Locked up in icy molecular cages hundreds of metres beneath the world’s permafrost and continental shelves is energy’s last frontier: enough clean-burning gas to power the entire planet for a century or two. Graham Chandler explores burning questions surrounding the planet’s most abundant clean hydrocarbon.

Gas hydrates are slushy, dry, ice-like solids made up of molecules of primarily methane (main constituent of natural gas) captured inside cages of water molecules under unique conditions of high pressure and low temperature. Production would be a massive prize – and for hundreds of scientists that’s the big challenge.

Hydrates are so abundant that even conservative estimates have pegged them to easily exceed the total amount of all forms of conventional hydrocarbons combined, including coal, oil and natural gas – 300,000 trillion cubic feet (tcf). To put that into perspective, total known conventional natural gas resources remaining in the Western Canadian Sedimentary Basin are less than 60 tcf. Gas hydrates have the potential to wipe out the planet’s energy supply worries for centuries. And if hydrates were used to replace sources like coal, greenhouse gas emissions would be reduced substantially.

Huge hurdles bar the way to large-scale production. A real understanding of how to handle hydrates is now just emerging. Intensive research is occurring in both the Mackenzie Delta and the Alaskan North Slope, not to mention in countries with substantial hydrate deposits but few other indigenous energy resources, such as India, China, Japan and South Korea. Challenges include production technology and transport infrastructure.

Producing hydrates is theoretically simple: decrease pressure or increase temperature, as these are the two variables that lock them together. The first option, decreasing pressure, is likely the first approach, but how you go about this depends on the formation.

“When you talk about hydrates they are of basically two forms,” explains Mike Dawson, president of the Canadian Society for Unconventional Gas (CSUG). “Those where the entire pay zone is hydrates, and the other are fields that are well defined and have a hydrate cap with a gaseous gas cap underneath.”

The latter can be produced with today’s technology. “You could drill a well through the hydrate solid and produce that conventional gas cap. As you depressurize the gas cap underneath, you’re changing the pressure/temperature conditions, leading to more dissociation of the hydrate in the solid. In other words, the hydrates turn into a gas and recharge the reservoir down below. The technology for that is here today.” True, but nobody has tried it yet.

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