Trapped beneath the permafrost, and under the deep ocean floor that surrounds continents, is enough natural gas to power humankind for thousands of years.

This natural gas, mostly methane, is frozen in water in a form we call methane hydrates. The methane came from decaying organic matter or migrated up from deeper natural gas deposits, and was then trapped in very high concentrations in frozen layers of sediment at high pressures.

When brought to the surface, the hydrates melt, releasing around 160 times their volume in natural gas.

This sounds like a very promising energy source, and companies and countries, especially those with limited resources like Japan, are trying to recover the gas.

But test plants have produced very little. This is partly because processing methane hydrates is a new and difficult engineering challenge. And partly because we know very little about them.

To study methane hydrates, scientists have built special high-pressure, low-temperature labs, where they can be kept in their frozen state.

One innovative project in Alaska is trying to pump in liquid CO2 under high pressure to liberate the gas. If successful, this new process could make methane hydrate deposits not just an energy source but a place to sequester carbon.

Eventually, engineers will probably figure out cost-effective, low-impact ways to produce methane from methane hydrates—one more reason that natural gas will likely play a larger role in our energy future.