KPN: RockStore - develop, demonstrate and monitor the next generation BTES systems

RockStore's objective is to monitor investigate and develop the design and operation of borehole thermal energy storage (BTES) systems for large buildings, district heating and neighborhoods. RockStore follows up a selection of energy systems using BTES for energy-efficient and cost-effective heating and cooling of buildings. The project's flagship is GeoTermos, the energy system at Fjell school in Drammen. Drammen Kommune has constructed an underground borehole thermal energy storage consisting of 100 boreholes of 50 m for seasonal storage of heat. The heat is taken from the air in the warmer periods by using a solar PV--run air to water heat pump and injected into the boreholes. The RockStore projects contributes with distributed monitoring of the temperature in the boreholes by use fiber optic temperature measurements (DTS) and data analysis of the measurements and simulations of operation and possibilities for improvements of the design of the BTES. The temperature in the BTES after two seasons was 43 C. Geotermos won the prize for the best local climate solution in 2020. The preliminary results have been presented in national and international meetings. The energy systems at Kalnes Energisentral and Scandic Flesland Airport have been followed up in RockStore. These facilities are Norwegian cases in IEA HPT Annex 52, Long term performance measurement of GSHP Systems serving commercial, institutional and multi-family buildings, and the energy systems are reported according to templates developed in this international collaboration. The RockStore team has contributed to optimize the operation of Kalnes Energisentral by balancing the operation of the BTES regarding injection and extraction of heat. The RockStore and IEA HPT Annex 52 project (supported by Enova) hosted an open webinar on November 17. Scandic Flesland Airport, Geotermos, Kalnes and three other facilities were presented. 156 participants were registered at the webinar. A BTES guideline will be the final deliverable of the project. The work with the guideline is in progress

The RockStore project aims at investigating the potential for Borehole Thermal Energy Storage (BTES) to be integrated in an energy system. The increasing emphasis on decarbonizing the energy system has drawn awareness to the energy storage technologies as tools for efficient use of energy resources and balancing energy production and demand. We will target the following knowledge gaps * Lack of performance monitoring data and methodology, * Need for understanding, improvements and special designed BHEs * New methodology for integration of BTES with District Heating (DH) and other surplus energy sources The scientific methods applied are based on extensive background competence on geology and hydrogeology, state-of-the-art monitoring and novel fiber optic technology, fluid- and thermodynamics, energy calculations and statistical analysis.To meet the needs for performance monitoring data and methodology, RockStore?s research approach is to collect large amount of data from case studies with different properties. To meet the need for understanding, improvements and special designed BHEs, RockStore will perform specific tests in pilot BHEs established in the project to verify their performance by high temperatures, hydrostatic pressures, collector design and operation of the BHEs. Based on the findings, BTES concepts for DH and neighborhoods including HHT-BTES and CHP will be developed.