Tropical frog inspires new way to convert solar energy to biofuel

Natural photosynthesis isn't as efficient as we would like it to be, and incorporating solar energy into useful products is the subject for much collective research. Engineering researchers from University of Cincinnati have found a way to artificially create a photosynthetic material from foam which uses plant, bacterial, frog and fungal enzymes to produce sugars from sunlight and carbon dioxide.

Back to grade nine biology: natural photosynthesis takes carbon from the air, sugars from the soil. and using energy from the sun converts them to sugar for the plant and oxygen for Earth's atmosphere. This system is exactly the same, but uses enzymes encased in foam to carry out photosynthesis and uses the sugars produced to make ethanols and other biofuels.

The advantage to this method is that all of the captured solar energy is converted to sugars, unlike natural organisms who must use a large proportion of the sun's energy to maintain life functions. Additionally, the foam does not need soil to photosynthesize, unlike plants, and therefore does not require valuable space that could be used for food production. Furthermore, in natural plant systems, photosynthesis shuts down in the presence of highly-enriched carbon dioxide environments, but the foam is not limited by this due to its bacterial-based photo-capture strategy.

The design was inspired by the foam nests of a semi-tropical frog called the Tungara frog, which creates long-lived foams for its developing tadpoles. Foam allows effective concentration of reactants, but also allows for good light and air penetration.

While other methods that use sunlight to split water to oxygen and hydrogen are in development, this approach could prove more efficient and economical in harnessing the physiology of living systems, working with nature and not against it.

“Specifically in this work it presents a new pathway of harvesting solar energy to produce either oil or food with efficiencies that exceed other biosolar production methodologies. More broadly it establishes a mechanism for incorporating the functionality found in living systems into systems that we engineer and build," says Dean Montemagno, Dean of College of Engineering and Applied Science whose Department of Biomedical Engineering lab provided the basis for the research.

The paper, additionally co-authored by research assistant Professor David Wendell and student Jacob Todd was published online in “Artificial Photosynthesis in Ranaspumin-2 Based Foam” (March 5, 2010) in the journal Nano Letters. The next stage for the team will be to look into other short carbon molecules they can make by altering the enzyme cocktail, and developing a strategy to extract both the lipid shell of the algae (used for biodiesel) and the cytoplasmic contents (the guts), and reusing these proteins in the foam. It's hoped this will make the technology feasible for large-scale applications like carbon capture at coal-burning plants.

Via University of Cincinnati.