Scholarly Works, Biological Systems Engineering
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Browsing Scholarly Works, Biological Systems Engineering by Author "Adams, Michael W. W."
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- Advances in Biochemical Engineering-BiotechnologyZhang, Y. H. Percival; Rollin, Joseph A.; Ye, Xinhao; Del Campo, Julia S. Martin; Adams, Michael W. W. (Springer, 2014-07-15)In vitro hydrogen generation represents a clear opportunity for novel bioreactor and system design. Hydrogen, already a globally important commodity chemical, has the potential to become the dominant transportation fuel of the future. Technologies such as in vitro synthetic pathway biotransformation (SyPaB)—the use of more than 10 purified enzymes to catalyze unnatural catabolic pathways—enable the storage of hydrogen in the form of carbohydrates. Biohydrogen production from local carbohydrate resources offers a solution to the most pressing challenges to vehicular and bioenergy uses: small-size distributed production, minimization of CO2 emissions, and potential low cost, driven by high yield and volumetric productivity. In this study, we introduce a novel bioreactor that provides the oxygen-free gas phase necessary for enzymatic hydrogen generation while regulating temperature and reactor volume. A variety of techniques are currently used for laboratory detection of biohydrogen, but the most information is provided by a continuous low-cost hydrogen sensor. Most such systems currently use electrolysis for calibration; here an alternative method, flow calibration, is introduced. This system is further demonstrated here with the conversion of glucose to hydrogen at a high rate, and the production of hydrogen from glucose 6-phosphate at a greatly increased reaction rate, 157 mmol/L/h at 60 [degrees] C.
- High-Yield Hydrogen Production from Starch and Water by a Synthetic Enzymatic PathwayZhang, Y. H. Percival; Evans, Barbara R.; Mielenz, Jonathan R.; Hopkins, Robert C.; Adams, Michael W. W. (2007-05-23)Background. The future hydrogen economy offers a compelling energy vision, but there are four main obstacles: hydrogen production, storage, and distribution, as well as fuel cells. Hydrogen production from inexpensive abundant renewable biomass can produce cheaper hydrogen, decrease reliance on fossil fuels, and achieve zero net greenhouse gas emissions, but current chemical and biological means suffer from low hydrogen yields and/or severe reaction conditions. Methodology/Principal Findings. Here we demonstrate a synthetic enzymatic pathway consisting of 13 enzymes for producing hydrogen from starch and water. The stoichiometric reaction is C₆H₁₀O₅ (l)+7 H₂O (l)-> 12 H₂ (g)+ 6 CO₂ (g). The overall process is spontaneous and unidirectional because of a negative Gibbs free energy and separation of the gaseous products with the aqueous reactants. Conclusions. Enzymatic hydrogen production from starch and water mediated by 13 enzymes occurred at 30 degrees C as expected, and the hydrogen yields were much higher than the theoretical limit (4 H(2)/glucose) of anaerobic fermentations. Significance. The unique features, such as mild reaction conditions (30 degrees C and atmospheric pressure), high hydrogen yields, likely low production costs ($~ to 2/kg H₂), and a high energy-density carrier starch (14.8 H₂-based mass%), provide great potential for mobile applications. With technology improvements and integration with fuel cells, this technology also solves the challenges associated with hydrogen storage, distribution, and infrastructure in the hydrogen economy.