28 July 2009

Applying math to fuel cells

Talk still abounds about powering vehicles in the future with fuel cells, but the continuing bug-a-boo remains how to get an efficient power plant into the car. That is where math comes in.

Concerns about dwindling fossil fuel resources, current levels of petroleum consumption, and growing pressure to shift to more sustainable energy sources are among the factors prompting the transition from our current energy infrastructure to one that uses less carbon and requires the efficient conversion of energy.

This means collecting energy from sources including wind, solar, and geothermal power, and converting it into appropriate forms for distributing electricity. While it is possible to distribute this electric power efficiently, conversion is necessary for use in automobiles and large-scale storage is problematic.

Right now, the fuel cell of choice is Polymer Electrolyte Membrane (PEM).

The PEM in particular takes hydrogen and oxygen from the air to create electricity. They typically see use in automobiles, according to Keith Promislow of the Michigan State University and Brian Wetton of the University of Vancouver, co-authors of a paper on the subject. When pure hydrogen is the fuel, these fuel cells emit only heat and water as byproducts, eliminating concerns about air pollutants and greenhouse gases.

Fuel cells have the potential to replace the internal combustion engine in vehicles and provide power in stationary and portable power applications as they are energy-efficient, clean, and fuel-flexible, according to the U.S. Department of Energy.

The paper “PEM Fuel Cells: A Mathematical Overview” examines the mathematical issues that arise when modeling PEM fuel cells. To read the paper, go to http://www.siam.org/journals/siap/70-2/72080.html. To learn more about PEM fuel cells and how they work, go to http://www.fueleconomy.gov/feg/fcv_PEM.shtml

PEM fuel cells are good examples of energy conversion systems that have several levels of interacting functional structures. The interactions range from proton exchange at the nanoscale level to interactions at the macroscale level. Accurately simulating the resulting multiscale interactions requires carefully constructed mathematical models that faithfully represent the physics at the various scales.

Modeling and analysis of PEM fuel cell structures, their construction, performance, and degradation also requires the development of new mathematical solutions and highly structured and highly adaptive numerical techniques. Mathematical analysis and scientific computation will play a large role in the resolution of these important issues and as a result will affect the progress of PEM fuel cell research and development.

For related information, go to www.isa.org/manufacturing_automation.