Professor uses bacteria to catalyze carbon-neutral methane

Aug. 2, 2012, 2:29 a.m.

Stanford microbiology professor Alfred Spormann has partnered with Penn State University professor Bruce Logan to find a groundbreaking method of creating carbon-neutral, renewable methane gas. The process, which uses microbes as a catalyst, only requires electricity to convert atmospheric carbon dioxide into pure methane, the primary ingredient in natural gas.

To conduct this research, Spormann’s lab is raising colonies of bacteria, called methanogens, which use electrical energy to transform atmospheric carbon dioxide into methane. According to Spormann, there is potential to develop a new technology based on the activity of microbial factories converting electrical energy to chemical energy.

“It has significant implications for green energy technologies,” Spormann said. “It’s a technology that allows [us] to substitute fossil chemicals, chemicals derived from fossil fuels, which the chemical industry heavily relies on, with chemicals synthesized from atmospheric carbon dioxide.”

This process of converting electricity to methane involves bacteria that can generate electrical currents in microbial fuel cells, which are fuel cells that use bacteria instead of hydrogen and precious metals like platinum, elements needed to catalyze regular fuel cells.

“The entire process is cyclical,” Spormann explained. “The carbon dioxide used to make methane is derived from the atmosphere, and once you combust methane, you release the carbon dioxide again.”

Because the carbon dioxide is recycled, the process is entirely carbon-neutral. The methanogens dine on atmospheric carbon dioxide and electricity, converting them efficiently into methane.

“When you’re using chemical catalysts [to generate methane] you tend to get a lot of side-product, and the system isn’t self-sustaining; it needs high temperatures or precious metal catalysts,” Logan said. “Here the microbes are the catalysts– and they make only methane.”

The researchers envision a cost-effective system that will be able to produce clean methane used to fuel ships, airplanes and other vehicles. Ideally, cultures of methanogens would be fed electricity as they metabolized carbon dioxide into methane.

“The goal is to turn a source of reusable electrical power into methane– it’s a way of either creating a fuel that would be used in vehicles or storing energy in the form of methane,” Logan said. “The idea is to create something useful in our current energy infrastructure.”

Currently, Spormann and Logan are working on cultivating the methanogens and optimizing the process. They are trying to engineer the system to maximize its effect and understand the fundamentals of the process.

“We need to understand the fundamental science behind the process and then see how we can scale it up to a process where we can produce cubic meters of methane every day,” Spormann said.

Logan emphasizes the need to build on their research before renewable methane becomes a part of our everyday lives.

“We know how to [create carbon-neutral methane], but we don’t know how to economically do it or how to optimize the process,” Logan said. “We need to make it work better and we need to make it work cheaper. We need to make this inexpensive and useful.”

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