Freeze it, ship it & forget it

Storing and shipping natural gas by trapping it in ice--using technology being developed by researchers at the U.S. Department of Energy--could cut shipping costs for the fuel, making it easier for countries to buy natural gas from many different sources, and eventually leading to more stable supplies worldwide.

The technology traps natural gas in the form of methane hydrate, in which methane, the main component of natural gas, is confined within cage-like ice crystals.

Conventional technologies for making methane hydrate take hours or days: they involve mixing water and the hydrocarbon in large pressurized vessels. The new approach forces water and methane through a specially designed nozzle that creates the methane hydrate "almost instantaneously," says Charles Taylor, the lead researcher on the project at the DOE's National Energy Technology Laboratory in Pittsburgh. As the mixture exits the nozzle, it quickly forms hydrate, which looks like snow.

Making methane hydrate involves mimicking the high pressure and low temperatures at which it forms in nature, typically deep under the ocean. (Huge reserves of methane hydrate exist in places such as the Alaskan North Slope, both threatening to become another source of greenhouse gases and potentially offering a huge source of natural gas.)

Once the ice crystals form, they keep the methane confined even if the surrounding pressure is lowered, so the methane hydrate can be shipped at atmospheric pressure as long as it's kept frozen. The snow-like hydrate can be packed into cubes and loaded into the refrigerated ships, boxcars, and trucks now used to ship frozen food at -10 °C. That temperature is far easier and cheaper to manage than the -162 °C required for LNG. While the methane hydrate can burn, the methane is released slowly enough that it's not explosive.

Now that's smart thinking for you. Transport costs and leaks are among the major concern of gas supplies.