Research Papers: Gas Turbines: Electric Power

An Expanded Cost of Electricity Model for Highly Flexible Power Plants

[+] Author and Article Information
S. Can Gülen

Principal Engineer

Indrajit Mazumder

Lead Engineer
GE Energy,
1 River Road, Building 40-412,
Schenectady, NY 12345

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the Journal of Engineering for Gas Turbines and Power. Manuscript received June 25, 2012; final manuscript received July 13, 2012; published online November 21, 2012. Editor: Dilip R. Ballal.

J. Eng. Gas Turbines Power 135(1), 011801 (Nov 21, 2012) (11 pages) Paper No: GTP-12-1217; doi: 10.1115/1.4007379 History: Received June 25, 2012; Revised July 13, 2012

Cost of electricity (COE) is the most widely used metric to quantify the cost-performance trade-off involved in comparative analysis of competing electric power generation technologies. Unfortunately, the currently accepted formulation of COE is only applicable to comparisons of power plant options with the same annual electric generation (kilowatt-hours) and the same technology as defined by reliability, availability, and operability. Such a formulation does not introduce a big error into the COE analysis when the objective is simply to compare two or more base-loaded power plants of the same technology (e.g., natural gas fired gas turbine simple or combined cycle, coal fired conventional boiler steam turbine, etc.) and the same (or nearly the same) capacity. However, comparing even the same technology class power plants, especially highly flexible advanced gas turbine combined cycle units with cyclic duties, comprising a high number of daily starts and stops in addition to emissions-compliant low-load operation to accommodate the intermittent and uncertain load regimes of renewable power generation (mainly wind and solar) requires a significant overhaul of the basic COE formula. This paper develops an expanded COE formulation by incorporating crucial power plant operability and maintainability characteristics such as reliability, unrecoverable degradation, and maintenance factors as well as emissions into the mix. The core impact of duty cycle on the plant performance is handled via effective output and efficiency utilizing basic performance correction curves. The impact of plant start and load ramps on the effective performance parameters is included. Differences in reliability and total annual energy generation are handled via energy and capacity replacement terms. The resulting expanded formula, while rigorous in development and content, is still simple enough for most feasibility study type of applications. Sample calculations clearly reveal that inclusion (or omission) of one or more of these factors in the COE evaluation, however, can dramatically swing the answer from one extreme to the other in some cases.

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Marsh, W. D., 1980, Economics of Electric Power Utility Power Generation, Oxford University Press, New York.
U.S. Energy Information Administration, 2009, Annual Energy Outlook 2010, DOE/EIA-0383.
Maize, K., and Peltier, R., 2010, “The U.S. Gas Rebound,” Power, 154(1), pp. 20–31.
Carrino, A. J., and Jones, R. B., 2011, “Coal Plants Challenged as Gas Plants Surge,” Power, 155(1), pp. 47–49.
Cox, J., 2010, “Implications of Intermittency,” Mod. Power Syst., 30(1), pp. 22–23.
Peltier, R., 2010, “Flexible Turbine Operation is Vital for a Robust Grid,” Power, 154(9), pp. 50–54.
Aabadi, K. A., Lhomme, K., Panozzo, G., Stoisser, C., Verlin, R., and Vittu, V., 2009, “EDF Martigues Repowering Project Design and Construction of Two Modern and Efficient CCGT Units,” Proceedings of POWER-GEN Europe, Cologne, Germany, May 26-28.
Gülen, S. C., and Jacobs, J. A., 2003, “Optimization of Gas Turbine Combined Cycle,” Proceedings of POWER-GEN International 2003, Las Vegas, NV, December 9–11.
IEEE Power and Energy Society, 1987, “IEEE Standard Definitions for Use in Reporting Electric Generating Unit Reliability, Availability, and Productivity,” ANSI/IEEE Standard 762-1987 [CrossRef].
Husak, M., Jones, C., and Tegel, D., 2006, “Combined Cycle Plant Operational Flexibility,” Proceedings of POWER-GEN International 2006, 2006, Orlando, FL, November 28-30.
Gülen, S. C., and Jones, C. M., 2011, “GE's Next Generation CCGT Plants: Operational Flexibility is the Key,” Mod. Power Syst., 31(6), pp. 16–18.
Della Villa, S. A., Jr., and Koeneke, C., 2010, “A Historical and Current Perspective of the Availability and Reliability Performance of Heavy Duty Gas Turbines: Benchmarks and Expectations,” Proceedings of the ASME Turbo Expo 2010, Glasgow, UK, June 14-18, ASME Paper No. GT2010-23182, pp. 835–845. [CrossRef]
Grace, D. S., 2008, “Combined Cycle Power Plant Maintenance Costs,” Proceedings of the ASME Turbo Expo 2008, Berlin, Germany, June 9-13, ASME Paper No. GT2008-51357, pp. 1007–1016 [CrossRef].
Grace, D., and Christiansen, T., 2012, “Risk-Based Assessment of Unplanned Outage Events and Costs for Combined Cycle Plants,” Proceedings of the ASME Turbo Expo 2012, Copenhagen, Denmark, June 11-15, Paper No. GT2012-68435.
Diakunchak, I. S., 1992, “Performance Deterioration in Industrial Gas Turbines,” ASME J. Eng. Gas Turbines Power, 114, pp. 161–168. [CrossRef]
U.S. EPA Report, 2006, “Global Mitigation of Non-CO2 Greenhouse Gases,” Office of Atmospheric Programs (6207J), Washington, DC, Report No. EPA 430-R-06-005.
PJM Interconnection, 2011, “eRPM Users Guide, Version 1.6,” www.pjm.com
Gülen, S. C., 2011, “A Simple Parametric Model for Analysis of Cooled Gas Turbines,” ASME J. Eng. Gas Turbines Power, 133, p. 011801. [CrossRef]
Robb, D., 2011, “The Gas Turbine Four Minute Mile,” Turbomach. Int., 52(4), p. 6.
U.S. Energy Information Agency, Office of Energy Analysis, 2010, “Updated Capital Cost Estimates for Electricity Generation Plants,” U.S. DOE, Washington, DC.
Lefton, S. A., Besuner, P. M., and Grimsrud, G. P., 2002, “The Real Cost of Cycling Power Plants: What You Don't Know Will Hurt You,” Power, 146(8), pp. 29–34.
Leyzerovich, A. S., 2007, “Reduce Stress With Proper On-Line Rotor Temperature Monitoring,” Power, www.powermag.com
Pasha, A., and Taylor, D., 2010, “HRSGs for Next Generation Combined Cycle Plants,” Proceedings of POWER-GEN International 2010, Las Vegas, NV, December 13-15.
Gülen, S. C., 2011, “A More Accurate Way to Calculate the Cost of Electricity,” Power, 155(6), pp. 62–65.
Balling, L., 2010, “Fast Cycling and Rapid Start-Up: New Generation of Plants Achieves Impressive Results,” Mod. Power Syst., 31(1), pp. 35–41.


Grahic Jump Location
Fig. 1

Example cyclic duty profile (one day—Monday after the weekly shutdown) for a gas turbine combined cycle power plant. (Adopted from Ref. [7].) This particular profile is sometimes described as the plant “two-cycled” daily. Possible variations are myriad (e.g., the plant being brought down to a minimum load overnight instead of being shut down).

Grahic Jump Location
Fig. 3

Annual ambient temperature variation for a typical site in southern Europe

Grahic Jump Location
Fig. 2

A sample annual load profile table. Entries in each cell are the operating hours at the corresponding ambient temperature with the corresponding power output. If a GTCC product is unable to satisfy a particular load requirement (e.g., for example a high load point on a very hot day), it is left out when calculating its total MW h production (marked by o). The balance is made up while evaluating the COE via capacity/energy replacement terms.

Grahic Jump Location
Fig. 4

Typical advanced heavy duty gas turbine CC power plant ambient and part load correction factors

Grahic Jump Location
Fig. 5

Conventional combined cycle start (per Fig. 2 of Ref. [10]). The parameter α quantifies the true MW h generated (the area below the start curve) as a fraction of the simple estimate (the triangular area below the straight line between t = 0 and t = ΔH).

Grahic Jump Location
Fig. 6

Typically expected GTCC nonrecoverable performance loss due to parts aging, deformation, and similar degradation, which cannot be rectified via scheduled maintenance and repairs

Grahic Jump Location
Fig. 8

Breakdown of COE difference between base and advanced GTCC plants (per Eq. (11), $135.5/MW h and $112.1/MW h, respectively, in Table 6)

Grahic Jump Location
Fig. 7

Impact of better part load heat rate, fast start, and load ramps on plant efficiency (normalized basis)



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