Microbes convert energy to pure methane

Microbes that convert electricity into methane gas have been discovered by scientists from Stanford and Penn State universities.

Researchers at both universities are raising colonies of microorganisms — methanogens — with the ability to turn electrical energy into pure methane, the key ingredient in natural gas.

“Most of today’s methane is derived from natural gas, a fossil fuel,” said Alfred Spormann, professor of chemical engineering and civil and environmental engineering at Stanford.

“And many important organic molecules used in industry are made from petroleum. Our microbial approach would eliminate the need for using these fossil resources.”

The researchers envision large bioreactors filled with methanogens – single-cell organisms that produce methane.

In 2009, Logan’s lab was the first to demonstrate that a methanogen strain known as Methanobacterium palustre could convert an electrical current directly into methane.

For the experiment, Logan and his Penn State colleagues built a reverse battery with positive and negative electrodes placed in a beaker of nutrient-enriched water.

“The microbes were about 80 percent efficient in converting electricity to methane,” Logan said.

At Penn State, Logan’s lab is designing and testing advanced cathode technologies that will encourage the growth of methanogens and maximize methane production.

The Penn State team is also studying new materials for electrodes, including a carbon-mesh fabric that could eliminate the need for platinum and other precious metal catalysts.

“While conceptually simple, there are significant hurdles to overcome before electricity-to-methane technology can be deployed at a large scale,” said Bruce Logan, Evan Pugh Professor and Kappe Professor of Environmental Engineering, Penn State.

“That’s because the underlying science of how these organisms convert electrons into chemical energy is poorly understood.”