The future role of energy geostructures in fifth generation district heating and cooling networks

Energy geostructures are novel dual use engineering sub-structures that can be used for heat transfer and storage as well as original structural function. Their use is becoming increasingly popular in delivering cost-effective shallow geothermal energy. Currently, they are mostly used as a part of ground-source heat pump (GSHP) systems for supplying partial or full heating and cooling demands of different types of buildings. The recent introduction of fifth generation district heating and cooling (5GDHC) networks can pave the way for the exploitation of energy geostructures as ground-coupled low-temperature energy sources and stores for providing energy demands of a wider range of energy users in districts rather than single buildings. In this article, the capability and feasibility of the novel concept of integration of energy geostructures into the 5GDHC networks are evaluated through reviewing different aspects of thermal performance of operating energy geostructures and 5GDHC networks. The potential advantages and challenges along with the knowledge gaps in such integration are discussed, and some practical recommendations are provided concerning dealing with some implementation challenges. It is highlighted that the incorporation of energy geostructures in 5GDHC networks can enhance the sustainability, flexibility and resilience of the network. There is the potential to exploit a greater share of cost-effective geothermal energy, and the ability to act as both thermal energy sources and stores for efficiently supplying both heating and cooling demands. However, since the development of fifth generation thermal networks and energy geostructures, particularly energy walls and energy tunnels, are still in their infancy, further research is required to assess the magnitude of the opportunities and quantify the advantages of integrating energy geostructures into the 5GDHC networks.