Carbon Footprint of Biomimetic Carbon Fixation by Immobilizing Nature’s CO2-sequestering Enzyme and Regenerating Its Energy Carrier

Abstract

In the Calvin cycle of photosynthesis, ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) catalyzes the conversion of ribulose 1,5-bisphosphate to 3-phosphoglyceric acid (3-PGA) while incorporating atmospheric CO2 into an organic molecule. Thus, RubisCO is nature’s CO2-sequestering enzyme that is present in chloroplasts. As an effort to mitigate climate change, biomimetic carbon fixation technologies have been developed through RubisCO immobilization into nanostructures to form nanostructure–RubisCO complexes. The technologies mimic the plant cellular environment’s ability to convert CO2 into higher-value products. In this work, a carbon footprint of 3-PGA produced through carbon fixation by the complexes is investigated using the LCA approach. Serine, an amino acid for pharmaceutical applications, is identified as a potential product from 3-PGA. Hotspot processes in terms of the carbon footprint are identified to suggest potential improvements for emerging technologies. Conducting LCA for emerging technologies has many challenges. A sensitivity analysis is performed for uncertain data, and the adenosine triphosphate (ATP) preparation process for the 3-PGA production is identified as a hotspot inventory. We identify that the carbon footprint to produce 3-PGA can be significantly lowered by integrating carbon fixation technologies with an electrochemical ATP regeneration technology.