Professor, student work to bury CO2

Alex Robinson

Graduate student Melisa Pollak and assistant professor Elizabeth Wilson want the state to bury its carbon emission problems – literally.

The pair is trying to figure out a way to pump millions of tons of carbon dioxide – one of the greenhouse gases that damages the ozone layer and contributes to global warming – more than half a mile deep below the earth’s surface.

Once the carbon is pumped deep enough, it would be left there, ideally for millions of years.

But before carbon dioxide can be buried, it has to be captured.

Pollack said carbon could most efficiently be captured at coal burning power plants. Coal is composed of mostly carbon dioxide and hydrogen.

There is now technology capable of turning solid coal into a gas and separating the hydrogen from the carbon dioxide. The hydrogen would still be burned for energy and the carbon would be stored, Pollack said.

The Minnesota Legislature has called for an 80 percent emissions decrease by 2050, and Pollack said this technique could be one way to achieve that goal.

“Carbon capture and sequestration is one of the few technologies that can fill the gap,” Pollack said.

Wilson said the biggest difficulty in advancing carbon capture and sequestration is getting businesses to buy into it, because the technology required to capture carbon is expensive.

“The only reason to do this is to stop greenhouse gases from going into the atmosphere,” Wilson said. “It costs more, it’s expensive to manage and legally it’s a little difficult to manage the contracts.”

Wilson said that policies need to change in order to entice businesses into practicing carbon capture.

“The lack of climate change policies in the United States is the single biggest barrier,” Pollack said.

Worldwide there are four sites currently practicing carbon capture and sequestration, and none of the sites are in the United States.

Excelsior Energy, in Northern Minnesota, is proposing a plan to capture carbon dioxide, Pollack said.

Anthony Runkel, chief geologist for the Minnesota Geologic Survey, said he has been casually looking at the midcontinent rift in Minnesota as a possible sequestration site.

The midcontinent rift is a 1-billion-year-old tear in the bedrock buried in Eastern Minnesota.

Runkel said selecting the correct place to bury carbon is one of the most important phases in the entire process.

The perfect geologic area for sequestration is an area about 10 kilometers long with porous and permeable sandstone buried deep beneath the surface, Runkel said.

If the proper site isn’t chosen, there is a chance the buried carbon dioxide could escape through fault lines or pollute ground water. Carbon is a naturally buoyant gas, so it has a tendency to rise.

If the carbon dioxide escapes into a concentrated area, there is a very small chance it would be dangerous to people, Pollack said.

Illinois and North Dakota have geology that has more potential for carbon sequestration, Runkel said.

“Illinois and North Dakota are far beyond Minnesota in both time and money spent in geologic sequestration,” Runkel said. “We’re years behind those states.”

The Plains C02 Reduction Partnership is currently preparing a test project for carbon dioxide sequestration in North Dakota. The organization is part of a $300 million program looking to cut carbon dioxide emissions in three regions across the country.