There has not been a major find on U.S. soil since Prudhoe Bay in 1968, which means most major exploration has moved to the deep waters of the Gulf of Mexico, where drilling and production are difficult and expensive. Last year, a Chevron-led consortium announced the discovery of the Jack field, 270 miles off Louisiana. It may hold 15 billion barrels, which would more than double domestic reserves. "The technology that is being brought to bear is phenomenal," says energy writer Robert Bryce, author of Gusher of Lies. "What we are seeing today in offshore drilling is the terrestrial version of the space program." Bryce is among those pushing to open offshore leases along the East and West coasts currently under federal moratorium but estimated to hold as much as 19 billion barrels of oil and 86 trillion cu. ft. of natural gas.

Tapping vast unconventional sources that don’t flow to the surface is also hugely challenging. The oil sands of Alberta, Canada, contain 175 billion barrels of proven reserves—the largest in the world outside Saudi Arabia—but the oil costs as much as $15 per barrel to produce, compared to $2 for Saudi crude. Likewise, shale deposits in Colorado, Utah and Wyoming hold promise, but no one has yet figured out how to extract them at a profit. Royal Dutch Shell has placed a $200 million bet that it can unlock Colorado’s Green River Formation, which could produce 4 million barrels per day—20 percent of current U.S. consumption.