And we've hardly gotten to the really ingenious part yet. While the rock is cooking, at about 650 or 750 degrees Fahrenheit, how do you keep the hydrocarbons from contaminating groundwater?

Why, you build an ice wall around the whole thing. As O'Connor said, it's counterintuitive.

But ice is impermeable to water. So around the perimeter of the productive site, you drill lots more shafts, only 8 to 12 feet apart, put in piping, and pump refrigerants through it. The water in the ground around the shafts freezes, and eventually forms a 20- to 30-foot ice barrier around the site.

Next you take the water out of the ground inside the ice wall, turn up the heat, and then sit back and harvest the oil until it stops coming in useful quantities. When production drops, it falls off rather quickly. That's an advantage over ordinary wells, which very gradually get less productive as they age.

Then you pump the water back in. (Well, not necessarily the same water, which has moved on to other uses.) It's hot down there so the water flashes into steam, picking up loose chemicals in the process. Collect the steam, strip the gunk out of it, repeat until the water comes out clean. Then you can turn off the heaters and the chillers and move on to the next plot (even saving one or two of the sides of the ice wall, if you want to be thrifty about it).

Most of the best territory for this astonishing process is on land under the control of the Bureau of Land Management. Shell has applied for a research-and-development lease on 160 acres of BLM land, which could be approved by February. That project would be on a large enough scale so design of a commercial facility could begin.

The 2005 energy bill altered some provisions of the 1920 Minerals Leasing Act that were a deterrent to large-scale development, and also laid out a 30-month timetable for establishing federal regulations governing commercial leasing.

Shell has been deliberately low-key about its R&D, wanting to avoid the hype, and the disappointment, that surrounded the last oil-shale boom. But O'Connor said the results have been sufficiently encouraging they are gradually getting more open. Starting next week, they will be holding public hearings in northwest Colorado.

I'll say it again. Wow.

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Linda Seebach is an editorial writer for the Rocky Mountain News. Contact her at rockymountainnews.com.