"Researchers at Penn State University, led by Dr. Bruce Logan,
have found that methane can be directly produced using a
biocathode containing methanogens in electrochemical systems
(abiotic anode) or microbial electrolysis cells (MECs; biotic
anode) by a process called electromethanogenesis."

Link:

http://www.greencarcongress.com/2009/03/researchers-show-direct-bacterial-production-of-methane-from-electricity-and-co2.html#more

Best Wishes,
--
Gabriel Espinosa