Renewable Hydrogen Production and Storage Via Enzymatic Interconversion of CO₂ and Formate with Electrochemical Cofactor Regeneration

Abstract

The urgent need to reduce CO 2 emissions has motivated the development of CO 2 capture and utilization technologies. An emerging application is CO 2 transformation into storage chemicals for clean energy carriers. Formic acid (FA), a valuable product of CO 2 reduction, is an excellent hydrogen carrier. CO 2 conversion to FA, followed by H 2 release from FA, are conventionally chemically catalyzed. Biocatalysts offer a highly specific and less energy-intensive alternative. CO 2 conversion to formate is catalyzed by formate dehydrogenase (FDH), which usually requires a cofactor to function. Several FDHs have been incorporated in bioelectrochemical systems where formate is produced by the biocathode and the cofactor is electrochemically regenerated. H 2 production from formate is also catalyzed by several microorganisms possessing either formate hydrogenlyase or hydrogen-dependent CO 2 reductase complexes. Combination of these two processes can lead to a CO 2 -recycling cycle for H 2 production, storage, and release with potentially lower environmental impact than conventional methods.

Carbonic anhydrase assisted acidogenic fermentation of forest residues for low carbon hydrogen and volatile fatty acid production: enhancedin situCO2reduction and microbiological analysis

“…26,27 As such, CA has the potential to mitigate CO 2 levels in bioconversion processes resulting in elevated levels of CO 2 uptake by the microbes or enzymes and providing a viable carbon supply for the production of high-added value products, such as biofuels and chemicals. [28][29][30][31] In a study pertaining to ethanol fermentation, the use of CA in situ during fermentation was found to enhance the production of ethanol by 20%. 28 In the present study, we evaluated the effect of supplementation of CA derived from Desulfovibrio vulgaris to the acidogenic fermentation process towards biohydrogen and volatile fatty acids production from forest residue hydrolysates derived through stem explosion pretreatment.…”

“…26,27 As such, CA has the potential to mitigate CO 2 levels in bioconversion processes resulting in elevated levels of CO 2 uptake by the microbes or enzymes and providing a viable carbon supply for the production of high-added value products, such as biofuels and chemicals. 28–31 In a study pertaining to ethanol fermentation, the use of CA in situ during fermentation was found to enhance the production of ethanol by 20%. 28…”

Enzyme-accelerated CO2 capture and storage (CCS) using paper and pulp residues as co-sequestrating agents

“…where M is a metal, such as Ca or Mg. Carbonic anhydrase (CA) is a metalloenzyme that catalyzes the limiting step in mineral weathering (CO 2 hydration reaction (eqn (1))). It is one of the fastest existing enzymes with a turnover rate up to 10 7 s −1 , and has demonstrated potential for enhancing the yield in carbon capture, utilization, and storage (CCUS) applications, [14][15][16] and also in accelerating the weathering of carbonates. [17][18][19] Therefore, CA utilization could bring about enhanced mineral dissolution and a higher productivity of bicarbonates, which could then be converted further into a thermodynamically stable form (i.e., mineral carbonation).…”