Comparing Alternative Pathways for the Future Role of the Gas Grid in a Low-carbon Heating System

This paper uses a whole-system approach to examine different strategies related to the future role of the gas grid in a low-carbon heat system. A novel model of integrated gas, electricity and heat systems, HEGIT, is used to investigate four key sets of scenarios for the future of the gas grid using the UK as a case study: (a) complete electrification of heating; (b) conversion of the existing gas grid to deliver hydrogen; (c) a hybrid heat pump system; and (d) a greener gas grid. Our results indicate that although the infrastructure requirements, the fuel or resource mix, and the breakdown of costs vary significantly over the complete electrification to complete conversion of the gas grid to hydrogen spectrum, the total system transition cost is relatively similar. This reduces the significance of total system cost as a guiding factor in policy decisions on the future of the gas grid. Furthermore, we show that determining the roles of low-carbon gases and electrification for decarbonising heating is better guided by the trade-offs between short- and long-term energy security risks in the system, as well as trade-offs between consumer investment in fuel switching and infrastructure requirements for decarbonising heating. Our analysis of these trade-offs indicates that although electrification of heating using heat pumps is not the cheapest option to decarbonise heat, it has clear co-benefits as it reduces fuel security risks and dependency on carbon capture and storage infrastructure. Combining different strategies, such as grid integration of heat pumps with increased thermal storage capacity and installing hybrid heat pumps with gas boilers on the consumer side, are demonstrated to effectively moderate the infrastructure requirements, consumer costs and reliability risks of widespread electrification. Further reducing demand on the electricity grid can be accomplished by complementary options at the system level, such as partial carbon offsetting using negative emission technologies and partially converting the gas grid to hydrogen.