Utilities officials struggle to find the right image to describe a new device they hope will suck up some of the nasty stuff released from their coal-fired power plants.
A car wash? Too random and imprecise.
A Levolor blind? The Martin Drake Power Plant conference room grows quiet as people try to figure out what that actually means.
Speaking broadly, Drew Rankin, general manager of energy supply for Colorado Springs Utilities, gushes that the new technology could revolutionize the global energy industry by significantly lowering the cost for catching coal's impurities.
"It's more like exact surgery versus throwing a rock at it," Rankin says.
Rankin's analogy helps explain his enthusiasm for Purestream, the contraption developed locally by physicist David Neumann. Rankin and other Utilities officials see it as a potential game-changer that could make "clean coal" a reality and turn Colorado Springs into a production hub for the new technology.
Others see the concept differently.
"It seems to be throwing good money after bad," says Bruce Nilles, director of the Sierra Club's Beyond Coal Campaign. Echoing a warning from NASA climate scientist James Hansen that coal use needs to end within 20 years to preserve a livable climate, Nilles says increased regulation needs to make coal a lost cause.
"Who's going to get hosed [by continued investment in coal]?" he asks. "It's going to be people five to 10 years from now."
Clearly, if Rankin's hopes about Neumann's device pan out, Colorado Springs could become the epicenter of the fight over whether clean coal is worth pursuing.
For the moment, at least, coal is the backbone of local energy production, providing close to three-quarters of Colorado Springs' electricity. Utilities burns through about three train loads — or 39,000 tons — of it every week.
With the enterprise facing tightening regulations for emissions of sulfur dioxide, Rankin says, Neumann's device could save hundreds of millions over what it would cost to install traditional scrubbers, which typically require huge amounts of space to mix the flue gases released from burning coal with a mixture of limestone and water. When sulfur dioxide reacts with the lime, it becomes a paste that can be collected.
Neumann's device basically encourages the same reaction in a much smaller space. Flue gases are forced through special streams of liquid "sorbent" inside small, modular "boxes" only 10 inches tall, a few feet wide and 10 feet long. The revolutionary aspect of Neumann's invention is the way he controls the streams of liquid, which keep their shape even when buffeted with the hot flue gases — hence the car-wash and Levolor analogies.
Rankin is mum on what goes into these sorbents, but he says in early tests, his unit has trapped up to 99.5 percent of the sulfur dioxide in flue gases, compared to traditional scrubbers' 90 to 95 percent. The device shows similar promise removing nitrogen oxide, Rankin says.
The big question is what happens if the next few years bring regulations for carbon dioxide, a greenhouse gas released when any fossil fuel is burned.
"Nobody knows how we are going to solve the CO2 challenge," Rankin says.
Getting CO2 and other pollutants out of the flue gases is one part of the challenge; determining what to do with them once they're out is another. Rankin says sulfur and nitrogen compounds could become building materials or fertilizer, though Nilles argues other contaminants could make using these materials difficult.
If CO2 is regulated and the technology to remove it works out, Rankin sees three main options for disposing of it: pumping it into a deep aquifer, piping it to existing oil wells to increase oil recovery, or using an as-yet unproven technology to convert it into concrete.
Nilles is skeptical that all the byproducts of coal can safely be disposed.
"Clean coal," he says, "is not a dictionary term you will find."