Coupling biogas upgrading and carbon capture and utilization for enhanced environmental performance of water reclamation plants

Abstract

One of the primary sources of greenhouse gas (GHG) emissions in water reclamation plants is the anaerobic digestion process, which releases a significant amount of biogas. Today, wastewater treatment operators face immense pressure to find solutions that reduce the GHG emissions associated with this process. This paper proposes a conceptual design for a plant that couples biogas upgrading and carbon capture and utilization to mitigate GHG emissions from biogas release at a water reclamation facility in Singapore. A comprehensive model of the plant is first developed using a process simulation tool to assess its technical feasibility. Next, the plant’s economic and environmental implications are evaluated by calculating the net carbon abated, operating cost, and carbon abated cost. The results indicate that the plant has the potential to reduce GHG emissions by 84–90%, depending on the type of hydrogen used (gray, blue, or green). Although the plant exhibits a negative cash flow, its operating costs are lower than Singapore’s projected carbon tax rate in 2030, except in the scenario where green hydrogen is used. Overall, the study demonstrates the technical, economic, and environmental viability of the plant for reducing GHG emissions from water reclamation facilities.