PhD, EngD and MSc by research theses (SWEE)

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Browsing PhD, EngD and MSc by research theses (SWEE) by Publisher "Elsevier"

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    A novel integration of a green power-to-ammonia to power system: reversible solid oxide fuel cell for hydrogen and power production coupled with an ammonia synthesis unit
    (Elsevier, 2021-03-31) Mukelabai, Mulako Dean; Gillard, Jonathon M.; Patchigolla, Kumar
    Renewable energy is a key solution in maintaining global warming below 2 °C. However, its intermittency necessitates the need for energy conversion technologies to meet demand when there are insufficient renewable energy resources. This study aims to tackle these challenges by thermo-electrochemical modelling and simulation of a reversible solid oxide fuel cell (RSOFC) and integration with the Haber Bosch process. The novelty of the proposed system is usage of nitrogen-rich fuel electrode exhaust gas for ammonia synthesis during fuel cell mode, which is usually combusted to prevent release of highly flammable hydrogen into the environment. RSOFC round-trip efficiencies of 41–53% have been attained when producing excess ammonia (144 kg NH3/hr) for the market and in-house consumption respectively. The designed system has the lowest reported ammonia electricity consumption of 6.4–8.21 kWh/kg NH3, power-to-hydrogen, power-to-ammonia, and power-generation efficiencies of 80%, 55–71% and, 64–66%.
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    The value of manure - Manure as co-product in life cycle assessment
    (Elsevier, 2019-04-19) Leip, Adrian; Ledgard, Stewart; Uwizeye, Aimable; Palhares, Julio C.P.; Fernanda Aller, M.; Amon, Barbara; Binder, Michael; Cordovil, Claudia M.d.S.; De Camillis, Camillo; Dong, Hongming; Fusi, Alessandra; Helin, Janne; Hörtenhuber, Stefan; Hristov, Alexander N.; Koelsch, Richard; Liu, Chunjiang; Masso, Cargele; Nkongolo, Nsalambi V.; Wang, Ying
    Livestock production is important for food security, nutrition, and landscape maintenance, but it is associated with several environmental impacts. To assess the risk and benefits arising from livestock production, transparent and robust indicators are required, such as those offered by life cycle assessment. A central question in such approaches is how environmental burden is allocated to livestock products and to manure that is re-used for agricultural production. To incentivize sustainable use of manure, it should be considered as a co-product as long as it is not disposed of, or wasted, or applied in excess of crop nutrient needs, in which case it should be treated as a waste. This paper proposes a theoretical approach to define nutrient requirements based on nutrient response curves to economic and physical optima and a pragmatic approach based on crop nutrient yield adjusted for nutrient losses to atmosphere and water. Allocation of environmental burden to manure and other livestock products is then based on the nutrient value from manure for crop production using the price of fertilizer nutrients. We illustrate and discuss the proposed method with two case studies.