Clean Coal: Is Carbon Capture and Storage Fossil Fuels' Best Hope?
Two recent projects to capture and store carbon emissions from large coal-fired powerplants have had very different outcomes: One was completed this spring and is undergoing testing and commissioning; the other is months behind schedule and way over budget.
The Boundary Dam project in Saskatchewan went up relatively smoothly, although there were challenges during the construction phase, says SaskPower President and CEO Robert Watson. But the Kemper County carbon capture and storage (CCS) project in Mississippi has been plagued with problems and setbacks; most recently, this spring, Southern Co., the owner, announced the plant would likely not be operational until the first quarter of 2015.
Still, Dept. of Energy officials and the Obama administration have high hopes for the Kemper facility, which they believe will show CCS can be achieved at a utility-scale powerplant in the U.S. DOE Secretary Ernest Moniz visited the Kemper facility in November 2013 and praised Southern Co. for "leading us all toward a 21st-century energy portfolio."
CCS is important because it is a key component of the Obama administration's efforts to mitigate the effects of climate change. According to the U.S. Environmental Protection Agency, powerplant emissions account for more than 40% of U.S. CO2 emissions each year.
In fall 2013, EPA unveiled its proposed New Source Performance Standards (NSPS), which would require coal- and oil-fired plants to drastically reduce their emissions of CO2 and other greenhouse gases. The best tool, according to EPA, is CCS technology. But while EPA has made CCS the linchpin of its proposed standards for new powerplants, power and construction industry experts argue the technology has not been adequately demonstrated at a commercial scale.
Power executives acknowledge CCS is important, but they say the current regulations miss the mark and could create a disincentive to develop the technology further. As a result, conservative lawmakers are lining up with the power sector to oppose what they contend is the administration's environmental overreach, and many observers expect a legal challenge to the regulations once they become final sometime next year.
Michael Wara, an associate professor at Stanford University's law school who has worked with the Brookings Institution and with environmental groups on cap-and-trade and other issues, says the key question with the NSPS rule is: "Is CCS adequately demonstrated? It's going to be a hard-fought legal battle."
Carbon Capture Inescapable
The EPA proposal does not mandate CCS. But many industry experts say that in order for coal-fired plants to meet the target reductions of 1,100 lb of CO2 per megawatt-hour gross over a 12-month operating period, or a 1,000 lb to 1,050 lb CO2/MWh gross reduction over a seven-year period, partial (65%) capture is required. Separate targets were established for natural-gas plants. Further, on June 2, EPA released its proposed rule for reducing greenhouse emissions from existing powerplants. It does not require CCS as a solution, although utilities have the option to use it if it works for them.
In drafting the proposal for new powerplants, EPA relied on Section 111(b) of the Clean Air Act, which requires that EPA establish the best systems for emissions reductions that are technically feasible and adequately demonstrated. For the EPA, that means partial CCS. But numerous engineering firms and utilities argue the technology has not been adequately demonstrated at a commercial scale.
CCS has not yet been successfully deployed at a single utility-scale powerplant, says Melissa McHenry, an American Electric Power spokeswoman. "It has not actually been deployed at a working powerplant, except at a very small, 20-MW scale," she says.
In 2009, AEP built a 20-MW postcombustion CCS unit at its 1,300-MW Mountaineer Station in New Haven, W.Va. Although the plant successfully demonstrated CCS works at that scale, AEP canceled plans to move forward with a utility-scale plant due to regulatory uncertainty and dismantled the demonstration project, McHenry says.
A pilot project such as the Mountaineer CCS is not an adequate demonstration the technology will work at utility scale, McHenry adds. For example, the Mountaineer project was not subjected to conditions typical at a powerplant, such as having to ramp up power when needed and running the plant around the clock.
Environmental advocates contend this is a specious argument. "The way utilities put this, it's a self-fulfilling prophecy," says George Peridas, scientist at the Natural Resource Defense Council's Climate Center in San Francisco. "They are saying, 'We haven't built 20 of these, therefore we can't build 20 of these," Peridas says, adding that there is more than ample evidence that CCS works.
CCS is not a new technology, adds Don Broeils, vice president of power at Irving, Texas-based Fluor Corp. The company used a form of postcombustion CCS at a commercial-scale industrial facility in Bellingham, Mass., beginning in 1989, says Broeils. The plant operated successfully, producing food-grade CO2 for about 15 years before it was shut down in 2005.
Since then, Fluor has developed pilot and demonstration CCS projects around the world. One pilot project in Wilhelmshaven, Germany, is using monoethanolamine (MEA) as the solvent for efficient post-combustion capture of C02 at a coal plant. Broeils says, "We are continuing to perform work there to enhance our technology, working to drive down our energy costs and increase efficiency."
Still, while Fluor has done development projects all over the world, "it has yet to build one of commercial size" at a coal-fired powerplant, notes Dennis Johnson, executive director for process and specialty engineering for Fluor's power business.
The argument that there are no viable examples of CCS at commercial-scale powerplants may lose some steam when the two CCS plants start operations within the next year. SaskPower's $1.35-billion Boundary Dam project in Saskatchewan currently is undergoing commissioning and expects to be fully on line in a few months.
The CCS unit, incorporated into an existing 824-MW plant, uses a postcombustion regenerative amine system to capture the CO2 from one of the plant's 130-MW combustion units. Then, the gas is compressed into a supercritical state and transported via pipeline to a storage site as well as an oil field for enhanced oil recovery. The retrofitted unit will capture 1 million metric tons per year—approximately 95% of the unit's CO2 emissions.
According to SaskPower's Watson, the project is nearly on time and on budget. Nevertheless, he acknowledged there were "a tremendous amount of challenges that we overcame. The lessons learned will be enormous." SaskPower is analyzing the myriad challenges but gives the example of finding asbestos in old generating units that had to be removed and halted work for several weeks.
Meanwhile, work continues on Southern Co.'s $5.5-billion Kemper County project in Mississippi. The project is a year behind schedule and $250 million over budget. In fact, it has had problems almost since its inception. "They are really taking it on the chin," says Stanford's Wara.
Kemper's difficulties have less to do with CCS technology than with construction problems with the plant and its associated infrastructure. John Huggins, vice president of generation at Mississippi Power, a subsidiary of Southern Co., says the design team underestimated how much piping and wiring was needed. "It just took time to install the actual quantities after the detailed design revealed what the actual quantities were going to be," he notes. And a more drawn-out schedule has an impact on cost, especially labor costs. "If there's additional quantities to install, it's going to cost you more to do that," Huggins says. The project is expected to come on line in the first quarter of 2015.
A third project, expected to break ground this year, is the $1.65-billion FutureGen project at Unit 4 at Ameren's powerplant in Meredosia, Ill. Funded largely through a $1-billion DOE grant, the project will use oxycombustion, which burns coal in purified oxygen to create a concentrated CO2 stream. The CO2 will be compressed and piped for underground storage at a nearby saline aquifer. The project is projected to come on line some time in 2017.
Penny-Wise Utilities
Despite the development of a few utility-scale CCS plants in North America, power companies are hesitant to launch new projects, although there are a handful in development in the U.S., Europe and China, says the Global Carbon Capture and Storage Institute.
"The New Source Performance Standards pretty much prevent the construction of any new coal plants," AEP's McHenry says. "With the proposed standards for new plants, you couldn't build one without CCS, and that technology isn't proven, so you wouldn't take that risk," she says. Additionally, issues of liability for who owns the CO2 after it is sequestered have yet to be worked out, she says.
Brian Toth, environmental assessment manager for Southern Co., says, "We would have liked [EPA] to have shown some actual operating data of recently constructed plants and a set a limit that is consistent with those kinds of projects." The list would include the modern, highly efficient supercritical pulverized- coal plants "but would not have included CCS," he says. Toth notes that CCS may be workable for some plants, such as Kemper County's, but requiring CCS on all new plants is pushing utilities to use more expensive, first-generation technology on all new plants at the expense of developing second-gen technology.
A key complaint among utilities is that CCS is not economical in today's market. The American Coalition for Clean Coal Electricity estimates that installing first-generation CCS technology on a 600-MW coal plant could add as much as $1 billion in capital costs.
A typical commercial fossil-fuel powerplant creates a large mass of CO2 that needs to be captured and disposed. With postcombustion CCS, "there's a significant amount of energy that has to be used to run the process and compress the CO2 into a liquid for transport to either a sequestration site or enhanced oil recovery site," Broeils says.
Pamela Tomski, a senior adviser for the Americas at the Global CCS Institute, says, "In current market conditions, [CCS] just can't compete with other options, particularly natural gas and combined-cycle plants."
Most of the plants that have either been built or are in development have received partial subsidies from the federal government. For example, Kemper received $270 million under DOE's Clean Coal Initiative. Subsidies help, but incentives to develop CCS policy changes at the federal and state levels would do more, Tomski observes. One potential incentive would recognize CCS as an important component of a low-carbon portfolio and include the technology in programs such as clean-energy portfolio standards or tax credits designed to drive clean-energy deployment, she says. Additionally, more funds should be set aside for R&D efforts, she believes.
The EPA regulations "are one component that can help drive commercial deployment, and they need to be coordinated with policy incentives and policy actions. … If they are issued in silos, then we don't get anywhere," she says.
NRDC's Peridas adds, "The reason we have not seen more of [CCS] is not because there is no one out there willing to stick their neck out. The reason? Laws and regulations governing putting CO2 into the atmosphere haven't made this a necessity or even an attractive proposition." He says EPA's NSPS proposal will help "level the playing field" and ensure that no new plants are built with uncontrolled CO2 emissions.
Despite concerns about the viability of scaling-up the technology for commercial powerplants, utilities and engineering, procurement and construction (EPC) firms acknowledge that CCS is important. Southern Co., AEP and others are investing in research and development through entities such as Southern's National Carbon Capture Center in Birmingham, Ala. The DOE also supports research into emerging technologies through a grant program. "We think it's important that research continues [given] the way we see the regulations going in the future," says Southern's Toth.
Advanced Chemistry
Much of the research being done by engineering firms around the world is focused on making CCS more efficient. R&D efforts also are looking at promising second-generation technologies such as chemical looping, a process in which coal reacts with iron oxide-based oxygen carrier particles. The chemical reaction converts the coal to a concentrated stream of CO2 for use in enhanced oil recovery or for permanent storage and reduces iron-oxide. The reduced oxygen carrier particles are re-oxidized in a second reactor in which heat is liberated and made available to produce steam for electricity generation.
Chemical looping is considered a more cost- effective method for capturing and sequestering CO2 because it can operate without an air-separation unit on the powerplant, says Kip Alexander, vice president of technology at Babcock & Wilcox's Power Generating Group (B&W PGG). "It has lower power consumption and lower capital costs," he says.
In May, B&W PGG received a $2.5-million DOE award for phase-two development of iron-based coal direct chemical looping technology in a laboratory setting. B&W PGG previously worked with Ohio State University to successfully validate the technology at bench scale.
Alexander says, "We've either got to get the cost down" through continued research into more efficient and cost-effective CCS technologies "or there's got to be some other mechanism to draw it into the market." He adds, "[Otherwise] there will not be any new coal in the U.S. for the foreseeable future."
The best and most effective incentive, several sources say, is to develop a cap-and-trade approach with a price on CO2.
"EPA has been dealt a very difficult hand," says Stanford's Wara. In the best-case scenario, "we would have a cap-and-trade program or a carbon tax that put a price on carbon emissions that was high enough to induce technological innovation."
But the EPA does not have the authority under the Clean Air Act to do that. Wara concludes, "Working within the framework that they have, I think they are trying to craft a solution that is as tough as it can be and still be legal."
| PRECOMBUSTION-INTEGRATED GASIFICATION COMBINED CYCLE: Fuel is first gasified with oxygen to produce a synthesis gas, which is then chemically converted into separate streams of CO2 and hydrogen.Examples: Kemper county, Miss. (Under construction) and Texas Clean Energy project for summit power group in Penwell, Texas (in planning stages). |
| POSTCOMBUSTION: This type of capture uses chemical solvents, such as amine, to separate CO2 from the flue gas.Example: Boundary Dam project for SaskPower in Saskatchewan (in commissioning). |
| OXY-COMBUSTION:This process burns coal at a higher temperature in an atmosphere of pure oxygen and carbon dioxide.Example: FutureGen at Unit 4 at Ameren’s powerplant in Merodosia, Ill. (construction expected to begin later in 2014). |
| Source: Massachusetts Institute of Technology |
