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Kai Ryssdal: The higher oil prices go, of course, the more creative engineers get about getting it out of the ground. Deep sea oil rigs today can withstand as much as 40,000 feet of water pressure -- that's deeper than the oceans actually go, by the way.
But hard-to-reach reserves exist on land as well. There's oil to be had in the sands of Alberta, Canada, and in the Rocky Mountains of the Amercan West.
Janet Babin reports from the Marketplace Innovations Desk on the latest energy source that's getting some attention.
Janet Babin: It may be the largest untapped source of oil in the world, located in Colorado, Utah and Wyoming.
Interior Secretary Dirk Kempthorne described its potential:
Dirk Kempthorne: This area's estimated to contain as much as 800 billion barrels of oil, 72 percent of which is located on federal lands.
That's enough to meet current U.S. oil demand for 110 years. But this oil is trapped inside oil shale, a brownish rock -- fossilized algae really.
Adam Brandt studies oil shale at the University of California at Berkeley.
Adam Brandt: From looking at it you wouldn't know that it was anything other than just a rock.
There is one easy way to tell oil shale from regular rock: Put a lit match to it
Brandt: It will burn. In power plants in some places, like Estonia, they burn it in place of coal.
But extracting the oil from the rock takes a lot more than just lighting a match. It's energy intensive and costly. You have to bake a ton of rock, to squeeze out just one barrel of oil.
John Reilly at MIT says the method also releases a lot of carbon dioxide, a greenhouse gas.
John Reilly: A lot of energy is used in the processing, so the CO2 emissions are about twice that of oil, so it's much dirtier even than coal.
But with oil prices spiking over $100 a barrel, at least five companies are researching cleaner and more efficient oil shale extractions.
Chevron has the most experimental approach. The company's shale manager Robert Lestz says his team uses chemicals to extract the oil. It injects a fluid -- a liquid form of CO2 -- into the rock.
Robert Lestz: The fluids that we're looking at using is the same type of fluid that now being used to remove caffeine from coffee.
Lestz says commercialization is at least 10 years out. Shell Oil's been conducting shale research more than two decades and has spent millions. It slow heats the rock for months to get at the oil. It freezes surrounding rock to protect ground water from nasty residue.
Brandt at UC Berkeley says the process shows promise.
Brandt: I've run the calculations on it. It seems like from an energetic perspective it's going to work. You get more energy out of the shale than you put into it.
Brandt also raises concerns about water contamination, but analysts think over time technology will solve these problems. And any oil shale developments on public lands would have to be vetted by the U.S. Environmental Protection Agency.
I'm Janet Babin for Marketplace.