Cost-benefit analysis of emergency backup power systems for mission critical applications

This paper presents a method for cost-benefit analysis of backup power systems for information and communications technology (ICT) applications. In recent years, ICT systems have played a very important role in modern society and life. For stable operation of the ICT systems without interruption, the electric power quality and reliability (PQR) must meet certain requirements for each type of load equipment. To improve and maintain PQR and to meet the requirements, various types of backup power supplies must be installed at the customer-side. It is advisable to estimate the cost benefits before introducing an expensive backup power supply. However, cost-benefit analysis is very difficult because of unknown and uncertain parameters, such as interruption frequency and economical damage. In this paper, a general expression for cost-benefit analysis is reported. The expression uses discounted cash flow methods, such as the net present value, and interruption frequencies obtained through reports and field surveys in Japan. In accordance with the proposed method, two case studies were carried out to show payback time for the backup equipment of the ICT systems.