Hybrid heat pumps

Hybrid heat pumps combine a heat pump with a backup technology (e.g. a gas boiler), which supplies heat when conditions are not optimal for the heat pump’s operation. Those conditions could include periods of extreme cold weather or times of high electricity prices. Under extremely low outdoor temperatures, the backup system can supply either part of the energy demand, allowing the heat pump to operate at high efficiencies, or all the demand by switching off the heat pump. The system can be operated at maximum efficiencies and lowest costs by controlling the balance between the heat pump’s and the backup technology’s operation. The backup technology is typically a gas or biomass boiler, but solar technologies or even micro combined heat and power units can be used.

Hybrid heat pumps are suitable for both large- and small-scale residential, industrial and district heating systems (Beccali et al., 2022). They do require an effective control system that factors in weather, comfort and market conditions. They can thus support the use of new innovative control management systems, including artificial intelligence (AI) techniques.

While the hybridisation of heat pumps with gas boilers may not be the optimal solution for rapidly decarbonising the energy system, hybrid heat pumps can speed up the market roll-out of heat pumps by addressing some of the concerns about heat pump-only systems and allowing users to install heat pumps on top of their existing systems. Hybrid heat pumps can also accelerate the adoption of smart electrification strategies and the use of additional clean technologies, such as solar or geothermal energy. Hybrid heat pumps should thus be viewed as a transitional innovation.