Courtesy United States Geological Survey
Huge amounts of methane are being found on the ocean floor, trapped within cages of water molecules.
Methane clathrate, also called methane hydrate or methane ice, is a solid form of water that contains a large amount of methane within its crystal structure (a clathrate hydrate). wikipedia
Geologists estimate that significantly more hydrocarbons are bound in the form of methane hydrate than in all known reserves of coal, natural gas and oil combined. India and China plan to spend hundreds of millions of dollars learning how to tap into this huge reservoir of energy (Spiegel online).
Relying on this carbon based energy instead of renewable energy sources could worsen global warming by releasing more greenhouse gases. To be carbon neutral the carbon dioxide from burning carbon fuels needs to be captured and sequestered (locked up). Harvesting methane ice offers just this opportunity.
When a certain amount of pressure is applied to the cage-like crystal structure, carbon dioxide can penetrate the layer of ice, at which point it displaces the methane. Then a new cage of frozen water molecules forms around the carbon dioxide. Klaus Wallmann, Uni Kiel
Wallman is also impressed by the ratio at which the gases are exchanged. For each dissolved molecule of methane released, up to five molecules of carbon dioxide disappear into the ice cage. Wallmann hopes to see, in the not-too-distant future, tankers filled with CO2 heading out to sea to pump their climate-damaging cargo into the depths.
You might also read about research being done at Columbia University, "Carbon Neutral Methane Production Via Hydrates".