Life-Cycle Analysis for Transmission Line Design

Joel M. Rinebold and Louise F. Mango

Life-cycle analysis, incorporating both traditional costs and environmental considerations, is gaining increasing recognition as an important decision-making tool in the evaluation of utility projects and as a key element of future environmental management programs. In this study of electric transmission options, life-cycle costs, consisting of all capital and operating costs, are assessed for seven single-circuit overhead line configurations, eight double-circuit overhead line configurations, seven single-circuit underground line configurations, and nine double-circuit underground line configurations. All life-cycle costs are unit based for each five-mile segment of construction and are broken out between fixed construction costs and 35-year life-cycle costs. Typical electric and magnetic field levels also are assessed for each line configuration. Fixed variables include load and operating conditions, structure and conductor types, and cost factors in 1995 dollars. Environmental life-cycle costs associated with the development and operation of typical overhead or underground electric transmission lines are identified and discussed, but could not be quantified and included in cost assessments. Methods for evaluating and comparing such costs, either quantitatively or qualitatively, are assessed, and recommendations are made for future use in identifying environmental life-cycle costs for transmission projects. This life-cycle information provides a benchmark that will assist project managers, regulators, and community leaders in the preliminary identification and comparison of transmission line design, least-cost options, right-of-way management, environmental costs, and low electric and magnetic field alternatives.

Keywords: Life-cycle cost comparison, electric transmission lines, environmental life-cycle costs, underground vs. overhead transmission analysis