Two key initiatives are being used to optimize the performance of coal-fired power plants – performance management using performance data, and environmental management using technological innovations.
Consistent with historical trends, coal is expected to continue to be the dominant source of fuel for power generating facilities. In its February 2012 Short-Term Energy Outlook, the U.S. Energy Information Administration (EIA) projected that coal will account for about 42 percent of the total electricity generated in 2012, followed by natural gas with a share of about 26 percent (Figure 1).
With the continued reliance on coal, the abundance of coal reserves and the emphasis on clean coal technology, significant collaborative efforts have been underway for some time by both the U.S. Department of Energy (DOE) and power companies to optimize the performance of coal-burning power plants. A primary challenge, however, has been striking a balance between performance and cost of complying with environmental regulations to address emissions and greenhouse gases, especially CO2.
Power plant emissions regulations such as the Cross State Air Pollution Rule (CSAPR) and Maximum Achievable Control Technology (MACT) standards are expected to take effect between 2012 and 2015. The short-term impact of these regulations on the electricity generation fuel mix is not clear.
It is anticipated that extended power plant outages might be necessary to install pollution control equipment. Also, the exact level and timing of retrofit outages, or even possible retirements, is unknown.
Performance management of a coal-fired power plant is a function of several factors. These include size, age, outages, economics, reliability, organization, engineering, safety and environmental regulations (Figure 2). There is obviously interdependency among one or more of these factors.
The overall performance of a coal-fired power plant is dependent on the performance of its individual systems, subsystems, equipment and components. From analysis of the North American Electric Reliability Corp. (NERC) Generating Availability Data System (GADS) power plant performance data for the period 1997-2010, the leading causes of lost electricity generation for the following 4 plant groups include:
Boiler & Auxiliaries
- Overhaul (minor and major)
- Waterwall (furnace wall)
- Tube Leaks (boiler, superheater, reheater, economizer)
- Other (air heater, opacity, burners, pulverizers, induced draft fans, instrumentation and controls, miscellaneous)
- Turbine overhaul (major)
- Generator stator and rotor windings, bushings, terminals
- Generator overhaul (major)
- Turbine inspection
- High pressure (HP) turbine problems
- Turbine control valves
- Low pressure (LP) turbine blades
- Exciter problems
Balance of Plant
- Feedwater pump
- HP feedwater heater tube leaks
- Other (plant modifications for regulatory compliance, condensate hotwell pumps, LP feedwater heaters, circulating water system, miscellaneous)
1997-2010 GADS lost generation trends
Figure 3, Figure 4, Figure 5 and Figure 6, respectively, show the lost generation expressed as percentage of megawatt hours (MWh) for the overall plant, as well as for each cause associated with plant groups 1, 2 and 4, based upon analysis of the GADS power plant performance data for the years 1997-2010.
Areas for performance improvements
From the above analysis of the 1997-2010 GADS power plant performance data, the following are the areas, in order of their importance, that merit performance improvements.
Boiler & Auxiliaries
Of all the plant groups, this is the dominant group, accounting for consistently more than 70 percent of the total plant lost generation.