Use Of Hydrogen Research Articles

Hydrogen Storage Capacity Improvement of Nanostructured Materials

AbstractSafe, lightweight, and cost-effective materials are required to practically store hydrogen for use in portable fuel cell applications. Compressed hydrogen and on-board hydrocarbon reforming present certain advantages, but their limitations must ultimately render them insufficient. Storage in hydrides and adsorption systems show promise in models and experimentation, but a practical medium remains unavailable. To study hydrogen storage properties a new volumetric testing apparatus was designed and constructed. Adsorption conditions are evaluated up to pressures exceeding 250 bar and a broad range of temperatures. RF sputtering was used to introduce metals to carbon nanotubes with the aim to enhance hydrogen storage. Here we show a significant improvement in the gravimetric storage density over that of as-prepared single-wall nanotube samples that may be due to the unique interface introduced.

Molecular simulation of hydrogen adsorption in graphitic nanofibres

Rodriguez, Baker and co-workers (A. Chambers, C. Park, R. T. K. Baker and N. M. Rodriguez, J. Phys. Chem. B, 1998, 102, 4253; C. Park, C. D. Tan, R. Hidalgo, R. T. K. Baker and N. M. Rodriguez, Proc. 1998 US DOE Hydrogen Program Reiew, (http://www.eren.doe.gov/hydrogen/docs/25315toc.html); C. Park, P. E. Anderson, A. Chambers, C. D. Tan, R. Hidalgo and N. M. Rodriguez, J. Phys. Chem. B, 1999, 103, 10572) have reported uptake of hydrogen in graphitic nanofibres (GNFs) of 40% by weight. If these results are confirmed, then this class of material could be a suitable storage medium for hydrogen for use in fuel cell vehicles. In order to test whether these results are feasible, we report results for grand canonical Monte Carlo simulation of hydrogen adsorption in graphitic pores. A classical technique was employed but the results obtained were shown to be consistent with previous path integral Monte Carlo calculations of Wang and Johnson (Q. Wang and J. K. Johnson, J. Chem. Phys., 1999, 110, 577; Q. Wang and J. K. Johnson, J. Phys. Chem. B, 1999, 103, 277). The interaction between hydrogen and the graphitic surface was modelled initially by dispersion forces. The predicted uptake (up to 1.5%) was much lower than the Baker–Rodriguez results. The results were found to be fairly insensitive as to whether the hydrogen molecule was modelled as a Lennard-Jones sphere or a dumbbell fluid with two Lennard-Jones sites. Two models for a hypothetical potential for chemisorption were also used in the simulation. The potential was based on calculation of the interaction between atomic hydrogen and a graphitic surface. Adsorption of up to 17 wt.% was measured with the stronger model potential but there was negligible desorption at ambient pressure, making it impractical. A more plausible, though still hypothetical, potential gave loadings of up to 8 wt.% in the model system. These results are still much lower than the Baker–Rodriguez data in spite of the fact that there is no evidence to suggest that chemisorption actually occurs in a real system.

MEMBRANE REACTOR ADVANTAGES FOR METHANOL REFORMING AND SIMILAR REACTIONS

Membrane reactors achieve efficiencies by combining in one unit a reactor that generates a product with a semipermeable membrane that extracts it. One well-known benefit of this is greater conversion, as removal of a product drives reactions toward completion, but there are several potentially larger advantages that have been largely ignored. Because a membrane reactor tends to limit the partial pressure of the extracted product, it fundamentally changes the way that total pressure in the reactor affects equilibrium conversion. Thus, many gas-phase reactions that are preferentially performed at low pressures in a conventional reactor are found to have maximum conversion at high pressures in a membrane reactor. These higher pressures and reaction conversions allow greatly enhanced product extraction as well. Further, membrane reactors provide unique opportunities for temperature management which have not been discussed previously. These benefits are illustrated for methanol reforming to hydrogen for use with PEM (polymer electrolyte membrane) fuel cells.

Oxide-ion conductivity of bismuth aluminates

Novel compounds in the Bi-Al-O and La-Bi-Al-O systems were prepared and tested for conductivity at high temperatures (500–800°C) in an oxygen gradient cell. The purpose is to develop an electrolyte material that will permit operation of a solid oxide fuel cell at 500–800°C instead of the 1000°C now used. The Bi-Al-O and La-Bi-Al-O compounds were found to have conductivities of about 10 −2 ohms −1 cm −1 and 10 −1 ohms −1 cm −1 at 800°C, respectively, in an oxygen gradient and ma y have the needed conductivity and stability toward humidified hydrogen for use as fuel cell electrolytes.

Catalytic production of hydrogen for use in road vehicles

Catalytic production of hydrogen for use in road vehicles

Projected Costs for Electricity and Products from OTEC Facilities and Plantships

The vast ocean thermal resource of the tropics can be used to serve all areas of the U.S. through the production at sea of fuels or energy-intensive products that can be transported to market by ship. This paper addresses ammonia, liquid hydrogen, methanol, and liquid methane, which could be sold as fuels or chemicals or used as hydrogen sources for onshore fuel-cell power systems. Estimated costs of their production on 325-MWe ocean thermal energy conversion (OTEC) plantships and their delivery to U.S. ports and inland cites are presented. The most promising product is ammonia, first for use in fertilizers and the chemical industry, and later as the least costly carrier of hydrogen for use in fuel cells. Estimated costs of delivering OTEC electricity by undersea cables from moored offshore plants to U.S. islands and Gulf Coast states are compared with costs of electricity from OTEC ammonia and from coal and nuclear power. Commercial viability for both OTEC approaches by the 1990-1993 period is indicated. The potentials for private cost-sharing in the initial 40-MWe demonstration facilities and plantships also are discussed.

Liquid Hydrogen as a Propulsion Fuel, 1945-1959

A historical review is presented on the research and development of liquid hydrogen for use as a propulsion fuel. The document is divided into three parts: Part 1 (1945-1950); Part 2 (1950-1957); and Part 3 (1957-1958), encompassing eleven topics. Two appendixes are included. Hydrogen Technology Through World War 2; and Propulsion Primer, Performance Parameters and Units.

Hydrogen evolution from water using solid carbon and light energy

Using solar energy to decompose water and produce hydrogen for use in hydrogen energy systems has attracted much attention. Some semiconductors (such as TiO2 and SrTiO3) can decompose water to produce hydrogen and oxygen using the energy1 of light and the decomposition of water using powdered semiconductors has been reported2,3. One problem with powdered semiconductors is that when H2O decomposes into H2 and O2 in one cell an explosive gas is produced. Furthermore, although Schrauzer and Guth reported2 that traces of H2 and O2 were detected after the decomposition of water gas on TiO2, the reverse reaction will increase simultaneously as product is evolved. Hydrogen evolution stopped after a few hours. Hence the hydrogen or oxygen produced should be converted to more stable gaseous chemical species. The use of solid carbon is an interesting problem in relation to coal gasification and we have now examined the photocatalytic decomposition of water on TiO2 using solid carbon. We found that reactions (1) and (2) occur producing hydrogen gas from water vapour and solid carbon when mixed powders of TiO2, RuO2 and active carbon exposed to water vapour at room temperature ∼80 °C are illuminated. The free energies are increased by 63 and 92 kJ mol−1 respectively, utilising light energy.

Notes on an experimental investigation into the production under pressure of electrolytic hydrogen for use as a substitute fuel

Notes on an experimental investigation into the production under pressure of electrolytic hydrogen for use as a substitute fuel