Grabbing the tail of the methane emissions dragon [Making Sense of Methane]
Natural gas is primarily composed of methane (CH4), a clean fuel that emits few air pollutants when burned in stove tops, in power plants to generate electricity, or in motor vehicle engines.
But when methane is emitted directly into the atmosphere – not burned – it is a potent greenhouse gas. Methane emissions are quickly becoming a significant global climate issue, and more attention is focusing on the natural gas industry’s contribution to total emissions.
The potential impact of methane emissions on climate change challenges the industry’s claim that natural gas can make a positive contribution in a lower carbon economy, distracting efforts to encourage the greater use of natural gas in the future energy mix to reduce air pollution and CO2 emissions by displacing other fossil fuels.
It is widely believed that a quick reduction of methane emissions is one of the most cost-effective pathways to initially tackle climate change by contributing to the plateauing of CO2 equivalent emissions in the atmosphere.
According to the Intergovernmental Panel on Climate Change (IPCC) – the United Nations’ body for assessing the science related to climate change – methane is a short-lived climate forcer (SLCF). This is to say methane has a shorter atmospheric lifetime than CO2.
Quicker isn’t always better
Early mitigation action on SLCFs, such as methane, could affect temperatures and climate impacts experienced by today’s decision-makers; however, SLCFs will have little impact on the warming experienced by future generations, according to an Oxford Martin Policy Paper titled The Science and Policy of Short-Lived Climate Pollutants. In fact, unless reductions in SLCFs are accompanied by ambitious reductions in CO2 emissions, early SLCF mitigation will have very little impact on eventual peak warming.
Accounting of methane emissions is currently not an exact science and as such the estimates of their impact on climate change vary. Differing approaches to how the overall climate change impact is calculated and different methodologies used to estimate the overall emissions levels has resulted in gaps in actual emission data. Further, new and emerging technologies are now available and being used to reveal sources of emissions that were previously harder to detect.
In 2012, the latest year for which comprehensive data are available, global methane emissions were estimated to be around 570mn metric tons (mt). This includes emissions from natural sources (around 40% of emissions) and from anthropogenic sources (the remaining 60%). The largest source of anthropogenic methane emissions is agriculture, responsible for around a quarter of the total, closely followed by the energy sector, which includes emissions from coal, oil, natural gas and biofuels.
In its World Energy Outlook (WEO) 2017, the International Energy Agency (IEA) estimated there were 76mn mt of methane emissions from oil and gas operations in 2015, split in roughly equal parts between the two. These emissions, according to Tim Gould, head of the WEO energy supply outlook division, and Christophe McGlade, WEO senior analyst, came from a wide variety of sources along the oil and gas value chains, from conventional and unconventional production, from the collection and processing of gas, as well as from its transmission and distribution to end-use consumers. Some emissions are accidental – perhaps a faulty seal or leaking valve – while others are deliberate, often carried out for safety reasons or due to the design of the facility or equipment.
In WEO 2017, the large oil and gas-producing areas of Eurasia and the Middle East were estimated to be the highest emitting regions, accounting for nearly half of the total methane emissions globally, followed by North America. Averaged globally, WEO 2017 estimated emissions from the natural gas chain (42mn mt in 2015) translates into an emission intensity for gas of 1.7% percent – that is the average percentage of gas produced that is lost to the atmosphere before it reaches the consumer.
While methane emissions from the oil and gas industry may not seem very significant from the perspective of total natural and anthropogenic emissions, the focus and intensity on the natural gas industry has been increasing over the recent years. Fugitive methane emissions – the direct release of methane into the atmosphere – are being used to discount the advantages of replacing coal with natural gas at a time when countries are making their fuel choices.
Natural gas is recognized as an abundant, clean energy resource that can provide needed energy to billions of people. When substituted for coal and other higher CO2 emitting fossil fuels, natural gas can dramatically reduce CO2 emissions and improve the quality of air. However, natural gas’ growing role as a clean energy resource is being challenged by concerns about the extent of fugitive methane emissions that occur during its production, transportation and distribution. This issue is clearly evolving as one of the most critical challenges for the future growth of the industry.
EDF sees oil and gas as main methane culprit
According to the Environmental Defense Fund (EDF), methane can come from many sources, both natural and man-made, with the largest source of industrial methane emissions coming from the oil and gas industry. In 2018, EDF released the results of a five-year research series which estimates the current leak rate from the US oil and gas system is 2.3%, versus the current US Environmental Protection Agency inventory estimate of 1.4%. EDF researchers suggest, however, that while the percentages may seem small, the volume represents enough natural gas to fuel 10mn homes – lost gas worth an estimated $2bn.
The Union for Concerned Scientists (UCS) estimates that 1% to 9% of all produced natural gas escapes into the atmosphere, the equivalent to the heat-trapping emissions of between 35 and 314 average coal power plants. This wide potential range, the UCS says, is due largely to differences in assumptions, methodologies, measurement techniques, industry practices, and regional variations that result in a high level of uncertainty in the data.