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[Due to the increasing size of the archives, each topic page now contains only the prior 365 days of content. Access to older stories is now solely through the Monthly Archive pages or the site search function.]
Bio-Platinum Hybrid Catalyst for Solar Hydrogen Production Can Deliver Up to 25x Greater Energy Yield Than Current Biomass-to-Fuel Strategies
November 11, 2009
| Schematic of the electron flow in the photosystem I catalytic nanoparticle. Source: Iwuchukwu et al., Nature Nanotechnology. Click to enlarge. |
Researchers at the University of Tennessee at Knoxville have shown that a combination of photosystem I from a thermophilic bacterium and cytochrome-c6 can, in combination with a platinum catalyst, generate a stable supply of hydrogen in vitro upon illumination. A paper on their work was published online 8 November in the journal Nature Nanotechnology.
The system produces hydrogen at temperatures up to 55 °C (131 °F) and is temporally stable for >85 days with no decrease in hydrogen yield when tested intermittently. The maximum yield is ~5.5 mmol H2 h-1 mg-1 chlorophyll and is estimated to be ~25-fold greater than current biomass-to-fuel strategies. If scaled linearly, a solar collector 1 acre in size with a solution depth of 10 cm operating at 55 °C would be capable of producing hydrogen with an energy yield equivalent to that of 300 litres of gasoline per hectare per day (gross yield, ignoring production separation and distribution energy costs).
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Researchers Discover How Oxygen Attacks Hydrogen-Producing Enzymes in Photosynthetic Organisms; Insight Could Assist Identification of New Pathways for Bio-Hydrogen Production
September 29, 2009
An international team of scientists from the UK, Germany and France have discovered how oxygen stops photosynthetic organisms such as green algae from producing hydrogen. The findings could help advance development of the microbial production of hydrogen from sunlight and water. They reported their results in two papers, one last week in the Journal of the American Chemical Society and one in the Proceedings of the National Academy of Sciences, published this week.
One promising approach to the renewable production of hydrogen is the use of microorganisms. Enzymes called hydrogenases are responsible for evolving hydrogen in biological processes ranging from fermentation to photosynthesis. There are two main classes of hydrogenases: nickel-iron [NiFE]- and iron-iron [FeFe]-. These are highly efficient enzymes, and have been shown to function as superb electrocatalysts of hydrogen oxidation and production. However, the [FeFe]-hydrogenases, considered the most active in hydrogen production, are irreparably damaged when exposed to oxygen.
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Chinese Researchers Show Enhanced Hydrogen Production from Corn Stover by Anaerobic Fermentation
June 26, 2009
Researchers at Zhengzhou University, China, have shown the enhanced production of hydrogen from pretreated corn stalk biomass by mixed culture using manure from the lesser panda as the source of the hydrogen-producing bacteria. The study is reported in Issue 54 (8)the Chinese Science Bulletin, a journal co-sponsored by the Chinese Academy of Sciences and the National Natural Science Foundation of China. The annual yield of natural cellulosic biomass in China exceeds 0.7 billion tons, in which the amount of corn stalk is around 220 million tons.
The maximum cumulative H2 yield of 176 ml/g-TS (total solids) and H2 production rate (14.5 ml/g-TS h-1) were obtained at pH 5.5, 36 °C by treating a substrate of 15 g/L. The hydrogen content in the resultant biogas was 57.2% and there was no significant methane gas observed.
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Enzymatic Process Converts Cellulosic Materials and Water into Hydrogen at Low Temperature; Close to Theoretical Yield of H2 From Glucose
February 17, 2009
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| Hydrogen production from cellodextrin and water by a synthetic enzymatic pathway. Ye et al. (2009) Click to enlarge. |
Researchers at Virginia Tech, Oak Ridge National Laboratory (ORNL), and the University of Georgia have produced hydrogen gas in a spontaneous, “one-pot” process using an enzyme cocktail, cellulosic materials from non-food sources, and water. The hydrogen yield was 11.2 moles per mole of anhydroglucose unit of cellobiose, corresponding to 93.3% of the theoretical yield of 12 moles. A paper on the work was published online in the journal ChemSusChem on 2 February.
In 2007, the researchers had reported the development of a novel method using a combination of 13 enzymes to form an unnatural enzymatic pathway to completely convert starch and water in one reactor into hydrogen. (Earlier post.)
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DOE Awards $1.75M for Hydrogen and Ethanol from Cellulosic Biomass Project
November 13, 2008
The US Department of Energy (DOE) has awarded University of Rochester Professor David Wu a $1.75 million grant to investigate a way to turn waste biomass, such as grass clippings, cornstalks, and wood chips, into usable hydrogen or ethanol.
Wu has been studying Clostridium thermocellum—an anaerobic, thermophilic, cellulolytic, and ethanologenic bacterium. (Earlier post.) Coupled with its preference to grow at high temperature, the microorganism promises distinct advantages as a candidate for developing industrial hydrogen and ethanol production processes from cellulosic biomass.
