ECN publication
Validation of methane emission inventories for NW-Europe
Published by: Publication date:
ECN 1997
ECN report number: Document type:
ECN-C--96-088 ECN publication
Number of pages: Full text:
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Results of research on tropospheric methane concentration and isotopiccomposition of tropospheric methane are summarized. Current methane emissions estimates in Northwest-Europe (NW-Europe) are validated for the period March 1993 - July 1996. Methane concentrations were monitored at the 200m meteorological tower at Cabauw, Netherlands. Isotope analysis in methane was carried out in order to reveal methane source types. From the database of Cabauw methane concentration, methane emissions for NW-Europe were deduced using a transport model called COMET. The COMET estimates of the emissions generally were more or less equal to or higher than the current inventory estimates, derived from statistical data. An important result is that the developed method of concentration monitoring combined with transport modelling provides an independent method to assess the methane emissions for a large region that can be used to validate the emission inventories. Using the same measurements, local emission estimates were derived for the region close to the Cabauw tower. These estimates compare well with the inventory data. Transport modelling was also used to determine the "1"4CH4 emissions by Pressurised Water Reactors (PWRs) in NW-Europe. The modelling indicated that the "1"4CH"4 emissions by PWRs are probably higher by a factor of 1.5.4 than published values. This larger amount of "1"4C from PWR must be diluted with more fossil methane (devoid of "1"4C) in order to derive the global "1"4CH4 budget, suggesting that the global fossil contribution to atmospheric methane concentrations is larger than previously thought. From the monitoring station near Amsterdam (Durgerdam) a methane emission for this urban area has been calculated based on a half-year continuous methane record. The estimate amounts to 2-34 Gg.yr"-"1. Expressed per unit of area this emission is quite similar to the average emission of methane of the Netherlands as a whole. As the Amsterdam area can be considered to be representative for urban areas in the Netherlands it can be concluded from this that urban areas in the Netherlands are not major sources of methane. 43 figs., 19 tabs., 43 refs.

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