Description Thermal storage in many forms has been proposed for balancing the renewable grid and meeting the heating demands through heat networks. This project explores the potential of vertical shafts adjacent or under buildings to be used as heat storage for short, medium or long term benefit and provide support for the transition to 100% renewable energy. Several concepts for this form of storage are to be evaluated including different storage media, temperatures, and heat injection methods (heat pumps, direct heating) and practical aspects considered. Key Objectives Complete a concept design evaluation study for vertical shaft thermal storage as grid balancing and renewable heating mechanism.