Preserving Coal in the Future Generation Mix:
Coal Technology Design and Assessment: FAQ

Q: What are the generation planning economics underlying the resurgence in the interest in new coal plants in addition to CT/CC in North America?

Q: How does a CT/CC stack up against other fossil generation in a CO₂ constrained world?

A: Given the uncertain long-term prospects for natural gas prices, some power producers are investigating new clean coal-based generation additions to re-balance the future fuel mix. Aiming for fuel flexibility, some of these plant developers are also evaluating integrated gasification combined cycle plants (IGCC), with an eye toward their benefits in a future CO₂ constrained world.

A recent EPRI study compared the costs of various clean coal technologies with that of a natural gas-fired combustion turbine/combined-cycle (NGCC) power plant (using F-class CTs). For power plants of about 500 MW net output operating at an 80 percent capacity factor at Kenosha, WI, the 20-year levelized, total cost of electricity (COE) for the NGCC ($31.1/MWh) was significantly less than the COE for various clean coal technologies ($40.3/MWh - $43.5/MWh). Assumed fuel costs were $0.948/GJ ($1/MBtu) HHV for Illinois #6 coal and $2.50/GJ ($2.64/MBtu) HHV for natural gas. The clean coal technologies included pulverized coal (PC), atmospheric fluidized bed combustion (AFBC), and integrated gasification combined cycle (see Table 1).

Technology	PC subcritical	PC supercritical	PC ultra supercritical	AFBC subcritical	IGCC E-gas	NGCC
Plant Size (MW)	500	500	500	500 (2x250)	590 (2x295)	506 (2x253)
Total Plant Cost ($/kW)	1186	1215	1231	1240	1306	455
Heat Rate kJ/kWh HHV (Btu/kWh) avg annual	10070 (9547)	9550 (9054)	9402 (8914)	10224 (9693)	8891 (8430)	7646 (7249)
COE ($/MWh)	40.3	40.3	40.5	43.5	42.1	31.1
Table 1. Comparison of total cost of electricity (COE) for various clean coal technologies and natural gas-fired CT/CC at 80 percent capacity factor

At a price of $2.50/GJ ($2.64/MBtu) HHV for natural gas, the NGCC was more economical. At the 80 percent capacity factor, as natural gas prices rise, the NGCC plant remained economical up to a gas price of $3.71/GJ ($3.91/MBtu) HHV.

However, since power plant dispatch is often conducted based on incremental (variable) costs, plants with high fuel costs (e.g., NGCC) are typically operated at lower capacity factors than 80 percent. At the same coal costs of $0.948/GJ ($1/MBtu) and the same natural gas costs of $2.50/GJ ($2.64/MBtu) as the previous analysis, the NGCC was roughly the same cost (total COE) at 40 percent capacity factor as the PC and IGCC plants at 80 percent capacity factor. Hence, these fuel costs are roughly the breakeven point for clean coal plants and NGCC plants operating at these different capacity factors (see Table 2).

Technology	PC subcritical	IGCC	NGCC	NGCC	NGCC
Plant Size (MW)	500	590 (2x295)	506 (2x253)	506 (2x253)	506 (2x253)
Capacity factor (%)	80	80	80	65	40
Heat Rate kJ/kWh HHV (Btu/kWh) avg annual	10070 (9547)	8891 (8430)	7646 (7524)	7936 (9693)	8166 (7742)
COE ($/MWh)	40.3	41.8	31.1	34.0	41.9
Table 2. Comparison of COE for various clean coal technologies and natural gas-fired CT/CC for various capacity factors

Continued advances in the various coal technologies and changes in market-based costing of gas turbines and boilers create a need for ongoing updating of economic assessments.

Source: Updated Cost and Performance Estimates for Clean Coal Technologies - 2001 by EPRI’s Neville Holt and George Booras.

Back to top

A: A recent EPRI study that examined the costs of various clean coal technologies and a natural gas-fired combustion turbine/combined-cycle (NGCC) power plant (using H-class CTs) addressed the cost of CO₂ removal. This study assumed a coal cost of $1.18/GJ ($1.24/MBtu) HHV and a natural gas cost of $2.56/GJ ($2.70/MBtu) HHV.

Beginning from a baseline cost of electricity (COE) for NGCC, pulverized coal (PC), and integrated gasification combined cycle (IGCC, with H-class turbines), the study recalculated the COE with the addition of CO₂ removal equipment (see Table 3). For the NGCC and PCs, flue gas scrubbing using monoethanolamine (MEA) was assumed; for the IGCC plant, CO₂ was removed from the syngas prior to combustion. Several studies have shown that removal of CO₂ from syngas in an IGCC prior to combustion is significantly less costly than CO₂ removal from the huge volumes of stack gases after combustion at atmospheric pressure—the method used in PCs and NGCCs. (However, many new CT/CC sites are unlikely to be suitable for IGCC since provision has not been made for coal delivery, gasifier trains, and associated permitting.) Despite this inherent advantage of IGCC, for the assumed fuel costs, the NGCC was the lower cost solution ($48.8/MWh) than the IGCC ($59.1/MWh) and PCs ($70 - $72/MWh).

Technology	NGCC H	IGCC H	Supercritical PC	Ultra supercritical PC
COE ($/MWh) without CO2 removal	30.7	45.1	45.0	44.3
COE ($/MWh) with CO2 removal	48.8	59.1	71.9	70.7
COE ($/MWh) with CO2 removal, transportation and sequestration	53.4	67.7	82.1	81.3
Breakeven cost natural gas $/GJ ($/MBtu) with CO2 removal, transportation and sequestration		4.28 (4.52)	60.02 (6.35)	5.92 (6.24)
Table 3. Comparison of cost of electricity (COE) for various clean coal technologies and natural gas-fired CT/CC, accounting for CO2 removal, transportation and sequestration costs

When the additional costs of CO₂ transportation and sequestration ($10/metric tonne of CO₂) are considered, the NGCC’s advantage increases due to the fewer number of tons of CO₂ emitted and hence removed. In addition, as natural gas prices rise, the NGCC plant remained economical up to a gas price of $4.28/GJ ($4.52/MBtu) HHV compared to the IGCC; and the NGCC plant remained economical up to a gas price of $5.92/GJ ($6.24/MBtu) HHV compared to the ultra supercritical PC plant.

Advances in various carbon sequestration technologies and methods, and changes in market costs of turbines and boilers call for periodic updating of these engineering and economic assessments.

Source: Updated Cost and Performance Estimates for Clean Coal Technologies - 2001 by EPRI’s Neville Holt and George Booras. This work is an update of original work performed by Parsons and EPRI with U.S. DOE co-funding and published in EPRI Report 1000416.

Back to top

‹‹ Back to Category Menu ››

‹‹ Back to CT Information and Resource Center ››