Confidence bounds for energy conservation in electric motors: An economical solution using statistical techniques

Abstract

Power crisis is a sensitive issue which can handicap activities of any country at large. In Pakistan, industries consume the majority of energy, of which 28% is the electrical energy. About 30–80% of the electrical energy consumed by industries is due to electric motors. This study aims to promote electrical energy conservation in industries of Pakistan by presenting benefits of replacing existing standard efficiency motors through EEMs (energy efficient motors). A sample of existing SMs (standard motors) obtained by surveying some industries of Pakistan is used for statistical analysis. The benefits of EEMs are emphasized in terms of annual energy savings, cost savings and paybacks. By using t-distribution, 90% confidence bounds for these parameters are constructed. It is found that future replacements of SMs by EEMs, will achieve an average energy saving of atleast 1009.747 kWh/year and atmost 3404.047 kWh/year, and an average cost saving of atleast Rs. 10859.719/year and atmost Rs. 33550.065/year. The average payback period would be between 0.177796 and 0.265912 years. The sensitivity analysis of the results is provided. The presented confidence bounds can be used to encourage the government and financers for the large scale replacement of SMs by EEMs to conserve electrical energy sufficiently in Pakistan industries.