Fuel cells in transportation, portable electronics, distributed power
LOS ALAMOS, N.M., January 2003 -- Fuel cell technology promises to impact environmental and economic issues facing the United States and the world every day. Modern lifestyles, high prices for diminishing supplies of fossil fuels, and the environmental impact of energy production have all made alternative power generation technology like fuel cells a necessity.
Los Alamos has worked with industry on fuel cell and related technology since the mid-1970s, through both the government-funded core research program and through cooperative research and development agreements (CRADAs) and licensing.
Fuel cell technology has the potential to transform the transportation industry. Fuel cell-powered ultra-low and zero emission vehicles represent significant progress in the movement to make vehicular travel more environmentally sound. Fuel cells not only create few, if any, harmful emissions, but they also use fuel more efficiently than traditional power sources.
Since the emergence of polymer electrolyte membrane (PEM) fuel cell technology over 20 years ago, Los Alamos has been a research leader in support of transportation applications. The DOE's Office of Advanced Automotive Technology has relied on LANL researchers' innovations at all stages of the technology's development.
Among Los Alamos' most important accomplishments are:
* Early fuel cell demonstrations that jumpstarted the fuel cell transportation industry.
* Presentation of the first data-supported model explaining fuel cell water management, pointing the way to high performance fuel cell membranes.
* Dramatic improvements in impurity tolerance, allowing the use of fuels other than hydrogen.
* Development of critical reactor components for fuel processing and clean-up, allowing for greater flexibility in fuels.
* Participation in the first demonstration of gasoline-fed fuel cells.
* Collaboration with General Motors in the 1990s resulting in the establishment of their own fuel cell program.
* Developmental support of fuel cell systems and components for industry leaders like W. L. Gore, 3M, and Plug Power, all of whom began their fuel cell work at LANL.
Highly efficient fuel cells based on polymer electrolyte catalysts, known as proton-exchange membrane fuel cells, were developed by General Electric for the Gemini space program, but required large amounts of a costly platinum catalyst. The heart of the PEM fuel cell is a polymer membrane that has thin films of catalyst bonded on both its major surfaces, providing effective catalytic sites for the electrode processes.
In the 1980s, Los Alamos National Laboratory scientists and others demonstrated how to achieve efficient energy conversion and power density in a PEM fuel cell with very low amounts of precious metal catalysts. Making fuel cells with minimal quantities of catalyst is crucial to achieving high performance and reliability at low cost. Los Alamos researchers came up with a breakthrough method of increasing the utilization of active catalyst, which allowed them to reduce the amount of platinum needed. This method reduced the amount of platinum needed by roughly 90 percent in some applications.
Los Alamos scientists also improved the structure and composition of the thin films of catalyst. They reduced the cost of materials, modified material properties for specific applications and identified new materials or material combinations for various fuel cell components. Los Alamos has tested advanced electrode technology in single cells for more than 3,000 hours, demonstrating negligible losses in performance; developed a way to avoid catalyst deactivation in the presence of trace impurities in the hydrogen fuel; and improved the properties of the membrane for effective water management.
Los Alamos and General Motors formed a major engineering development partnership in 1988 and worked together for nearly eight years to perfect a PEM fuel cell and improve fuel processing. Through the partnership, which also involved Dow Chemical Co. and Ballard Power Systems, Los Alamos developed diagnostic equipment for single fuel cells, stacks, combusters and other components. These high-quality measurements made possible further developments in PEM fuel cells, including operation of a 10 kilowatt demonstrator.
Los Alamos has led in developing better ways to process the fuels needed to operate fuel cell-powered vehicles. One earlier achievement in this area was Los Alamos' solution of how to operate PEM fuel cells on impure hydrogen fuel. Traces of carbon monoxide in hydrogen fuel - which are generated in processing liquid fuels such as gasoline or methanol - hurt fuel cell performance. By bleeding low levels of air into the fuel feed stream, Los Alamos researchers removed the carbon monoxide catalytically within the cell, allowing fuel cells to run as well on contaminated hydrogen as on highly pure hydrogen. This development opened the way to practical use of PEM fuel cells with realistic hydrogen fuel feed streams derived from the processing of liquid fuels.
Los Alamos currently is involved in development of a multi-fuel reformer, which makes it possible for the same fuel cell to use hydrogen derived from gasoline, natural gas, methane or ethanol. Los Alamos also developed and is perfecting the preferential oxidizer, or PROX, an essential part of a fuel cell delivery system.
In the delivery system, fuel in whatever form is heated and mixed with warm air and steam. The partially burned fuel and other reaction products are channeled through a bed of catalysts, then to shift reactors that increase the amount of hydrogen in the mix.
The PROX then adds a small amount of air and preferentially burns carbon monoxide in the presence of hydrogen, converting the carbon monoxide to carbon dioxide while burning less than one percent of the hydrogen gas. The PROX is crucial, because carbon monoxide in amounts as small as 100 parts per million can poison the reaction at the electrode, decreasing voltage drastically.
The array of fuel cells, or stack, developed by Plug Power L.L.C. for an experiment at A.D. Little used Los Alamos' technology for making effective, low-cost catalyzed membranes for fuel cells. The Plug Power fuel cells also incorporated Los Alamos' air bleed technique to remove effects of fuel impurities within the stack.
Los Alamos National Laboratory is operated by the University of California for the National Nuclear Security Administration (NNSA) of the U.S. Department of Energy and works in partnership with NNSA's Sandia and Lawrence Livermore national laboratories to support NNSA in its mission.
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