With oil at $90/barrel, turning oil shale into fuel is a bright idea. Those evil oil companies are busy investing millions to make it work.

Above northwestern Colorado’s rolling hills studded with piñon, juniper and sagebrush rises a maze of giant pipes and frost-covered tubes that circle a football-sized testing site and plunge into wells bored a quarter-mile into the pale rock below.

A refrigeration and pump unit the size of a warehouse pumps cooling fluid into the wells in an effort to turn the groundwater into walls of ice that will line the holes.

These ice walls are a centerpiece of Shell Exploration and Production’s attempts to convert the rock that underlies this region into fuel. Using a mixture of heat and ice, it’s one of three companies attempting to develop oil shale.

“If it’s a total failure, which is hard to comprehend, I’d say we’d have to step back and reconsider what we’re going to do,” said Tracy Boyd, communications and sustainability manager for Shell.

Unlike past attempts to unleash the energy potential locked in oil shale, which involved open pit mining and baking out the petroleum liquid called kerogen, Shell, like most other companies pursuing oil shale, is considering an “in situ” process that would drop long heating units into wells, some 3,000 feet deep, heat the rock to 650-750 degrees for about three years, then pump out the kerogen, which could be used for gasoline, diesel and jet fuel.

Chevron and EGL Resources are also pursuing oil shale in the region using the federal program, but Shell may be alone in its hope to use freeze walls, meant to line the wells, keep groundwater out of the wells and keep the fuel out of groundwater.

Just how much oil is in the rock?

The federal government estimates as much as 1.8 trillion barrels of oil could lie in a region that reaches into Utah and Wyoming. But the vast majority of it lies in western Colorado’s Piceance Basin. That’s equal to world oil supplies, or as Jerry Boak, of the Colorado School of Mines, puts it, as much oil as has ever been consumed.

“It’s just a huge, huge resource,” Boak said.

Federal estimates suggest maybe 800 million barrels could be recoverable, the equivalent of 110 years of domestic energy, based on current consumption.