Whilst it’s true that CO2 emissions during combustion of fossil gas are lower than that of coal and oil, this industry catch-phrase is only one facet of this climactic picture, devoid of considerations of methane emissions or the entire life-cycle emissions of the gas supply chain.
So-called ‘natural gas’ is primarily composed of methane, which has 86 times more Global Warming Potential (GWP) than CO2 in a 20 year time period.
Methane leaks directly into the atmosphere intentionally and accidentally all along the gas lifecycle.
Whilst the invisibility of gas leaks creates ambiguity in quantifying total gas emissions, recent peer-reviewed studies estimate U.S. gas industry emissions 50 to 60 percent higher than official numbers published by the U.S. administration.
Even with this uncertainty in mind, Anderson and Broderick find that overall methane emissions are at dangerously high levels, in line with the most pessimistic end of scenarios as postulated by the International Panel on Climate Change.
They find that all the man-made methane emissions, including these gas leaks, are likely to add 0.6°C global warming. To me, this does not sound ‘clean’ or ‘green’. But that’s not all.
The revival of the Liquefied Natural Gas (LNG) sector has brought with it a huge carbon footprint. LNG is fossil gas that has been cooled to -160°C into a liquid to shrink its volume by 600 times. It is then stored and transported across the globe via ships, and turned back into gas at regasification terminals.
Anderson and Broderick find that ‘the additional emissions of LNG and long distance pipelines are approximately double those of short distance conventional production’.
The additional emissions from LNG mean that its lifecycle emissions can be as high as 134 percent of the end use combustion of CO2.’
Clearly, focus from lobbyists on end combustion has distracted from the much wider and larger life-cycle emissions of gas, including methane leaks and LNG.