Speaker: Dr Paul Balcombe (Imperial College London)
CO2 emissions from natural gas are lower than other fossil fuels, but methane emissions from the supply chain reduce this climate benefit and are highly variable. Additionally, the appearance of super emitters in every stage of the supply chain skews the distribution significantly. Methane is a very potent but short-lived greenhouse gas, where Global Warming Potentials are typically used to compare gases with ‘CO2 equivalences’, but there is growing acknowledgment of their limitations and a desire to use other metrics and time horizons. Research at the Methane and Environment Programme, Sustainable Gas Institute at Imperial College London, examines the effect of the variability of methane emissions and the use of different climate metrics, and time horizons, on the potential contribution of natural gas to governmental decarbonisation pathways. The research develops a technology-rich probabilistic emissions model and conducts life cycle assessments of different supply chains and end-uses. We assess the benefits of using different climate metrics, such as the global temperature change potential (GTP), as well as other timeframes, for different industrial, governmental and academic applications. Results from the probabilistic assessment shows extremely heavily skewed emissions, resembling a log-log-logistic distribution for most supply chains: estimates vary by a factor of 100 across metrics, gas fields and supply chain routes. The role of natural gas in decarbonisation pathways must be managed carefully to avoid unintended consequences of increased supply chain methane emissions. Given the short-lived nature of atmospheric methane, the timing of natural gas production (and emissions) is a key consideration in energy transitions and minimising peak temperatures.