Drill for it and use it.
Make a car that runs off methane.
We have done some test drilling on the Alaskan North Slope.
The problem is you not only need to reach it, you need to get the ice crystals to release it.
http://www.freerepublic.com/focus/f-news/1787903/posts
It will be done, but the most economical method it still being researched.
More recent update
Gas-hydrate tests to begin in Alaska
http://www.freerepublic.com/focus/f-news/2833971/posts
13 January 2012