The cost of transmission for wind energy in the United States: A review of transmission planning studies

Rapid development of wind capacity in the United States has been coupled with a concern that increasing wind capacity will require substantial transmission infrastructure. This report summarizes the implied transmission cost per kW of wind from a sample of 40 transmission studies. This sample of studies, completed from 2001 to 2008, covers a broad geographic area across the U.S. The primary goal in the review is to develop a better understanding of the transmission costs needed to access increasing quantities of wind generation. A secondary goal is to gain a better appreciation of the differences in transmission planning approaches, in order to identify those methodologies that seem most able to estimate the incremental transmission costs associated with wind development. The total range in transmission costs per kW of wind implicit in the study sample is vast - ranging from $0/kW to over $1500/kW. The median cost of transmission from all scenarios in the sample is $300/kW, roughly 15-20% of the cost of building a wind project. The median cost of transmission is near the upper end of the range implied by two higher-level assessments of transmission required to provide 20% wind electricity in the U.S. by 2030.