The challenge for energy producers to supply continuous, uninterrupted power to customers is constant. Forced outages, which usually occur because of unexpected component failures or systemic problems, can prove costly to the power supplier and undermine its effort to attract and maintain satisfied customers. To reduce the frequency and duration of forced outages, Calpine Corp. is implementing a comprehensive predictive maintenance (PdM) program.
Founded in 1984 and headquartered in San Jose, Calif., Calpine is one of North America's largest power generation companies. In recent years, the company has evolved from solely a leading developer of power plants to a major power-plant operator and service provider. As an electricity wholesaler, Calpine provides electricity to a variety of customers, including electric utilities, industrial manufacturers, municipalities and government institutions. Using two types of fuel -- natural gas and geothermal steam -- to produce electricity, Calpine has the capacity to generate more than 26,000 megawatts from its 92 energy centers in 21 states. Additionally, Calpine operates plants in Canada and the United Kingdom.
Downtime at $11,000/hour
To meet the growing demand for electricity across North America, Calpine continues to increase production while instituting process changes to maximize existing capacity. Our business strategy is centered on expanding generating capacity and optimizing production capability, thereby increasing revenue and maximizing profits by reducing expenses.
In the power generation industry, as well as the Calpine Predictive Maintenance Department, downtime expense is calculated in cost-avoidance terms based on the profit from generating a megawatt-hour of electricity plus the avoided cost of repair. Depending on the plant and the spark spread (a theoretical margin represented by the difference between the price of electricity sold and the price of the fuel used to generate it), the profit for a megawatt-hour varies drastically -- ranging from $5 to more than $50 per hour. For example, at a 560-megawatt Calpine plant in California, the cost avoidance is calculated based on an average of $21 per megawatt-hour. Therefore, average downtime at this particular plant could cost $11,000 an hour ($264,000 a day) or more.
With this much potential profit at stake, maintaining energy production, reducing forced outages (caused by unplanned shutdowns or equipment failure), and avoiding generator deratings (when a unit fails to deliver power at its rated capacity) are top priorities for management and employees alike.
Strategy based on ROI
Recognizing that rates always will fluctuate based on changes in market and supply demands, we began to focus on controlling costs: reducing forced outages and streamlining maintenance and repair costs. In 2002, only a handful of Calpine’s plants routinely practiced PdM techniques, with each conducting its own PdM activities in a nonstandardized manner. As a result, no uniform technology or strategy was used, sharing of best practices and successes was limited, and each plant handled equipment failures in its own unique manner.
After reviewing the options and potential strategies for meeting uptime, reliability and profitability goals, senior management decided to develop and begin implementing a comprehensive PdM program across the Calpine fleet of plants. Committed to providing consistent power to our customers, our primary goal was to reduce forced deratings and outages, both of which are catastrophic events. Simply stated, we can’t allow our customers to be without power. To make sure that doesn’t happen, we needed a uniform PdM program that could readily be implemented at the majority of our plants.
We reviewed the PdM programs offered by three maintenance solution providers for critical elements including user-friendly interfaces; operating system compatibility; integration with other PdM data; the ability to interface and share information with other programs, such as Maximo CMMS; open database structure/interoperability with other Calpine systems and future development directions.
Rolled out to the individual plants in late 2002, the new PdM program consisted of a variety of proactive tools and techniques, including condition-monitoring hardware and software from Rockwell Automation. The program was designed to help maximize return on investment and prevent unplanned downtime. By implementing common procedures and practices among the various plants, Calpine is to share experiences and documented successes, which will help drive further efficiencies and cost savings across plants. Cost savings also resulted from implementing an enterprise-networked system.
The per-plant savings achieved is approximately $15,000. Sixty-six Calpine plants are now set up in the Enshare system, which adds up to nearly $1 million in cost savings.
During the selection process, we found that only one software package, Entek Emonitor Enterprise software from Rockwell Automation, met our needs for supporting condition-based maintenance data as well as for sharing information across our disparate sites. With database storage capabilities, the Emonitor Enterprise system serves as a central repository for the information gathered from the power plants enrolled in the program. The system allows engineers and technicians to access any site’s database to examine equipment life-cycle trends and determine if common failures occur on specific types or models of equipment. Additionally, we are using the Emonitor Enterprise system to help pinpoint repetitive equipment failures at the same plant or at multiple plants.
Focus on critical equipment
At each location, on-site maintenance personnel identify the equipment where vibration data will be collected (Figure 1). Vibration analysis is conducted on equipment deemed critical to maintaining production, including gas turbines, steam turbines, cooling fans and critical oil and water pumps.