Achieving decarbonization considering green hydrogen production: Case study of Oman

Abstract

Life Cycle Assessment (LCA) method is employed to study and mitigate negative environmental impacts using various approaches via OpenLCA software. This paper investigates the LCA of green hydrogen gas production from produced water in Oman, using the Activated Sludge Method (ASM) and Fluidized-Bed Bioreactor (FBB), as treatment technologies. Different scenarios were considered, utilizing the ReCiPe midpoint impact method over 100 years, to evaluate global warming potential (GWP100), fossil depletion potential (FDP), and water depletion (WDP). The objective is to compare and evaluate the sustainability of Dark Fermentation (DF) and Electrolysis methods for hydrogen gas production from both treatment technologies to achieve Oman's Vision 2040. The DF method involves utilizing sludge from both primary and secondary treatment stages, while the Electrolysis method uses the tertiary treatment stage. Results show that using 50 % (15,000 m³/day) of the flow for hydrogen production, the DF yields 60,000 kg of H2/day, while the electrolysis method produces 833,333 kg of H2/day. This difference arises because the DF method depends on sludge production, impacting hydrogen gas production, whereas, the electrolysis method relies entirely on treated water. Both processes significantly impact GWP100. Incorporating solar power for ASM and FBB, as a green energy source, reduces CO2 emissions by 7560.28 kg CO2-eq for DF and 8245.18 kg CO2-eq for electrolysis. This study provides a novelty application, which contributes to advancing sustainability practices through evaluating the environmental impacts of using produced water for green hydrogen production in waste-to-energy and advocates for energy policy making regarding recent climate change commitments.

Keywords

• Sustainable hydrogen production
• Greenhouse gas emission minimization
• Produced water management
• Life cycle assessment
• Dark fermentation
• Electrolysis method