New research from Woods Hole Oceanographic Institution (WHOI) published Aug. 19, 2019, in the Proceedings of the National Academy of Science provides evidence of the formation and abundance of abiotic methane—methane formed by chemical reactions that don't involve organic matter—on Earth and shows how the gases could have a similar origin on other planets and moons, even those no longer home to liquid water. Researchers had long noticed methane released from deep-sea vents. But while the gas is plentiful in the atmosphere where it's produced by living things, the source of methane at the seafloor was a mystery.
source https://phys.org/news/2019-08-massive-methane-reservoir.html