Giant planet landing on a giant planet may or may not be possible, depending on the size and composition of its core. Gas giants consist mostly of hydrogen and helium. The Solar System's gas giants, Jupiter and Saturn, have heavier elements making up between 3 and 13 percent of their mass. Gas giants are thought to consist of an outer layer of molecular hydrogen, surrounding a layer of liquid metallic hydrogen, with a probable molten core with a rocky composition. Jupiter and Saturn's outermost portion of the hydrogen atmosphere has many layers of visible clouds that are mostly composed of water and
Power-to-gas produce hydrogen. This microbial power-to-gas reaction occurs at ambient conditions, i.e. room temperature and pH 7, at efficiencies that routinely reach 80-100%. However, methane is formed more slowly than in the Sabatier reaction due to the lower temperatures. A direct conversion of CO to methane has also been postulated, circumventing the need for hydrogen production. Microorganisms involved in the microbial power-to-gas reaction are typically members of the order "Methanobacteriales". Genera that were shown to catalyze this reaction are "Methanobacterium", "Methanobrevibacter", and "Methanothermobacter" (thermophile). The synthetic methane generated from electricity can also be used for generating protein rich feed for cattle,