title: Efficient solar-to-fuels production from a hybrid microbial-water-splitting catalyst system.
abstract: Photovoltaic cells have considerable potential to satisfy future renewable-energy needs, but efficient and scalable methods of storing the intermittent electricity they produce are required for the large-scale implementation of solar energy. Current solar-to-fuels storage cycles based on water splitting produce hydrogen and oxygen, which are attractive fuels in principle but confront practical limitations from the current energy infrastructure that is based on liquid fuels. In this work, we report the development of a scalable, integrated bioelectrochemical system in which the bacterium Ralstonia eutropha is used to efficiently convert CO2, along with H2 and O2 produced from water splitting, into biomass and fusel alcohols. Water-splitting catalysis was performed using catalysts that are made of earth-abundant metals and enable low overpotential water splitting. In this integrated setup, equivalent solar-to-biomass yields of up to 3.2% of the thermodynamic maximum exceed that of most terrestrial plants. Moreover, engineering of R. eutropha enabled production of the fusel alcohol isopropanol at up to 216 mg/L, the highest bioelectrochemical fuel yield yet reported by >300%. This work demonstrates that catalysts of biotic and abiotic origin can be interfaced to achieve challenging chemical energy-to-fuels transformations.
authors: Department of Systems Biology, Harvard Medical School, Boston, MA 02115;
authors: Joseph P
authors: JP
authors: Torella
authors: Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138; and.
authors: Christopher J
authors: CJ
authors: Gagliardi
authors: Department of Systems Biology, Harvard Medical School, Boston, MA 02115;
authors: Janice S
authors: JS
authors: Chen
authors: Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138; and.
authors: D Kwabena
authors: DK
authors: Bediako
authors: Department of Systems Biology, Harvard Medical School, Boston, MA 02115;
authors: Brendan
authors: B
authors: Colón
authors: Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115.
authors: Jeffery C
authors: JC
authors: Way
authors: Department of Systems Biology, Harvard Medical School, Boston, MA 02115;
authors: Pamela A
authors: PA
authors: Silver
authors: Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138; and dnocera@fas.harvard.edu.
authors: Daniel G
authors: DG
authors: Nocera
mesh_terms: D000438:Alcohols; D001674:Bioelectric Energy Sources / Q000382:microbiology*; D056804:Biofuels / Q000382:microbiology*; D019149:Bioreactors / Q000382:microbiology; D002374:Catalase / Q000494:pharmacology; D002384:Catalysis; D020118:Cupriavidus necator / Q000166:cytology / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D004566:Electrodes; D005818:Genetic Engineering; D050296:Microbial Viability / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D012993:Solar Energy; D014867:Water
chemical_list: D000438:Alcohols; D056804:Biofuels; D017382:Reactive Oxygen Species; D014867:Water; C007807:fusel oil; D002374:Catalase
keywords: Ralstonia; bioelectrochemistry; biofuel; isopropanol; renewable energy