In a pursuit to increase the efficiency of district heating system there has been a continuous focus to reduce the system operating temperatures. This has led to the current state of the art district heating systems, commonly referred to as the 4th generation district heating, also known as low temperature district heating (LTDH). The success of the LTDH has fuelled a lot of research interest in district energy systems, one of the new research topics has been focusing on reducing the operating temperatures down to the ambient temperature (ATDH), commonly referred as 5th generation district heating. In these systems the supply temperature is insufficient for fulfilling the heating demands of the connected buildings, which then requires end-user located heat pumps to raise the supply temperature to the level required by the buildings. As of today, number of ATDH systems have been realized as part of various research projects. The question however remains if ATDH brings additional benefits compared to LTDH. This paper compares the levelized cost of heat from these two systems types for two countries with different climate zones. The results of the analysis indicate that LTDH is the favourable solution in both countries.
Heat pumps as a way to Low or Zero Emission district heating systems
