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Methane-Producing Microbes as New Source of Renewable Energy


Researchers from Stanford and Penn State are studying microbes that can convert carbon dioxide to methane using electricity. These microbes could be potential sources of renewable energy.

Methane is the main component of natural gas, which is a fossil fuel. Many organic compounds used in industry are derived from fossil fuels. The goal of the researchers is to create large microbial factories to produce methane and other valuable chemical compounds using electricity derived from solar, wind and nuclear power.

Alfred Spormann, professor at Stanford, says burning methane produced by these microbes, called methanogen, do not contribute to atmospheric carbon dioxide. The microbes use CO2 from air to form methane, hence, burning the fuel just returns the extracted gas. Whereas burning fossil fuels release CO2 previously trapped underground for millennia.

According to Bruce Logan, professor at Penn State, there are considerable obstacles that prevent the commercialization of this electricity-to-methane technology. Chief among them is the poorly understood mechanism of how these microbes convert electrical energy to chemical energy.

In an ideal situation, excess electricity from renewable sources would be used by methanogens in bioreactors to produce methane gas. The gas would be stockpiled and distributed via existing pipelines to fuel airplanes, ships and vehicles.

Methane from microbes is more ecofriendly than other biofuels produced from feedstock like corn ethanol. It does not compete with food production and other agricultural resources like land, irrigation and fertilizers.

The ability of a methanogen strain known as Methanobacterium palustre to convert electrical current into methane was discovered in 2009 by Logan’s research team. In their experiment, Logan and his colleagues built a reverse battery whose electrodes were dipped in beakers containing the microbes. Logan reported that the microbes successfully converted 80 percent of the electricity into methane.

Logan and his team in Penn State are continuously designing and testing different cathode technologies that will promote the growth of methanogens and maximize methane output. The researchers are also looking at new electrode materials that could replace platinum and other precious metal catalysts.

Logan says many of these materials have already been studied in bacterial system, but not with methanogens or other archaea. Their research group is looking for a cost-effective system that efficiently and robustly produces methane from clean energy. The research is risky, but the results will be rewarding, as new technologies are needed for energy storage and for synthesis of useful organic compounds without fossil fuels.

The Global Climate and Energy Project at Stanford funds this project.

[via eurekalert]

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