The front cover artwork for Issue 01/2014 is provided by the research group of Nano-Bioengineering at the Department of Applied Physics, Osaka University (Japan). The image illustrates the concept of using gold nanoparticle-decorated carbon nanotubes to directly electrochemically oxidize brown macroalgae derived-alginate into valuable chemicals and simultaneously extract bioenergy. Read the full text of the article on page 135.
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What prompted you to investigate this topic/problem?
12345Currently, lignocellulosic biomass such as corn and sugarcane are being exploited as renewable energy and chemical resources. The “food-versus-fuel” paradox has, however, sparked significant controversy over their future availability and applicability. Therefore, we have targeted inedible brown macroalgae since they require no fresh water, fertilizer, or arable land and do not interfere with the human food chain. To realize the establishment of brown macroalgae in biorefineries, we work in a research team of the CREST project with other groups who are in search of an appropriate microbial platform that can convert the algae’s sugars to ethanol. Among those sugars, alginate, which accounts for about a third of them, remains a formidable challenge despite the huge investments into genetic engineering processes. To solve this obstacle, we sought to extract energy and valuable chemicals from macroalgae through a fuel cell system that exploits the direct electrochemical oxidation of alginate by gold nanoparticle-decorated functionalized carbon nanotubes, without any external input of energy.
What future opportunities do you see?
Obviously, there is no perfect solution to the search for renewable energy and chemical resources. Although macroalgae have, in principle, huge potential to become the next biofuel, their future is not yet realized as its primary sugar, alginate, is not easily fermented. In addition to traditional genetic engineering approaches, our direct oxidation approach based on designed catalytic systems has provided strong evidence to the capability of macroalgae as cost-effective and renewable sources of biomass. We hope that our preliminary result will attract more catalysis scientists to explore this field as extensively as that of lignocellulosic biomass. Further research could be devoted to the development of inexpensive catalysts by using abundant transition metals.
This work is financially supported by JST, CREST. We are grateful to our colleagues at Osaka University and to our collaborators for stimulating and insightful discussions.