Exploratory Efforts 2009
Efficient Cell-Free Hydrogen Production from Glucose
James Swartz, Chemical Engineering and of Bioengineering, Stanford University
The major goal of this exploratory project is to achieve efficient hydrogen production from glucose derived from cellulosic hydrolysates using a cell-free technology based on enzymes made in E. coli. The expression of hydrogen producing enzymes will be induced in densely grown and specially engineered E.coli cells. The unique features that will be engineered into the E.coli will increase hydrogen production yields and rates compared to reported methods. The concentrations of cofactors such as nicotinamide adenine dinucleotide phosphate (NADP) and enzymes of the electron transport chain will be adjusted to direct reactions towards the production of hydrogen. The flow of glucose into the glycolysis breakdown pathway will be blocked using an inhibitor making more of it available for hydrogen production. With these adjustments, this cell-free technology will allow precise control over metabolic fluxes having the potential of reaching a production level of 8 mmoles hydrogen per mole of glucose at a rate of 3 mmoles hydrogen/gram of cells/hour, higher than any system has reportedly achieved to date.
Carbon-ion Conducting Thin Film Membranes Towards Efficient CO2 Separation
Fritz Prinz, Mechanical Engineering; Turgut Gur, Materials Science and Engineering, Stanford University
Thin-film membrane materials that selectively transport carbon ions through electrochemical means may create a method of capturing and separating CO2 in a single process step. This project will identify, design, dope, fabricate, and screen ion-conducting carbide materials and demonstrate selective transport of carbon ions through a dense nonporous membrane. When a direct current bias is applied across the carbide-membrane material, it provides extremely steep gradients of virtual pressure. This gradient combined with an ultra-thin membrane can yield high fluxes practical for CO2 capture and separation at a large scale, such as in flue gas streams of coal-fired power plants.
Fundamental Studies of Plasma Air Separation
Mark Cappelli, Mechanical Engineering, Stanford University
This research explores the use of an atmospheric-pressure dielectric plasma discharge to enrich an air flow with oxygen, with the ultimate goal of providing a novel low-cost technology for air separation. This work will lead to better understanding of the fundamental challenges that need to be addressed to generate negatively charged oxygen ions in such a plasma configuration and to effectively separate oxygen by having the plasma impart momentum to the neutral air molecules. Results from this project will provide the scientific basis necessary to assess the feasibility of this air separation technology.
High Capacity Molecular Hydrogen Storage in Novel Crystalline Solids
Wendy Mao, Geological and Environmental Sciences, Stanford University
A major barrier to the use of hydrogen as an energy carrier is finding a practical hydrogen storage material for mobile applications. Extreme environments provide a broader space to search for phases with desirable properties. For example, one promising compound discovered at high pressure is tetrahydrogen-methane (CH4(H2)4), which contains 33.4 wt% molecular hydrogen, not including the hydrogen in the methane itself. This exploratory activity uses a closely coupled experimental and theoretical approach to identify several promising hydrogen-rich, crystalline solids, determine their structures, and then attempt to stabilize these phases near ambient conditions (e.g. by the addition of chemical promoters). The goal of this effort is to ultimately provide guidance in developing improved hydrogen storage materials.
Next Generation High-Efficiency Low-Cost Thin Film Photovoltaics
May 2009 - April 2011
Bruce Clemens and Alberto Salleo, Materials Science and Engineering, Stanford University
This research investigates ion-beam assisted deposition (IBAD) of textured templates that can be used to make efficient crystalline-Si thin-film solar cells. The idea behind this approach is that ion beams can be used to selectively determine the crystal orientation of the deposited crystalline films. By means of this technique, one could grow a polycrystalline film with well-aligned grains and therefore “smoother” grain-to-grain interfaces. As a result, the charges generated within the light-absorbing thin-film would undergo much fewer recombination processes at the grain boundaries and the overall conversion efficiency of the photovoltaic cell would be substantially improved.