New oilsands extraction method could eliminate tailings ponds (5/4/2008)

Selma Guigard holds raw oilsands in one hand and a tube filled with glass beads and bitumen extracted from oilsands using a new waterless method she is developing.

A University of Alberta engineering professor is researching a new method of extracting bitumen from oilsands that uses almost no water and would solve the industry's toxic tailings ponds dilemma.

Selma Guigard, in the Department of Civil and Environmental Engineering, is developing an extraction method that uses carbon dioxide and solvents other than water to flush bitumen from oilsands. By comparison, the hot-water extraction method presently used to mine northern Alberta's oilsands uses approximately three barrels of water to produce one barrel of oil.

One byproduct of the hot-water extraction technique is tailings ponds, which contain toxins like heavy metals, and oil. The Syncrude tailings ponds made international headlines this week when some 500 ducks died after landing in one of the ponds.

"I am doing this research because I want to get rid of the tailings ponds, because I want industry to use less energy in mining the oilsands, and I want them to draw less water from the Athabasca River," said Guigard.

"The recent event of 500 ducks landing on a tailings pond in northern Alberta enforces the fact more research needs to happen to develop new waterless extraction technologies that would avoid creating these tailings ponds."

Guigard says her experimental technique is similar to the process used to make decaffeinated coffee.

"I know it is a different scale, but we've got to be able to do something with the oilsands," she said.

In applying the method, Guigard mixes carbon dioxide and other solvents with raw oilsands, then heats and pressurizes it. Under pressure, carbon dioxide becomes a "supercritical fluid" that is neither liquid nor gas.

"It isn't a gas and it isn't a fluid-it has the best qualities of both," Guigard said. "It behaves like a liquid solvent but it also penetrates things even better than a gas can; it moves into nooks and crannies and gets at things you couldn't get at with a conventional solvent."

Once the new C02-based "solvent" permeates the oilsands sample, the mixture is depressurized and the bitumen separates naturally from the solvent, which is recycled to separate the next batch of oilsands.

"People say 'You're using C02, and that's a greenhouse gas' but we're recycling it, and we aren't generating any C02," said Guigard.

While the process might require some water to transport oil sands in pipelines to the extraction process, Guigard says it's possible that water from the existing tailings ponds could be used, eliminating the need to draw on freshwater resources.

Guigard added that she has been able to successfully extract bitumen from the oil sands and expects that she will be able to extract as much or more than hot-water separation methods do. She estimates that, on a large scale, her extraction process would probably cost about $20 per barrel, "which is in the ballpark of what is going on right now."

The engineering professor is currently applying for funding to conduct her research on a larger scale. And she stresses that it would be unreasonable to expect industry to adopt new techniques overnight.

"The challenge is that there is such an infrastructure up there right now," she said. "It would be a big change but I'd like to see it brought in on a parallel system. I'm saying that 10 years down the road I'd like to see a pilot program operating. But who knows, maybe things could go faster."

Note: This story has been adapted from a news release issued by the University of Alberta

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