year time frame and taking aerosol impacts into account. Methane leaks (3.3% in the US based on the latest US EPA data and as high as 7.9% for methane from “fracking” coal seams). Using this information one can determine that burning gas for electricity is much dirtier than coal burning greenhouse gas-wise. While gas burning for power generates twice as much electrical energy per tonne of CO2 produced (MWh/tonne CO2) than coal burning and the health-adverse pollution from gas burning is lower than for coal burning, gas leakage in the system actually means that gas burning for power is worse GHG-wise than coal burning whether the gas comes from conventional sources or from "frackjing" (for detailed, documented analysis see the "Gas is not clean energy" website: https://sites.google.com/site/gasisnotcleanenergy/ ).

Unfortunately pro-gas politicians and gas producers variously add to the popular misconceptions that “gas is clean energy ” or “gas is cleaner energy than coal”. While pricing any bad item (e.g. coal burning, smoking, drinking) is useful the devil is in the detail as to any desired Carbon Price and Carbon Tax as a market-based GHG pollution mitigation mechanism. Thus the Australian Government has made it clear that a significant intent of its proposed Carbon Tax is to promote a coal to gas transition. However, as set out in the "Gas is not clean energy" website a coal to gas transition will be disastrous, involving huge national investments to achieve an INCREASE in GHG pollution.

From a pro-environment perspective the Gillard Labor Government's spin-driven Carbon Tax-ETS-Ignore Agriculture (CTETSIA) plan is disastrous because it:

(a) promotes a counterproductive conversion from coal burning to gas burning (that is just as dirty GHG-wise because of methane leakage of circa 3.3% (US) to 7.9% (coal seam -derived) and because methane is 105 times worse than CO2 as a GHG on a 20 year time frame and including aerosol impacts;

(b) institutes a futile cycle of increased prices coupled with obviating consumer compensation;

(c) scuppers science-demanded 100% renewable energy by 2020 (see the BZE ZCA2020 plan );

(d) institutes an empirically ineffective, disastrously counterproductive and utterly fraudulent carbon emissions trading scheme (ETS);

(e) ignores agriculture which is responsible for over 50% of GHG pollution;

(f) trashes Australia's international reputation; and

(g) compromises and divides the pro-environment, climate change action movement that is vital for requisite climate change action by Australia.

Pro-coal, pro-gas Gillard Labor's disastrous, spin-driven Carbon Tax-ETS-Ignore Agriculture (CTETSIA) plan is a very unfortunate example of when "doing something" is actually much worse than "doing nothing".

Dr Gideon Polya, Melbourne

"Unlike coal, it contains no toxic mercury, arsenic or other heavy metals."

Perhaps not:
NRDC - Natural Gas Sector

One of the only public literature refernces to Hg content of Austrailian Nat Gas fields indicates some North West Shelf fields contain mercury at 38ug/m3.
A rethink of the mercury removal problem for LNG plants

If applied to the whole Carnarvon Basin, this kind of concentration would yield upwards of a tonne of mercury each year, and while any processing facility preparing LNG would remove that mercury before processing, it is not necessarily the case that this mercury would be disposed of or recycled. Its possible mercury would be mixed back into sales gas to be emitted during combustion, or that it would be emitted or combusted on site.