PLEASANT PRAIRIE, Wis. -- One engineer romantically described the smelly six-story tangle of pipes, wires and catwalks snuggled next to the base of a huge, belching stack in this coal-fired power plant as "Vatican City in the middle of Italy."
And so it might be -- but only if the experimental equipment produces the miracle that the coal industry is praying for: an affordable way to catch and remove carbon dioxide from electricity plants.
The apparatus is the first of its kind and is testing a technology known as ammonia chilled carbon capture. The engineering team is giddy, not just from the stinging smell of ammonia, but because initial results show that the technology is performing close to expectations.
"It's giving encouraging results," said Arlyn Petig, the engineer overseeing the project for Alstom, an international equipment and service provider for power companies.
The objective is to remove 90 percent of the carbon from a small sampling of flue gas that's intercepted and redirected through the experimental technology before being pumped back into the towering 450-foot stack.
The carbon is caught and then released. In the future, the captured carbon would be sent to a pipeline and later sunk deep underground into saline aquifers or oil reservoirs for centuries-long storage.
Climate objectives depend on carbon capture
The experiment comes as the United States faces a dilemma. Coal-fired power plants accounted for 41 percent of the nation's CO2 emissions in 2006, making the sector the largest single contributor to climate change, according to the EPA. And it's growing.
Power plants like this one, the largest in Wisconsin, are obvious targets of regulators and legislators sensitive to the sharpening focus on the effects that greenhouse gases have on the warming world. So it's critical for power providers to find the cheapest method of sponging carbon from their systems.
"There will be legislation on carbon reduction," said Ed Morris, a senior engineer at the plant owned by We Energies, the state's largest power supplier. "We have to start looking at what's out there."
That's not an easy task. Carbon capture and sequestration, or CCS, is being actively used in only a few places around the world. There's a reason for that: It's very expensive.
The process routinely saps 30 percent of a plant's power, resulting in the uncomfortable conundrum of having to burn more coal to clean coal-dirtied discharge. It also drives up the cost of electricity.
Researchers hope chilled ammonia is different.
"Our target is to be able to get the cost of CO2 capture down significantly," said Hank Courtright, senior vice president of the Electric Power Research Institute, a partner in the project along with American Electric Power and a number of other utilities.
No 'free lunch' when reducing emissions
Researchers are hopeful that the process will use about 15 percent of a plant's electricity capacity, a substantial decrease from other forms of carbon capture. Yet it could still hike the cost of electricity for consumers by 30 percent.
"There is no free lunch in the process," said Clay Perry, an EPRI spokesman. "It's going to cost quite a bit of money [and] it's going to cost quite a bit of plant efficiency."
But the alternative could be more costly.
Electricity plants in the United States depend on coal to generate about half their power, with the rest largely coming from nuclear, natural gas, hydroelectric and geothermal sources. If coal were abandoned as a primary fuel source, massive new developments in solar, wind and other renewable sources would be needed to fill the hole.
That could cost twice as much as widespread implementation of carbon capture and sequestration, according to Richard Newell, a professor of environmental and energy economics at Duke University.
"If one imagines continuing to use coal for electricity production and at the same time decrease greenhouse gas emissions, carbon capture is really the only way to go at this point," he said.
Last month, the International Energy Agency's policy analysis director, Pieter Boot, provided a simple message for those attending a climate change conference at The Hague: "One can argue that without CCS, climate policy will not succeed."
World relies on unproven technology
Carbon capture is being factored into future emission reductions. The worldwide goal of halving CO2 output by 2050 depends on CCS to account for 21 percent of that drop.
Yet there are few examples to draw on.
Germany launched an experiment in June that will inject 60,000 tons of CO2 into porous saline aquifers 2,000 feet underground over the next two years. But that's one of many test projects occuring around the world.
One of the largest commercial operations is in southeastern Saskatchewan, Canada, where about 20 million tons of CO2 will be injected into the Weyburn oil field over a 20-year span ending in 2020. The gas comes from a more complex plant in North Dakota that gasifies coal, burns the synthetic gas that results and then ships the CO2 removed in the gasification process through a 205-mile pipeline to the sequestration site.
Otherwise, there are only a handful of commercial projects on Earth, including two in Norway and another in Algeria.
Ammonia CCS could be ready in 12 years
The Wisconsin project is in the initial stage of a process that developers hope will make the technology widely available by 2020.
"This is kinda like taking the first baby steps," Courtright said. "But until you can get up on your feet and start running with it, you've got to do this first."
The unit looks like the product of child's erector set. There are no walls, just skeletal beams encasing a multitude of gadgets, pipes, hoses and sensors. A large white plastic jug, perhaps 10 feet tall, sloshes with liquid.
Together, they perform three steps. Flue gas leaving the plant's boiler is cooled to 35 degrees Fahrenheit before it's sent to two tall towers that rain down an ammonium bicarbonate slurry onto the gas, absorbing the carbon dioxide. The solution is then pumped to a regeneration system, where the liquid is heated and the absorption process is reversed, leaving pure carbon dioxide ready for release.
If the experiment is successful, larger experiments will be conducted that expand the capture testing and introduce the sequestration of carbon dioxide.
"It's a long time, but a major new technology introduction is often a decade in length," Courtright said.