Techno-economic and environmental analysis of alternative pathways for urea fertilizer production.

Sammanfattning: The increasing global population has placed significant pressure on meeting food demands, leading to the widespread use of fertilizers to enhance crop yields. Urea, being the most used fertilizer globally, has contributed to improved agricultural productivity. However, conventional urea production technologies heavily rely on fossil fuels, resulting in substantial greenhouse gas emissions and contributing to climate change.  As the demand for urea fertilizer is projected to rise in the future, there is a growing societal concern for environmental sustainability. Consequently, alternative technologies are being developed to produce urea with claims of reduced environmental impacts compared to conventional production technologies.  The objective of this master's thesis was to identify available production technologies for the materials involved in urea production, analyse different technological pathways and compare their environmental impacts and cost implications. The analysis considered several scenarios involving variations in the sources of electricity, methane gas and water used during the production process.  The analysis focused on Global Warming Potential (GWP), Primary Energy use (PE) and associated costs. The environmental analysis was conducted through a cradle-to-gate perspective based on a life-cycle impact assessment (LCIA). The cost analysis was based on a material flow cost accounting (MFCA).  The results for the green, hybrid and progressive technological pathways were benchmarked against the traditional pathway for urea production. The findings indicate that all these alternative pathways can reduce the GWP or PE values, which could be linked to the utilization of electricity sources with low GWP, such European and Swedish electricity mix, and the generation of by-products in the pathways However, within the context of the research assumptions, it was not possible to achieve a simultaneous reduction that included cost reductions alongside GWP and PE.  The study highlights the challenges of outperforming the efficiency levels of traditional technologies with other technological alternatives. Furthermore, it emphasizes the importance of carefully considering the integrations of the technologies and better utilization of residues and by-products exploring an integration of systems under an industrial symbiosis approach.  Finally, it is important to consider the trade-offs between environmental performance and cost when defining technological pathways for urea production.