Opening image: Methane clathrate (crystalline state). For clarity, only the first hydration shell is shown. spacefill.
Gas hydrates are macroscopic solids termed clathrates in which individual molecules of gas are trapped within a rigid hydrogen-bonded network of water molecules. Gases such as methane are actually hydrophobic, yet the hydrophobic guests are essential in stabilizing the overall structure. They are also of considerable industrial interest, as gas hydrate formation is a major cause of gas and petroleum pipeline blockages; also, there are vast deposits of naturally-occurring methane hydrate, and these could provide a major source of natural gas in the 21st century. Whether or not crystalline clathrates are relevant to the hydrophobic effect, their very existence has strongly influenced our views of how nonpolar solutes behave in water.