Arne Hoeg presents three Stirling heat pump designs at International Stirling Engine Conference 2026
21st International Stirling Engine Conference
Arne Høeg will present three generations of Stirling cycle industrial heat pump designs on Wednesday, 26 August at 9am at the 21st International Stirling Engine Conference (ISEC), held 25–27 August 2026 in Pau, France.
“The conference brings together distinguished professors and researchers from industry and academia worldwide to discuss the latest advances in Stirling and other "hot air engine" technologies,” according to the ISEC conference website.
The Stirling engine
For most of the 20th century, Stirling engines were assumed to need large temperature gaps to operate efficiently. That assumption was overturned in 1980, when a working engine ran on just 30°C of a temperature difference.
By 1990, that gap had narrowed to half a degree, still achieving measurable Carnot efficiencies above zero. The question that followed was simple, but radical: could a Stirling machine maintain high Carnot efficiency across any temperature difference?
Three generations of Stirling heat pumps
That hypothesis set inventor and mechanical and thermodynamic engineer Arne Høeg and his colleagues on a path through simulation, design and three generations of industrial-scale pilot reverse Stirling heat pumps.
Replacing fossil-fuelled industrial boilers — responsible for nearly 20% of global CO₂ emissions — remains one of the toughest challenges in the energy transition, largely because conventional heat pumps struggle to cope with the sector’s highly variable process conditions and high temperatures.
Heating and cooling in one system with impressive lab results
Most companies solving industrial heat need one system for heat and a completely separate one for cooling. Enerin’s high-temperature HoegTemp™ heat pump does both, in a single machine. On the hot side, it delivers industrial steam and process heat up to 250°C commercially, while in lab testing the machine has been pushed to 670°C.
On the cold side — the same machine delivers deep cooling, down to -60°C commercially, and -168°C in the lab. The same core process, the same unit, working in both directions. Enerin produces modular units, with a 500 kilowatt thermal energy output, running on helium, delivering up to 70% lower energy consumption than conventional systems.
Enerin’s heat pumps are unique because they can follow industrial demand to supply heat, steam and cooling in a similar way to that of a boiler.
“Because our automated system adapts to varying process conditions, it allows factories to decarbonize without redesigning operations. This flexibility, and standardisation is what finally makes clean industrial heat available and profitable at scale,” Arne Høeg said in the company’s press release on the Series A funding close announcement last year.
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