Green washed: LNG emits 33%more carbon than coal, new report finds
Oct 9, 2024
Oneof the world’s leading methane scientists has called out LNG for being a largeremitter of carbon dioxide (CO2) than coal – by a whopping 33 per cent over itslife cycle.
Thefinding flies in the face of LNG advocates who have long claimed the fossilfuel is cleaner than coal, arguing that if the alternative is to burn more ofthe latter then the former deserves a place as a “greener” alternative.
Comparinglife cycle emissions over a 20 year period led to a figure of 160 gCO2-equivalent/MJ for LNG versus 120 g CO2-equivalent/MJ for coal. The report’sauthor, Dr Robert Howarth from Cornell University, says that is because methaneemissions from the extraction of fossil gas are higher than for coal.
“Asa greenhouse gas, methane is more than 80 times more powerful than carbondioxide when considered over a 20-year period,” he said in a paper published in the EnergyScience & Engineering journal.
“Clearly,greenhouse gas emissions from LNG must be larger than from the natural gas fromwhich it is made, because of the energy needed to liquefy the gas, transportthe LNG, and regasify it. The liquefaction process alone is highlyenergy-intensive.”
UsingGWP20 (Global Warming Potential over 20 years), accounted for the impact ofmethane which is more potent but breaks down much faster than carbondioxide.
Asa result, accounting for the destructive nature of the gas over the time it isactually in the atmosphere (as opposed to over 100 years, or GWP100, as manyAustralian reports use) bumps up the impact of emissions from LNG by aboutthree times.
“Overall,the greenhouse gas footprint for LNG as a fuel source is 33% greater than thatfor coal when analyzed using GWP20,” Haworth wrote.
“Evenconsidered on the time frame of 100 years after emission (GWP100), which severelyunderstates the climatic damage of methane, the LNG footprint equals or exceedsthat of coal.”
Getting the feedstock is the killer
Haworth’sresearch focused on exports of US shale gas, an industry that took off in the2000s to the point where the country was swimming in so much gas the federalgovernment lifted LNG export bans.
Hemeasured methane and CO2 emissions created by gas extraction, storage andprocessing plants, and from the high-pressure pipelines that bring gas to LNGliquefaction facilities, liquefaction, transport and regasification, andburning by the end user.
Howarthfound US domestically-produced gas used at home for electricity has a lifecycle greenhouse gas footprint similar to coal.
Butthe footprint of LNG, which requires extra processing and extra transport,dwarfed these even when shipping distances were short.
“Thegreenhouse gas footprint for LNG is 28 per cent greater than that of coal forthe shortest cruises and 46 per cent greater for the longest cruises,” thepaper says.
Doingso revealed where the big leaks and emissions creations came in the supplychain.
BurningLNG for fuel accounts for a little over a third of the total carbon footprint.
Contraryto many studies in Australia, it was the production, storage and transport ofgas to liquefaction plants that was the biggest contributor to LNG emissions,accounting for 46-48 per cent of the total.
Thetechniques required to get shale gas out of the ground – hydraulic fracturingor fracking – mean other gases and particularly methane also escape.
Liquefactionitself makes up just 8.6-9 per cent of the footprint, while transporting LNG isa little tricker, as it depends on the fuel used by the tanker and the way it’sburned, accounting for 2.4-4.4 per cent of the total.
Theremainder comes from regasification and transport to, usually, electricitygenerators.
Australian LNG unlikely to be better
Thereis little accurate data on methane emissions from Australia’s gas industry, butnon-industry monitoring as well as what is known about the CO2 content ofdomestic gas sources suggests it could be much, much higher than companies arereporting.
TheGorgon gas field in Western Australia has the highest average CO2 content atabout 15 per cent of all global LNG sources looked at by a Nature studyin 2020 into the greenhouse gas intensity of LNG exported to China.
“Andthus the highest processing emissions,” the paper said.
Andwhile shale gas exploration is in its infancy in Australia, the coal seam gasreserves in Queensland and New South Wales (NSW) require similar tech to getout of the ground as the shale gas in the US – fracking.
Lastyear, Clean Air Task Force infrared camera study found 101 leaks and methane venting at 15 of 38 sites visited in NSW, and at 20 of 42 sites visited in Queensland.
Atsome sites there were multiple emissions points from a single piece ofequipment.
Venting,where gas is deliberately released, was found at four of seven Santos coal seamgas wells surveyed in the Pilliga/Bibblewindi forest in NSW, and at theAPA-operated compressor station at the Wallumbilla Gas Hub.
InAugust, the federal government agreed to a series of reforms to change how methane emissions are measured by the coal and gas industry, after finding that current data is horribly inadequate.
Meanwhile,AAP reports that new monitoring platform Open Methane – which usessatellite-based measurements and ground-based verification to track emissions –estimates methane levels could be twice as high as what is currently reported.
Chairof climate think tank The Superpower Institute and former consumer watchdoghead Rod Sims has officially launched the new Open Methane platform.
“Accuratedata is the foundation of effective climate policy: if we can’t measure it, wecan’t manage it,” he said.
Australia’s20 highest emitting locations were all linked to coal or gas extraction,suggesting these sectors could be producing as much methane as the agricultureindustry, if not more.
RachelWilliamson is a science and business journalist, who focuses on climatechange-related health and environmental issues.
