Lean Six Sigma in Power Plants

Historically, the instances where Six Sigma demonstrated limited success were among discrete manufacturers where distinct items were produced such as automobiles or consumer electronics. Quality could readily be measured. The assembly line could be shut down to investigate a bottleneck. Every hold point in the process could provide its own set of statistical measures.

As manufacturers lost their mojo, Black Belts sought greener pastures. Several convinced chemical, pharmaceutical or petroleum industries that Six Sigma would “revolutionize.” Some even sold themselves into power plant management roles. But there exist problems with this idea.

  • Process industries are fundamentally different from discrete manufacturing in that materials flow in a continuous stream instead of separate and distinct batches. In power plants, fuel and water make steam which spins a turbine to generate electricity. That series of continuous processes does not stop.
  • The quality and/or reliability of discrete manufacturing products can be recognized and measured. Both the steam produced and the electricity generated in power plants are commodities; their quality is consistent and cannot be quantified.
  • Customer satisfaction can easily be measured among discrete manufacturers in the forms of product returns or customer complaints. Regarding power generation, the focus tends to be on technical issues rather than on customer satisfaction; end customers are disconnected from and anonymous to the electrical grid.
  • Power industry engineers solve technical problems whereas Black Belts minimize defects.
  • Six Sigma requires data collection and evidence to improve things that may not be worth improving or that can be improved more simply by other means.
  • Power plant processes are often developed organically through iterations of personnel and maintained via “tribal knowledge.” An accurate portrait of a particular process, if one exists, is found among a “group conscience” of many and is difficult to capture.
  • Six Sigma suppresses creativity because it stresses more on process analysis tools than on identifying root causes and solutions.

Potential Case Studies

  • The electric efficiency of a conventional thermal power station, considered as saleable energy (in MWe) produced at the plant busbars as a percent of the heating value of the fuel consumed, is typically 33% to 48% efficient. Improvement in this efficiency could be an objective of a Six Sigma Black Belt project.
  • Improvement in waste heat utilization (cogeneration) can be another project.
  • If freshwater production and electricity are co-products, then the objective of enhancement of these could be taken up as Six Sigma projects.
  • Since the efficiency of the plant is fundamentally limited by the ratio of the absolute temperatures of the steam at turbine input and output, efficiency improvements require use of higher temperature, and therefore higher pressure, steam. Ensuring consistency in high temp and resulting high pressure could be taken up as Six Sigma project as well.

Maintenance improvement in terms of the following are additional projects

  • Improving OEE (Overall Equipment Effectiveness)
  • Reducing MTTR (Mean Time to Repair)
  • Increasing MTBF (Mean Time between Failures)