Walking the Walk: Considering Non-Transmission Alternatives in Utility Planning, Part Deux

Bruce Bentley, Central Vermont Public Service Corporation
John Plunkett, Green Energy Economics Group

Keywords

Abstract

The proposal to defer transmission with energy efficiency is alive and well in Southern Vermont. Efficiency Vermont, the statewide energy efficiency utility in Vermont is targeting the delivery of energy efficiency in Southern Vermont to defer potential upgrades to the distribution utility's 46 kV sub-transmission system as described here last year (Plunkett et al 2006). A filing was made for the development of two synchronous condensers to solve immediate reliability issues on that same 46 kV system and the Vermont Public Service Board issued a certificate of Public Good in Docket 7246 on March 28, 2008. A separate filing is underway in Vermont (Docket 7373) to propose a bulk system 345 kV transmission line upgrade to meet regional reliability needs and to support another feed into the 46 kV system to solve local reliability issues. A separate public review process and separate NTA analysis was conducted as support for the decision-making process. Striking differences emerged from this new review and analysis. First, while the Southern Loop reliability and capacity needs are driven by winter peaks, the new line upgrade (the Coolidge Connector or CC) was driven by summer load in Central and Northwest Vermont. Second, the NERC reliability criterion is a stringent, deterministic N-1-1 scenario where the line is tested by two major contingencies. Third, regional load growth in New Hampshire and New York affects the need for the bulk system line. Fourth, the need for the line is imminent so the time to develop and implement NTAs is very short - some peak load reductions are needed immediately before the line can even be constructed, and the line or NTAs are needed by 2011. Fifth, the deployment of NTAs in Vermont can result in local rate impacts, while the benefits are distributed more broadly across the bulk system including to non-Vermont participants. Sixth, since this is a bulk power line and the driving load is much larger the NTAs are larger and can utilize utility size generation in addition to distributed generation. Sixth, since the affected area covers 80% (but ironically not the Southern Loop area) of Vermont the decision affects multiple utilities. At this point in time the decision is uncertain but the sponsoring utilities deemed the use of NTAs infeasible to avoid or defer the proposed bulk-system upgrade given the expected case assumptions.