Methane Estimates Could Fall Vastly Short, Ignore 80% of Actual Emissions, Researcher Says

Methane releases from natural gas extraction and distribution could be 23% lower or up to 316% higher than standard measurement systems show, raising new questions about how countries can measure and meet their ambitious targets for reducing methane emissions, a McGill University study concludes.

And the calculations leaves out at least 80% of the global warming across the natural gas life cycle that occurs when the product is burned in power plants in the United States, said Sarah Jordaan, an associate professor in McGill’s Department of Civil Engineering.

“This results is very specific to the upstream, from the production of natural gas all the way through to delivery to the consumer,” Jordaan told The Energy Mix. But “if you’re looking to really balance viewpoints on this, the vast majority of emissions from the full life cycle assessment are actually when the natural gas is used.”

While accurate measurement of emissions across the natural gas supply chain is something “that we really need to worry about,” she added, “that combustion component can be as much as 80% of the emissions, which are not accounted for in this particular model.”

In 2005, Jordaan said in an email, power plant combustion accounted for 84% of the global warming potential from gas over a 100-year span, rising to 86% in 2010 and 90% in 2015, although hydraulic fracturing (fracking) techniques for gas extraction have since shifted more of the impact to the earlier stages of gas production.

The startling results show up in a recent paper in the journal Cell Reports Sustainability, for which Jordaan was lead author. The research team had been hired to develop a “democratized”, open-source model to help fossil companies, regulators, and anyone else measure climate pollution from natural gas supply chains across the U.S.

A McGill media release says Jordaan and her team initially developed the new system for the U.S. National Petroleum Council and the U.S. National Renewable Energy Laboratory (which some of us will always still recognize as NREL), after a request from Biden-era energy secretary Jennifer Granholm.

Emissions of methane, a climate super-pollutant with 84 times the global warming impact of carbon dioxide over a 20-year span, are released right across the natural gas supply chain, Jordaan said in the release. But because natural gas supply chains are complex, life cycle assessment models don’t always capture the full impact.

“Countries need comprehensive and accurate emission estimates across the entire NG (natural gas) supply chain, but measurements of methane emissions have been shown to exceed engineering-based calculations, raising concerns about the adequacy of available governmental inventory data to effectively inform policy and target emission reduction efforts,” the paper states. So the new model, called SLiNG-GHG, calculates both methane and carbon dioxide releases across natural gas transmission, distribution, and ocean shipping.

Missed Targets

Although it should be relatively easy for industry to cut methane emissions by 75% by 2030, Jordaan said that potential is slipping out of reach.

In 2021, more than 160 countries signed on to a 30% emissions reduction this decade. But the International Energy Agency maintains a 75% target would be affordable, and could even deliver economic benefits, since the methane companies could be capturing is a marketable product.

That line of thought “leads to this really important dichotomy, whereby the measurements are really tricky, but it’s really low-hanging fruit that we should be solving quickly,” Jordaan told The Mix. Yet to hit 75% by 2030, “we would really have to see industry taking advantage of this quickly and implementing it in advance of regulation”—particularly in the U.S., where “the regulatory landscape is obviously going to be a little bit slower in the short term”.

In Canada, as well, a federal commitment to a 75% reduction by 2030 has since been undercut by last November’s sweeping memorandum of understanding between the federal and Alberta governments, and Jordaan said actual methane reductions currently stand somewhere above 35%. “Right now, politically, it’s a really tricky time with a lot of competing goals,” she added, although “the fact that we actually have such pledges in place is obviously a very positive thing.”

Marketability Depends on Accurate Data

The paper stresses the commercial value of getting methane measurement right.

“The future marketability of U.S. NG at least partially depends on accurate estimates, sparking interest from the U.S. Department of Energy in quantifying emissions and identifying solutions for mitigation,” it states. “While the U.S. seeks continued growth in NG production, the European Union seeks to ensure that its liquefied NG (LNG) purchases have low embodied GHG emissions, implementing regulations that require measurement, reporting, verification, and mitigation.”

Until 2011, Jordaan and her team add, life cycle assessments (LCAs) for natural gas operations in the U.S. focused on conventional production for domestic use. Since then, however, the rise of fracking and the growing U.S. interest in gas exports have added a layer of uncertainty to the analysis, which SLiNG-GHG sets out to solve.

The new model is also meant as a more accessible solutions for policy-makers and citizens who aren’t technical experts in life cycle assessment. The McGill team found that existing LCA models aren’t generally available or open source. When they are, they’re complicated and hard to verify, and suffer from discrepancies in the industry data the EPA collects for natural gas and LNG operations. Those inventories “have been found, on average, to underestimate methane emissions compared with measurement studies,” the paper says.

To get a handle on those complexities, Jordaan and her colleagues analysed and harmonized 16 different LCA models using data from 2016 and 2021 and categorized them according to three “gates” for gas extraction and distribution: a transmission pipeline to a major end user like a gas plant; a distribution pipeline to a smaller end user like a private home; and an LNG tanker arriving at a foreign destination in either Europe or Asia. The model adds up all methane emissions, and also identifies the sources of carbon dioxide pollution for each pathway.

The study found that LNG shipping:

• Produces the highest life cycle emissions of the three “gates”, followed by distribution and then transmission;

• Has the highest variability in accurately measuring global warming potential, and shows the lowest accuracy over the crucial 20-year span when humanity will be scrambling to get climate change under control.

Fracking sites are still the biggest single contributor to methane emissions from natural gas over a 20-year span, at 30 to 44% of the total. But “shipping to foreign destinations results in significant additional emissions compared with the other gates, and, evidently, long-distance shipping results in higher emissions,” the paper says. “Notwithstanding geopolitical, energy security, and economic considerations, our contribution analysis confirms that domestic use of NG (gates 1 and 2), on average, significantly lowers the GHG footprint of NG use compared with LNG export (gate 3) if used in equivalent end uses.”

Cover photo:  byrev/pixabay