Life cycle assessment of ammonia production from renewable energy
Nguyen, Ngoc Hong Linh (2025)
2025
Master's Programme in Environmental Engineering
Tekniikan ja luonnontieteiden tiedekunta - Faculty of Engineering and Natural Sciences
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Hyväksymispäivämäärä
2025-06-16
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202506147180
https://urn.fi/URN:NBN:fi:tuni-202506147180
Tiivistelmä
Mitigating climate change is one of the primary goals of many countries all over the world. A lot of efforts have been made to reduce anthropogenic greenhouse gas emissions, especially from manufacturing industries. Ammonia is an important synthesis chemical due to its essential use in producing fertilizer, which is extremely important to secure the global food supply. In addition, ammonia also has many applications in chemical industries. Currently, ammonia is mainly produced from natural gas. The production process is very energy-intensive and releases high CO2 emissions. Therefore, more sustainable production pathways are needed to decarbonize the ammonia industry.
Firstly, the thesis aimed to explore the legislative frameworks that incentivize the development of green ammonia in Europe and Estonia, where the case study is located. Secondly, a life cycle assessment (LCA) study was conducted for the green ammonia plant in Estonia to understand the environmental impacts of green ammonia production. The LCA results were used to analyze the environmental impacts of green ammonia production, as well as identify the most relevant impact categories linked with green ammonia production and the largest contributors to the total environmental impacts in the level of life cycle stages and single processes. The results of the thesis were compared with other studies on green ammonia production and conventional ammonia production via steam methane reforming to understand the relative magnitudes of the environmental impacts of the case study.
The main legislative frameworks affecting ammonia production in Europe are the Renewable Energy Directive and the two delegate acts supporting the Directive. The objectives and strategies set in the European Hydrogen Backbone initiative and ‘Estonia 2035’ are the motivations for developing a hydrogen supply chain in Estonia. Also, the Estonia Hydrogen Roadmap was created to guide the hydrogen development activities, which aimed to create an abundant and carbon free hydrogen industry in Estonia by 2050. As hydrogen is an input for ammonia production, the development of green hydrogen supply chain is very necessary to promote green ammonia development.
The environmental impacts of green ammonia production in Estonia were evaluated using the LCA method. It was shown that the green ammonia production system has the highest impacts on resource use (minerals and metals), resource use (fossils), climate change, human toxicity (cancer), human toxicity (non-cancer), and freshwater eutrophication. Throughout the life span of the plant, the electricity consumption for hydrogen production is the major source of environmental impacts. Solar electricity was found to have less environmental impacts than wind electricity in the electricity profile consisting of 25% solar and 75% wind power. In terms of the impacts on climate change, the production of 1 kg of ammonia was estimated to produce 0.925 kg CO2-eq to the environment. 80% of the emissions came from hydrogen production and 20% came from nitrogen production. Through the comparison with other studies on green ammonia in the literature, the environmental impacts of the case study on climate change and freshwater eutrophication are generally higher than other green ammonia systems. The reasons could be due to a more detailed inventory of the water electrolysis and the inclusion of a solar farm in the system boundary of the thesis. However, further analysis is needed to identify the actual causes of these high environmental impacts compared to other studies. Through comparison with other SMR-based systems, ammonia production from renewable energy is found to have a lower impact on climate change and a higher impact on freshwater eutrophication compared to ammonia production via SMR. These findings are aligned with some of the studies in the literature. In the future, the LCA model for the case study can be improved by using actual data from the plant and expanding the system boundary.
Firstly, the thesis aimed to explore the legislative frameworks that incentivize the development of green ammonia in Europe and Estonia, where the case study is located. Secondly, a life cycle assessment (LCA) study was conducted for the green ammonia plant in Estonia to understand the environmental impacts of green ammonia production. The LCA results were used to analyze the environmental impacts of green ammonia production, as well as identify the most relevant impact categories linked with green ammonia production and the largest contributors to the total environmental impacts in the level of life cycle stages and single processes. The results of the thesis were compared with other studies on green ammonia production and conventional ammonia production via steam methane reforming to understand the relative magnitudes of the environmental impacts of the case study.
The main legislative frameworks affecting ammonia production in Europe are the Renewable Energy Directive and the two delegate acts supporting the Directive. The objectives and strategies set in the European Hydrogen Backbone initiative and ‘Estonia 2035’ are the motivations for developing a hydrogen supply chain in Estonia. Also, the Estonia Hydrogen Roadmap was created to guide the hydrogen development activities, which aimed to create an abundant and carbon free hydrogen industry in Estonia by 2050. As hydrogen is an input for ammonia production, the development of green hydrogen supply chain is very necessary to promote green ammonia development.
The environmental impacts of green ammonia production in Estonia were evaluated using the LCA method. It was shown that the green ammonia production system has the highest impacts on resource use (minerals and metals), resource use (fossils), climate change, human toxicity (cancer), human toxicity (non-cancer), and freshwater eutrophication. Throughout the life span of the plant, the electricity consumption for hydrogen production is the major source of environmental impacts. Solar electricity was found to have less environmental impacts than wind electricity in the electricity profile consisting of 25% solar and 75% wind power. In terms of the impacts on climate change, the production of 1 kg of ammonia was estimated to produce 0.925 kg CO2-eq to the environment. 80% of the emissions came from hydrogen production and 20% came from nitrogen production. Through the comparison with other studies on green ammonia in the literature, the environmental impacts of the case study on climate change and freshwater eutrophication are generally higher than other green ammonia systems. The reasons could be due to a more detailed inventory of the water electrolysis and the inclusion of a solar farm in the system boundary of the thesis. However, further analysis is needed to identify the actual causes of these high environmental impacts compared to other studies. Through comparison with other SMR-based systems, ammonia production from renewable energy is found to have a lower impact on climate change and a higher impact on freshwater eutrophication compared to ammonia production via SMR. These findings are aligned with some of the studies in the literature. In the future, the LCA model for the case study can be improved by using actual data from the plant and expanding the system boundary.