Smart Sharing: Optimizing Borehole Use Between a Supermarket and Residential Building

Objective/short description

This thesis investigates a shared geothermal system between a supermarket and a residential building in Örebro, Sweden, focusing on optimizing performance, control, and stakeholder cooperation. Conducted in collaboration with the company Assemblin, the project aims to improve system efficiency and propose guidelines for future designs. It contributes to the growing field of integrated energy systems by showing how shared geothermal resources can boost building performance and support sustainable urban development.

Background

This thesis investigates a shared geothermal energy system between two adjacent buildings in Örebro, Sweden: a supermarket and a residential building. Both buildings utilize a common borehole field, which serves two purposes:

• For the residential building, the boreholes act as a heat source for a ground source heat pump (GSHP), primarily used for space heating during colder months.

• For the supermarket, the same boreholes function as a heat sink, absorbing excess heat from the refrigeration system via subcooling, especially during warmer periods.

In theory, this dual use of the geothermal resource can balance the thermal loads on the borehole field. During winter, waste heat from the supermarket can raise ground temperatures, improving the efficiency of the heat pump. In summer, the low ground temperatures can enhance subcooling in the refrigeration system, reducing its energy use. When optimally managed, this synergy can lead to increased energy efficiency and reduced operational costs for both systems.

The system has been operational since 2023 and has already undergone a commissioning phase, during which its performance and control strategy were analyzed and optimized.

Task description

This thesis will focus on the following key areas:

• Optimal Operation Strategy: Identify the operating conditions under which both the refrigeration system and the heat pump can maximize performance and energy efficiency using the shared boreholes.

• Balanced Benefit for Stakeholders: Develop an operational strategy that ensures equitable energy and cost benefits for both the supermarket and residential building owners.

• Borehole Field Sizing and Optimization: Evaluate whether the current borehole field size is optimal for both systems. Assess technical and economic trade-offs and identify if there's an economically optimal design for such integrated systems.

• Stakeholder Cooperation Agreement: Propose a cooperation model or agreement between the two building owners that ensures fair usage, maintenance, and cost-sharing of the shared geothermal system.

• Design Guidelines for Future Projects: Based on the findings, develop a set of practical guidelines for designing and implementing similar shared geothermal systems in future urban developments.

Learning outcomes

By the end of this thesis project, the student will be able to:

• Analyze the performance of shared geothermal systems in mixed-use buildings.

• Optimize control strategies for heat pump and refrigeration systems using a common borehole field.

• Assess technical and economic feasibility of integrated energy systems, including borehole sizing.

• Develop stakeholder cooperation models for shared energy infrastructure.

• Propose practical design and operation guidelines for future shared geothermal installations.

Duration

Starting in January 2026

Supervisors

Examiner