Developing Guidelines for Determining the Reliability of Capacity Savings Estimates

  • March 27, 2017

The Northwest Power and Conservation Council’s 7th Power Plan, estimated that cost-effective electricity savings from energy efficiency could contribute to 7,900 MW of capacity benefits during the region's winter peak (6:00 p.m. on a weekday in December, January, and February) and 5,500 MW of capacity benefits during the summer peak (6:00 p.m. on weekday in July and August) by 2035.

Some of you may be asking yourselves “What are capacity benefits exactly?” To state it simply, not only does energy efficiency save electricity over the lifetime of a measure, it also reduces the strain on the electricity system during key periods of peak electricity demand. Decreasing the need for electricity at specific points in time reduces the need for additional power system capacity (MW). This translates to avoided costs in terms of investments in additional generating resources (peaker plants), transmission lines, and distribution infrastructure to meet potential high points of electricity use. For example, installing high efficiency LED light bulbs throughout your home helps reduce your home’s energy consumption throughout the year, but has an added benefit of reducing lighting load when demand on the electricity system is the greatest; during dark winter months when people return home from work. This reduction in load at the moment of peak demand frees up system capacity.

As part of the 7th Power Plan, the Council directed the RTF to develop guidelines around determining the reliability of capacity savings estimates generated from RTF energy savings analyses. The crux of determining the reliability of capacity savings estimates lies in how well we know the average load profiles for each energy efficiency technology upon which the estimates are based. The average load profiles used by the RTF are not always completely indicative of real world energy usage. Climate change and colder winters may drive up cooling or heating load, changing demographics may change what time peak load occurs, different mixes of technologies will change the time and amount of energy savings that occur, and sampling bias may affect the generalizability of the profiles. It is for these reasons, among others, that the RTF is engaged in this work of assessing the quality of its capacity benefits estimates.

Currently, the RTF has contracted with Cadmus to complete a two phase project to develop guidelines language around capacity reliability, and to develop a tool to systematically assess the reliability of each individual hourly load profile for each RTF UES measure. Phase 1 of this project was completed in January 2017, which culminated in Lakin Garth of Cadmus presenting a draft white paper to the RTF at the January 2017 meeting. Cadmus is now beginning scoping for the development of a method/tool to systematically evaluate the hourly profiles, and to begin reviewing all measure hourly profiles and identify gaps in reliability. To track this work, interested parties can check the Guidelines Subcommittee webpage here for updates.