In the United Kingdom, heating in buildings is one of the largest energy-consuming sectors and a major source of greenhouse gas emissions. Therefore, decarbonising heating is essential to reaching the legally binding net-zero target of 2050. This dissertation uses a whole-system modelling approach for optimal infrastructure planning for decarbonising heating in buildings. We developed the HEGIT (Heat, Electricity and Gas Infrastructure and Technology) model to analyse the coordinated planning of electricity, gas and heating systems as well as assess the effects of different policies and strategies for decarbonising heating on the operation and long-term planning of the electricity and gas grids. Moreover, we soft-linked HEGIT with the thermodynamic and component-costing model of heat pumps in order to conduct a multi-scale analysis of heat electrification and evaluate the impacts of different heat pump design features and smart operational and investment schemes on the operation and long-term planning of electricity and gas grids.
We used the HEGIT model in three case studies to investigate some of the key issues surrounding heat decarbonisation in the UK. In the first case study, we examined different pathways for decarbonising heating in the context of different scenarios for the future of the gas grid and identified cost-optimal strategies in which decarbonising heating in buildings could contribute to achieving other policy objectives, such as energy security. In the second case study, we looked into smart planning strategies and operational schemes on the consumer side that can enhance the system value of electrifying heating and explored the trade-offs between consumers’ investment in fuel switching and infrastructure requirements for decarbonising heating. Lastly, we used HEGIT for system-informed heat pump design and studied the electrification of heating using heat pumps from an engineering perspective. This was done through conducting a sequential multi-scale analysis of heat electrification and assessing the value of different heat pump designs within the context of the system they would operate in.
Our results show that although electrification of heating using heat pumps is not the cheapest option for decarbonising heating in the UK, it has clear co-benefits, as it enhances fuel diversity, reduces energy security risks and avoids locking in a system with a high demand for fossil fuels and their complementary CCS infrastructure. A combination of different strategies, such as grid integration of heat pumps, increasing thermal storage capacity, load sharing with electric resistance heaters, using hybrid heat pumps with natural gas boilers, and smart technology selection should be implemented to moderate the infrastructure requirements, mitigate the reliability risks associated with widespread electrification of heating, balance the long-term fuel security risks and enhance the energy equity in the electrification pathway. These strategies have different implications in terms of consumer investment requirements and could be employed in different regions or for different con- sumer groups, as appropriate.
Complementary options such as carbon offsetting using negative emission technologies and partial conversion of the gas grid to hydrogen were also shown to effectively mitigate the strain on the electricity grid and reduce consumers’ investment. However, their role in decarbonising heating in the UK will depend on decisions about the future of the gas grid and system-wide factors such as the availability of biomass resources and natural gas, as well as the availability and rate of deployment of CCS.