Growing estimates of natural gas resources, including a new category of ?unconventional? gas, suggest that accessible supplies of this least carbon-intensive of the fossil fuels may be far more abundant than previously assumed.

The world is now in the early stages of an energy revolution that over the next few decades could be as momentous as the emergence of oil-and electricity-based economies a century ago. Double-digit market growth, annual capital flows of more than $100 billion, sharp declines in technology costs, and rapid progress in government policies all herald a promising new energy era.