Techno-economic and environmental assessments of implementable wastewater-to-hydrogen production technologies: Pathway towards circular hydrogen economy in South Korea

The Korean government has highlighted hydrogen (H₂) utilization in various sectors to substitute fossil-fired energy resources. However, H₂ production has relied on it as a byproduct from the petrochemical industry, yet; sustainable hydrogen production methods should be developed for the clean energy transition. This study aims to examine implementable wastewater-to- H₂ production technologies via biogas from anaerobic digestion (AD) in wastewater treatment plant (WWTP) based on techno-economic assessment (TEA) and life-cycle assessment (LCA). Various H₂ production pathways combining biogas upgradation, hydrogen production, and carbon capturing systems were compared to search sustainable pathway towards a circular hydrogen economy in South Korea. Then nationwide supply and demand scenario through 2050 was analyzed based on the wastewater big dataset from more than 3000 WWTPs in South Korea. The results verified that BUS-TRMre-CCU (Tri-reforming of methane with flue gas recycling, biogas upgrading system, and carbon capturing unit) was assessed as the best candidate for wastewater-to-H₂ production because it can produce the hydrogen as 4.49 $/kg H₂ and GHG potential of 8.14 kgCO₂-eq/kgH₂. This H₂ production pathway has competitiveness compared to conventional off-site H₂ production due to on-site H₂ production in WWTPs across South Korea. In alignment with strict action towards a circular hydrogen economy, this research indicated that the BUS-TRMre-CCU can be practically implemented to accelerate the hydrogen economy by covering regional H₂ demand as on-site H₂ supply across South Korea.