Book of presentations of the 2nd Symposium on High-Temperature Heat Pumps

Heat pumps operating at higher temperatures enable the supply of energy efficient and emission free process heat. High temperature heat pumps are the "hidden champions" when it comes to decarbonizing the industry in order to meet the climate targets of the Paris agreement. Utilizing this potential of industrial heat pumps is highly attractive since it allows the industry not only to reduce emissions but also their primary energy consumption.

However, there are challenges connected with implementing heat pump technology, especially in high temperature applications like industrial processes and district heating. There is a need for technical innovations to achieve lower specific investment costs and increased energy efficiency while maintaining technical feasibility and stable operation.

The 2nd Conference on High-Temperature Heat Pumps was organized in collaboration of SINTEF Energi, the Technical University of Denmark (DTU) and the Danish Technological Institute (DTI). It was held on the 9th of September in Copenhagen, Denmark.The day comprised 15 oral presentations and 12 poster presentations with speakers from in total 11 different countries.

The presentations were organized in three sessions with oral presentations, and the day was concluded by a poster session. The poster session created the possibility for fruitful discussions of the posters as well as the oral presentations. The presentations were organized in three sessions with a focus on: - Potential and demand for high-temperature heat pumps- Industrial cases and examples of successful integration of heat pumps - Current developments and trends for high-temperature heat pumps.

There was a wide consent among the presenters and the participants about the large potential of high-temperature heat pumps (HTHP). A broad variety of potential applications was presented and the considerable potential that HTHPs imply with respect to reducing GHG emissions by electrifying the industrial heat supply becomes apparent.

Thomas Nowak, European Heat Pump Association, underlined in his keynote speech, that this potential may only be exploited, if the CO2 emissions are internalized, if the tax burden on electricity and fossil fuels for heating is reviewed and if the subsidies for fossil fuel-based technologies are stopped.The presentations about the technical developments revealed that there are different systems under development, which are (close to) becoming commercially available for supply temperatures of up to 150 °C in different capacity ranges.

The beneficial impact of HTHPs was presented for different case studies. It was found to be highest, if the integration process comprised a simultaneous optimization of both the process and the heat pump system.The presentations did however also reveal the requirement and the potential of further developments.

The required developments are covering a broad range and aim among others on improved performances, decreased investment costs and simplified and improved integration processes. The conference presentations indicated the following developments to be promising contributions for accelerating the deployment of high-temperature heat pumps:- Optimization of cycle layout and component performances‹ Improved integration procedures considering a re-evaluation of supply temperatures, buffer tanks and possibilities to access cheap electricity- Compressors capable of high supply temperatures and lubrication systemsif required‹ Reduction of investment costConsidering the rapid development of R&D activities that we experienced since the organization of the previous event in 2017, we are looking forward to following up with the ongoing developments and especially with the new developments that may be expected in the next two years.

As the organizing committee, we want to thank all participants for their attendance and in particular the speakers for interesting and well-prepared presentations. In the following, a compilation of all presentations and posters, supplemented with an extended abstract, can be found.