by A recent, more accurate method of calculating methane emissions from offshore oil and gas production suggests that the UK is grossly underestimating its greenhouse gas emissions. Researchers conclude that oil and gas production emits up to five times more methane than reported.
Methane is the second most important greenhouse gas after carbon dioxide and contributes about 1 degree Fahrenheit to today’s global warming compared to pre-industrial times. A major source of methane into the atmosphere is the extraction and transport of oil and gas. Countries are required to report their greenhouse gas emissions to international bodies such as the United Nations Framework Convention on Climate Change, but recent studies suggest that current methods of calculating methane emissions rely on outdated and incomplete information and may not accurately represent actual emissions.
A recent study by researchers from Princeton University and Colorado State University finds that the current methodology for estimating methane emissions from offshore oil and gas exploration in the UK systematically and grossly underestimates emissions. The study finds that UK oil and gas production emits up to five times more methane than government estimates. The researchers arrived at this conclusion by critically assessing the current UK method for calculating methane emissions, proposing alternative peer-reviewed methods and producing revised emission estimates.
As many other countries use similar methods to calculate methane emissions from oil and gas production, this gross underestimate is probably not unique to the UK.
“Knowing when, where, and how much methane is being emitted from each of its sources is critical to prioritizing emission reductions,” said Denise Mauzerall, co-author and core faculty member of the Center for Policy Research on Energy and the Environment at the Princeton University. “We hope our work will facilitate improved emission estimates and reductions not only from the UK but also from other countries that produce methane from oil and gas exploration,” Mauzerall said.
Due to its impact on climate and indirect health (methane is a precursor to ozone, which is an air pollutant that harms human health and crops), abatement of methane has recently become a global policy priority. Its relatively short lifespan of around 12 years and high heat storage capacity per molecule make reducing methane emissions one of the most effective ways to slow global warming. As a result, countries signed the Global Methane Pledge in 2021, committing to reduce methane emissions by at least 30% of 2020 levels by 2030. To track progress, countries compile national emissions data in inventories, such as NAEI), which are then reported to international monitoring bodies.
This study focuses on methane leaks associated with the discovery, exploration and production of oil and natural gas. These methane emissions are typically calculated by multiplying the activity levels of various processes – namely venting, flaring, processing and combustion activities on production platforms, offshore oil loading and gas transfer through high-pressure pipelines – by “emission factors”, which are standard estimates of the methane emissions associated with each activity.
Researchers found that the emission factors used in UK reporting are either outdated, based on unpublished or non-public industry research, or use generic values recommended by the IPCC. In addition, these emission factors are usually “static”, meaning they are not sensitive to factors such as environmental conditions and management practices that might affect emissions from different processes. In addition, leakage can occur when offshore drilling rigs are idle — an “activity” that currently has no associated emission factor.
In light of these shortcomings, researchers updated and revised the estimation techniques for each process, using dynamic rather than static emissivity factor formulations wherever possible that account for different environmental conditions. They also included direct, boat-based measurements of methane concentrations around offshore gas platforms in the North Sea collected in the summer of 2017, documented in a study also led by the authors. These updates resulted in an estimate of total methane emissions that was more than five times higher than reported emissions.
“Methane emissions from offshore facilities are largely uncertain at this time, and since on-site sources only emit for short periods of time, direct survey methods such as satellite or drones are likely to capture only about 25% of actual emissions,” said Stuart Riddick, lead author and research scientist at the Colorado State University. “To generate representative baseline emissions for the entire sector, we need to work with industry to develop practical, effective, and collaborative measurement strategies,” said Riddick.
Previous research has shown that reducing leaks in the oil and natural gas supply chain can advance climate and air quality goals while being economically viable – a win-win opportunity for industry and climate.
This study adds to a growing base of literature showing that current measurements of anthropogenic methane emission inventories are underestimated. With the world’s first “global inventory” of progress towards implementation of the Paris Agreement due to be completed in 2023, researchers argue that improved measurement of emissions deserves urgent attention.
“We are confident that our work will enable more accurate emission inventories and lead to critically important reductions in methane leakage – a win for industry and the environment,” Mauzerall said.
