Experts explain power plant technology Holland is considering; public forum 7 tonight at Haworth Conference Center

Thu, Aug 28, 2008    to del.icio.us

HOLLAND — Holland's James De Young power plant is one possible test site for a full-scale carbon sequestration program, but how does the technology work?

Producing electricity creates carbon dioxide. In carbon sequestration, that gas is captured and compressed to the consistency of oil, then pumped thousands of feet underground.

There's more to it than that, though.

First in the process is electricity production.

A typical coal-fired boiler burns coal and air together to create heat — and, ultimately, steam, which turns a turbine to create electricity. The process creates a flue gas that is about 8 to 10 percent carbon dioxide, said Chuck McConnell, Praxair Inc.'s vice president for Oxy-Coal technology and gasification.

Praxair is one company seeking U.S. Department of Energy Clean Coal Power Initiative grants totaling $300 million to test full-scale carbon capture and sequestration. It is estimated a grant for a 78-megawatt boiler project at the Holland Board of Public Works' plant could be about $150 million.

By burning pure oxygen with the coal, Praxair says its Oxy-Coal technology will produce a more concentrated flue gas as much as 85 percent carbon, making it more economical and efficient to store.

More than 90 percent of the carbon dioxide is captured as well as sulfur oxide, nitrogen oxide, mercury and other pollutants.

The process is sure to add to consumer costs, McConnell said. Paying for capital, energy and operating costs could add anywhere from 40 to 60 percent to electricity costs, he said.

"That is the cold hard facts of carbon sequestration," McConnell said.

Jamestown, N.Y., is Praxair's first site choice. Holland is the company's alternate site.

If the Department of Energy chooses Praxair and the company chooses Holland as a site for this technology, research would have to come before construction and the project would be complete as early as mid-2013.

It is one of many pieces of a solution, said Neeraj Gupta, a senior research leader at Battelle Memorial Institute.

"To meet the goals of climate, you will need all the technologies," Gupta said.

Gupta leads geologic storage research for Battelle. The nonprofit group is partnered with Praxair and engineers Black & Veatch.

After the carbon is captured, it is compressed to what is called the "super-critical phase" — or to about the consistency of oil and won't mix with water, Gupta said.

A well pumps the carbon dioxide about 5,000 feet down where the pressure is about 2,500 pounds per square inch, he said. There, you would find brine three to five times more salty than sea water.

The well injects the carbon dioxide at a pressure high enough to move it into position, but not high enough to fracture the "cap rock," Gupta said. The composition of sandstone under hard "cap" rock is what makes much of the state so desirable, he said.

"(The geology) has sustained that pressure for a long time — millions of years," he said.

It's that pressure researchers say will keep the carbon dioxide at the right consistency and the right place.

The Michigan governor's office is exploring carbon capture and sequestration and is working with Praxair to see if the company might qualify for state money under the Centers of Energy Excellence program, said Gov. Jennifer Granholm's press secretary, Liz Boyd. The Michigan Strategic Fund uses money from tobacco settlements to support economic development and technology projects.

"Michigan is one of the more attractive states for this technology," Gupta said. "Southwestern Michigan seems to be pretty promising."