Journal of Natural Sciences

Options to dissociate CO2 and H2O for sustainable sunlight-to-fuel pathways: Comparative assessment of current R&D hurdles and future potential
Christoph J. Meinrenken, Klaus S. Lackner

Abstract
The IPCC's 5th assessment report has heightened the urgency of steep reductions in atmospheric CO₂ concentrations. The transportation sectorcontributes 22% of global CO₂ emissions from fuel combustion. Solar-to-fuel technologies thus offer tremendous potential to contribute significantly to such reductions. Engineering offers a multitude of pathways to produce liquid hydrocarbon fuels starting from CO₂ and H₂O. In these pathways, downstream processes such as fuel synthesis are generally well understood and often commercially available. In contrast, upstream processes such as the dissociation of CO₂ and H₂O are usually less mature (exception: low temperature water electrolysis). Here, we first analyze recent research on various CO₂ and H₂O dissociation technologies and then assess their future potential to be used at scale. The dissociation technologies range from thermolysis, to thermochemical cycling, low and high temperature electrolysis, photo-electro-chemical splitting, and artificial photosynthesis. In addition to the state-of-the-art of thesetechnologies, we compare their inherent disadvantages and advantages as well as key future R&D requirements. For completion, other steps of the pathways, namely CO₂ capture, providing water, and fuel synthesis, are addressedbriefly as well. We conclude with a discussion of the relative future potential of the various pathways and an R&D outlook.

Full Text: PDF     DOI: 10.15640/jns.v2n2a2