Explaining the emergence and absence of seasonal thermal energy storage in the UK: Evidence from local case studies

Large-scale energy storage is highlighted as key for decarbonisation, yet there lacks consensus on the optimal types of storage required. Seasonal Thermal Energy Storage (STES) is an established feature of effective energy transitions in some countries, such as Denmark and the Netherlands, but it remains a marginal technology in the UK. This paper contributes to understanding how STES may develop in the UK, and the mechanisms and challenges for widescale STES deployment, through case studies of five local heat projects. Based on an analysis of both the emergence and absence of STES in local energy projects, we identify key factors enabling and inhibiting STES deployment, intersecting technological, economic, organisational and governance. We conclude that the limited extent of STES in the UK reflects the inconsistent alignment of these factors in local level heat projects, and disconnects between national energy policy, local energy planning, and project-level contingencies. Our findings suggest that without resolving these tensions, the UK heat transition will continue to be haphazard rather than strategic. While the situatedness of low carbon heat supply, storage and demand suggests moves towards more local energy governance, this needs to be accompanied by multi-level alignment and capacity building.