After evaluating several high temperature processes, IFE decided to focus on an absorption/compression process described by August Osenbrück already in 1895, that had never been made commercially viable. The technology involved converting low temperature energy to high temperature energy at standard pressure (25 bar) with a natural refrigerant based on a mixture of ammonia and water (NH3 and H2O) and a Global Warming Potential (GWP) of zero.
In 2000 researchers made it happen in the laboratory, and I 2002 the first high temperature Hybrid Heat Pump, delivering 95°C was installed at a dairy in Norway. Two years later, Hybrid Energy AS was formed.