Northern Sweden’s leading hospital, Norrlands University Hospital (NUS), is home to one of the world’s largest Borehole Thermal Energy Storage (BTES) systems. The hospital's buildings are linked into a thermal network, allowing for energy to be efficiently shared across the facility. Surplus heat from areas like scanners, refrigeration, and facility-critical cooling infrastructure is redirected to spaces that require warmth, such as patient care areas. The system meets 95% of the hospital’s cooling needs with renewable energy while reducing energy costs by nearly €1 million per year.
In 2014, the County Council Executive Committee partnered with Energy Machines to implement an integrated geothermal energy solution for its 345,000m² NUS hospital campus, with the aim of reducing reliance on purchased energy while lowering costs and environmental impact. Energy Machines designed and installed an integrated heating and cooling solution with four borehole thermal energy storage reservoirs across the hospital campus. Today, the system covers over 20% of NUS’s total heat demand and 95% of its cooling needs using near-surface geothermal energy and the hospital's own waste heat.
By leveraging ground storage, NUS can extract heat from bedrock in winter and use it for cooling in summer. This provides a stable, low-cost energy supply for critical hospital spaces like operating rooms, blood banks, and laboratories. Additionally, surplus heat is stored during warm months and reused in winter, creating a continuous energy cycle that minimizes waste.
“Previously, we paid for energy three times—buying district heating, district cooling, and electricity simultaneously. Now, we only purchase electricity for heat pumps, allowing us to fully utilize the energy already available in our buildings,” said Jesper Burlin, Technical Coordinator at NUS.
The hospital’s ground storage system consists of a series of borehole reservoirs located beneath the hospital campus. As one of the world’s 30 largest BTES installations, it supplies approximately 5,000 MWh of cooling and 7,000 MWh of heating—equivalent to the heat required for around 450 homes. This has doubled the hospital’s capacity for producing heating and cooling, further reducing dependence on external energy sources.
Four heat pump energy centers, with a combined capacity of 2.5 MW, operate across the campus. They are connected by a thermal network that circulates water through a system of pipes, linking all hospital buildings.
“NUS’s geothermal energy solution not only lowers energy costs but also represents an investment in the environment,” said Hans Johansson, then Property Area Manager at NUS. “By producing heating and cooling internally, we have turned waste heat into a valuable resource, ensuring long-term energy savings for the County Council.
The project was implemented in phases, with the final of four heat pump energy centers commissioned in 2021. Looking ahead, the City Council plans to invest further in optimizing the hospital’s cooling and heating infrastructure.
