Coal Gasification Economics and Efficiency: A Comparison Study

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Coal Gasification Economics and EfficiencyA
Comparison Study

• By David Fenton
• November 20th, 2006

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Contents

• Purpose
• Conventional
• Basis
• Results
• IGCC
• Basis
• Results
• Comparisons
• Conclusions

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Purpose

• To compare conventional coal and IGCC power
  plants in the following aspects
• Plant efficiency
• Pollution amounts
• Capital cost
• Operating cost

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Conventional Coal Basis

• 500 MW, supercritical steam power plant
• Dry gas scrubbing for SOx
• Low NOx burners
• Baghouses for PM
• Data for economics taken from TXU data for new
  Texas power plants

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Conventional Plant Layout
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Conventional Results Efficiency

• Net efficiency 38
• Supercritical steam loop increases efficiency
• Ultra-supercritical technology could increase net
  efficiency to 45-50

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Conventional Results Pollution
Pollutant Pre-Control (lb/hr) Post-Control (lb/hr)
CO2 1,300,000 1,300,000
PM 3,750 37.5
SO2 8,600 960
NOx 1,840 920
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Conventional Results Costs

• Expected capital cost 550 million
• 1100 / kW for supercritical plant
• Expected operating costs
• Fuel 213 tons / hr 87.7 million / year
• OM 2.7 / MWh 11.1 million / year
• Total 100 million / year
• Data from TXU for current power plants
• Expected parameters for new Texas power plants

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IGCC Basis

• 500 MW net, coal-gasification
• High-pressure, high-temp Texaco gasifier
• MDEA sulfur removal system to pure sulfur
• Includes air separations plant for oxygen gen.
• Does not include CO2 sequestration (costs)
• Data and economics from Tampa Electric IGCC and
  Wabash River IGCC plants

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IGCC Basis (cont.)

• Texaco gasifier
• High-pressure
• High throughput per reactor volume
• Reduces compression needed during combustion
• High-temperature
• Increases ratio of CO and H2 to CO2 and CH4
• Higher efficiency at higher temperature
• Also allows syngas cooler to generate high
  pressure steam

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IGCC Plant Layout
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IGCC Results Efficiency

• Gross power generation is 50 efficient
• Gasifier efficiency 82.5
• Based on heat balance, literature was 80-85
• Power train efficiency 60
• Matches efficiency of natural gas
• Net generation is 40 efficient
• After including ASU and auxiliary power
• 20 of generated electricity used within plant

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IGCC Results Pollution
Pollutant Post Control (lb/hr)
CO2 1,300,000
PM 20
SO2 100
NOx 350
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IGCC Results Costs

• Expected capital cost 700 million
• 1400 / kW for supercritical plant
• Expected operating costs
• Fuel 208 tons / hr 85.6 million / year
• OM 5.2 of cap 36.3 million / year
• Total 122 million / year
• Data from DOE for current power plants
• Capital cost based on economy of scale and
  applying past experience

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Comparisons
Parameter Conv. IGCC Change
Efficiency 38 40 5
PM 37.5 lb/hr 20 lb/hr -47
SOx 960 lb/hr 100 lb/hr -90
NOx 920 lb/hr 350 lb/hr -62
Capital cost 550 M 700 M 27
Oper. cost 100 M/yr 122 M/yr 22
Using 1 sulfur coal
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Conclusions

• IGCC is successful in lowering chemical emissions
  (particularly SO2),
• CO2 sequestration would lower emissions,
  although it could add capital cost
• There is not a significant gain in overall
  thermodynamic efficiency compared to current coal
  technologies
• Advantages of combined cycle offset by
  gasification and utilities requirements

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Conclusions (cont.)

• Capital and operating costs are significantly
  higher for IGCC power plants
• Results from added complexity of process, as well
  as need for ASU and sulfur treatment units
• Unless environmental factors are the driving
  force, IGCC does not provide an economical or
  fuel conservative alternative to conventional
  coal power plants
• Environmental credits?