Siemens Power Generation, Inc. has awarded Assistant Professor Srikanth Gopalan (MFG) a grant to study how to extract more electrical power from solid oxide fuel cells.
Siemens, a leader in solid oxide fuel cell technology, named recipients of its 2007 University Embryonic Technologies Program grants in May. With the one-year, $50,000 grant, Gopalan will examine how fuel cells might gain efficiency by changing the material and design of the cathode – one layer of material in the cell stack.
Although solid oxide fuel cell technology has yet to debut on the commercial stage, it holds promise as a form of clean energy, providing electricity for houses, offices and buildings, as well as auxiliary power for long-haul transport, such as keeping air conditioners running while a trucker sleeps overnight in his cab. The cells can run on a variety of fuels including hydrogen, ethanol or gasoline. Though these cells do not eliminate use of carbon based fuels — which even get used in creating hydrogen fuel — they trim use to as little as possible. “Our claim to fame is efficiency, efficiency, efficiency,” said Gopalan. “We cut down on pollution because we generate very little carbon dioxide.”
A solid oxide fuel cell contains layer upon layer of electrode sandwiches, each about two millimeters thick. Each sandwich contains a cathode and anode, with an electrolyte between the two. The anode is exposed to fuel, the cathode to oxygen gas. Electrons from the fuel flow towards the cathode through an external circuit, generating electricity. Oxygen moves in the opposite direction, slipping through the porous cathode, ionizing and continuing through the electrolyte and anode to react with hydrogen and produce the byproduct water.
The materials making up these layers dictate how well the fuel cell works. “A lot of the performance loss occurs at the cathode,” said Gopalan. With the Siemens grant, he will study exactly how the cathode seeps efficiency. “They recognize there’s lots of fundamental science to be understood,” he said. Researchers today can get a general indication of how well a cathode works, but do not know which specific properties help or hinder its efficiency. Gopalan will use a model system to tease apart what parts of cathode design work well, and which others have potential to improve. Efficiency might be gained in changing the physical interaction between the cathode and the next layer in a cell, the electrolyte. Using different materials might also improve the cathode’s electrochemical kinetics, the rate at which reactions take place. “If we really want to go to the next generation of fuel cells we have to be able to decombinate these effects,” said Gopalan.
At the current level of efficiency, a stack of cells about the size of an oil furnace could provide five kilowatts, enough electricity for the average household. Improvements that increase efficiency mean a smaller stack could power the same house. “We want to achieve improved power density to the point that they’re commercially attractive,” said Gopalan.
Solid oxide fuel cells are not new, but high costs hold them back from widespread use. Gopalan works on removing this obstacle by improving the cells’ efficiency and by simplifying their manufacturing process to reduce cost. “Cost and performance go hand in glove,” he said. By attacking the problem on both fronts, Gopalan brings solid oxide fuel cells ever closer to commercial viability.