Minnesota imports most of the oil and natural gas that helps drive our economic engine from Canada, the Saudi Arabia of the north.

"And you don't need a U.S. battle group to protect it," Ronald Liepert, the Alberta oil minister, reminded me last week on a visit to Minneapolis.

Canada, largely because of Alberta's vast deposits of oil sands, has the second-largest known oil reserves in the world.

Our No. 1 trading partner to the north, which also is a healthy democracy and buys $4 billion-plus worth of Minnesota goods annually, provides about a 25 percent of the more than 12 million barrels per day of imported oil that Americans consume.

Canada, through its western oil sands, is increasing daily production from 2 million to 3 million barrels over the next several years. Although it doesn't bear the higher risks of deep-water drilling in the Gulf of Mexico, tar sands production still presents significant environmental concerns.

That's why Liepert and Alberta's top diplomat in Washington, Gary Mar, are part of a Canadian offensive to address concerns in America about those "dirty tar sands" that critics say are an environmental disaster. The thick bitumen must be heated with steam from natural-gas fired boilers in order to strain the thick oil and send it by pipeline to our Pine Bend or other U.S. refineries.

This is also a huge issue for Prime Minister Stephen Harper, whom one Canadian opinion writer recently said "seems hell-bent in exploiting our natural resources for economic gain, regardless of the environmental consequences."

These arguments frame critical pipeline discussions now underway between Canada and the United States amid the continuing discussion over cutting our carbon emissions and making progress on gradually reducing our oil use.

The Canadians make a solid case for their oil exports, producing statistics that demonstrate the "life-cycle" emissions from Alberta crude are less than emissions from Middle Eastern or Nigerian crude. The reasons? The tar-sands extraction process is getting more efficient. And shipping the oil through a pipeline is a lot less polluting than hauling it aboard diesel-powered super tankers from the other side of the world.

Moreover, Canada is committed to cutting carbon emissions by nearly 20 percent by 2020 from 2005 levels. And they detailed the extensive efforts to return the sands to their original state after mining, and to curb water usage and pollution.

Alberta already has a carbon tax of $15 per ton that funds environmental remediation. And the oil sands harvesting area, home to an estimated 170 billion barrels of proven reserves, is about half the size of Hennepin County in a province about the size of Texas.

Environmentalists argue that Canada is spoiling its land and our environment and that we should move more quickly to oil alternatives.

The experts at the Minneapolis-based Great Plains Institute try to find common ground among stakeholders in accelerating to a cleaner, more secure energy future.

Brendan Jordan, a scientist who heads the institute's bio-energy and transportation section, said Canadian tar sands are more polluting that conventional oil extraction.

"It feels in a way that we're devoting a lot of time to which oil is best," said Rolf Nordstrom, the institute's executive director. "It's like deciding whether smoking or drinking is better for you, when less of both is what you really need."

Great Plains is pushing for next-generation fuel sources, beyond corn ethanol, and also championing efforts to use waste carbon from U.S. coal-fired power plants to be pumped into partially depleted underground oil fields around this country.

"Enhanced oil recovery can increase our U.S. proven reserves by three to five times," Nordstrom said. "And this leaves the polluting carbon dioxide buried in the ground" instead of out the smokestack to pollute.

It's going to take time as we transition to more efficient vehicles, cleaner fuels, electric- and natural gas-powered transport and other measures that will result in a cleaner, more powerful, job-producing American economy that doesn't spend $400 billion annually for imported oil.

In the meantime, we also are going to need that Canadian crude. The Canadians have already committed to a carbon cap; Alberta has a carbon tax to fund environmental remediation. A cap or a tax on carbon pollution in the United States would spur us to cut emissions, not just for environmental but also for economic and efficiency reasons.

Unless you like being held hostage to foreign oil producers, that's the conservative and smart way to go.

Neal St. Anthony • 612-673-7144 • nstanthony@startribune.com