Prospectors have known about the oil shale deposits in the Rockies for more than a century, but the technology to extract it has remained imperfect, expensive and polluting.
A variety of experimental methods have been developed. Although details are closely held, the broad outlines are similar.
Shell has the most mature technology, which it has been experimenting with at its Mahogany test site, near Rifle, Colo. Tucked into a rolling landscape of empty range land, the company has sunk heaters half a mile into oil shale seams and subjected the rock to 700-degree temperatures. Over weeks or even months, a liquid known as kerogen is produced, which can be refined into diesel and jet fuel.
To prevent the brewing hydrocarbons from spoiling groundwater, the heated rock core is surrounded by 20-to-30-foot-thick impermeable ice walls, frozen by electric refrigeration units.
Other companies' methods are more akin to open pit mining, in which millions of tons of rock are excavated and then fed into a massive above-ground cooker.
All of the processes require prodigious amounts of water, either for the electrical plants needed for heating and freezing or for the web of industrial facilities needed to extract the oil.
But for all the years of research into oil shale extraction, there is little hard information on exactly how much water would be drained from the region.
In its recent environmental review of proposed oil shale projects, the federal Bureau of Land Management, which oversees energy leasing on public lands, was unable to estimate the industry's region-wide water use.
Mike Vanden Berg, the Utah Geological Survey's principal researcher for oil shale projects, said, "I still don't know how much water is used. . . . No one does."
Meanwhile, already- parched Western states bracing for more growth are completing water supply inventories. A Colorado study projected that by 2050, with the state's oil shale operations at full capacity, the industry will require 14 times more power than currently generated by the state's largest power plant.
The study's sobering bottom line is that meeting oil shale's energy demands could require more water than Colorado is entitled to under an interstate compact.
"Can groundwater be protected?" asked Harris Sherman, executive director of the Colorado Department of Natural Resources. "Areas where this technology will be used are all tributaries for the headwaters for all of the seven Colorado Basin states."
