JUNEAU, Alaska (AP) - The U.S. Energy Department is excited about what it calls unprecedented tests on Alaska's North Slope that produced a steady flow of gas from methane hydrates.

These are structures that look like ice but have natural gas locked inside.

The department says they're found onshore, including in the Arctic permafrost, and offshore, in ocean sediments along nearly all continental shelves worldwide. It sees methane hydrates as an untapped resource that holds great potential for U.S. economic and energy security.

The department worked with ConocoPhillips and Japan Oil, Gas and Metals National Corp. to test gas extraction using technology developed by ConocoPhillips and the University of Bergen, Norway.

Department spokesman Bill Gibbons says while this was an experiment, and work is still early, the department is excited about the future potential.