The volume of energy that is stored in methane hydrate deposits exceeds that of the world's coal, oil, and conventional natural gas combined.    Estimates are that twice as much  energy is available from methane hydrates as all of the world’s coal, oil, and conventional gas resources.  It may take 30-50 years before we see significant worldwide energy coming from methane hydrate as most is in deep marine environments beneath the ocean floor and methane hydrate occurs as a solid.  Countries with pressing economic and/or political motivations could begin mining within 10 years.  There could be border disputes on mining fields due to the high cost of energy.  As we move through coal we will begin to get our energy from methane hydrate as new robot mining methods are developed.    

Worldwide Estimates of Gas Hydrates:  cubic feet

Oceanic: 30,000 to 49,100,000 x 10¹²
Continental: 5,000 to 12,000,000 x 10¹²
 

Methane Hydrate Map

Blake Ridge Estimates

CRS  Report to Congress