In:
Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 19, No. 15 ( 2019-08-02), p. 9787-9796
Abstract:
Abstract. Since 1850 the concentration of atmospheric methane (CH4), a potent
greenhouse gas, has more than doubled. Recent studies suggest that emission
inventories may be missing sources and underestimating emissions. To
investigate whether offshore oil and gas platforms leak CH4 during
normal operation, we measured CH4 mole fractions around eight oil and
gas production platforms in the North Sea which were neither flaring gas nor
offloading oil. We use the measurements from summer 2017, along with
meteorological data, in a Gaussian plume model to estimate CH4
emissions from each platform. We find CH4 mole fractions of between 11
and 370 ppb above background concentrations downwind of the platforms
measured, corresponding to a median CH4 emission of 6.8 g CH4 s−1 for each platform, with a range of 2.9 to 22.3 g CH4 s−1.
When matched to production records, during our measurements individual
platforms lost between 0.04 % and 1.4 % of gas produced with a median
loss of 0.23 %. When the measured platforms are considered collectively
(i.e. the sum of platforms' emission fluxes weighted by the sum of the
platforms' production), we estimate the CH4 loss to be 0.19 % of gas
production. These estimates are substantially higher than the emissions most
recently reported to the National Atmospheric Emission Inventory (NAEI) for
total CH4 loss from United Kingdom platforms in the North Sea. The NAEI
reports CH4 losses from the offshore oil and gas platforms we measured
to be 0.13 % of gas production, with most of their emissions coming from
gas flaring and offshore oil loading, neither of which was taking place at
the time of our measurements. All oil and gas platforms we observed were
found to leak CH4 during normal operation, and much of this leakage has
not been included in UK emission inventories. Further research is required
to accurately determine total CH4 leakage from all offshore oil and gas
operations and to properly include the leakage in national and international
emission inventories.
Type of Medium:
Online Resource
ISSN:
1680-7324
DOI:
10.5194/acp-19-9787-2019
DOI:
10.5194/acp-19-9787-2019-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2019
detail.hit.zdb_id:
2092549-9
detail.hit.zdb_id:
2069847-1
