Turning C1-gases to isobutanol towards great environmental and economic sustainability via innovative biological routes: two birds with one stone

• Published in: Biotechnology for biofuels 2022-10, Vol.15 (1), p.1-107, Article 107
• Main Authors: Liang, Bobo, Fu, Rongzhan, Ma, Yingqun, Hu, Lizhen, Fei, Qiang, Xing, Xin-Hui
• Format: Article
• Language: English
• Subjects: Bioconversion; Biogas; Biomass; Biomass energy; Biosynthesis; Butanol; C1-utilizing microbe; Capital costs; Carbon; Carbon dioxide; Case studies; Climate change; Cost analysis; Cyanobacteria; Decision making; Design specifications; Discounted cash flow; Economic analysis; Economic aspects; Emissions; Environmental aspects; Environmental impact; Feasibility; Gases; Genetic engineering; Greenhouse effect; Greenhouse gas; Greenhouse gases; Isobutanol; Mathematical analysis; Natural gas; Operating costs; Parameter sensitivity; Production management; Productivity; Sensitivity analysis; Simulation; Software; Substrates; Sustainability; Sustainable development; Techno-economic analysis
• ISSN: 2731-3654; 2731-3654; 1754-6834
• DOI: 10.1186/s13068-022-02202-1

The dramatic increase in greenhouse gas (GHG) emissions, which causes serious global environmental issues and severe climate changes, has become a global problem of concern in recent decades. Currently, native and/or non-native C1-utilizing microbes have been modified to be able to effectively convert C1-gases (biogas, natural gas, and CO.sub.2) into isobutanol via biological routes. Even though the current experimental results are satisfactory in lab-scale research, the techno-economic feasibility of C1 gas-derived isobutanol production at the industrial scale still needs to be analyzed and evaluated, which will be essential for the future industrialization of C1-gas bioconversion. Therefore, techno-economic analyses were conducted in this study with comparisons of capital cost (CAPEX), operating cost (OPEX), and minimum isobutanol selling price (MISP) derived from biogas (scenario #1), natural gas (scenario #2), and CO.sub.2 (scenario #3) with systematic economic assessment. By calculating capital investments and necessary expenses, the highest CAPEX ($317 MM) and OPEX ($67 MM) were projected in scenario #1 and scenario #2, respectively. Because of the lower CAPEX and OPEX from scenario #3, the results revealed that bioconversion of CO.sub.2 into isobutanol temporally exhibited the best economic performance with an MISP of $1.38/kg isobutanol. Furthermore, a single sensitivity analysis with nine different parameters was carried out for the production of CO.sub.2-derived isobutanol. The annual plant capacity, gas utilization rate, and substrate cost are the three most important economic-driving forces on the MISP of CO.sub.2-derived isobutanol. Finally, a multiple-point sensitivity analysis considering all five parameters simultaneously was performed using ideal targets, which presented the lowest MISP of $0.99/kg in a long-term case study. This study provides a comprehensive assessment of the bioconversion of C1-gases into isobutanol in terms of the bioprocess design, mass/energy calculation, capital investment, operating expense, sensitivity analysis, and minimum selling price. Compared with isobutanol derived from biogas and natural gas, the CO.sub.2-based isobutanol showed better economic feasibility. A market competitive isobutanol derived from CO.sub.2 is predicable with lower CO.sub.2 cost, better isobutanol titer, and higher annual capacity. This study will help researchers and decision-makers explore innovative and effective approaches to neutral