26 September 2012 – Scientists from Stanford and Pennsylvania State universities have discovered a process to convert electricity into methane, the main constituent of natural gas, using microbes. The fuel is carbon neutral and can use the excess electricity from renewable sources.
The carbon for the methane comes from atmospheric CO2 which means that methane which is produced by the microbial electro synthesis is essentially carbon neutral.The electricity comes from clean energy like wind and solar that would otherwise be lost. Wind farms and solar photovoltaic power plants often produce more electricity than can be used or stored. This microbial technology could turn that excess electricity into useable fuel.
As electricity flows through the cathode, the microbes pick up the electrons and metabolise them, releasing methane as a by-product. Bruce Logan, a professor of civil and environmental engineering at Penn State, was the first to demonstrate the process in a lab, using a methanogen called methanobacterium palustre. The microbes were spread on a cathode that was then submerged in nutrient-rich water. When an electrical current was applied, the microbes began producing methane at an 80% efficiency rate.
But while researchers have successfully converted electricity to methane in the lab, there are still gaps in their understanding before they can take this technology to a larger scale. This includes how the enzymes are controlled and what makes this process stable and scalable.
The ultimate vision is for large-scale application of the technology, with microbe cultures churning out methane that can be stored, channelled to various locations using existing natural gas pipelines, and used to fuel everything from airplanes to cars.
A working prototype is expected within a few years.