Coal Gasification Economics
and Efficiency:
A Comparison Study
By David Fenton
November 20th, 2006
Contents
• Purpose
• Conventional
– Basis
– Results
• IGCC
– Basis
– Results
• Comparisons
• Conclusions
Purpose
• To compare conventional coal and IGCC
power plants in the following aspects:
– Plant efficiency
– Pollution amounts
– Capital cost
– Operating cost
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
Conventional Plant Layout
Conventional Results: Efficiency
• Net efficiency:
38%
– Supercritical steam loop increases efficiency
– Ultra-supercritical technology could increase
net efficiency to 45-50%
Conventional Results: Pollution
Pollutant
CO2
Pre-Control
(lb/hr)
1,300,000
Post-Control
(lb/hr)
1,300,000
PM
3,750
37.5
SO2
8,600
960
NOx
1,840
920
Conventional Results: Costs
• Expected capital cost:
$550 million
– $1100 / kW for supercritical plant
• Expected operating costs:
– Fuel: 213 tons / hr = $87.7 million / year
– O&M: $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
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
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
IGCC Plant Layout
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
IGCC Results: Pollution
Pollutant
CO2
Post Control
(lb/hr)
1,300,000
PM
20
SO2
100
NOx
350
IGCC Results: Costs
• Expected capital cost:
$700 million
– $1400 / kW for supercritical plant
• Expected operating costs:
– Fuel: 208 tons / hr = $85.6 million / year
– O&M: 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
Comparisons
Parameter
Conv.
Efficiency
38%
PM
37.5 lb/hr
SOx*
960 lb/hr
NOx
920 lb/hr
Capital
$550 M
cost
Oper.
cost
$100
M/yr
*Using 1% sulfur coal
IGCC
40%
20 lb/hr
100 lb/hr
350 lb/hr
$700 M
% Change
+5%
-47%
-90%
-62%
+27%
$122 M/yr
+22%
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
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?