Highlight all of ASU's renewable energy research.

Professor strives for 'greener' power plants

June 30, 2009

Research to help make the next generation of power plants more environmentally sustainable will be led by Arizona State University chemical engineering professor Jerry Lin.

His project to capture carbon dioxide created in the combustion of coal, natural gas or biomass to produce hydrogen for energy generation will be supported by a recently announced grant of more than $650,000 from the U.S. Department of Energy. Download Full Image

The hydrogen resulting from this conversion method is used to produce heat that generates electrical power, but the carbon dioxide that escapes in the process contributes to greenhouse gases that are accumulating in the Earth’s atmosphere – with potentially negative long-term environmental impacts.

Lin is working on ways to capture such carbon dioxide emissions before the combustion required to produce hydrogen, preventing the release of carbon dioxide and allowing it to be safely sequestered.

His goal also is to make the conversion process more energy efficient. He wants to not only be able to separate carbon dioxide from hydrogen and contain it, but produce a higher yield of hydrogen from coal, natural gas or biomass.

Lin will assemble a team of ASU chemical engineering doctoral students and post-doctoral research assistants to work on the projects.

Joe Kullman

Science writer, Ira A. Fulton Schools of Engineering


Carbon nanotubes may lower cost of fuel cells

June 16, 2009

The high cost of manufacturing fuel cells makes their large-scale production for power generation next to impossible, but researchers at Arizona State University are working to change that so cars, electricity and much more can run on the “green” technology.

Engineering technology professor Arunachalanadar Madakannan (Kannan) has been studying the proton exchange membrane fuel cells (PEMFC) for more than eight years. The fuel cells Kannan and his graduate students are focusing on employ carbon nanotube-based catalysts and electrodes.

Fuels cells, which cleanly and quietly generate electric power by passing fuels like hydrogen over one electrode while passing air over a second electrode, have been around for more than 100 years. But their development has long been dogged by costs of the technology as well as safety concerns. Download Full Image

Kannan said PEMFC fuel cells have layers of electrode and electrolyte components. In a PEMFC, the cell is made up of an hydrogen-based anode (positive) terminal and oxygen-based cathode (negative) terminal, with carbon-particle supported platinum acting as a catalyst (electrode) to produce power.  While fuel cells produce electrical energy, the only waste generated is water, so it’s considered a very clean energy conversion system.

Scientists have been honing fuel cell technology since its inception, but, even after more than a century, the cost of producing fuel cells remains high because of the platinum-based catalysts.

“Platinum is the most effective electrocatalyst and a good conductor of electricity in fuel cells, but the cost is so prohibitive that we have not yet been able to use fuel cells widely,” says Kannan, an associate professor in the College of Technology and Innovation at ASU’s Polytechnic campus.

Kannan is working to create lower cost PEMFCs by directly growing carbon nanotubes on carbon paper substrates, otherwise known as the gas diffusion layer, rather than spherical carbon particles and then deposit platinum nanoparticles onto the surface of the nanotubes. This innovative approach allows for the use of less platinum, without impacting energy efficiency.

“This modified process saves about 10 to 15 percent of the cost compared to what exists today, without sacrificing any power output,” says Kannan.

During his research, Kannan was evaluating the performance of several different materials, measuring power output and efficiency along the way.

“The carbon nanotube-based electrode is more efficient because it has a greater surface area,” says Kannan, “which allows for less platinum to be needed.  In addition, the electrodes also perform extremely well under lower relative humidity, which will ultimately reduce the fuel cell system complexity.”

Kannan co-authored three papers on the topic, which were all recently published in the Journal of Power Sources as well as the International Journal of Hydrogen Energy.

In addition, ASU and Helsinki University of Technology along with VTT in Finland have entered into a project regarding an advanced material solution for PEMFCs. Currently ASU graduate student Chad Mason is in Finland testing and improving the performance of the gas diffusion layer materials, while lowering costs and increasing manufacturability.

“The next step is to make the development of the gas diffusion layer continuous, rather than a batch process, so that it can be commercially viable,” says Kannan. “Chad’s work overseas will allow us to move in this direction. We believe that PEM fuel cells will become commercially viable in a decade or so and help us move toward a hydrogen economy.”

Dr. Kannan, amk">mailto:amk@asu.edu">amk@asu.edu

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