In the midst of a worsening global energy crisis, Rensselaer’s research efforts toward creating and advancing renewable energy sources are more important and timely than ever. Fuel cells hold promise to become a widespread alternate source of energy for the 21st century, but many challenges remain.
Jordan Mader ’05, an accelerated B.S./Ph.D. student in Rensselaer’s School of Science, is helping to address this issue through her research on new polymer membranes for use in fuel cells. Since earning her undergraduate degree in 2005, she has been working toward her doctorate, which she expects to receive in May 2009 at the age of 24. The seven-year Accelerated B.S./Ph.D. program has been an excellent opportunity for Mader because she was able to start her research in her sophomore year at Rensselaer, whereas students at most other universities must wait until graduate school to begin serious research.
“Fuel cells are a green energy source that hold promise to solve some of the world’s major energy problems,” Mader said. “Right now, companies such as BASF and Plug Power are making fuel cells to provide alternate back-up power in the case of an outage due to a storm or earthquake. And in the next five to ten years, we could have fuel cells on the market here in the U.S. to power individual people’s homes, off-grid.”
A fuel cell is an electrochemical device that converts a supplied fuel into electricity and heat. The most common type is the Proton Exchange Membrane (PEM) Fuel Cell, which works by passing protons from hydrogen through the membrane to combine with oxygen and form water and heat, while electrons pass through an external circuit, providing electricity.
In 1999, a team of researchers at Rensselaer led by Professor Brian Benicewicz, started working to develop alternative fuel cell membranes with the polymer polybenzimidazole (PBI). For years, PEM fuel cell technology had been based on Nafion and other perfluorinated sulfonic acid-based membranes. These membranes have good conductivity and performance, but poor carbon monoxide tolerance and only work at less than 80 °C. Nafion is a dry film, and thus requires constant hydration. Maintaining a constant amount of water in these membranes is critical for performance and can lead to reliability issues.
To avoid these complications, polymer synthesis researchers at Rensselaer turned their research to PBI. Used for high-performance protective apparel for firefighters and astronauts, PBI has fiber characteristics important to building a successful and inexpensive fuel cell, such as having no melting point and being resistant to age, mildew, and abrasion. And most importantly, PBI (as developed at Rensselaer) is a gel, which soaks up and retains so much phosphoric acid that it requires no water for conductivity.
Benefits of the complete PBI system over conventional processes include high temperature operation (120 - 180 °C), exceptional thermal and chemical stability, high conductivity, and low cost. In addition, the fuel cell can operate at very low or zero humidity levels, eliminating the need for the external humidification procedures used with Nafion membranes.
Mader’s primary focus is creating these PBI polymer membranes and testing them in actual fuel cells. “Using our polybenzimidazole gel film, we can build fuel cells faster, and with a much cheaper and easier process than current industry methods for PBI fabrication,” Mader said. And industry is paying attention. Currently much of the Rensselaer team’s research funding comes from the multinational chemical manufacturing corporation, BASF. They also receive funding from the U.S. Department of Energy and Basic Energy Sciences.
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