Joule says it has improved the photosynthetic efficiency of its engineered cyanobacteria by nearly 100%
At the 2014 Society for Industrial Microbiology and Biotechnology (SIMB) Annual Meeting in St. Louis, Missouri, Joule reported that its has improved the overall photosynthetic efficiency of its engineered cyanobacteria by nearly 100%, and estimates a maximum 14% energy conversion efficiency in its biomass-to-fuels process. (Joule has developed a direct, single-step, continuous process for the production of solar hydrocarbon fuels earlier post).
Prior research has generally capped the photon energy conversion efficiency of photosynthetic processes at 2 – 3%. This was based on observations of photosynthesis in nature, where it encounters its two significant drains of useful energy—photorespiration and photoinhibition. These conditions prevent the optimal use of CO2 and light, and cannot be regulated in open outdoor environments, Joule noted.
By contrast, Joule has applied a systems approach that spans biocatalyst, reactor and process engineering to negate the effects of these conditions, resulting in many-fold greater energy conversion efficiencies and supporting Joule’s estimated process maximum of 14%.
The engineered biocatalysts are able to divert 95% of fixed carbon normally converted to biomass directly to fuel.
Joule presented at the SIMB Annual Meeting during a session on the metabolic engineering of photosynthetic microbes. Using a variety of techniques to genomically engineer these microbes, Joule has changed the products of this natural process into fuel molecules, including ethanol and diesel.