Methane hydrates – a crystalline form of methane gas and pure water that exists when pressures are sufficiently high, or temperatures sufficiently low. If you manage to keep that pressure high or that temperature low, it looks like a lump of ice. There are mega-tons of the stuff at the bottom of the ocean all over the world and in the Arctic permafrost (about 300,000 trillion cubic feet of it) and it is the cleanest and most abundant source of energy in the world. There is at least twice as much of it around as fossil fuels (some say 10 times as much). And, when burned as a fuel, it releases less carbon dioxide pollution than anything else around.
So why aren’t we using it?
Plain and simple, methane hydrates are hard to get at, and once gotten at, hard to transport. Its crystalline form will change to gas when pressures are lowered, or temperatures rise (like when it’s brought to the sea surface) and in doing so it will expand 164 times, representing definite storage and transport issues.