Integrated Gasification Combined Cycle (IGCC)

An Integrated Gasification Combined Cycle (IGCC) is a technology that aims to extract the maximum energy out of a fuel that is burnt. In the case of coal, the carbon conversion efficiency in an IGCC plant is higher than that in a conventional pulverised coal (PC) fired power plant. This is achieved by gasification, which converts coal into synthetic gas or syngas.

Syngas is a mixture containing mainly carbon monoxide (CO) and hydrogen (H2) and some carbon dioxide. The hot exhaust from the gas turbine passes through a heat recovery steam generator (HRSG) where it produces steam that drives a steam turbine. Electric power is produced from both the gas and steam turbine-generators. By removing the emission-forming constituents from the syngas under pressure before combustion, an IGCC power plant produces lower levels of criteria air pollutants (nitrous oxide, sulfur dioxide, and particulate matter) and volatile mercury.

The argument is that because coal is cheap and abundant, the technology allows for the continued use of coal as emission regulations tighten.

The gasification process can produce syngas from high-sulfur coal, heavy petroleum residues, and biomass.

The plant is called integrated because the syngas produced is used as fuel in a gas turbine which produces electrical power. To improve the overall process, efficiency heat is recovered from both the gasification process and also the gas turbine exhaust in the 'Waste Heat Boilers' producing steam. This steam is then used in steam turbines to produce additional electrical power.

The Pros and Cons of IGCC plants

IGCC plants are also touted as having other advantages over pulverised coal plants. Firstly, they use approximately one-third less water than an equivalent-sized plant, which can make them more attractive where water availability is a critical issues. Secondly, Power reports that the ash in the feedstock becomes a "a glassy, nonleachable slag" which is easier to handle, store and transport than fly ash. (The magazine states that it is used in "the manufacture of cement or roofing shingles, or as asphalt filler or aggregate.") It also states that "IGCC plants may have an advantage because the technology required for pre-combustion CO2 capture has already been used successfully on coal gasification (but not IGCC) technology".

However, as the technology is still developing, the costs of these plants are substantially higher than convention coal plants and more expensive still compared to gas-fired plants. Opposition to coal has made obtaining approvals and finance difficult. In the U.S. there has also been reluctance of public utility commissions to approve higher costs, even where they have given in-principle approval to the technology. The U.S. Department of Energy estimates that the addition of carbon capture to the plant would also not only increase the cost by approximately one-third, it would result in roughly 15% less power output. The combined effects of this would be to produce power 40% higher.

Existing IGCC Plants

In 2007 there were only two IGCC plants generating power in the U.S. One is the Polk Power Station operated by TECO Energy; the other is the Wabash River Generating Station operated by Duke Energy. The DOE Clean Coal Demonstration Project helped construct 3 IGCC plants: Wabash River Generating Station, operated by Duke Energy in West Terre Haute, Indiana; Polk Power Station, operated by TECO Energy in Tampa, Florida (online 1996); and Pinon Pine in Reno, Nevada. In the Reno demonstration project, researchers found that then-current IGCC technology would not work more than 300 feet (100m) above sea level. The plant failed.

The largest unit is that at Puertollano in Spain with a capacity of 330 MWe. Poland's Kędzierzyn will soon host a Kedzierzyn Zero-Emission Power & Chemical Plant that combines coal gasification technology with Carbon capture and storage (CCS). It is planned to include up to 10% biomass in the combustion process.

Proposed IGCC Plants

Click here for a list of IGCC pages on SourceWatch, including a number of proposed plants.

Numerous IGCC plants were expected to come online in the U.S. in the 2012-2020 time frame, but most have been cancelled. These include:

• Polk Power Station Unit 6 - Cancelled by TECO Energy in October 2007.
• Southern Illinois Clean Energy Center - This 545 MW IGCC proposal, sponsored by Steelhead Energy, was declared inactive by the EPA in December 2007.
• PacifiCorp Sweetwater Project - In December 2007, PacifiCorp and the state of Wyoming cancelled this jointly sponsored IGCC and coal sequestration demonstration project at the site of PacifiCorp's Jim Bridger Station. The unit had been scheduled for operation in 2013.
• Stanton Energy Center - In November 2007, two months after breaking ground, Orlando Utilities Commission and Southern Company shelved plans for this 285 MW IGCC plant in Orange County, citing concerns about future carbon controls in Florida.
• Mesaba Energy Project - In August 2007 the Minnesota Public Utilities Commission announced its decision that Excelsior Energy’s 600 MW Mesaba IGCC plant "is not in the public interest." The developers of the plant continue to pursue the project, but the plant's projects are considered dim.
• Nueces IGCC Plant - In June 2007 Tondu Corp. abandoned plans for this IGCC plant proposed for Corpus Christi, Texas, citing rising costs and uncertain construction schedules for IGCC. Instead, the company plans to build a gas plant.
• Marion Gasification Plant - Madison Power’s 600 MW IGCC plant in Marion, Illinois was placed on hold in October 2007 due to construction of a nearby supercritical coal plant which hindered power demand and tied up transmission and coal transport infrastructure.
• Huntley Generating Station - This 680 MW IGCC plant proposed by NRG Energy was placed "on hold" in 2007 while the developers sought "cost reductions to maintain state-awarded financial support."
• Buffalo Energy Project - This proposed IGCC plant in Wyoming was been cancelled in 2007 due to transmision constraints, rising construction costs, limited available technology guarantees and an unsuccessful bid for funding.
• Unnamed Xcel Energy Plant - On October 31, 2007, Minneapolis-based Xcel Energy announced that it was shelved plans for a 600 M IGCC plant in Colorado for at least two years, citing rising construction costs and slowing demand.
• Bowie IGCC Power Station - In September 2007 Southwestern Power Group canceled this proposed 600 MW IGCC project in Arizona in favor of pursuing a natural gas fired plant. The company cites economics and regulatory uncertainty.
• Lima Energy - This 600 MW IGCC plant is sponsored by Global Energy and was planned for Lima, Ohio. Construction began in 2005 but was placed on hold in October 2006 due to financing problems. In Jan. 2008, the Sierra Club filed suit against Lima Energy, charging that the company is moving ahead on the project without securing valid permits.
• Great Bend IGCC - This 629 MW IGCC plant was placed on hold in Feburary 2009 by sponsor AEP Ohio due to economic conditions.
• Ashtabula IGCC Generating Facility - This 830 MW IGCC facility was abandoned by sponsor Nordic Energy, a subsidiary of Global Energy.

IGCC faces barriers

As prospects dimmed for carbon legislation, gas prices declined while shale production rose and recession eroded the need for new generation, leading many of the nearly 20,000 MW of proposed IGCCs to be abandoned or replaced with natural gas, at least temporarily. In 2012, only Duke Energy's 618-megawatt Edwardsport coal project in Indiana and Southern Co's 582-MW Kemper County project in Mississippi were IGCC plants under construction out of the more than three dozen proposed in the U.S. EmberClear will use gas, rather than coal, to fuel its 300-MW Good Spring plant in Pennsylvania, dropping the IGCC component for now. Tenaska may build a gas-fired power plant and defer the gasification component on its Taylorville IGCC project in Illinois. Other active IGCC projects include Summit Energy's 400-MW Texas Clean Energy project, Hydrogen Energy California in Kern County, and ERORA's 770-MW Cash Creek IGCC in Kentucky.

IGCC and Pollution

The first generation of IGCC plants polluted less than contemporary coal-based technology, but also polluted water; for example, the Wabash River Plant was out of compliance with its water permit during 1998–2001 because it emitted arsenic, selenium and cyanide: "As a result, process waste water arising from use of the current feedstock, remains out of permit compliance due to elevated levels of arsenic, selenium and cyanide. To rectify these concerns, plant personnel have been working on several potential equipment modifications and treatment alternatives to bring the discharge back into compliance. Wabash River is currently obligated to resolve this issue by September 2001. Elevated levels of selenium, cyanide and arsenic in the waste water have caused the process waste water to be out of permit compliance. Daily maximum values, though not indicated in the table above, were routinely exceeded for selenium and cyanide, and only occasionally for arsenic." The Wabash River Generating Station is now wholly owned and operated by the Wabash River Power Association.

IGCC and Carbon Capture

IGCC is now touted as capture ready and seen as a potentially ready for carbon capture and storage. (See FutureGen) There are advantages and disadvantages when compared to conventional post combustion carbon capture.

Cost and reliability

The main problem for IGCC is its extremely high capital cost, upwards of $3,593/kW. Official US government figures give more optimistic estimates of $1,491/kW installed capacity (2005 dollars) v. $1,290 for a conventional clean coal facility, but in light of current applications, these cost estimates have been demonstrated to be incorrect.

Outdated per megawatt-hour cost of an IGCC plant vs a pulverized coal plant coming online in 2010 would be $56 vs $52, and it is claimed that IGCC becomes even more attractive when you include the costs of carbon capture and sequestration, IGCC becoming $79 per megawatt-hour vs. $95 per megawatt-hour for pulverized coal. Recent testimony in regulatory proceedings show the cost of IGCC to be twice that predicted by Goddell, from $96 to 104/MWhr. That's before addition of capital intensive and efficiency sucking carbon capture and storage (sequestration is not available or probable on commercial level)—capture at a 30% rate is expected to have a $50/MWh additional cost.

Wabash River was down repeatedly for long stretches due to gasifier problems, and the gasifier problems have not been remedied—subsequent projects, such as Excelsior's Mesaba Project, have a third gasifier and train built in. In addition, both facilities experienced significant down time as a result of erosion, corrosion, fouling, and pluggage of their high-temperature heat recovery units. However, in 2009 Wabash River has been running more reliably.

General Electric is currently designing an IGCC model plant that should introduce greater reliability. GE's model features advanced turbines optimized for the coal syngas. Eastman's industrial gasification plant in Kingsport, TN uses a GE Energy solid-fed gasifier. Eastman, a fortune 500 company, built the facility in 1983 without any state or federal subsidies and turns a profit.

There are several refinery-based IGCC plants in Europe that have demonstrated good availability (90-95%) after initial shakedown periods. Several factors help this performance:

1. None of these facilities use advanced technology (F type) gas turbines.
2. All refinery-based plants use refinery residues, rather than coal, as the feedstock. This eliminates coal handling and coal preparation equipment and its problems. Also, there is a much lower level of ash produced in the gasifier, which reduces cleanup and downtime in its gas cooling and cleaning stages.
3. These non-utility plants have recognized the need to treat the gasification system as an up-front chemical processing plant, and have reorganized their operating staff accordingly.

Another IGCC success story has been the 250 MW Buggenum plant in The Netherlands. It also has good availability. This coal-based IGCC plant currently uses about 30% biomass as a supplemental feedstock. The owner, NUON, is paid an incentive fee by the government to use the biomass. NUON is constructing a 1,300 MW IGCC plant in the Netherlands. The Nuon Magnum IGCC power plant will be commissioned in 2011. Mitsubishi Heavy Industries has been awarded to construct the power plant.

A new generation of IGCC-based coal-fired power plants has been proposed, although none is yet under construction. Projects are being developed by AEP, Duke Energy, and Southern Company in the US, and in Europe by Kedzierzyn Zero-Emission Plant, Centrica (UK), E.ON and RWE (both Germany) and NUON (Netherlands). In Minnesota, the state's Dept. of Commerce analysis found IGCC to have the highest cost, with an emissions profile not significantly better than pulverized coal. In Delaware, the Delmarva and state consultant analysis had essentially the same results.

The high cost of IGCC is the biggest obstacle to its integration in the power market; however, most energy executives recognize that carbon regulation is coming soon. Bills requiring carbon reduction are being proposed again both the House and the Senate, and with the Democratic majority it seems likely that with the next President there will be a greater push for carbon regulation. The Supreme Court decision requiring the EPA to regulate carbon (Commonwealth of Massachusetts et al. v. Environmental Protection Agency et al.) also speaks to the likelihood of future carbon regulations coming sooner, rather than later. With carbon capture, the cost of electricity from an IGCC plant would increase approximately 30%. For a natural gas CC, the increase is approximately 33%. For a pulverized coal plant, the increase is approximately 68%. This potential for less expensive carbon capture makes IGCC an attractive choice for keeping low cost coal an available fuel source in a carbon constrained world.

In Japan, electric power companies, in conjunction with Mitsubishi Heavy Industries has been operating a 200 t/d IGCC pilot plant since the early '90s. In September 2007, they started up a 250 megawatt (MW) demo plant in Nakaso. It runs on air-blown (not oxygen) dry feed coal only. It burns PRB coal with an unburned carbon content ratio of <0.1% and no detected leaching of trace elements. It employs not only F type turbines but G type as well. The CO2 extracted from gas turbine exhaust gas is utilized in this system. Using a closed gas turbine system capable of capturing the CO2 by direct compression and liquefication obviates the need for a separation and capture system.

Recent Emerging IGCC Emission Controversy

In 2007, the New York State Attorney General's office demanded full disclosure of "financial risks from greenhouse gases" to the shareholders of electric power companies proposing the development of IGCC coal-fired power plants. "Any one of the several new or likely regulatory initiatives for CO₂ emissions from power plants - including state carbon controls, EPA's regulations under the Clean Air Act, or the enactment of federal global warming legislation - would add a significant cost to carbon-intensive coal generation"; U.S. Senator Hillary Clinton from New York, a 2008 Presidential Candidate, has proposed that this full risk disclosure be required of all publicly-traded power companies nationwide. This honest disclosure has begun to reduce investor interest in all types of existing-technology coal-fired power plant development, including IGCC.

Senator Harry Reid (Majority Leader of the 2007/2008 U.S. Senate) told the 2007 Clean Energy Summit that he will do everything he can to stop construction of proposed new IGCC coal-fired electric power plants in Nevada. Reid wants Nevada utility companies to invest in solar energy, wind energy and geothermal energy instead of coal technologies. Reid stated that global warming is a reality, and just one proposed coal-fired plant would contribute to it by burning seven million tons of coal a year. The long-term healthcare costs would be far too high. "I'm going to do everything I can to stop these plants.", he said. "There is no clean coal technology. There is cleaner coal technology, but there is no clean coal technology."

Articles and resources

Related GEM.wiki articles

• Clean Coal
• Carbon capture and storage
• Coal-to-liquids
• Syngas
• Key private sector decision makers on coal
• United States and coal
• Global warming
• Federal coal subsidies
• Proposed Synfuels Plants in the United States
• Existing U.S. Coal Plants
• Coal-to-Liquids Fuel Promotion Act of 2007

External Articles

• Saqib Rahim, "States Wrestle With Clean Coal Technology, With Varying Results" NY Times, Sep. 21, 2010

External resources

Wikipedia also has an article on Integrated Gasification Combined Cycle (IGCC). This article may use content from the Wikipedia article under the terms of the GFDL.