We all know most of world’s greatest inventions have been made by mistake. A team of researchers from the Penn State, led by Bruce E.Logan, Kappe Professor of Environmental Engineering, discovered how to produce methane from water and carbon dioxide. Here’s what he says: “We were studying making hydrogen in microbial electrolysis cells and we kept getting all this methane. We may now understand why.”
They discovered a microbe that produces that methane, more than expected under normal circumstances, by adding a small voltage on their testing solution. The microbe is called Archaea, and it can convert CO2 and water to methane without any other organic material, bacterial or hydrogen normally found in microbial electrolysis cells.
Logan, working with Shaoan Cheng, senior research associate; Defeng Xing, post doctoral researcher, and Douglas F. Call, graduate student, environmental engineering, confirmed that the microscopic organisms produced the methane. The researchers created a two-chambered cell with an anode immersed in water on one side of the chamber and a cathode in water, inorganic nutrients and carbon dioxide on the other side of the chamber. They applied a voltage, but recorded only a minute current. The researchers then coated the cathode with the biofilm of Archaea and not only did current flow in the circuit, but the cell produced methane.
“The only way to get current at the voltage we used was if the microbes were directly accepting electrons,” said Logan. He notes that the electrochemical reaction takes place without any precious metal catalysts and at a lower energy level than converting carbon dioxide to methane using conventional, non-biological methods.
The whole system has about 80 percent efficiency, and if the electricity is derived from renewable and carbon-free sources like the Sun and the wind, then the process as a whole would be carbon-neutral, because when burned, the methane’s CO2 output would match the CO2 input of the producer. The only problem would be that the burning would take place far from where it has been produced, but integrated on a larger scale, it’s the same.
Methane is preferred to hydrogen, at least economically, because an infrastructure of transporting it already exists all over the world.
