AbstractIn the context of mitigating climate change and reducing dependency on natural gas, district heating and cooling could have a strong potential in reducing consumption of primary energy and lowering emissions of greenhouse gases. Recent developments of these systems include integrating renewable energy and more energy efficient buildings. These developments are being addressed in the latest generations (4th and 5th) of district heating and cooling. In this research, environmental impacts of 5th generation district heating and cooling (5GDHC) systems are assessed. 5GDHC is a relatively new district heating technology
and strives to further decarbonize district heating and cooling networks. Having more knowledge about environmental impacts of 5GDHC and how these compare to other heating technologies can contribute to further improvements of DHC systems. In addition, it can provide insights to policymakers which system is most advantageous to implement regarding environmental impacts.
The environmental assessment of 5GDHC systems focusses on implementation practices in Europe. Therefore, five different pilot projects with 5GDHC are selected for the assessment. These pilot projects are part of the Interreg NWE project D2GRIDS and are located in Bochum (GE), Brunssum (NL), Paris-Saclay (FR), Glasgow and Plymouth (UK). Firstly, the impacts of energy use are assessed by analysing the different energy flows in the pilot projects and calculating emissions of CO2eq, different local impact pollutants and capacity of
renewable energy installed. The outcomes are subsequently compared to other heating and cooling solutions/scenarios (a 4GDHC system, a conventional district heating system, a system with natural gas boilers and a system with air-source heat pumps providing all heat and cold). Secondly, impacts of heat pump usage are assessed with regard to leakage of refrigerant, resulting in possible emissions of hydrofluorocarbons (HFCs). This is done by inventorying experiences with leakage of refrigerant and heat pumps used in the 5GDHC
pilot systems. Thirdly, based on literature study, impacts of storage of heat and/or cold and use of geothermal energy on the subsurface water quality are evaluated.
Since the assessed 5GDHC systems are currently still under development, mainly
assumption-based data from design plans is used. Furthermore, different assumptions were used in calculating the different emissions and scenarios. Despite the limitations and uncertainties of this research, it shows that 5GDHC systems can contribute to lowering emissions of CO2eq and local impact pollutants, especially when compared to conventional systems with natural gas boilers and air conditioners. With respect to this, regarding CO2eq
emissions, reductions of 51-134 gCO2eq/kWh are found in the 5GDHC pilot sites when comparing to a conventional system with natural gas boilers and air conditioners. However, no marked difference was found when compared to a 4GDHC system or system with airsource heat pumps providing all heat and cold. This difference is expected to become more convincing by further enhancing exchange of heat and cold between buildings and thereby potentially reducing emissions substantially. The quantification of possible HFC emissions is
strongly assumption based, since no data could be obtained on whether leakage of HFCs takes place in practice. Estimated CO2eq emissions due to leakage of HFCs from heat pumps range from 0,1-11% of the total CO2eq emissions of the five assessed 5GDHC pilot systems. Hereby, avoiding leakage of refrigerants from heat pumps and striving to use heat pumps without HFCs, can further enhance the environmental benefits of 5GDHC systems.
|Date of Award||10 Jul 2023|
|Supervisor||Wilfried Ivens (Examiner), Jetse Stoorvogel (Co-assessor) & Eugenia Bueno Martinez (Supervisor)|
- Master Environmental Sciences