Greenhouse Gas Emissions Along the Norwegian Gas Value Chain

摘要

Norway is the third largest gas exporter in the world and the second largest exporter of piped-gas to Europe. Natural gas, mostly consisting of methane, has a low CO2 emission per unit of energy produced during combustion compared to other fossil fuels. However, methane itself is a powerful greenhouse gas and a high level of methane emissions along the value chain could potentially offset the climate benefits of natural gas in a comparison with more CO2-intensive fossil fuels. With this background in mind, the present study examines greenhouse gas emissions along the Norwegian pipedgas value chain. The study boundaries extend from production on the Norwegian Continental Shelf to end-user delivery on the British and German gas markets. Primary emissions data are used for production and processing (the upstream and midstream sectors), while results from recent international studies are used for transmission and distribution (the downstream sector). The aggregated results are presented in the perspective of a coal vs. natural gas comparison. The emissions attached to Norwegian gas are also benchmarked in the European context. The greenhouse gas intensity associated with Norwegian gas delivered to customers in the United Kingdom and Germany appears to be significantly lower than the corresponding average for all gas consumed in Europe. Methane represents just 4% of the total GHG emissions. For the gas value chain from the Norwegian Continental Shelf to end-users in the United Kingdom and Germany, over 90 % of methane emissions occur in the transmission and distribution sectors. Considering the gas value chain from production to gate-delivery to customers in the United Kingdom and Germany, the methane emissions associated with Norwegian gas are below 0.3%, while the average for all gas consumed in Europe is 0.6%. These performances are related to the quality of the Norwegian subsea transport network, a high CO2 tax, focus on minimizing methane leakage due to safety risk and a close cooperation between the gas producers and the Norwegian authorities with regard to methodological developments. Overall, the estimated levels of methane emissions support the climate benefits of natural gas compared to coal, both for the Norwegian gas and for the average of all gas consumed in Europe.