August 2001

From Virginia Tech

Federal agencies, private industry provide major funding to advance fuel cells materials and systems, speed development and adoption

BLACKSBURG, VA, August 9, 2001—Fuel cells have the potential to produce energy that is environmentally clean for running automobiles, heating homes, and efficiently running lap tops, cell phones and other portable devices; but lack of knowledge about the cells and their components has thus far limited their usefulness.

Virginia Tech researchers have demonstrated improved materials and systems. As a result, a research team led by Virginia Tech will receive a $2 million two-year grant from the U.S. Department of Energy (DOE) clean-energy science and technology initiative, a $600,000 two-year grant from the National Science Foundation’s Partnerships for Innovation (PFI) program, and a $500,000 three-year contract from International Fuel Cells of South Windsor, Conn.

The DOE grant is to develop the next generation of polymer electrolyte membranes (PEMs), membrane electrode assemblies, and related fuel-cell material systems. One challenge is that polymer properties change with time and temperature, which restricts applications. Elevated temperatures can shorten the life of the PEM materials. Virginia Tech faculty members and students have created new materials that have demonstrated the ability to operate at 110 to 120 degrees C instead of only 80 degrees C, and better conductivity.

The PFI program will help build creative interactions among colleges and universities, governmental agencies, foundations, and private corporations to accommodate research and development at the local and regional level, specifically to provide the science and the understanding to develop and commercialize next-generation fuel-cell materials and systems.

"We will extend understanding of several critical factors on transport properties for optimizing and developing new materials for use in fuel cells," said James McGrath, director of Virginia Tech's Materials Research Institute. One of the visions of the work is to employ expertise in PEM fuel-cell materials with improved thermal stability developed at Virginia Tech, the lead institution, and Virginia Commonwealth University, in partnership with several industries, including Newport News Shipbuilding, Acadia Elastomers in Blacksburg, United Technologies, ChemFab, Dias Analytic, BP-Amoco, and the Los Alamos National Laboratory (LANL). Other collaborating universities are Hampton University and Grambling State.

The universities will integrate their work with current critical needs of industries working in this area. For example, they will work with Tom Zawodzinski of LANL and look at PEMs that might work at higher temperatures than those currently available. Dias Analytic is interested in fuel cells to run computers. Gary Wnek, chair of chemical engineering at Virginia Commonwealth University will be the contact for that work.

In addition, the group will collaborate with LANL via student exchanges. LANL is interested in Virginia Tech because of its expertise in polymeric membranes, adhesives, and composites for their fuel-cell components.

Newport News Shipbuilding Co. will provide systems engineering analysis of membrane electrode assembly (MEA) fuel stacks, with Michael von Spakovsky, director of Virginia Tech’s Energy Mangement Institute, heading that work. Ken Reifsnider of Virginia Tech's Materials Response Group will develop the predictive modeling of the durability of MEA systems.

Fuel cells are composed of membranes and catalysts that convert fuel such as hydrogen or methanol to energy, and include collector plates. Proton-exchange membrane fuel cells — the most suitable for automotive, home, and computer-power uses because they operate at moderate temperatures — are polymer-based. In hydrogen-powered fuel cells, the polymer membranes critically transports hydrogen protons away from hydrogen electrons, producing electrochemical energy. The hydrogen then reacts with the oxygen in air with environmentally benign water as a byproduct.

Thus, PEMS and MEAs are used in a water environment at around 80 degrees Centigrade. Higher temperatures would be more practical, but there must be a way to hydrate the PEMs since the water will turn to steam at 100 degrees Centigrade (212 degrees Fahrenheit). In a dry environments such as Arizona’s, where the water evaporates, the PEM do not work well even at 80 degrees.

As part of the DOE research, "We will try to develop membranes less sensitive to the degree of humidity in the area," McGrath said, "and there also is the possibility of identifying ways they could be used at temperatures higher than 100 degrees. We have some approaches that we will be trying to see if we can make work at 150 degrees Centigrade." They also will try to find ways to use gas and diesel fuels without spewing so much sulfur byproducts into the air.

However, carbon monoxide at 80 degrees Centigrade interferes with catalysts. "If we could get the temperature up to 150 degrees, it would no longer be much of a problem. There’s tremendous interest in being able to do that," McGrath said.

Status of fuel cells -- applications and infrastruce

Fuel cells are being used in automobiles, such as the prototype Chevrolet Lumina "Future Car" the Virginia Tech engineering group built with a fuel-cell propulsion system. It runs on a PEM system that McGrath’s group plans to improve. However, several things must be considered, such as materials, mechanics, and other systems issues.

Other major applications are for stationary power such as homes that are not accessible to electric or gas heating. They could have a separate unit based on a fuel cell, McGrath said. "There are a lot of companies interested in that," he said.

Another area of the application of fuel cells is to replace batteries in computers. Fuel cells are intrinsically more efficient and have the potential to operate much longer. McGrath has discussed this with Motorola, which is interested in this aspect, as are other companies.

"One of the big issues is to make these materials cheaper and less exotic than the materials NASA has been using for 30 or 40 years," McGrath said. "The users would like to choose materials inherently less costly than existing systems. "We hope some of our partners will commercialize some of these materials."

Fuel-cell energy involves the reaction of hydrogen and oxygen (or air). The main fuel-cell reaction product is water, so instead of having harmful substances such as unburnt hydrocarbons or sulfur impurities come out of tailpipes, theoretically they could have zero harmful emissions. "We’ll never get to zero," McGrath said. "But it can be very much lower in hazardous emissions."

Fuel cells burn hydrogen, and when reacted with oxygen (e.g., from the air), it produces water and the energy. There are several sources for the hydrogen, although no infrastructure is available to make it readily available now. The system that is probably going to be used first, McGrath said, is methyl alcohol (methanol), a liquid, in contrast to hydrogen, a gas that must be stored under pressure. Methanol will be used first in powering computers, and possibly later in homes and automobiles.

Second, some of the portable power of interest to the military can use a compound that contains hydrogen in solid form, such as a metal hydride. These compounds can be decomposed to generate hydrogen when needed and some portable devices will do that.

The third major source of hydrogen is to start with gasoline or diesel fuel. Instead of burning it directly, it would be put through a reforming process similar to what is being done in the petroleum industry now, but this would have to be done on a miniaturized scale. In this way, liquid gasoline can be catalytically converted into hydrogen in a process that is much less polluting than direct burning of the hydrocarbon or gas.

"The oil industry would probably like to see this happen," McGrath said. "The existing infrastructure of gasoline stations could be used with the addition of a converter in the car to transform gasoline into hydrogen." Major automobile companies such as Daimler Chrysler are talking about having a significant number of cars operate this way by 2004, McGrath said. There will also be hybrid engines as well, McGrath said.

Natural gas, which is essentially methane, also can be used to make hydrogen.

A final issue, McGrath said, is that of adhesion and composites. The fuel cell requires several cells that will have to be stacked together. The mechanical aspects of combining individual fuel cells into "generating stacks" include how to put the fuel cells together and how long they will hold together. Von Spakovsky and Reifsnider will head that study.

In addition to NSF grant investigators McGrath, Reifsnider, von Spakovsky, and Wnek, co-principal investigators of the DOE grant are Donald G. Baird, professor of chemical engineering, and John Dillard, professor of chemistry, both at Virginia Tech. The work will be done in collaboration with Zawodzinski of LANL.

The DOE clean-energy science and technology initiative.included 18 cost-sharing contracts with industry -- three with International Fuel Cells of South Windsor, Conn., including a $7.5 million contract to develop polymeric proton exchange membranes that incorporate advanced cathode catalysts and are capable of operating in fuel cells at high temperatures. McGrath's group will receive $500,000 over three years as a partner in this research.

McGrath is a University Distinguished Professor of Chemistry at Virginia Tech. Learn more about his work at http://www.macro.vt.edu/faculty/james_mcgrath.htm.

PR CONTACT: Sally Harris
540-231-6759 slharris@vt.edu












This article comes from Science Blog. Copyright © 2004
http://www.scienceblog.com/community

Archives 2001 E