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A photo of a truck carrying a Carbon Dioxide absorber.

A 210-foot-tall carbon dioxide absorber is moved to Southern Company's Kemper, Mississippi, power plant site.

PHOTOGRAPH BY MISSISSIPPI POWER

Robert Kunzig in Meridian, Mississippi

National Geographic

Published March 31, 2014

In Juliette, Georgia, Southern Company operates a coal-fired power plant that is the single largest source of planet-warming carbon dioxide emissions in the United States.

In Kemper County, Mississippi, the same company is pioneering a technology that many experts believe will be crucial to preventing a climate disaster: It's building the world's first new power plant designed to capture and store most of its carbon.

Carbon capture and storage, or CCS, has been hailed for decades by some as an essential solution to the climate problem, and pilloried by others as unworkable and a dangerous distraction. This year, at last, it will be tested at full commercial scale. (See related, "Can Coal Ever Be Clean?" and photo gallery, "The Visible Impacts.")

The test ground won't be only a new power plant in Mississippi. It also will be about 1,600 miles north of here, in Saskatchewan, Canada, where a public utility is attempting to show that an old coal-fired power plant can be cleaned up. SaskPower has almost finished retrofitting one 110-megawatt unit of its Boundary Dam Power Station to capture 90 percent of the CO2 before it flies out the smokestack. In Saskatchewan as in Mississippi, the CO2 will be pumped underground into a partially depleted oil field and—after it has helped squeeze valuable oil to the surface—stored there indefinitely.

The battle to forestall climate change, President Barack Obama said in a speech last summer, requires us "to put an end to the limitless dumping of carbon pollution from our power plants." But because coal is one of the cheapest ways to fuel electricity, with abundant stores all around the world, global carbon pollution is growing. (See related "Quiz: What You Don't Know About Electricity.") Over the next two decades, when science says aggressive steps must be taken to curb greenhouse gas emissions, several hundred million people in the world will be getting electricity for the first time—and a lot of it will be fueled by coal. Many believe the world won't be able to stop drastic climate change without a technology for curbing emissions from the cheapest, most-carbon intensive fuel. (See related "Quiz: What You Don't Know About Climate Change Science.")

An aerial photo of the Kemper County energy facility.
In February, construction was nearing completion at Kemper. The facility expects to go on line by the end of this year.
PHOTOGRAPH BY MISSISSIPPI POWER

In the vanguard of the effort is a company that has always fought mandated government limits on CO2.

In 2009, Southern Company lobbied hard against the climate bill passed by the House of Representatives—which died the following year in the Senate—on the grounds that it would have raised energy prices too much. It is now opposing regulations, promised by Obama and proposed in January by the Environmental Protection Agency, that would require new power plants to capture roughly half their CO2. (See related story: "As U.S. Cleans Its Energy Mix, It Ships Coal Problems Abroad.")

But in Mississippi, Southern is building a plant designed to capture 65 percent of its CO2—a coal plant that would be as clean as the cleanest natural-gas-fired one. After delays and cost overruns that have doubled its price tag to more than $5 billion, the 582-megawatt Kemper plant is scheduled to go online late this year. That would put it among the larger U.S. coal plants. When fully operational, it is designed to provide power for 165,000 Mississippi homes and businesses. Ratepayers will shoulder much of the cost, and the U.S. Department of Energy (DOE) has contributed $270 million. But Southern's shareholders have already absorbed a loss of more than $1.1 billion on the project.

"Southern has definitely been one of the more resistant" companies to federal carbon restrictions, said Sally Benson, a Stanford University researcher and expert on carbon storage. "Yet look what they're doing [at Kemper]. They've really gone out on a limb. It's a fantastic thing."

"A Lot of Pots and Pans"

Twenty miles north of Meridian on highway 493, the thing itself rises like a fantastic industrial castle from the pinewoods and cow pastures of eastern Mississippi. "If you were driving here a few years ago, you were either hunting or lost," said Jeff Shepard, a spokesman for Mississippi Power, a Southern subsidiary. Now you're almost certainly headed to the Kemper County Energy Facility. A sea of parked cars separates it from the highway; more than 5,000 construction workers are mostly hidden inside, putting the finishing touches on a bewildering mass of pipes, silos, tanks, and domes.

"We're taking coal and converting it into gas to burn in a gas turbine," said Randall Rush, a chemical engineer from Southern's research facility in Wilsonville, Alabama. "That takes a lot of pots and pans."

As one tours the site with Rush and his colleagues, the maze of piping gradually becomes penetrable—as do Southern's reasons for building it in this corner of Mississippi. Mississippi Power owns 42 square miles (109 square kilometers) of land around the Kemper plant. Under that land, at a depth of 25 feet to 125 feet (8 to 38 meters), lies a 9-foot (2.7-meter) thick seam of lignite—part of an enormous formation that arcs out of Mexico through Texas and Louisiana.

Lignite and other low-rank coals make up half the world's coal reserves, but not many American power plants use them. Lignite has high ash and water and low heat content. (See related, "Germany Plans to Raze Towns for Brown Coal and Cheap Energy.") But at the Wilsonville lab, with support from the DOE, Southern has spent nearly two decades perfecting a system for gasifying and burning lignite efficiently. Kemper is its commercial debut.

On the south side of the power plant, at the Liberty Mine, a giant dragline is already taking 86-cubic-yard (65.7-cubic-meter) bites out of the countryside. From the edge of the pit, trucks must drive only a few hundred yards to dump their loads of coal onto a conveyor belt that carries it up and into the power plant. There the coal will be crushed, dried—the Kemper lignite is 45 percent water—and pulverized to a consistency "between beach sand and face powder," Rush said.

The coal grains will be blown at high pressure into the gasifier—essentially a tall pipe. Swirling in steam and air, the coal is heated to 1,800°F (982°C), but without enough oxygen to burn it completely. That converts most of the coal into "syngas," which is mostly hydrogen and carbon compounds, and the rest into ash.

The hydrogen will get burned in two gas turbines-essentially jet engines strapped to the ground. "The thrust that would make an airplane fly is used to turn a shaft and make electricity," Rush explained. "The gases that come out of that jet engine are hot, and you recover that heat in a steam generator, and you use it to turn a shaft in a steam turbine. So you're making electricity in two places."

A photo of a Carbon Dioxide absorber being installed.
A crane lifts one of Kemper's six CO2 absorbers into place.
PHOTOGRAPH BY MISSISSIPPI POWER

Cleaning Up

That system, called an IGCC (for "integrated gasification combined cycle"), makes burning syngas more efficient than burning coal directly. But syngas is also easier to clean up. At Kemper, the "gas cleanup unit" stands between the gasifier and the power block and a little to the north. It will strip out most of the dust, 90 percent of the toxic mercury, and 99 percent of the hydrogen sulfide—all of which is required by existing Clean Air Act regulations. It will also remove 65 percent of the CO2, even more than would be required by regulations proposed by the EPA in January. (See related, "Poland Hosts Climate Talks, While Boosting Coal Industry.")

CO2 capture was not part of the original plan for Kemper. The plan was to remedy Mississippi Power's problem—an aging fleet of power plants concentrated on the Gulf Coast, where one was damaged by Hurricane Katrina—by tapping into the lignite at Kemper. "The CO2 was added later," said Rush. That was in 2009, when it seemed likely that Congress might pass a climate bill.

As it turns out, though, CO2 can be removed from syngas with the same liquid solvent, Selexol, that strips out the sulfur; it just takes more pots and pans. The basic principle is simple. You fill a tall tank with packing material, said Rush, to increase the surface area where gas and solvent meet. You pour Selexol in at the top and pump syngas into the bottom at 600 pounds per square inch—about 20 times the pressure in car tires. Under high pressure, the CO2 dissolves in the Selexol as it does in Coke. When you release the pressure, it's like popping the cap on a Coke bottle—the CO2 comes bubbling out in pure form.

Carbon capture graphic.
JOHN TOMANIO AND ALEXANDER STEGMAIER, NGM STAFF. art: Álvaro Valiño (TOP). Sources: howard herzog, MIT; U.S. Energy Information Administration

The Kemper plant will capture 3.5 million metric tons of CO2 a year and compress it to a liquid-like state. The energy required to do that will use up the efficiency gained by the IGCC process. But there's a bright side: Mississippi Power will actually sell the CO2, delivering it by pipeline to Denbury Onshore and another independent oil company. Those companies already use CO2 for "enhanced oil recovery" at aging fields along the Gulf Coast. Right now they mine their CO2 from a natural deposit near Jackson, a hundred miles west of Kemper.

The Kemper plant will also sell 150,000 tons a year of sulfuric acid to the Gulf Coast chemical industry, which is flourishing these days because of cheap natural gas. The fracking boom has transformed the electric power industry too; coal-fired plants all over the country have been switching to natural gas. Since 2008, Southern has cut its reliance on coal in half, from 69 percent to 36 percent of its generating capacity. Mississippi Power already generates 75 percent of its power from gas.

The Sierra Club, which strongly opposes the Kemper project—"It's dirty, it's expensive, and it's unnecessary," said Louie Miller, the Club's state director—argues that the state as a whole has excess generating capacity and that Mississippi Power, which serves southern Mississippi, could have bought an existing natural gas plant at a fraction of the cost of building Kemper. To help pay for the plant, in the poorest state in the nation, the utility has already raised rates 18 percent—about $270 a year for its average customer. It expects to ask for another hike of 4 to 6 percent next year. Miller predicts more rate hikes will follow.

Southern says it doesn't want to rely too much on natural gas, which has a history of volatile prices. At Kemper, Southern owns the lignite and has a long-term contract with North American Coal to extract it. The price is stable and cheap. In fact, said Southern start-up manager David Hardin, with revenues of at least $50 million a year expected from the sale of CO2 and other byproducts, "it's almost like the fuel is free."

There are 600 million tons of lignite at Kemper, more than three times as much as the plant will burn in its 40-year lifetime. "Maybe somewhere down the road we'll want to put in another facility that burns lignite," Hardin said.

A photo of a coal conveyor from the top of gasifier to the dome.
The conveyer belt will carry lignite from the adjacent mine into the Kemper plant. The dome on the right protects a few days' supply of coal from Mississippi rains.
PHOTOGRAPH BY MISSISSIPPI POWER

Boundary Dam

The view from southern Saskatchewan is similar. "We sit on top of a 300-year supply of coal," said SaskPower CEO Robert Watson. But the regulatory outlook is clearer.

Under Canadian regulations that will take effect in July 2015, any new coal-fired plant, and any existing one that's at least 50 years old, can emit no more than about 925 pounds of CO2 per megawatt-hour. (EPA's proposed limit is 1,100 pounds per megawatt-hour for new plants; Kemper will emit around 800 pounds.) When a Canadian power plant turns 50, it must either be shut down or start capturing carbon.

The Boundary Dam station consists of six separate units that burn pulverized lignite. SaskPower shut down the oldest unit last year and plans to close a second one. Unit 3 will turn 50 in 2017. "We had to do a major reno or shut it down," Watson said. "We determined it would be the perfect unit to try out new technology."

Gasifying the coal and capturing the CO2 before combustion was not an option; that would have required an entirely new plant like Kemper. SaskPower will do its cleanup after the coal is burned. Because CO2 is less concentrated and at much lower pressure in smokestack gases than it is in syngas, it won't spontaneously dissolve into a liquid solvent. SaskPower will use a solvent called an amine that reacts with CO2 chemically and grabs it out of the air.

That process had been considered more costly, but the technology has been improving. SaskPower claims it will actually spend less energy capturing CO2 than Kemper will—with a technology that can be applied to existing coal plants, not just fancy new IGCCs. And SaskPower aims to capture 90 percent of the CO2, from that one unit at least, to bring its emissions downs to about 330 pounds per megawatt hour. That's "far better than any other fossil fuel unit around," Watson said.

An aerial photo of the Kemper County.
Mississippi Power owns 42 square miles of land and 600 million tons of lignite around the Kemper plant.
PHOTOGRAPH BY MISSISSIPPI POWER

The CO2 will be sold to Canadian oil company Cenovus Energy and injected into the Weyburn oil field in Saskatchewan. That field has been the site of a long-running experiment in carbon storage monitored by the Paris-based International Energy Agency. So far no major leaks or other problems have been reported.

The renovation of Boundary Dam Unit 3 is costing about $1.2 billion, of which the Canadian government is paying close to 20 percent. Like Southern, SaskPower hopes to sell its technology overseas, especially in China. "We think we will show a model to the world," Watson said, "to allow companies to keep burning coal, but do it cleaner. Everybody agrees we've got to clean it up." (See related, "Harbin Smog Crisis Highlights China's Coal Problem," and "Coal Burning Shortens Lives in China, New Study Shows.")

Adequately Demonstrated?

The amine process that SaskPower is relying on is not new; it has been widely used in other industries. It has also been successfully tested at a Southern Company plant near Mobile, Alabama. As of last fall, Southern had stored 100,000 metric tons of CO2 underground. Like other companies in the industry, though, Southern opposes EPA's efforts to require carbon capture and storage on the grounds that the technology has not been "adequately demonstrated," as the Clean Air Act requires.

There is much debate about what that term means. "'Adequately demonstrated' doesn't mean it has to have been run at commercial scale," said Howard Herzog, senior research engineer and carbon capture specialist at Massachusetts Institute of Technology. "If it's been shown to work at pilot plants, it's adequately demonstrated. As far as the capture goes, there's no doubt that the technology is here today. It's demonstrated that it will work."

What's still uncertain is the long-term cost of CCS—and that's why the two plants that are coming online this year are so important. The new Boundary Dam unit will be switched on this summer, Watson said. Mississippi Power expects to start making syngas at Kemper in June, and to connect to the grid by the end of the year. A half-million-ton pile of coal is already mined and waiting.

"Psychologically it's very important for Kemper to work," said Herzog. "But the Boundary Dam is probably a truer test of how carbon capture can be adapted to the marketplace."

"You've got to give Southern credit though—they really are trying to push the technology. From an engineering viewpoint, Boundary Dam was a much simpler project. This is a very ambitious project Southern is doing. I'm hoping they're going to pull it off." (See related interactive map: "Four Ways to Look at Global Carbon Footprints.")

9 comments
Istvan Kalmar
Istvan Kalmar

Coal should be used as raw material . It can integrate petcoke the non degradable biomass, solid and fliud waste (after preparation, animal dung etc when making the syngas by sterilising all of added components. The syngas produced can than turned into fretiliser and transport fuel (methanol or derivate) or other chemicals. The second step syngas processing can integrate the mine methan,UCG once commercially available, biogas also hydrogen from renewables or nuclear in low demand times can be stored chemically in the process.The O2 generated is just fine for the gasification process. In countries where shale gas does not make NG cheap that is the solution to use own resources.

CO2 can be an important raw material once the conversion technolgies become economical.

The undreground storage of the CO2 should not be considered as the long term solution but rather a temporary storage for later use (exept the EOR today)

The technology and economy of the CO2 capture has still a long way to go

before being profitable.

Bruce Williams
Bruce Williams

CCS is an insane, inefficient, Rube Goldberg scheme that only exists because of the coal lobby.  No self respecting scientist or energy economist thinks it has any chance at all of being viable.   Coal is dirty and dangerous from the mine to the mercury in our streams and rivers.  CO2 is just one of the negative impacts. Mother Nature took millions of years to capture all that carbon out of the atmosphere and store it securely underground so that we could have a nice stable climate, which is the only way you can have port cities and industrial agriculture.  Why don't we just leave it there?  If we put that money into energy storage research, we can solve the storage problem and renewables would become a no-brainer to solve all our problems very quickly.  

john Duczek
john Duczek

If we put all the money that is going into Carbon capture and storage into Research and development into cheap efficient Hydrogen generation and low pressure storage, we could have a Solar / Hydrogen economy in a Decade or two. Then we could retrofit all the power stations to run on Hydrogen.  The USA went from no atomic weapons to their development in a rapid time frame, that same Wartime effort is needed to get us onto a New clean Fuel  economy and sought out our Climate Change woes which are of our making. The shame in this tragedy, is with the big Corporations which have  fought the change from all Hydrocarbon Fuels as all they see is Big Profit. Maybe these People should look at the children and they may wake up, for they will have to try and live with the mess we are making. We need to get off Oil, Coal and Natural Gas  asap and go directly to a clean renewable fuel ( Hydrogen ).  We should keep the Hydrocarbons as chemical fuel stocks for Industry  not simply burn them as a fuel. As long as we try to have our cake and eat it too, our Earth will suffer from Pollution and contamination. look at all the spills of oil on land in the Oceans and the horrors that come from it. Our health, our animals and Nature all suffer. How many people die from Pollution as a direct result from our Greed to get every drop of Oil, coal and Gas out of the ground.  One thing is certain, we can not go on like this forever. Our Earth, our only home is changing and not for the better, our time to sought out this mess out is ticking by and Big Corporations and Government need to wake up. Even if we stopped the use of all Hydrocarbon fuels today, we still have a huge problem with latent heat that is in the Earths systems. It will take  Hundreds of  years plus to artificially remove Co2 from the atmosphere  to pre Industrial levels and stablise the Worlds temperature. There is so much heat in the Earths  Natural system now  that it will be impossible to avert a large Change in our Climate. The Oceans have absorbed huge volumes of Co2  and heat and are becoming acidic too. We have barely seen any real large temperature changes as yet, the Oceans have been soaking up large amounts of heat and co2, once it can't take any more than Climate change will become really apparent to even the most ardent sceptics. It seems we have learnt nothing as yet as we continue on the road to oblivion. One thing is certain, we will lose a lot of the things which we have taken for granted and then one day, we will see the folly of making all this money, making the Earth a ruined husk and living is just  barely tolerable if at all........ John from Kapunda, AUSTRALIA

paul gracey
paul gracey

It appears that both of these plants are relying upon an oil drilling company nearby to take the CO2. That and the usual coal ash that such poor quality coal produces in huge quantities may mean that this will not be commercially successful once greener energy sources become fully competitive. Southern probably also is taking advantage of decisions long ago in the age of steam railway engines to buy up that lignite bearing property. I imagine they could not justify this plant to their Board without that fact in play. This also adds to the unique set of circumstances that have to be present for such technology to be developed voluntarily.

If we are to really address our carbon emissions it will only be through a carbon emissions levy by regulators so that the the market forces apply to all such companies. Cap and Trade has too many chances for loopholes, and requires that their be some gross polluters left in play to provide for the trading.

KENNETH LANE
KENNETH LANE

Not to worry--our National Corporations will never let their bottom line be bothered in the least by governance.  In fact we can be assured that they will bribe, steal, murder and throw elections as always with total impunity.  They do not own this nations media outlets for nothing---

Seth Kingsley
Seth Kingsley

Sweet article, real interesting. 
This technology would have been appropriate decades ago, though at our current predictions capturing a portion of a massive CO2 output are no longer acceptable. If this amazing feat of withholding 65% per annum is reached at this Mississippi plant, 3.5 million metric tonnes will be captured. This is apparently a justification for the other 35% to be released into the atmosphere guilt free, all 1.8 million metric tonnes of it (that's equivalent to the entire CO2 output of Laos back in 2010). 

We will never have clean coal power, only less dirty coal power. But hey, clean energy is easier said than done.  

 

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