Comparative life cycle assessment of two desiccant wheel dehumidifiers with industrial application

Sammanfattning: Humans spend around 80 percent of their lifetime indoors. The humidity level plays an essential part in indoor climate, both in non-industrial applications, such as thermal comfort, and industrial ones. Dehumidification is a technology in the field of thermal comfort and indoor climate to control humidity levels. The need for the technology is essential for maintaining indoor humidity levels and lowering dew points. Based on the lack of studies that focus on the complete life cycle of the given dehumidification technology as well as the recently introduced EU Taxonomy there is an urgent need to evaluate the environmental impacts of the dehumidification systems. In this thesis, a comparative Life Cycle Assessment (LCA) is performed for two desiccant wheel dehumidifiers with industrial application driven fully by electric energy The intent of the LCA is to quantify the environmental performance of the two dehumidifier systems throughout their lifetime. The scope of this study is cradle-to-grave and includes four main life stages: cradle-to-gate, usage, maintenance and end-of-life. The objective is to identify the main drivers of selected environmental impact categories in each life phase and suggest areas of improvement. Seven categories are chosen based on the ReCiPe 2016 impact assessment method and that are related to the planetary boundaries. The two commonly available dehumidifiers will be analysed separately and in comparison. The functional unit used is 1 kg of water removed from the air which is independent of the performance of the system and focuses only on the wanted effect of humidity control. A base case is defined and scenarios are developed to cover different operational modes.  It is found that the usage stage which mainly consists of electricity demand contributes the most, varying between 65% and 99% of the overall impact in all categories. The cradle-to-gate stage, which shows the second biggest impact, has its most significant share in fine particulate matter formation, caused by the equipment for pre-treatment of air. Maintenance has the biggest variation depending on the scenario and application of the dehumidifiers where the number of maintenance occasions can vary significantly. This stage is however less crucial in the selected base case based on its small impact in most categories. End-of-life is insignificant for the results of this study having an average impact of less than 1%. The scenario analysis shows that a significant variation of the impact during usage is expected for different locations. This is mainly caused by the changing composition of the grid electricity which is identified overall main driver. The key parameters that influence the outcomes of this study are the operational hours of the systems, the target supply humidity as well as the climatic data. Potential for improvement is seen for an increased recycled content during the cradle-to-gate stage, the integration of sustainable energy technology as well as the connection of the systems to energy-efficient equipment during usage. Finally, it is concluded that an increase in material consumption may be tolerated by the systems if the energy performance is improved due to the dominating burden during the usage stage. The presented study may serve as example on how the EU Taxonomy can be applied within the field of dehumidification regarding environmental sustainability. It can also be used as a reference for further studies including the complete life cycle of dehumidifiers. Additional work may include other configurations of desiccant wheel dehumidifiers and extension to different assessment methods.