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.”

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Media Contact:
Chris Lambrakis, lambrakis">">
(480) 727-1173
Public Affairs at ASU Polytechnic campus

Study: Phoenix-area home prices have 'reached a turning point'

June 16, 2009

Phoenix-area homeowners can take some comfort from a new Arizona State University study that indicates the Valley housing market is finally starting to turn around.

The Arizona State University-Repeat Sales Index (ASU-RSI) measures changes in average Phoenix-area home prices from year to year. The latest report shows a record 37-percent drop in the index from March 2008 to March 2009. However, that’s stagnant from the same 37-percent fall noted from February 2008 to February 2009. It’s also followed by preliminary estimates of a lesser 35-percent drop for April 2008 to April 2009, and a 33-percent dip from May 2008 to May 2009. Download Full Image

“If they hold up, the April and May figures would be the first evidence that the housing market has reached a turning point,” says Karl Guntermann, the Fred E. Taylor Professor of Real Estate at the W. P. Carey School of Business at Arizona State University, who calculates the ASU-RSI with research associate Adam Nowak. “This indicates the rate of decline is slowing, and even though actual home prices continue to drop, they’re falling by much smaller amounts than they typically have during the past 18 months.”

The index has now declined for 25 months in a row, the longest drop in Valley history. From March 2008 to March 2009, Glendale experienced the worst fall of any local city at 40 percent. Tempe saw the mildest decline in the index at 18 percent.

Preliminary estimates show the median Phoenix-area home price at $115,000 in May. That would put prices back at the same level as October 1998.

“The large number of foreclosed properties being sold at distressed price levels suggests that the median price is unlikely to increase significantly in the near future,” says Guntermann, who points out the positive, that this makes homes in the area more affordable

The ASU-RSI is based on repeat sales, the most reliable way to estimate price changes in the housing market. Repeat sales compare the prices of a single house against itself at different points in time, instead of comparing different homes with different quality factors.

The ASU-RSI is produced through the Center for Real Estate Theory and Practice at the W. P. Carey School of Business. The current report and archived reports are available at the Division">">Division of Real Estate – Repeat Sales Reports. Further ASU-RSI analysis is available at">">