Verifying and improving methane emission inventory data using atmospheric measurements in the Netherlands (IMEO-VIME-NL)

Methane is an important greenhouse gas that contributes to about 12% to Dutch greenhouse gas emissions. In previous studies, top-down modelling and satellite inversions have indicated that methane emissions in the Netherlands as represented in bottom-up inventories might be underestimated. The IMEO-VIME-NL project aims to make use of the abundant data sets of methane measurements in the Netherlands to compile a national measurement-based methane emission baseline.A compilation of available measurement data shows that not all sectors are covered equally. While sectors like peatlands and wastewater treatment plants were frequently targeted by measurements, other sectors, like biodigesters and domestic combustion, are lacking measurement data. Sometimes data are mainly concentrated on a subsector, e.g. most measurement data for the agriculture sector, the main contributor to Dutch methane emissions, focus on dairy farms. This data set collection is then used for upscaling to national total emissions.An important outcome of the project is a compilation of upscaling methods that could potentially be transferred to other countries. Sensitivity studies are employed to test different data coverages and different activity data when upscaling to national total emissions. For wastewater treatment plant emissions, two different types of activity data are readily available, inhabitants and water usage. Using these activity data for estimating emissions results in similar emission estimates that are higher than the inventory emission. In a similar way, methane emission measurements and available activity data for other sectors are compiled together and upscaled to a measurement-based national methane emission baseline.