Abstract
The chemical industry must decarbonize to align with UN Sustainable Development Goals. A shift toward circular economies makes CO(2) an attractive feedstock for producing chemicals, provided renewable H(2) is available through technologies such as supercritical water (scH(2)O) gasification. Furthermore, high carbon and energy efficiency is paramount to favorable techno-economics, which poses a challenge to chemo-catalysis. This study demonstrates continuous gas fermentation of CO(2) and H(2) by the cell factory, Cupriavidus necator, to (R,R)-2,3-butanediol and isopropanol as case studies. Although a high carbon efficiency of 0.75 [(C-mol product)/(C-mol CO(2))] is exemplified, the poor energy efficiency of biological CO(2) fixation requires ∼8 [(mol H(2))/(mol CO(2))], which is techno-economically infeasible for producing commodity chemicals. Heat integration between exothermic gas fermentation and endothermic scH(2)O gasification overcomes this energy inefficiency. This study unlocks the promise of sustainable manufacturing using renewable feedstocks by combining the carbon efficiency of bio-catalysis with energy efficiency enforced through process engineering.