VATIS UPDATE Article

An international team of researchers has taken the first step in converting methane directly to electricity using bacteria, in a way that could be done near the drilling sites. “Currently, we have to ship methane via pipelines,” said Thomas K. Wood, holder of the biotechnology endowed chair and professor of chemical engineering, Penn State. “When you ship methane, you release a greenhouse gas. We can’t eliminate all the leakage, but we could cut it in half if we didn’t ship it via pipe long distances.”

The researchers’ goal is to use microbial fuel cells to convert methane into electricity near the wellheads, eliminating long-distance transport. That goal is still far in the future, but they now have created a bacteria-powered fuel cell that can convert the methane into small amounts of electricity.

The researchers created a consortium of bacteria that produces electricity because each bacterium does its portion of the job. Using synthetic biological approaches, including DNA cloning, the researchers created a bacterium like those in the depths of the Black Sea, but one they can grow in the laboratory. This bacterium uses methane and produces acetate, electrons and the energy enzyme that grabs electrons. The researchers also added a mixture of bacteria found in sludge from an anaerobic digester — the last step in waste treatment. This sludge contains bacteria that produce compounds that can transport electrons to an electrode, but these bacteria needed to be acclimated to methane to survive in the fuel cell. They report the results of their work today (May 17) in Nature Communications.

Once electrons reach an electrode, the flow of electrons produces electricity. To increase the amount of electricity produced, the researchers used a naturally occurring bacterial genus — Geobacter, which consumes the acetate created by the synthetic bacteria that captures methane to produce electrons.

To show that an electron shuttle was necessary, the researchers ran the fuel cell with only the synthetic bacteria and Geobacter. The fuel cell produced no electricity. They added humic acids — a non-living electron shuttle — and the fuel cells worked. Bacteria from the sludge are better shuttles than humic acids because they are self-sustaining. The researchers have filed provisional patents on this process.