We describe a novel solar-based process for the production of methanol from carbon dioxide and water. The system utilizes concentrated solar energy in a thermochemical reactor to reenergize CO 2 into CO and then water gas shift (WGS) to produce syngas (a mixture of CO and H 2 ) to feed a methanol synthesis reactor. Aside from the thermochemical reactor, which is currently under development, the full system is based on well-established industrial processes and component designs. This work presents an initial assessment of energy efficiency and economic feasibility of this baseline configuration for an industrial-scale methanol plant. Using detailed sensitivity calculations, we determined that a breakeven price of the methanol produced using this approach would be 1.22 USD/kg; which while higher than current market prices is comparable to other renewable-resource-based alternatives. We also determined that if solar power is the sole primary energy source, then an overall process energy efficiency (solar-to-fuel) of 7.1% could be achieved, assuming the solar collector, solar thermochemical reactor sub-system operates at 20% sunlight to chemical energy efficiency. This 7.1% system efficiency is significantly higher than can currently be achieved with photosynthesis-based processes, and illustrates the potential for solar thermochemical based strategies to overcome the resource limitations that arise for low-efficiency approaches. Importantly, the analysis here identifies the primary economic drivers as the high capital investment associated with the solar concentrator/reactor sub-system, and the high utility consumption for CO/CO 2 separation. The solar concentrator/reactor sub-system accounts for more than 90% of the capital expenditure. A life cycle assessment verifies the opportunity for significant improvements over the conventional process for manufacturing methanol from natural gas in global warming potential, acidification potential and non-renewable primary energy requirement provided balance of plant utilities for the solar thermal process are also from renewable (solar) resources. The analysis indicates that a solar-thermochemical pathway to fuels has significant potential, and points towards future research opportunities to increase efficiency, reduce balance of plant utilities, and reduce cost from this baseline. Particularly, it is evident that there is much room for improvement in the development of a less expensive solar concentrator/reactor sub-system; an opportunity that will benefit from the increasing deployment of concentrated solar power (electricity). In addition, significant advances are achievable through improved separations, combined CO 2 and H 2 O splitting, different end products, and greater process integration and distribution. The baseline investigation here establishes a methodology for identifying opportunities, comparison, and assessment of impact on the efficiency, lifecycle impact, and economics for advanced system designs.

No abstract

High-resolution 23Na and 39K nuclear magnetic resonance (NMR) spectra of perfused, beating rat hearts have been obtained in the absence and presence of the downfield shift reagent Dy(TTHA)3- in the perfusing medium. Evidence indicates that Dy(TTHA)3- enters essentially all extracellular spaces but does not enter intracellular spaces. It can thus be used to discriminate the resonances of the ions in these spaces. Experiments supporting this conclusion include interventions that inhibit the Na+/K+ pump such as the inclusion of ouabain in and the exclusion of K+ from the perfusing medium. In each of these experiments, a peak corresponding to intracellular sodium increased in intensity. In the latter experiment, the increase was reversed when the concentration of K+ in the perfusing medium was returned to normal. When the concentration of Ca2+ in the perfusing medium was also returned to normal, the previously quiescent heart resumed beating. In the beating heart where the Na+/K+ pump was not inhibited, the intensity of the intracellular Na+ resonance was less than 20% of that expected. Although the data are more sparse, the NMR visibility of the intracellular K+ signal appears to be no more than 20%.

No abstract

No abstract

Designing and building a full scale hydrogen storage system revealed several engineering challenges and also demonstrated the capabilities of complex hydrides. Three kg of hydrogen was stored in a four module system using modified sodium alanate as the storage media. Extensive testing of this system demonstrated the ability to follow aggressive hydrogen demand schedules that simulate actual driving. Extensive use of detailed models greatly improved the design and eventual performance of the storage system; the test data permitted further refinement of the models.

Cleaning of extreme ultraviolet lithography optics and masks using 13.5 nm and 172 nm radiation A "thermophoretic pellicle" has been proposed as an alternative to the traditional organic pellicle as a means of protecting extreme ultraviolet ͑EUV͒ lithographic photomasks from particle contamination. The thermophoretic pellicle protects a mask from particles by exploiting the thermophoretic force, which is exerted on a particle by a surrounding gas in which a temperature gradient exists. Two critical requirements of the thermophoretic pellicle are: ͑1͒ the mask is kept warmer than its surroundings and ͑2͒ the surrounding gas pressure is kept sufficiently high to enable thermophoretic protection. Experiments are presented which verify the viability of thermophoretic protection for EUV masks. In these experiments, wafers are exposed to a monodisperse, polystyrene-latex-sphere aerosol under carefully controlled experimental conditions. Robust thermophoretic protection is observed over a wide range of argon gas pressures ͑50-1600 mTorr or 6.66-213 Pa͒, particle sizes ͑65-300 nm͒, and temperature gradients ͑2-15 K/cm͒. Numerical simulations of the thermophoretic pellicle show good agreement with the data.

Hydrogen storage technologies based on solid-phase materials involve highly coupled transport processes including heat transfer, mass transfer, and chemical kinetics. A full understanding of these processes and their relative impact on system performance is required to enable the design and optimization of efficient systems. This paper examines the coupled transport processes of titanium doped sodium alanates (NaAlH4, Na3AlH6) enhanced with excess aluminum and expanded natural graphite. Through validated modeling and simulation, we have illuminated transport bottlenecks that arise due to mass transfer limitations in scaled-up systems. Individual heat transport, mass transport, and chemical kinetic processes were isolated and experimentally characterized to generate a robust set of model parameters for all relevant operational states. The individual transport models were then coupled to simulate absorption processes associated with rapid refueling of scaled-up systems. Using experimental data for the absorption performance of a 1.6 kg sodium alanate system, comparisons were made to computed results to identify dominant transport mechanisms. The results indicated that channeling around the compacted porous solid can contribute significantly to the overall transport of hydrogen into and out of the system. The application of these transport models is generally applicable to a variety of condensed-phase hydrogen sorption materials and facilitates the design of optimally performing systems.