CALGARY — Alberta's oilsands will allow the province to become a superpower energy producer, retired U.S. Federal Reserve chairman Alan Greenspan told an audience of business and energy leaders on Friday.

"We in the United States trust you,'' Greenspan told 2,500 people who each paid $300 to listen to him in a question and answer session. "When you sign a contract, it doesn't have a Russian signature on it.''

Greenspan's reference to Russia, which before the collapse of the Soviet Union was the arch rival of the United States, reflects its emergence as the biggest oil and gas exporter that's not part of the OPEC oil cartel.

Canada is already the top exporter of petroleum products to the United States, followed by Mexico and Saudi Arabia. Each of the three countries exported more than 1.25 million barrels per day of crude oil to the United States in the first six months of 2006.

It was Greenspan's first speaking engagement in Canada since retiring on Jan. 31 after more than 18 years at the helm of America's central bank. At 80, the retired economist is still considered to be a leading authority on American domestic economic and monetary policy.

He noted that getting crude oil out of the oilsands bitumen is still a complicated process: "You're using a lot of natural gas to create heat to get the crude out of the sands.

There is also a severe shortage of refineries in the United States which will take years to solve, he said.

But Greenspan said the rising price of oil has caused the U.S. to look more closely at new technology and alternate fuel sources such as corn ethanol -- and that may impact Alberta in the future.

"There is a possibility ... that the United States may finally be weaning itself off petroleum products,'' said Greenspan, noting that one of every seven barrels of the world's crude oil is consumed on U.S. highways.

Still, he said any change will take a long time.

"If you took all the corn we grow and put it into ethanol, it could create 3.5 million barrels a day -- we use three times that,'' he said.

That leaves the door open to change if alternate fuel sources are developed.

"If we can (reduce) that 11 million (barrels) a day, we can take a big chunk out of the world consumption,'' he said.

Greenspan said while he accepted the impact that greenhouse gas emissions have had on global warming and the climate, he said moves to legislate reductions in energy use -- such as the Kyoto protocol -- won't work in a world that operates through free market opportunties.

"The people in charge of these limits are only looking at one side of the issue,'' he said. "It reduces pollution but it does other things, too. As soon as you put a cap on uses of energy, you get job losses and sharp (price) increases.''