The rat’s nest of pipes and columns snaking across the desert harbors a secret process that will use cobalt to turn natural gas into a powerful, clean-burning diesel fuel.

By next year, rulers of this tiny desert sheikdom hope, these gas-to-liquids (GTL) reactors under construction will bring in billions of dollars while clearing big city smog belched by trucks and buses.

Petroleum experts who have sniffed vials of gin-clear GTL diesel speak of it with reverence.

“It’s a beautiful product,” says Jim Jensen, a Massachusetts-based energy economist. “The kerosene smells like perfume.”

In all, some $20 billion has been committed to build an unprecedented array of clean diesel plants in this Gulf shore industrial park.

Those chipping in include oil titans Royal Dutch/Shell Group, ChevronTexaco Corp. and Exxon Mobil Corp., which is making a $7 billion bet on GTL, the largest investment in the corporate history of America’s largest company.

Smaller plants in Malaysia, South Africa and the United States have proved the technology works, but none is nearly as large as those planned here. In a few years, says Andy Brown, who heads Shell’s office in Qatar, the country will be “the GTL capital of the world.”

“This really is where GTL will come of age, where the industry will be born,” he said.

By 2011, the Qatar plants should be producing 300,000 barrels of liquid fuels and other products daily. The largest GTL plant now producing is Shell’s plant in Bintulu, Malaysia, churning out 14,700 barrels per day.

The investments amount to a big gamble on a clean alternative to pollutant-rich crude oil, based on an obscure “synthetic fuel” process developed to make fuel from coal in 1920s Germany.

Like Qatar’s headlong rush to produce liquefied natural gas, the ruling sheiks here are pushing GTL as an idea whose time has come.

The clean-burning fuel, with almost none of the smelly sulfur soot belched by engines firing on conventional diesel, appears tailor-made for countries looking to reduce emissions in line with the Kyoto Protocol on global warming.

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