Theoretical Hybrid Photosynthesis Models: Thermodynamic and Rate Consequences.

Abstract

With increasing concerns about climate change due to the greenhouse effect due to the rise in CO2 levels attributed to anthropogenic activities, it is crucial that we find solutions that reduce CO2 levels in the atmosphere. Hybrid photosynthesis combines harnessing of solar energy in photovoltaics more efficient than biological systems are capable of and the flexibility of biological systems that allow for selective biosynthesis of highly concatenated compounds. Four different means of integrating abiotic and biotic systems to mimic photosynthesis were investigated from rate and thermodynamic perspectives, and the consequences in favoring one aspect over the other. It is generally found that hybrid photosynthesis shows the greatest thermionic efficiency with H2- mediated hybrid photosynthesis, with the efficiency of a two-step H2-mediated hybrid photosynthesis dependent on the initial CO2 fixation potential. EET-mediated synthetic schemes usually show lower thermionic efficiencies than H2-mediated synthetic schemes, but may benefit from being able to practicably be concentrated in a comparatively smaller cross-sectional area at a comparative small cost in thermionic efficiencies. There are methods to improve EET-mediated transfers to reduce the thermionic efficiency losses resulting in favoring spatial convenience of the experimental set-up, and methods of making H2-mediated hybrid photosynthesis spatially less challenging are possible through increasing the flux through the reaction.