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Techno-economic assessment of converting CO2 and H2 into e-methane through biological process
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School of Chemical Engineering |
Master's thesis
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en
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102
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The global effort to reduce climate change has increased the search for sustainable technologies that can reduce greenhouse gas emissions, particularly carbon dioxide (CO₂). One promising approach is to utilize renewable hydrogen (H₂) and CO₂ to produce synthetic methane (e-methane). Among the various methanation pathways, biological methanation presents an attractive alternative due to its mild operating conditions, tolerance to gas impurities, and potential compatibility with circular bioeconomy systems. However, the scalability and economic viability of biological methanation at the industrial level remain underexplored.
This thesis focuses on evaluating the technical feasibility and economic viability of large-scale biological methanation, comparing it with other renewable and conventional methane production methods. The study begins with a comprehensive literature review comparing chemical, biological, and bio electrochemical methanation technologies. The focus is placed on the hydrogenotrophic methanation pathway, in which methanogenic archaea convert CO₂ and H₂ into methane under thermophilic conditions. Detailed process design, reactor configurations, and mass balance calculations are performed, followed by simulations using ASPEN Plus software. The economic analysis includes the estimation of fixed capital investment (CAPEX), operational costs (OPEX), and net present value (NPV).
The findings indicate that while biological methanation offers a potential viable pathway for sustainable methane production, it faces significant challenges such as low hydrogen solubility and large reactor volumes. An innovative multi-tubular reactor design is proposed to address these challenges by optimizing gas-liquid mass transfer and microbial activity. However, the total capital investment and operational costs remain substantial. Compared to catalytic methanation and fossil-based methane, the biological pathway is currently less economically competitive, with a higher cost of methane production. This thesis contributes to the advancement of sustainable chemical production methods and supports decision-making for future technology development investments.
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Oinas, PekkaThesis advisor
Kajaste-Rudnitskaja, RailiScheller, Silvan