New fuel cell uses solar and biomass

February 25, 2014 | By Barbara Vergetis Lundin

Despite the benefits of low-temperature fuel cell technologies, they cannot directly use biomass as a fuel because of the lack of an effective catalyst system. However, Georgia Institute of Technology researchers have developed a low-temperature fuel cell that directly converts a wide variety of biomass sources -- including starch, cellulose, lignin, and even switchgrass, powdered wood, algae and waste from poultry processing -- to electricity with a catalyst activated by solar or thermal energy.

Credit: Georgia Institute of Technology

The device could be used in small-scale units to provide electricity for developing nations, as well as for larger facilities to provide power where significant quantities of biomass are available.

"We have developed a new method that can handle the biomass at room temperature, and the type of biomass that can be used is not restricted -- the process can handle nearly any type of biomass," said Yulin Deng, a professor in Georgia Tech's School of Chemical and Biomolecular Engineering and the Institute of Paper Science and Technology (IPST). "This is a very generic approach to utilizing many kinds of biomass and organic waste to produce electrical power without the need for purification of the starting materials."

The challenge for biomass fuel cells is that the carbon-carbon bonds of the biomass cannot be easily broken down by conventional catalysts, including expensive precious metals. But Deng has overcome that challenge.

"If you mix the biomass and catalyst at room temperature, they will not react," said Deng. "But when you expose them to light or heat, the reaction begins. The POM (polyoxometalate) introduces an intermediate step because biomass cannot be directly accessed by oxygen."

The system can use soluble biomass, or organic materials suspended in a liquid. In experiments, the fuel cell operated for as long as 20 hours, indicating that the POM catalyst can be re-used without further treatment.

"I believe this type of fuel cell could have an energy output similar to that of methanol fuel cells in the future," he said. "To optimize the system, we need to have a better understanding of the chemical processes involved and how to improve them."

The researchers also need to compare operation of the system with solar energy and other forms of input energy, such as waste heat from other processes. Beyond the ability to directly use biomass as a fuel, the new cell also offers advantages in sustainability and potentially lower cost compared to other fuel cell types.

"We can use sustainable materials without any chemical pollution," Deng said. "Solar energy and biomass are two important sustainable energy sources available to the world today. Our system would use them together to produce electricity while reducing dependence on fossil fuels."

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