Road to COP28. Extending the temperature range and application for heat pumps

To promote decarbonation, “high temperature heat pumps should be designed using waste heat and renewables as a driving energy, and environmentally friendly working fluids”, according to Dr Mota Babiloni, IIR expert.

Road to COP28: The IIR interviews experts on sustainable refrigeration


As stated by the UN Environment Programme, the refrigeration sector is becoming a global priority. The 2023 UN Climate Change Conference will take place in Dubai, United Arab Emirates (UAE) from November 30 to December 12. Sustainable cooling will be the focus of COP 28 as one of the key solutions to tackle climate change. The IIR will be partnering with UNEP’s Cool Coalition and several other organisations to deliver a “Global Cooling Stocktake report” program promoting sustainable cooling.

In the run-up to COP28, the IIR's monthhly newsletter features the views of experts on sustainability in various areas of refrigeration.



In the field of heat pumps and energy recovery, Dr Mota Babiloni states that sustainability requires the electrification of heating production by extending heat pumps to any technically possible temperature range and application. Electrification of heating production reduces dependence on fossil fuel importations and promotes decarbonisation. The driving energy must be mostly based on renewable sources or waste heat, and working fluids must also be environmentally friendly. High temperature heat pumps must be designed for a highly energy-efficient operation to compete with fossil fuel boilers. 


Find out more about high temperatures heat pumps 


Priorities and barriers to achieve sustainability 


High-temperature heat pumps (HTHPs) should be integrated by considering heat sources in existing processes where heat was previously unused or wasted. According to the IIR, an estimated 42% of industrial waste heat is available worldwide at temperatures below 100°C. Despite the relatively low temperature of this heat, if used in high-temperature heat pumps, the overall industrial process is improved, simultaneously enhancing energy efficiency, profitability, and sustainability. Moreover, the release of heat into the ambient is a source of global warming, and in the future could be controlled by environmental protection policies, as is the case for chemical pollution or the water used in cooling towers. 


Dr Mota Babiloni underlines the importance of considering energy-efficient cycles and working fluids with negligible environmental impact when designing HTHPs. Sustainability also means investigating and developing refrigerants that work at such high temperatures. Current working fluids and components limit the practical application of high-temperature heat pumps to 180 °C at the most. Studies should look for industries or processes where a combination of a low-temperature heat source and a high-temperature heat sink is possible, and where the compression ratio is optimal. When the heat source or heat sink is unavailable, Dr Mota Babiloni suggests that heating networks and thermal energy storage should be considered for practical simultaneous heating and cooling. 


Dr Mota Babiloni believes that support from governments or public bodies must be increased worldwide to promote HTHP deployment providing tax benefits to companies that replace boilers with heat pumps in process heat, but also providing economic incentives for the heat produced with high-efficiency heat pumps. However, a vast deployment of heat pumps requires increasing the flexibility of high-temperature heat pumps. This means combining heat demand and heat supply. Besides the challenge of developing high-temperature heat pumps, heat storage systems with adequate energy storage density and stability should be considered for both heat sinks and heat sources. Moreover, components need to be standardised, accelerating the development of new HTHP products, and decreasing the expected production costs. Dr Mota Babiloni adds that other barriers are the trust of industry in the technology; and the need for refrigerants, lubricants, and compressors for higher heating production temperatures. 


Key technologies on the road to sustainability 


Annex 58 of the International Energy Agency provides an overview of the development of supplier technologies and demonstration cases. The Technology Readiness Level (TRL) of the listed supplier technologies ranges from 4 to 9. The maximum supply temperature observed was 230 °C (most units producing above 120 °C), and the heating capacity was up to 70 MW, presenting a high adaptability depending on the model. 

In the overview of demonstration cases, the heating capacity of the units ranged between 0.1 MW and 12 MW. The coefficient of performance (COP) indicated by the suppliers reaches a value of 5.3, most above 3.0. As the potential COP is relatively high and most units were tested with low global warming potential refrigerants, CO2eq emission reduction depends on the carbon emission factor of the national grid. The high-efficiency natural gas boiler can be considered as the baseline for the comparison. 


What about low- and middle-income countries? 


In countries where industries are being constructed from zero, the process and plant layout could be planned considering heat pumps as the heating production technology, Dr Mota Babiloni suggests. That way, there would be no need to replace operating fossil fuel boilers in good condition.  

Moreover, according to the World Bank, many low- and middle-income countries have very high practical solar photovoltaic potential. Solar energy could therefore be used to provide electricity to high-temperature heat pumps with renewable sources. 

HTHPs are particularly promising in high-heating capacity processes requiring a bigger initial investment. Dr Mota Babiloni adds that high income countries should provide funding and technology and transfer technology to low- and middle-income countries. 



Biography of Dr. Adrián Mota Babiloni

Junior member of the IIR B1 commission on “Thermodynamics & transfer processes” and the E2 commission on “Heat pumps, energy recovery”. 

Adrián Mota-Babiloni works as a postdoctoral researcher in the ISTENER research group of the Universitat Jaume I (UJI). His main line of research is low global warming potential (GWP) working fluids for refrigeration and air conditioning, ultralow-temperature refrigeration, organic Rankine cycles (ORC), and high-temperature heat pumps (HTHP) for industrial heat revalorisation.



Adrián Mota Babiloni would like to thank Prof. Alberto Coronas for his collaboration on this document. Prof. Alberto Coronas is the President of the IIR E2 commission on “Heat pumps, energy recovery”.


Disclaimer. The opinions presented in this article are those of the expert(s) and do not necessarily reflect the official position of the IIR.