PEFTEC 2019 - Abstract

Abstract Title: Methane source distribution in the complex landscapes of the United Kingdom: isotopic characterization, seasonal variation and inventory validation
Abstract Type: Poster
Session Choice: Current state of knowledge of anthropogenic methane emission sources
Presenter Name: Mr Dave Lowry
Company/Organisation: Royal Holloway University of London
Country: United Kingdom

Abstract Information :

The complex patchwork of urban, fossil and agricultural methane sources across NW Europe requires detailed ground surveys for characterization, unlike the big open landscapes of many continents with large area sources dominated by one particular methane emission type that can be isotopically characterized by flight measurements and sampling. Multiple seasonal, urban and rural measurement campaigns in the United Kingdom have been undertaken to:

  1. Assess source distribution and baseline in regions of planned fracking, and relate to on-site continuous baseline climatology.
  2. Characterize spatial and seasonal differences in the isotopic signatures of the UNFCCC source categories, and
  3. Assess the spatial validity of the 1 x 1 km UK inventory for large continuous emitters, proposed point sources, and seasonal / ephemeral emissions.
The UK inventory suggests that more than 80% of methane emissions are from 3 industrial sources: dairy farming, waste disposal and gas distribution. δ13C by bag sampling and GC-IRMS analysis shows that landfill gives a constant signature of -57 ±3 ‰ throughout the year, with biogas entering the national grid giving a similar signature. Fugitive gas emissions are consistent regionally depending on the North Sea supply regions feeding the network (-41 ± 2 ‰ in N England, -37 ± 2 ‰ in SE England). Dairy farms and their waste products paint a far more complex isotopic picture.

Currently available UK inventories distribute landfill and agricultural emissions equally across 5 x 5 km blocks, with fossil fuel distribution by population density at 1 x 1 km. The inventory catches the landfill emission hotspots and point sources from larger sewage treatment plants and gas compressor stations, giving a broad overview of emissions distribution for regional model validation, but is poor for other fugitive emissions. Mobile surveys combined with isotopic characterization have identified spatial distribution of gas pipe leaks, some persisting for at least 4 years (Zazzeri et al., 2015) Importantly existing significant gas leaks close to proposed fracking sites have been characterized so that any emissions to atmosphere with a different isotopic signature will be detected.