By Duane Schrag
Salina Journal
Proponents of the two coal-fired power plants that Sunflower Electric wants to build in Holcomb hold it up as an example of what is being called "clean coal."
Often touted is the proposed plant's bioenergy center, which would capture carbon dioxide from the plant and turn it into ethanol, biodiesel or nutrients for feedlots.
In fact, Senate President Steve Morris said in an interview in November that it was an important factor in his support for the plant.
"I suppose it would be different if this wasn't to be very environmentally friendly -- because of the bioenergy center associated with it and the clean technology that will be utilized," said Morris, R-Hugoton. "I think it is designed to capture about 45 percent of the total carbon dioxide produced."
It was the carbon dioxide emissions and their contribution to global warming that prompted Kansas Secretary of Health and Environment Rod Bremby to deny a permit last October for the plants. A group of electric utilities, led by Hays-based Sunflower Electric, proposed adding two 700-megawatt coal-fired power plants in Holcomb.
The price tag: $3.6 billion. New jobs: 106. Carbon dioxide emissions: 11 million tons a year.
"And then that's another question in my mind: You hear the figure 10 million tons, 11 million tons, but I'm not sure that's an accurate number either," Morris said. "I've heard different figures. I've heard 5 million, I've heard 10 million, I've heard 11 million. I really don't know what the true figure would be."
Tons of carbon dioxide
Actually, there is no real question how much carbon dioxide the plant, as proposed, would have generated.
Based on the federal government's analysis of coal from Campbell County, Wyo. -- the announced source of coal -- the plant would emit 2.8 million pounds of carbon dioxide an hour while operating at full capacity.
If the plant operated nonstop, it would emit 12.2 million U.S. tons (sometimes called short tons -- 2,000 lb. each) a year. Sunflower has said the plant is expected to operate at about 92 percent of capacity, which would put emissions at 11.2 million tons.
The real unknown is how much of that carbon dioxide would reach the atmosphere. Sunflower says the bioenergy center will capture 40 percent of the carbon dioxide and use it to grow algae.
But when asked for details about the scale of the carbon capture operation, Sunflower runs out of answers.
Algae we can grow
Algae really need two things to grow: sunlight and carbon dioxide.
Thus, the rate at which algae can be grown -- and therefore, the amount of carbon dioxide that can be absorbed -- is directly related to the area exposed to sunlight. Sparsely populated western states are considered ideal, both due to the availability of land and annual hours of sunlight.
Early algae reactors were little more than shallow ponds with paddles to agitate the water. But the latest research has focused on sophisticated, closed systems that increased productivity exponentially. They are considerably more expensive than open systems, but the hope is that the intensive algae production will more than offset the increased cost.
So how large an area would the Holcomb algae reactor cover?
"Unknown until we know how many plants will be built and further testing occurs," spokesman Steve Miller said in an e-mail response.
But what is the capture rate of such an algae reactor? How much carbon dioxide, on a per-acre basis, can an algae reactor utilize?
"I don't have that information," Miller said.
How to grow slime
Algae might be the alchemists of the 21st century: take something we have in surplus (carbon dioxide), combine it with something abundant and free (sunlight), supply a modicum of feed, and in no time you have slime that is 60 percent oil.
The possibilities aren't unlimited, but they're getting there.
"You can't grow more algae than the energy you supply from the sun," says David Bayless, professor of mechanical engineering at Ohio University and director of the Ohio Coal Research Center. "It truly is the limiting factor."
And there's a lot of that available. Even the most efficient bioreactors today utilize less than one-tenth of the available sunlight. None, of course, work at night.
In 1990 the Argonne National Laboratory estimated there is enough waste carbon dioxide available in suitable climates within the United States to generate up to 7 quadrillion BTUs of algae -- the equivalent of 40 percent of all the coal burned in 2007 to generate electricity in the United States.
For almost 20 years, the National Renewable Energy Laboratory studied the subject.
"Algal biodiesel could easily supply several 'quads' of biodiesel -- substantially more than existing oilseed crops could provide," NREL said in the report it issued upon closing the program. "Microalgal systems use far less water than traditional oilseed crops. Land is hardly a limitation. Two hundred thousand hectares (about 480,000 acres, slightly larger than Saline County) could produce one quad of fuel."
That is the energy equivalent of all the coal burned last year to generate electricity in Kansas, Oklahoma and Colorado combined.
Now, that's a big reactor
NREL's estimate of algae's energy potential was offered in 1996. The decade since has yielded significant gains in productivity.
But even so, an algae reactor that could swallow 25 million pounds of carbon dioxide a day is not trivial. Nothing on that scale has been built anywhere in the world. Miller suggested last year it could be as small as 3,000 acres. Bayless wonders if even that would be workable.
"The capital costs on that," he said. "I don't see anybody building 3,000 acres of bioreactor."
Nor would it capture but a fraction of the plant's carbon dioxide.
According to Sunflower Electric's Web site, GreenFuel Technologies, which is based in Cambridge, Mass., and is considered one of the leaders in algal reactor technology, is helping develop plans for the Holcomb bioenergy center.
Last summer GreenFuel completed an experimental project in Red Hawk, Ariz., in which carbon dioxide from a coal-fired power plant was used to grow algae.
"The performance of the ... system exceeded the target goal," the project report says. "... This is one of the most productive algal cultivation systems ever built."
The experiment was conducted over a 19-day period under highly controlled conditions. The daily algae yield averaged about 1 ounce for every three square feet. At that rate, capturing 1 lb. of carbon dioxide daily would take about 27 square feet. The Holcomb plant would generate 2.8 million pounds of carbon dioxide an hour.
Assuming a massive operation could operate year-around with the same efficiency, to capture 40 percent of the carbon emissions would require a 16,700-acre bioreactor -- roughly five times the area of Kanopolis Lake.
But how would it work
The reason only 40 percent of the carbon dioxide can be captured is because photosynthesis requires sunlight, but power plants operate around-the-clock.
"Nobody has any idea how to run a facility like this yet," says Al Darzins, group manager in NREL's National Bioenergy Center. "That's the thing I think people are going to have to get their hands around."
Trevor McKeeman is director of business development for the National Institute for Strategic Technology Acquisition and Commercialization, a Manhattan-based organization affiliated with Kansas State University that is a partner in the Holcomb bioenergy project. He acknowledges there is much that still isn't known about how to make such a project actually work.
"There are a lot of groups trying to figure out how to scale this up into commercial form," McKeeman said. "If it's figured out in Holcomb, there should be a lot of folks worldwide trying to see how we did it."
Blake Simmons is manager of Sandia National Laboratory's energy systems department. Sandia, which is based in Albuquerque, N.M., has access to some formidable resources: it is a partnership of the federal government and Lockheed Martin. Simmons is deeply involved in the effort to commercialize production of algae.
Simmons is very optimistic it is only a matter of time before the logistics are worked out. But nobody has reached that point yet.
"There are no algo-biorefineries in existence that can produce significant amounts of oil," he said. "Carbon dioxide scrubbing is not as efficient as hoped."
And then there's harvest
Growing the algae is just the beginning.
"One of the biggest expenses here is ... exactly how do you harvest and process it after it's grown?" Simmons said. A bioreactor that captured 40 percent of the Holcomb plants' carbon dioxide would produce about 12 million pounds of algae a day.
"That is a lot of biomass to produce. That's not saying it cannot be done; that's saying it's challenging," he said. "No one is doing it on that scale currently. If you're [using] all your carbon capture benefits on the amount of energy that's consumed to power the process, then it no longer makes sense, even from a carbon capture standpoint."
"Our take on this whole area is that, because it's so new, there are literally years and years of research that are needed before you can get to a large, viable - and that's important: viable -- commercial plant," Darzins said.
n Reporter Duane Schrag can be reached at 822-1422 or by e-mail at dschrag@salina.com.
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