Guest zero-point-zero by David Middleton

Offshore oil and gas rigs leak more greenhouse gas than expected
John Sullivan, Office of Engineering Communications
Aug. 15, 2019 9:49 a.m.

A survey of offshore installations extracting oil and natural gas in the North Sea revealed far more leakage of methane, a powerful greenhouse gas, than currently estimated by the British government, according to a research team led by scientists from Princeton University.

Using a laser-based instrument mounted on small fishing boats, the researchers estimated methane emissions from eight North Sea production platforms off the coasts of England and Scotland. Contrary to current expectations, they found that all the sampled offshore installations leaked even when they were not conducting operations expected to cause methane emissions. On average, methane leakage occurring during normal operations more than doubles each installations’ reported emissions to the U.K.’s National Atmospheric Emission Inventory.

In an article published Aug. 2 in the journal Atmospheric Chemistry and Physics, the researchers noted that previously reported leakage from operating oil and gas platforms appear low: 0.13% of production by U.K. government estimates. However, the researchers found that an additional 0.19% occurred during normal operations. For the U.K., this additional 0.19% corresponds to an additional 330,000 cars on the road (an increase of 1% in registered U.K. vehicles), the researchers said. 

[…]

Princeton University

Firstly, production platforms are not rigs.

Secondly, the bass-ackwards world of climate “science” must be the only field in which 97% is a YUGE number if it’s SkepSci bloggers agreeing with one another, 99.7% isn’t mentioned when it’s ice not melted or gas not leaked and the difference between 0.03% and 0.04% is a climate crisis.

Thirdly, slightly more than the Dean Wormer line is still the Dean Wormer line.

Using a laser-based instrument mounted on small fishing boats, [a stack of assumptions and a Gaussian plume model] the researchers estimated methane emissions from eight North Sea production platforms off the coasts of England and Scotland.

Before I shoot this down like an F-14 Tomcat vs. a Mitsubishi A6M Type 0, lets accept their conclusions.

The article is not pay-walled.

Key passage:

3.4 Uncertainties/shortcomings of Gaussian plume modelling

A range of scenarios were run using the Gaussian plume model to estimate uncertainty in average CH₄ emissions resulting from UGGA instrument precision, thermometer precision, varying wind speed, assessment of the PGSC, and uncertainty in distance between the emission source and the detector. Uncertainty in the UGGA and the thermometer has little effect on the average emission estimate (Sect. S3). The largest variability in wind speed was recorded during measurement of platform no.  3 on 6 July 2017 at 4.4±0.6 m s⁻¹(Sect. S1); using this variability in wind speed in the Gaussian plume model results in an uncertainty in average emission of ±12 %. Uncertainty in estimating the distance between the emission source and the detector results in an uncertainty in average emissions of ±8 %. The Gaussian plume model has the greatest response to the uncertainty in estimating the PGSC, resulting in an uncertainty of ±41 %. We estimate the overall uncertainty in the average CH₄ emission, calculated as the root of the sum of the individual uncertainties squared, to be ±45 %.

As mentioned in Sect. 2.5, the uniform vertical mixing assumption made in the Gaussian plume model may not hold here as the data we collected provide no information on vertical mixing. However, the Gaussian plume model only assumes a constant vertical mixing rate between the source and the detector. In most cases this distance is relatively short and unlikely to significantly affect the calculation of emissions. In future experiments, the vertical mixing rate could be calculated by measuring the vertical gradient of wind speeds to make an accurate thermodynamic profile.

Atmos. Chem. Phys.

Technically, in this particular case, the Zero shot itself down: 0.2% +/−45%…

What do 0.1% and 0.3% have in common? They both round down to…

Reference

Riddick, S. N. , Mauzerall, D. L., Celia, M., Harris, N. R. P., Allen, G., Pitt, J., Staunton-Sykes, J., Forster, G. L, Kang, M., Lowry, D., Nisbet, E. G. and Manning, A. J. “Methane emissions from oil and gas platforms in the North Sea”. Atmospheric Chemistry and Physics. 19, 9787–9796, 2019
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