Integration of High Temperature Heat Networks with Low Carbon Ambient Loop Systems

Heat networks are a key technology proposed in the UK Government's Clean Growth Strategy for delivering low carbon and low-cost energy to urban communities in the UK. Currently, around 2% of all heat in the UK is provided by heat networks compared to other countries such as Sweden/ Denmark, where they have more than 30% delivered in this way. Most of the Scandinavian systems use high temperature 3rd or 4th generation heat networks (>50-80ºC) [>122-176ºF] and these are often driven by fossil fuel powered Combined Heat and Power (CHP), which are carbon intensive and also impact on local pollution/ particulates. In the UK there is a drive towards 5th generation heat networks involving ambient temperature loops (13 - 25ºC) [55-77ºF]. These systems deliver additional benefits and savings as they are able to share heat/coolth across the network and capture waste heat from secondary heat sources like the heat from London Underground ventilation shafts and local data centres. They utilise heat pumps to deliver heat or cold from the loop to individual applications or buildings and they avoid emissions of particulates associated with CHP. This paper investigates how existing 3rd and 4th generation networks can be connected into 5th generation systems. It uses the 3rd generation Bunhill CHP installation in the London borough of Islington as a case study to investigate the relative performance when converting a system. The paper describes the techno-economic models developed to show how the Bunhill installation might perform when connected to 5th generation, including CAPEX and engineering connection approaches.