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Integrated Coal Gasification Integrated Coal Gasification Combined Cycle (IGCC): Combined Cycle (IGCC): Environmental Impacts and Environmental Impacts and Policy ImplicationsPolicy Implications
Clean Air Task ForceOctober 27, 2004
3
IGCC: What is it?IGCC: What is it?
Chemical conversion of coal to synthetic gas for combustion in a modified gas turbine
Inherently cleaner process because:– Coal is not combusted.– Pollutants are removed with greater efficiency because
clean-up occurs while syngas volume is relatively small compared with flue gas.
4
IGCC SchematicFeeds Gasification Gas Refining End-products
Syngas
Oxygen Electricity
CO2 Sequestration OptionSolids
SULFURRECOVERY
SULFUR /CO2
REMOVAL
H S2
HRSG Steam
Combustion Turbine
Syngas Chemicals
Hydrogen
Ammonia
MethanolCoalSyngas
Sulfur
REMOVAL
MERCURY
Mercury
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PC PlantPC Plant-- chemical plant at the back endchemical plant at the back end
Fuel
Bottom Ash
Fly Ash
FGD Byproducts and Waste
Stack Emissions
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SO2 EmissionsSO2 Emissions
Commercial technology can remove SO2 to trace levels.2 ppm (about 0.14 lb/MWh) is being achieved at new Japanese IGCC (heavy oil) unit (after 6 months of operation).0.15 lb/MWh has been demonstrated on a sustained basis at the ELCOGAS (coal) plant in Spain.Proposed new US IGCC seeking ~.30 lb/MWhSO2 permit limits
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SO2 EmissionsSO2 EmissionsCoal Plant SO2 Emission Rates
Pounds per MWH
10.272
0.934
0.3970.144
0.00
2.00
4.00
6.00
8.00
10.00
12.00
All Coal in 2002 Average of The Best 38Coal Plants
Best Coal Plant in 2002 New Japanese Plant
Lbs
per M
WH
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NOx EmissionsNOx Emissions
Potential issue: SCR operation may cause heat recovery steam generator foulingSCR at Japan IGCC achieving 2 ppm levels, or about 0.10 lb/MWh after 6 months of operation.Relatively low rates - 15 ppm permit limit, actual emissions 8 - 11 ppm at Polk without SCR.Proposed US IGCC plants seeking ~.5 lb/MWh NOx permit limit (no SCR).GE and Siemans are working to lower syngas NOx emissions rates to <2ppm without SCR
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NOx EmissionsNOx EmissionsCoal Plant NOx Emission Rates
Pounds per MWH
4.294
1.320
0.584
0.099
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
5.00
All Coal Plants in 2002 Average of the Best 30Coal Plants
Best Coal Plant in 2002 New Japanese Plant
Lbs
per M
WH
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Solid waste and water useSolid waste and water use
Solid Wastes– Less Volume: IGCC produce about half the solid
wastes of conventional coal plants.– Better Form: IGCC solid wastes are less likely to leach
toxic metals than fly ash from conventional coal plants because IGCC ash melts and is vitrified (encased in a glass-like substance).
Water Use– Less Water: IGCC units use 20%-50% less water than
conventional coal plants and can utilize dry cooling to minimize water use.
12
Carbon dioxideCarbon dioxide
Up to 100% of the carbon in syngas can be captured at IGCC plants with commercially available technology.
Carbon capture at IGCC plants is significantly easier and much more economic than at conventional pulverized coal plants and more economic on a $/ton basis than at natural gas plants.
Even without carbon capture and sequestration, IGCC plants are more efficient than conventional coal plants and emit less CO2.
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IGCC costs are close to IGCC costs are close to conventional coal plantsconventional coal plants
IGCC may cost slightly more than convention plants without carbon capture and sequestration (CCS) but costs much less when carbon is reduced.
Cost of Electricity in $/MWh
Conventional Coal IGCC
ConventionalCoal IGCC
Bituminous 46.6 45.8-48.3 75.4 61-67
Subbituminous 44 48-54 64-97 61
Without CCS With CCS
Source: EPRI, 2004
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New IGCC ProposalsNew IGCC Proposals
Significant new IGCC proposals have been announced in the last year:
– AEP:1000 MW IGCC– Cinergy: 600 MW IGCC– ArcLight Capital: 500 MW IGCC
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Policy Train WreckPolicy Train Wreck
IGCC proposals are becoming more common, but why build an IGCC if you can get a permit with much higher emission rates for a conventional coal plant?
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IllinoisIllinois-- Pending Permit Pending Permit ApplicationsApplications
Peabody, 1500 MW PC
ArcLight,544 MW IGCC & Methane Production
SO2 .182 lb/MMBtu
.034 lb/MMBtu
NOx .08 lb/MMBtu
.059 lb/MMBtu
Mercury .14 Tons/yr .0105 Tons/yr
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WisconsinWisconsin-- Elm RoadElm Road
SCPC IGCC% Increase due to SCPC
Sulfur Dioxide 0.15 0.03 400%Nitrogen Oxide 0.07 0.07 0%Carbon Monoxide 0.12 0.03 300%VOC 0.0035 0.0017 106%Hg 1.1E-06 5.6E-07 100%PM 0.018 0.011 64%Sulfuric Acid Mist 0.01 0.0005 1900%Notes: Elm Road Wisconsin permit limits issued by WDNR January 2004, expressed in lb/MMBtu. This air permit is a good comparison of IGCC and SCPC because it is for both technologies at the same site using the same Pittsburgh #8 bituminous coal.
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Solution to the Policy Train Solution to the Policy Train WreckWreck1. Require conventional coal plants to
evaluate IGCC in their BACT analysis
2. Insist on proper evaluation
3. Find IGCC as BACT when the specific situation merits that determination
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Best Available Control Technology (BACT) Best Available Control Technology (BACT) and IGCCand IGCC
If a conventional coal plant is proposed, should IGCC be evaluated as an alternative option?
– StatesYes: Illinois, Montana, New MexicoNo: Wisconsin, West Virginia, UtahUndecided: Many states
– Federal• May issue an opinion through permit appeal decision.
Have been reluctant to decide in other forums.
20
IGCC as BACTIGCC as BACT
Argument that IGCC is “redefining the source” do not apply because:– IGCC is an “inherently lower emitting
technology”– Legislative history of “innovative
combustion technique” identifies coal gasification as one example.
21
Observations and Observations and RecommendationsRecommendations
More IGCC plants are being proposed than in the past.IGCC plants are vastly cleaner than conventional coal-fired power plants.Costs of IGCC are close to that of conventional coal-fired power plants.Regulatory crossroads- Is IGCC BACT for producing electricity from coal?
You’ll never know if your state’s air permit applications don’t compare IGCC to conventional coal plants AND do the comparison accurately!!!
STAPPA/ALAPCO should urge USEPA to require IGCC be evaluated in BACT analysis for conventional coal plants