How It Happens | Carbon Capture
How It Happens | Carbon Capture
To fight against global warming, the world needs to sharply reduce emissions of carbon dioxide gas. A technology called carbon capture and storage can keep the gas out of the environment.
ESTEVAN, Saskatchewan — So much soot belched from the old power plant here that Mike Zeleny would personally warn the neighbors.
“If the wind was blowing in a certain direction,” Mr. Zeleny said, “we’d call Mrs. Robinson down the street and tell her not to put out her laundry.”
That coal plant is long gone, replaced by a much larger and cleaner one along the vast Saskatchewan prairie. Sooty shirts and socks are a thing of the past.
But as with even the most modern coal plants, its smokestacks still emit enormous amounts of carbon dioxide, the invisible heat-trapping gas that is the main contributor to global warming. So this fall, a gleaming new maze of pipes and tanks — topped with what looks like the Tin Man’s hat — will suck up 90 percent of the carbon dioxide from one of the boilers so it can be shipped out for burial, deep underground.
If there is any hope of staving off the worst effects of climate change, many scientists say, this must be part of it — capturing the carbon that spews from power plants and locking it away, permanently. For now, they contend, the world is too dependent on fossil fuels to do anything less.
If all goes as planned, the effort in Saskatchewan will be the first major one of its kind at a power plant, the equivalent of taking about 250,000 cars off the road. And at least in theory, that carbon dioxide will be kept out of the atmosphere forever.
“Think about how far we’ve come,” said Mr. Zeleny, who recently retired after four decades here, most recently as plant manager.
Despite President Obama’s push to from power plants across the United States, coal is not going away anytime soon. The administration expects coal will still produce nearly a third of the nation’s electricity in 2030, down from , even if Mr. Obama’s plan survives the political onslaught against it.
The challenge is even more stark overseas. China already burns almost as much coal as all other nations combined, and its appetite keeps expanding. Worldwide, coal consumption in 2020 will be what it was in 2000, according to the United States Energy Information Administration, and will continue to grow for decades.
Even the abundant natural gas unleashed by fracking, while cleaner than coal, is a major source of greenhouse gases. Ultimately, many scientists say, those emissions will need to be trapped and stored, too.
“If you want to carry on using those fossil hydrocarbons, that means cleaning up their emissions,” said Stuart Haszeldine, a geologist at the University of Edinburgh. Capturing carbon, he said, “is the single best way of doing that.”
Yet it is no magic bullet. Because it requires so much energy, sucking up carbon reduces a plant’s ability to make electricity — the whole point of its existence. There are basic questions of whether carbon dioxide can be safely stored underground. And the technology is expensive. Updating the Saskatchewan plant alone cost $1.2 billion — two-thirds of which went for the equipment to remove the gas.
In the pine woods of Kemper County, Miss., another carbon-capture effort is taking shape, in a massive new power plant that will be fed a steady diet of coal from the strip mine next door. Bruce Harrington, the operations manager, likened the hulking beast to an anthill: It seems curiously quiet on the outside, but deep within an army of workers is cutting, welding and testing. Disturb it, he said, and thousands of people will come pouring out.
Battling delays, the plant’s owner, , hopes to have it open next year. But it is more complex than the Saskatchewan effort, and the price tag has ballooned to $5.5 billion, more than double the original estimate.
“It’ll work,” Mr. Harrington said. “It won’t be easy at first, but it’ll work.”
Though the world has known for decades how to capture carbon dioxide from power plants, scant progress has been made. The United States and other nations have paid for research and helped some projects — Canada gave $220 million to the Saskatchewan plant’s owner, , and Southern Company received $270 million from the Department of Energy — but the costs are high enough that few other power companies have done much beyond study the concept.
“There’s no market,” said Edward S. Rubin, a professor of engineering and public policy at Carnegie Mellon University, unless governments impose “a requirement to substantially reduce emissions.”
That is precisely what is happening here in Saskatchewan, given the Canadian government’s on coal plants both old and new. But whether Mr. Obama’s new rules are aggressive enough to spur a change in the United States remains unclear.
Some experts see the Obama policy as a turning point, a moment that could help drive the business of collecting carbon dioxide. Yet the administration has been wary of pushing too hard, warning that any move to force existing coal plants to siphon off their carbon dioxide emissions “would affect the nationwide cost and supply of electricity.”
The Obama administration plans to require that future coal plants capture their carbon dioxide, a rule that some utilities and politicians, particularly from coal-producing states, have vowed to fight. But for now the mandate is largely an empty one, because coal is so uneconomical compared with natural gas that no one expects many new American coal plants to be built in the foreseeable future.
“If you give power companies a loophole, they’re not going to do the thing,” said Howard J. Herzog, the director of a research program on carbon capture and storage, known as C.C.S., at the Massachusetts Institute of Technology. “Why should we even consider C.C.S.? Let’s just do natural gas.”
So at a time when many experts say 10 or more projects need to be undertaken to improve the technology and reduce costs, the opposite is happening. Work to modify a coal plant in Texas is expected to start this year, but there are only a few other projects worldwide, all in the planning stage. And as some government subsidies have begun to dry up — notably, federal stimulus funds in the United States — several efforts have been delayed or canceled.
“I’m concerned,” Mr. Haszeldine said. “Governments around the world see C.C.S. as a good thing. But they’re not pushing hard enough on enabling that to happen.”
The technology has been around, in one form or another, for nearly a century, used at some refineries and other industrial plants, including large ones in Illinois, North Dakota, Canada and Norway.
But removing carbon dioxide from the swirl of gases unleashed at a power plant is challenging, akin to plucking just a few colored Ping-Pong balls out of the air from a swarm of mostly white ones.
To do the job, the equipment is enormous. At the Saskatchewan plant, called Boundary Dam, a liquid chemical latches onto carbon dioxide molecules after being sprayed onto a plume of combustion gases. The “stripper,” where the carbon dioxide is finally pulled away, is 160 feet high — so high it pokes out of the roof.
Beyond the equipment costs, efficiency is lost because some of the steam that would normally generate electricity goes to the stripper instead. And a monstrous motor compresses the carbon dioxide — until it effectively becomes a liquid — for transport. All told, capturing the carbon dioxide at Boundary Dam will sap electricity generation by about 20 percent, using as much energy as about 25,000 homes. Experts call it the “energy penalty.”
Injecting liquids deep underground can present problems, too. Pumping wastewater from oil and gas production into the ground has been linked to spates of small earthquakes in Arkansas, Ohio, Oklahoma and other states.
The carbon dioxide could taint drinking water, or eventually rise to the surface and bubble into the atmosphere, defeating the entire purpose.
In the most extreme case, leaking carbon dioxide could harm or kill people. In Cameroon, a volcanic lake suddenly released a cloud of naturally forming carbon dioxide in 1986, suffocating 1,700 people.
Still, carbon dioxide has been buried around the world with few problems. In Norway, a million tons have been stored every year since 1996, injected into sandstone about 3,000 feet beneath the North Sea. (By some estimates, that site alone could store as much carbon dioxide as the world could capture for years.)
Picking the right geological features could minimize the risk of earthquakes and leaks. But even then, storage wells would have to be monitored, presumably forever, at a cost someone would have to bear.
If done poorly, storing carbon dioxide can cause problems, said David Hawkins, the director of climate programs with the , an advocacy group. “But that’s also true with operating an oil refinery.”
Most of Boundary Dam’s carbon dioxide will not simply be buried in storage wells. Instead, the emissions from burning one fossil fuel — coal — will become a tool to extract and consume yet another: oil.
After being sold and shipped through a 40-mile pipeline to an oil field, the carbon dioxide will be pumped into old wells, where it will mix with the oil inside, making it flow better. The process is known as enhanced oil recovery, and while some of the carbon dioxide will come up with the oil, it will be compressed and injected again. Over time, nearly all of it should remain underground.
The oil and gas industry has done this for decades, mostly with naturally occurring carbon dioxide that accumulates underground. But each year in North America, more than 15 million tons of carbon dioxide from industry are used as well. Selling that carbon dioxide to the oil industry helps make a business case for capturing it at places like Boundary Dam.
The practice could be expanded at many oil fields around the United States and beyond, experts say, potentially storing billions of tons of carbon dioxide and serving as a bridge to the day when it becomes necessary, and economical, to store the gas elsewhere.
To prod the industry, Congress is weighing incentives, including tax credits, loan guarantees and tax exemptions.
“It’s not going to happen by itself,” said Senator Michael Bennet of Colorado, a Democrat who is chairman of a Finance Committee panel on energy. “There ought to be broad bipartisan support for measures like these.”
As for the apparent incongruity of using carbon dioxide captured from coal to produce more fossil fuels, Mr. Hawkins said his group had struggled with the issue.
“Our view is that the most likely consequence is not to encourage more consumption of oil,” he said. Rather, drawing more oil from existing fields will reduce the need to develop new ones, “and that’s an environmental plus,” he said.
Boundary Dam’s owner will evaluate the project for two years before deciding whether to capture carbon dioxide from other boilers at the plant, which it says it could do at lower cost. Part of the calculus is that, less than 10 miles away, there is an almost limitless supply of cheap coal that it otherwise might not be able to use as Canada’s new standards take hold.
“We had to figure out if we could continue using coal as a fuel source for the next 100 years,” said Mr. Zeleny, the former employee.
As for the United States and the rest of the world, the prognosis for carbon capture is less clear. If the United States moves forward, China and other countries may make bigger strides as well. This month, the United States and China for several collaborative research projects.
“How this will play out over time is hard to tell,” said Professor Rubin of Carnegie Mellon. “Inevitably, there will be a balance between technological capability, cost and political realities.”
Others were even more upbeat. Dan Reicher, who directs the Steyer-Taylor Center for Energy Policy and Finance at Stanford University, said the Obama administration’s recent moves on emissions could be a catalyst.
“We’re finally getting some clarity on where we’re headed on carbon emissions,” Mr. Reicher said, arguing that collecting carbon dioxide could become a significant industry.
“We need every tool in the toolbox to address climate change,” he said.