Capterio published a letter in response to Leslie Hook’s concerning article reports that methane levels in the atmosphere surged in 2020 – the biggest increase since records began.
The sources of methane emissions are well-documented: biological sources, such as wetlands; agriculture and ruminants, particularly belching cows; and extraction and processing emissions from fossil fuels, especially oil and gas.
Oil and gas methane emissions are predominantly associated with venting (intentional methane releases from compressors, pneumatic valves, etc.) and fugitives (accidental methane releases from pipes). But there is a consistent underestimate of the scale of methane emissions from incomplete flaring (so-called “methane slip”). It feels odd that methane emissions from flaring too frequently out of mind when plainly, it is not out of sight.
Whilst we know (from satellite-based measurements of the thermal anomalies associated with gas flaring) that 150 Billion Cubic Metres of gas was burned by flares in 2019, emissions from methane are less easy to quantify. A “best practice” gas flare combusts around 98% of the gas it receives (generating 2% “methane slip”) – and it is this figure that forms the base case of the IEA incomplete combustion figures.
But our discussions with oil and gas producers strongly suggest that methane slip rate are, in fact, much higher. Whilst there is a lack of clear data, we think it is not unreasonable for the global weighted average combustion efficiency to be more like 90% – although that may even be optimistic.
This means that the methane emissions associated with flaring are probably five times higher – and the total flaring emissions are closer to 1 billion CO2-equivalent tonnes per year (noting that methane is 84x more potent than CO2 over a 20-year timescale). Including a more realistic methane slip estimate means that emissions from oil and gas (when venting and leaking are included) from methane are likely underestimated by at least 13%.
Methane is a critical climate issue that needs attention in the immediate term. Incomplete flaring needs more attention, as the EU points out in its methane strategy. We have the technology to solve methane emissions in the oil and gas sector at little to no net cost, so what are we waiting for?