Primary and secondary electrical space power based on advanced PEM systems

For new space ventures, power continues to be a pacing function for mission planning and experiment endurance. Although electrochemical power is a well demonstrated space power technology, current hardware limitations impact future mission viability. In order to document and augment electrochemical technology, a series of experiments for the National Aeronautics and Space Administration Lewis Research Center (NASA LeRC) are underway at the Los Alamos National Laboratory that define operational parameters on contemporary proton exchange membrane (PEM) hardware operating with hydrogen and oxygen reactants. Because of the high efficiency possible for water electrolysis, this hardware is also thought part of a secondary battery design built around stored reactants - the so-called regenerative fuel cell. An overview of stack testing at Los Alamos and of analyses related to regenerative fuel cell systems are provided in this paper. Finally, this paper describes work looking at innovative concepts that remove complexity from stack hardware with the specific intent of higher system reliability. This new concept offers the potential for unprecedented electrochemical power system energy densities

Micro fuel cell

An ambient temperature, liquid feed, direct methanol fuel cell device is under development. A metal barrier layer was used to block methanol crossover from the anode to the cathode side while still allowing for the transport of protons from the anode to the cathode. A direct methanol fuel cell (DMFC) is an electrochemical engine that converts chemical energy into clean electrical power by the direct oxidation of methanol at the fuel cell anode. This direct use of a liquid fuel eliminates the need for a reformer to convert the fuel to hydrogen before it is fed into the fuel cell

Characterization of Devonian shales using laser pyrolysis-gas chromatography

Pulsed Nd pyrolysis with minimum sample pretreatment generates adequate quantities of products for analytical determinations. Significant quantities of pyrolysis products apparently result from methane and ethane released by thermal degradation. Focused power deposition leads to increased ethane production. This may result from a deeper penetration into the sample exploring regions removed from the surface that are less depleted in naturally occurring low molecular weight gases. Higher molecular weight components are readily apparent. These compounds may serve both as useful chemical markers and as component sections of the larger molecular weight species that contain the candidate gaseous fuels

Comparison of economics of in situ coal gasification with surface processing

The Los Alamos Scientific Laboratory (LASL) concept for underground coal conversion (gasification) involves preliminary hot-gas drying and pyrolysis steps followed by gasification of the resulting char through combustion with a carbon dioxide--oxygen mixture. This staged recovery process produces both an enhanced-Btu (1300 Btu/scf) fuel gas to mix with natural gas and a clean, low-Btu gas for electricity production. Detailed engineering and economic analyses have been completed that point to the feasibility of this approach. Comparable economic analyses, all based on costs of existing Lurgi surface technology, are given for three processes with roughly similar commercial goals, i.e., the LASL concept above; Lurgi gasification of surface-mined coal, followed by gas cleanup; and a steam--oxygen underground process analogous to those processes used at Hanna and Hoe Creek, WY, followed by gas cleanup. The analyses indicate that the costs of Lurgi and of current underground coal conversion technologies are similar at the present stage of the development of in situ technology. Simple modifications of the methods of underground conversion, which are evaluated in the paper, can be expected to improve the byproduct recovery and to much reduce the capital costs of conversion--such conversion systems appear to be economically competitive with strip mining plus pollution control. The analyses emphasize the critical importance of controlling capital costs. Thus well-completion and labor charges are less important expenses than gas cleanup costs; these latter costs enforce volume minimization throughout all process steps. As corollary, expensive and power-consuming systems including oxygen-generating units and pumps are required

Electrochemical energy storage using PEM systems

This paper gives the results of an engineering assessment for future, long-lived space power systems for extraterrestrial applications. Solar-based, regenerative fuel cell power plants formed from either alkaline or PEM components are the focus. Test results on advanced PEM fuel cell stack components are presented. 7 refs., 4 figs., 1 tab

Fuel cell powered propulsion systems for highway vehicles

Over the past thirty-five years, the transportation sector has accounted for approx.25% of the total gross energy consumption in the US. Transportation's share of petroleum use in this time frame has ranged from 50 to 55%. Therefore, the use of fuel cell power plants that could possibly operate more efficiently than internal combustion engines in this type of application has been examined. In addition, these fuel cell power plants can operate on methanol produced from indigenous, non-petroleum sources and thereby reduce US dependency on petroleum resources. Fuel cell power plant use in city buses and automobiles has been explored and feasibility determined from both performance and cost viewpoints. Fuel cell systems for transportation applications have been selected on the basis of state-of-development, performance (both present and projected), and fuel considerations. In the last 25 years, most of the development work by research organizations and industrial firms has focused on five types of fuel cells, classified according to the electrolyte used. In terms of the overall state-of-development of systems, the ranking is as follows: (1) phosphoric acid, (2) alkaline, (3) proton exchange membrane, (4) molten carbonate, and (5) solid oxide

Kinetics of Subbituminous Coal Drying

This paper explores both the effects of stress upon water removal from subbituminous coal and the consequences of drying upon underground coal conversion. Laboratory tests studying compressive stress effects on moisture transfer in the hygroscopic region are reported. Measurements of CO/sub 2/ permeability are also reported as a function of compressive stress and fluid saturation levels. Results indicate that molecular transport phenomena are unaffected by compressive stress levels while viscous transport is markedly influenced by stress. This flow decrease results from alteration of the size of larger flow channels which are necessary to support viscous fluid transport