Vermont weighs use of energy storage for RPS compliance


The Vermont PUC is seeking comments following an August workshop that focused on discussing the use of energy storage to meet Tier III Renewable Energy Standard (RES) obligations.

In June, the Vermont Public Service Department issued a Report providing its evaluation of utility compliance with Tier III of the state RPS. Tier III refers to “energy transformation” projects implemented after January 1, 2015, composed of projects that reduce fossil fuel consumption (e.g., energy efficiency, battery storage, EVs), as well as DG in excess of the Tier II DG target. The Tier III target is 2% of retail sales in 2017, increasing by 0.66% annually towards a target of 12% by 2032. The report summarizes the programs, projects, and 2017 compliance for the state’s largest utilities.

Notably, the report would disallow Green Mountain Power’s request for compliance credit for its residential battery storage program, based on reductions in fossil fuel electricity generation during peak times. The report would disallow this portion (0.25% of GMP’s goal) because the avoided fossil fuel use would take place on a regional level, outside of GMP’s service territory and likely outside of Vermont as well. This runs counter to how the PUC addressed the trading of Tier III credits in its 2016 order establishing rules for Tier III, which does not permit fossil fuel savings accrued in another utility service territory from contributing to a utility’s target. However, the report also notes that battery storage is specifically identified in the underlying RPS statute as a Tier III eligible technology, and therefore recommends that the rules on energy storage be clarified to specify the geographic scope of fossil fuel use reductions from battery storage (i.e., must it be at the customer level, the utility level, or the regional level).