Analyzing the carbon footprint and energy usage of producing alternative nitrogen fertilizers in the Swedish context : A factor-based scenario analysis conducted comparing Swedish and European urea production

Sammanfattning

Sweden aims to become independent in nitrogen fertilizer production after the international market proved volatile under the Russian invasion of Ukraine. Domestic organic recycling of nitrogen-based fertilizers is insufficient, and new domestic mineral fertilizer production is required to meet demand. The world also faces a climate crisis, and Sweden is working to reduce its climate impact. Knowledge of Nitrogen-Based Mineral Fertilizer (NBMF) production and the factors affecting its environmental performance is limited in Sweden, which lacks domestic production. The objective of this master’s thesis is therefore to provide broad insight for Swedish decision-makers regarding possible variations in urea production, the most common NBMF. To achieve that insight, the study aims to identify key factors shaping urea production’s environmental and energy performance across varying Swedish and European conditions, and with it answer whether Sweden offers climate benefits compared to continued European imports. This study conducts a Life Cycle Assessment of urea production, with the functional unit of 1 tonne of urea ready for market, produced in generalized locations in Sweden and Europe, which are the two options in the factor Geographical location. Inquired data reflect industry production and are aggregated into a mass and energy flow audit in a Python program, which also uses assessment data from the Ecoinvent3 database to estimate greenhouse gas emissions and primary energy usage. Potential key factors are identified using an uncertainty identification guide and then filtered for relevance, scope, and impact on the basic Python model (meaning without considering other factors). The chosen subset of factors is then implemented to form the factor-based scenario analysis, structured based on the Design of Experiments. The study´s findings are presented in a table of potential key factors affecting the environmental performance of urea production. All factors listed are estimated in the factor-based scenario analysis to create 36 distinct scenarios or are provided as rough estimates. Additional renewable input flows shift material and energy inputs to the best-performing renewable option from an environmental and energy perspective. It is the most prominent factor that reduces greenhouse gas emissions by an estimated 83% and 91% under Swedish and European conditions, respectively. The same factor also reduces primary energy usage by an estimated 37% and 48% under Swedish and European conditions, respectively. In addition, it has a consistent and significant impact across all scenarios. Geographical location also affects greenhouse gas emissions and primary energy, with Swedish conditions emitting 50% ± 10% greenhouse gases than similar European conditions in 2/3 of the scenarios. The geographical difference diminishes and eventually disappears as the share of Additional renewable input flows increases. Other factors have a rough estimate of their impact on normal Swedish and European conditions, as executed and discussed. The discussion addresses the knowledge gap regarding the impact of general factors on urea production. The validity of the study´s results is discussed, why the conclusions are trustworthy, and what the uncertainties can and cannot affect. The conclusion is that 16 factors affecting urea production are identified, however, it is challenging to determine which factors significantly affect the environmental performance of urea. However, Additional renewable input flows and Geographical location are identified as critical factors, with Additional renewable input flows as the most important factor in reducing greenhouse gas emissions and primary energy usage. Construction of domestic urea production is in line with Sweden's goals of fertilizer independence and reduced climate impact.