Environews Focus

CarbonCaptures Storage

Blue-Sky TechnologyarJust Blowing Smoke?

T owering 650 fcer over the sea surface

and spouting an impressive burning

Rare, it would be easy to mistake the Sleipner

West gas platform for an environmental

nightmare. Its eight-story upper deck houses

200 workers atid supports drilling equip-

ment weighing 40,000 tons. Located off the

Norwegian coast, It ranks among Europe's

largest natural gas producers, delivering more

than 12 billion cubic feet of the fiiel annually

to onshore terminals by pipeline. Roughly

9% of the natural gas extracted here is car-

bon diojiide (CO2), the main ctUprit behind

global warming. But iar from a nightmare,

Sleipner West is actually a bellwether for

environmental innovation. Since 1996, the

plants operators have stripped CO^ our of

the gas on-site and buried it 3,000 feet

below the sea floor, where they anticipate it

will remain for at least 10,000 years.

Environmental Health Perspectives • VOLUME 1151 NUMBEH 111 November 2007

We believe [CCS] is a viable way to cut global warming pollution..start moving forward.

We have the knowledge we need to

-David HawkinsNatural Resources Defense Council

Operated by StatoilHydro, Norway'siargest company, Sleipner is among the fewcommercial-scale facilities in the worldtoday that capture and bury CO., under-ground. Many experts believe this practice,duhbed carbon capture and storage (some-times known as carbon capture and seques-tration, but in either case abbreviated CCS),could be crucial for keeping industrial CO2emissions out of the atmosphere. Sleipnerinjects I million tons of COj annually intothe Utsira Formation, a saline aquifer bigenough to store 600 years' worth of emis-sions from al! European power plants, com-pany representatives say.

With mounting evidence of climatechange—and predictions that fossil fuelscould supply 80% of global energy needsindefinitely—the spotlight on CCS is shin-ing as brightly as the Sleipner flare. A panelof experts from the Massachusetts Instituteof Technology (MIT) recently concludedthat CCS is "the critical enabling technolo-gy to reduce C O T emissions significantlywhile allowing fossil fiiels to meet growingenergy needs." The panel's views were pre-sented in The Future ofCoaL a report issuedby MIT on 14 March 2007.

Environmental groups are split on theissue. Speaking for the Natural ResourcesDefense Council (NRDC), David Hawkins,director of tbe council's Climate Center anda member of the MIT panel's external advi-sory committee, says, "We believe [CCS] is aviable way to cut global warming pollution., , . We have the knowledge we need to startmoving forward." Other environmentalgroups, including the World ResourcesInstitute, Environmental Defense, and thePew Center on Global Climate Change,have also come out in support of CCS.

These groups view CCS as one amongmany alternatives (including renewableenergy) for reducing CO, emissions.

Greenpeace is perhaps the most vocalcritic of CCS. Truis Gulowsen, Greenpeace'sNordic climate campaigner, stresses thatCCS deflects attention from renewable ener-gy and efficiency improvements, which, hesays, ofFer the best solutions to the problemof global warming. "Companies are doing alot of talking about CCS, but they're doinglitde to actually put it into place," he says."So, they're talking about a possible solutionthat they don't really want to implementnow, and at the same time, they're trying topush for more coal, oil. and gas developmentinstead of renewables, which we alreadyknow can deliver climate benefits."

Coal Use Drives CCS AdoptionThe pressure to advance on CCS has beenfueled by soaring coal use worldwide. China,which is building coal-fired power plants attbe rate of two per week, surpassed theUnited States as the world's largest producerof greenhouse gases in June 2007, years ear-lier than predicted. Coal use in India andother developing nations is also on the rise,while the United States sits on the largestcoal reserves in the world, enough to supplydomestic energy needs for 300 years, statesthe MIT report. Coal already supplies morethan 50% of U.S. electricity demand andcould supply 70% by 2025, according to theInternational Energy Agency. Meanwhile,coal-flred power plants already account fornearly 40% of COj emissions worldwide, afigure that—barring some dramatic advancein renewable energy technology—seemspoised to rise dramatically. During a6 September 2007 hearing of the House

Select Committee on Energy Independenceand Global Warming, Chairman EdwardMarkey (D-MA) noted that more than 1 50new coal plants are being planned in theUnited States alone, with another 3,000likely to be built worldwide by 2030,

A mature CCS system would capture,transport, and inject those emissions under-ground to depths of at least 1 km. whereporous rock formations in geologically bvor-able locations absorb CO, like a sponge. Atthose depths, high pressures and tempera-tures compress the gas into a dense, liquid-like "supercritical" state that displaces brineand fills the tiny pores between rock grains.Three t>'pes of geological formations appearespecially promising for sequestration: .saline(and therefore nonpotable) aquifers locatedbeneath freshwater deposits; coal seams thatare too deep or thin to be extracted econom-ically; and oil and gas fields, where CO2stripped from fuels on-site can be injectedback underground to torce dwindlingreserves to the surface, a process called"enhanced recovery." Using C O T forenhanced recovery has a long history, partic-ularly In southwestern Texas, where oilyields have been declining for decades.

Of these three options, saline aquifers—with their large storage capacity and broadglobal distribution—are considered themost attractive. Thomas Sarkus, director ofthe Applied Science and Energy Tech-nology Division of the DOE NationalEnergy Technology Laboratory (NETL),su^ests saline aquifers in the central UnitedStates could conceivably store 2,000 years'worth of domestic CO, emissions.

Apart from Sleipner, only two otherindustrial-scale CCS projects are In opera-tion today. In Algeria, a joint venture

VOLUME 1151 NUMBER 111 November 2007 * Environmental Health Perspectives

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involving three energy companies—Statoil-Hydro, BP, and Sonatrach—stores morethan 1 million tons of CO-, annually undera natural gas platform near In Salah, anoa,sis town in the deseri. And in Weyburn,Canada, comparable volumes are being usedby EnCana Corporation, a Canadian energycompany, for enhanced recovery at an agingoil field. The CO, sequestered at Weyburncomes by pipeline from a coal gasificationplanr in Bculah, North Dakota, 200 milesaway, Unlike other enhanced recovery pro-jects—wherein the ultimate fate of CO2 isnot the primary concern—Weyburn com-bines fossil fuel recovery with research tostudy sequestration on a large scale.

What's needed now, says Jim Katzer, avisiting scholar at MIT's Laboratory forEnergy and the Environment, are morelarge-scale demonstrations of CCS in muiti-pk' geologies, integrated with policies thataddress sire selection, licensing, liability, andother issues. Katzer says there are a numberof investigations that are investigating stor-age in the 5,000- to 20,000-ton-capacityrange, and they re generating some usefulinformation. "Bur," he says, "none of themare getting us to the answer we really need:how are we going to manage storage in themillions of tons over long periods of time?"

Paying for Storage

The cask ot managing carbon storage is noth-ing if not daunting: In the United Statesalone, coal plants prcxJuce more than 1.5 bil-lion tons of COT evciy year. Sequestering thatamount of gas will require not only a vastnew infrastructure of pipelines and storagesites but also that tlie country's coal plantsadopt cosriy technologies for cirhon capture.Most existing U.S. plants—indeed, most of

There are currently three industrial-scale CCS operations under way around the world:the Great Plains Synfuel Plant in Beulah, North Dakota (top), which ships its CO^ 200 milesaway for use in enhanced recovery; Norway's Sleipner West gas platform (above), whichburies its emissions under the sea floor; and the In Salah project in Algeria (not pictured),which sequesters CO^ underground.

Environmental Health Perspectives • VOLUME 115 i NUMBER 111 November 2007

the world's 5,000 coal-fired power plants,including the ones now being built in China-—bum pulverized coal (PC) using technologiesessentially unchanged since the IndustrialRevolution. COT can be extracted from PCplants only after the fuel has been burned,which is inefficient because the combustionemissions arc highly diluted with air.

A more efficient approach is to capturehighly concentrated streams of CO2 fromcoal before it's burned. Precombustion cap-ture is tisually applied at integrated gasifica-tion combined cycle (IGCC) coal plants,which are extremely rare, numbering justfive worldwide, according to Sarkus. IGCCplants cost roughly 20% more to opetatebecause the gasification process requiresadditional power, which explains why thereare .so few of them.

Although they don't rule out the possi-bility, none of the industry sources inter-viewed for this article welcome theprospect of retrofitting traditional PC

plants for carbon capture. That wouldrequire major plant modifications andcould potentially double the cost of elec-tricity to consumers, they say. But byignoring existing facilities, industry will setback CCS expansion by decades—mostPC plants in use today have been designedfor lifetimes of 30 to 40 years.

Whatever path it takes, the transition toCCS will require enormous sums of money.When used for enhanced recovery, CO, is acommodity that pays for its own burial. Butonly a small fraction of the COj generatedby coai plants and other industrial processesIS used for that purpose. Creating a broadCCS infrastructure will ultimately require acharge on carbon emissions that, accordingto calculations described in The Future ofGoal shouid totaJ at least S30 per ton—S23per ton for COi capture and pressurizationand S") per ton for transportation and stor-age—with this figure rising annually inaccordance with inflation.

Sally Benson, a professor of energyresources engineering at Stanford University,points to different ways to pay that charge.One is a tax on CO, emissions, an optionshe concedes has little political support.Funds could also be raised with a "cap-and-trade" system, which sets area-wide limits onCO2 emissions that industries can meet bytrading carbon credits on the open market.A cap-and-trade system for CO, has alreadybeen established by the European Union,which regulates the greenhouse gas to meetobligations under the Kyoto Protocol. JeffChapman, chief executive officer of theCarbon Capture and Storage Association, atrade group based in London, suggests theEuropean cap-and-trade system could ulti-mately raise €62 billion.

In the United States, a national cap-and-trade system likely won't appear until thefederal government regulates COT as a pol-lutant, says Luke Popovich, vice president ofexternal cotiununications with the National

Capturing carbonTechnology and theory

Carbon dioxide can be absorbed incoal beds, allowing storage to beeffective at shallower depths; alsocan enhance methane recovery

SOURCE: Intergovern-mental Panel onClimate Change

Injected into saltformations or de-pleted oil andgas reserves atdepths below2,600 ft.

Governments are urged to step up research of a process calledcarbon capture and sequestration (CCS) - capturing carbondioxide and storing it underground or underwater.

Captured and trans-ported to CCS loca-tions from major emis-sion sources

Dissolved intoocean waterbelow 3,300 ft.through a fixedpipeline or ship

Released viaoffshore plat-form to form a"lake" on theocean floor

Caprockformations cre-ate a seal, pre-venting gassesfrom migrating tothe surface

AP

VOLUME 1151 MUMBER 111 November 2007 • Environmental Health Petsoectiveis

None of [the CCS studies under way] are getting us to the answer we really need: how are we going to^ ^ manage storage in the millions of tons over long periods of time?

-Jim KatzerMassachusetts Institute of Technology

Mining Association, a coal industry tradegroup in Washington, DC. In the mean-time, individual states—for instance,California, which sets its own air qualitystandards per a waiver under the Clean AirAct—are planning for their own cap-and-trade systems. California tegulatcs CO2under a state law called AB32, which directsindustries to reduce all greenhouse gas emis-sions by 25% over the next 13 years. CCSmay ultimately emerge on a state-by-statebasis in this country, where charges on car-bon emissions allow it, Benson su^ests.

Technical Questions Remain

Until the early 1990s, most researchersinvolved in CCS worked in isolation. But inMarch 1992, more than 250 gathered forthe first International Conference onCarbon Dioxide Removal in Amsterdam.Howard Herzog, a principal research engi-neer at the MIT Laboratory for Energy andthe Environment and a leading expert onCCS. says attendees arrived as individualsbut left as a research community that nowincludes funding agencies, industries, andnongovernmental organizations throughoutthe world. Unfortunately, that communitydoesn t have nearly the resources it needs tostudy CCS on a realistic scale, Katzer says.Indeed, The Future of Coal states emphati-cally that "government and private-sectorprograms to implement on a timely basisthe large-scale integrated demonstrationsneeded to confirm the suitability of carbonsequestration are completely inadequate."

Absent sufficient evidence, most expertssimply assume that vast amounts ofsequestered COT will stay in place withoutleaking to the atmosphere. They base thatassumption on available monitoring data

from the big three industrial projects—noneof which have shown any evidence of CO^leakage from their underground storagesites, according to 7̂ 1? Future of Coal—andalso on expectations that buried COT willbehave in essentially the same way as under-ground fossil fuel deposits. "We're opti-mistic it will work," says Jeffrey Logan, asenior associate in the Climate, Energy, andTransport Program at the World ResourcesInstitute. "The general theory is that if oiland gas resources can remain trapped formillions of years, then why not CO^?"

Franklin Orr, director of the GlobalClimate and Energy Project at StanfordUniversity, says monitoring data show thatCO2 injected underground for enhanced oiland gas recovery temains trapped there bythe same geological structures that trappedthe fuels for millions of years; specificallyoverlying shale deposits through which nei-ther fossil fuels nor CO2 can pass. Decadesof research by the oil and gas industries, inaddition to basic research in geology, haverevealed the features needed for C O ,sequestration, he says: "You're looking fordeep zones with highly porous rocks—forinstance, sandstone—capped by shale sealswith low permcabiiity. Sleipner andWeyburn are both good examples; bothhave thick shale caps that keep the CO^from getting out."

But Orr concedes that questions remainabout how large amounts of CO^ mightbehave underground. A key risk to avoid, hesays, is leakage through underlying faults orabandoned wells that provide conduits tothe atmosphere. Yousif Kharaka, a researchhydroiogist with the USGS In Menio Park,California, says an unknown but possiblylarge number of orphaned or abandoned

wells in the United States could pose a riskof leak^e to the atmosphere. And that, hewarns, would n ^ t e the climate benefits ofsequestration.

The likelihood that COj levels couldaccumulate and cause health or ecologicalinjuries is minimal, Kharaka says, echoingthe conclusions reached in The Future ofCoal. He says CO2 in air only becomesharmful to humans at concentrations of 3%or above, which is far higher than might beexpected from slow leaks out of the ground.Nonetheless, the possibility that CO, leak-ing from underground storage sites mightaccumulate to harmful levels in basementsor other enclosed spaces can't be discountedentirely, cautions Susan Hovorka, a seniorresearch scientist at the Bureau of EconomicGeology, a state-sponsored research unit atthe University of Texas at Austin. "It'simportant that we manage this substancecorrectly," she says. "If you determine thatthere's a risk to confined places, then youhave to provide adequate ventilation. Butwe have a high level of confidence that CO,will be retained at depth."

The greater concern says Kharaka, is thatmigrating CO, might mix with brine, form-ing carbonic acid that could leach metalssuch as iron, zinc, or lead from the underly-ing rock. In some cases, acidified brine alonecould migrate and mix with fresh groundwa-ter, posing health risks through drinking orirrigation water, he says. Results from aninvestigation conducted near Houston,Texas, led by Hovorka as principal investiga-tor along with Kharaka and other scientistsfrom 21 organizations, indicate that CO-,injected into saline aquifers produced sharpdrops in brine pH, from 6,5 to around 3.5.These results were published in the

Etivironmental Health Persoectives • VOLUME î 151 NUMBER 111 Noupmhpr 7007

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Coal companies are hoping to build new plants before cap-and-trade regulations go into effect—and theywill, soon—with the idea that the plants and their greenhouse gas emissions will be grandfathered in untilsequestration is technically and financially feasible. This is an enormously risky investment decision on theirpart, and morally irresponsible.

-Leslie HarrounOak Foundation

September 2007 report Water-Rock Inter-action: Proceedings of the 12th InternationalSymposium on Water-Rock Interaction, Kun-ming, China. 31 July-5 August, 2007. Chem-ical analyses showed the brine contained highconcentrations of iron and manganese, whichsuggests toxic metai contamination can't beruled out, Hovorka says. "I'd describe this asa nonzero concern," she adds. "It's not some-thing we should write off, bur it's noc ashowstopper." [For more on public percep-tion of CCS hazards, see "Of Two Minds:Groups Square Off on Carbon Mitigation,"p. A546 this issue.]

Experts in this area consistently pointCO che need for more detailed investiga-tions of CO2 movements at depch andtheir geochemical consequences. Hovorka'sinvestigation was among the firsc of thiskind, but its scale—jusc 1,600 tons—paledin comparison to realistic demands forCO2 mitigation to combat climate change.

¿Constrained by inadequate funding, theDOE has put much of its CCS investmentinto a project dubbed "FutureGen." Thisinitiative seeks to buÜd a prototype coal-fired power plant that will integrate allthree features of a CCS system, namely,carbon capture (achieved with IGCC tech-nology), CO2 transportation, and seques-tration. Supported by the DOE and analliance of industry partners, the four-year,$1.5 billion project was announced formallyby President Bush in his 2002 State of cheUnion Address. Once operational, theplant will supply 275 megawatts of power(compared with the 600-1,300 megawattssupplied by typical U.S. coal plants), enoughfor 275,000 hoüsehoid.s. Sarku.s. who is alsothe FucureGen director, says four pocencialsites for the plant and its COj reservoirs-

including two in Illinois and cwo in Texas—are under consideration. Final sire selection,he says, will depend on community support,adequate transportation lines, and proximityCO underground storage reservoirs.

The Bush administration's stance is thatFutureGen will promote CCS advancementsthroughout the coal and utility industries.But many stakeholders don't think it goes farenough toward meeting existing needs; theproject is "too much 'future' and not enough'generation,'" quips Hawkins. "What weneed is legislation that specifies future powerplants must be outfitted with CCS, period."To that, Katzt-r adds, "FutureGen wasannounced in 2002, and they still haven'tsettled on site selection, nor have theyresolved key design issues. Operations wereset to begin in 2012, and now that's slippingback even further. Assuming you start in2012 and operate for four years, you're look-ing at 2016 before you complete a singledemonstration project. That stretches thingsouc too far, and speaks to the need tor severaldemonstration projects funded now by theU.S. government so we can deal with CO^emissions in a cimely fashion."

The Developing Country FactorWith U.S. research efforts stuck in low gear,concerns over a comparable lack of progressin the developing world are growing. Chinaalready obtains more chan 80% of its domes-tic electricity from coal. And with a relentlesspush for economic growth, lowering COjemissions from its coal plants is a low priority.It's likely thac none of China's coal-firedplants arc outfitted for carbon capture, saysRichard Lester, a professor of nuclear scienceand engineering at MIT. "Given the scale andexpansion of China's electric power sector.

the eventual introduction of CCS there isgoing to be absolutely critical to global effortsto abate or reduce the atmospheric carbonburden," he says.

Meanwhile, India lags just a decade orless behind China in terms of its own eco-nomic growth, which is increasingly Rieledby coal use, Katzer says. The key differencebetween the two countries, he says, has to dowich planning lor environmental and energydevelopment. In China, Katzer explains,growth and environment strategies seem tobe dictated at regional levels without anycentral coordination, which is ironic consid-ering che country's socialist political struc-ture. India, on the other hand, seems to havewhat Katzer calls a "master plan" for growth."But they have no clue how to move for-ward in terms of COT reductions," Katzersays. "What officials in India say to me is,'We'll manage CO, if it doesn't cost toomuch.' That's the downside in all of this."

In the end, CCS seems to be stuck in Acatch-22: In the view of the developingworld, the United States and other wealthiernations should take the lead with respect toemissions reduction technology. Govern-ments in wealthier nations, meanwhile—-par-ticularly the United States—look to industriesin the iree market for solutions to the prob-lem. But U.S. industries say they can't affordlarge-scale research; in industry's opinion, thegovernment should pay for additional scudiestiiat lay che groundwork for industry researchand the technology's fiiture implementation.The government, however, doesn'c iijnd theDOE and other agencies at nearly theamounts required to achieve rhis. And at thesame cime, the two mechanisms thatcould possibly generate sufficient revenuesfor GCS^—carbon taxes and cap-and-trade

wniiJMF IIR I MHUBPR 11 1 Nnupmbpr ?nf)7 • Fnvirnnmpnr;!! HpflSrh Persnprtives

systems for CO, emissions—are trapped byperpetual political gridlock.

Leslie Harroun, a senior program officerat the Oak Foundation, a Geneva-hasedorganization that funds social and environ-mental research, warns that industry mightleverage the promise of CCS as a public rela-tions strategy today while doing little toensure its hroad-based deployment tomor-row. "The coal industry's many proposals tobuild 'clean' coal plants that are 'captureready' across the U.S, is a smokescreen," sheasserts. "Coal companies are hoping to buildnew plants before cap-and-trade regulationsgo into effect—and they will, soon—withthe idea that the plants and their greenhousegas emissions will be grandfathered in untilsequestration is technically and financiallyfeasible. This is an enormotisly risky invest-ment decision on their part, and morallyirresponsible, but maybe they think there ispower in numbers."

In a sense, the inenia surrounding CCSmight reflect a collective wilt in the face of aseemingly overwhelming technical and socialchallenge. To make a difference for climatechange, a CCS infrastructure will have tocapture and store many billions of tons ofCO2 throughout the world for hundreds ofyears. Those buried deposits will have to bemonitored by unknown entities far into thefuture. Many questions remain about whowill "own" these deposits and thereby assumeresponsibility for their long-term storage.Meanwhile, industry and the government areat an impasse, with neither taking a leadingrole toward making lai^e-scale CCS a reality.How this state of afïàirs ultimately plays outfor health ofthe planet remains to be seen.

Charles W. Schmidt

[Whatever Happened to Deep Ocean Storager

b ne CCS option that appears to have fallen by the v̂ -ayside is deep

ocean storage. Scientists have long speculated that enormous volumes

of COT could be stored in the ocean at depths of 3 km or more. High pres-

sure would compress the CO^, making it denser tban seawater and thus

enabling it to sink. So-called CO^ lakes would hover over the sea floor, sug-

gests Ken Caldeira, a Stanford University professor of global ecology.

"A coal-fired power plant produces a little under one kilogram of CO^ for

each kilowatt-hour of electricity produced," says Caldeira. "An individual

one-gigawatt coal-fîred power plant, . . . if completely captured and rhe CO^

stored on the sea floor, would make a lake ten meters deep and nearly one

kilometer square—and it [would grow] by that much each year."

But Caldeira and others acknowledge that deep ocean storage doesn't

offer a permanent solution. Unless the gas is somebow physically confined,

over time—perhaps 500 to 1,000 years^up to half the CO2 would diffuse

through the ocean and be released back into the atmosphere. Moreover, most

life within CO2 lakes would be extinguished. However, Caldeira believes this

consequence would be balanced by the benefits of keeping the greenhouse

gas out of the atmosphere, where under global warming scenarios it acidifies

and endangers sea life at the surface.

No one knows precisely what would happen during deep ocean storage

because it's never been tested. A planned experiment off the coast of Hawaii in

the late 1990s, with participation of U.S., Norwegian, Canadian, and

Australian researchets, was canceled because of opposition of local environ-

mental activists. According to Caldeira, who previously co-directed the DOE's

now-defunct Center for Research on Ocean Carbon Sequestration, govern-

ment program managers who backed the Hawaiian study were laterally trans-

ferred, sending a signal that advocating for chis type of research was politically

dangerous for career bureaucrats. "Today, there's zero money going into it,"

Caldeira says. "Right now, ocean sequestration is dead in the water."

Environmental Health Perspectives • VOLUME 115 ! NUMBER 111 November 2007