Incorporating energy efficiency into electric power transmission planning: A western United States case study

Driven by system reliability goals and the need to integrate significantly increased renewable power generation, long-range, bulk-power transmission planning processes in the United States are undergoing major changes. At the same time, energy efficiency is an increasing share of the electricity resource mix in many regions, and has become a centerpiece of many utility resource plans and state policies as a means of meeting electricity demand, complementing supply-side sources, and reducing carbon dioxide emissions from the electric power system. The paper describes an innovative project in the western United States to explicitly incorporate end-use efficiency into load forecasts – projections of electricity consumption and demand – that are a critical input into transmission planning and transmission planning studies. Institutional and regulatory background and context are reviewed, along with a detailed discussion of data sources and analytical procedures used to integrate efficiency into load forecasts. The analysis is intended as a practical example to illustrate the kinds of technical and institutional issues that must be addressed in order to incorporate energy efficiency into regional transmission planning activities. •Incorporating energy efficiency into electric power transmission planning is an emergent analytical and policy priority.•A new methodology for this purpose was developed and applied in the western U.S. transmission system.•Efficiency scenarios were created and incorporated into multiple load forecasts.•Aggressive deployment of efficiency policies and programs can significantly reduce projected load.•The approach is broadly applicable in long-range transmission planning.