Constructing a Microgrid for a Wastewater Treatment Facility

This project provides a case study of the construction of a microgrid at the city of Santa Rosa’s Laguna Wastewater Treatment Plant in Sonoma County. The project documents construction of a microgrid for a wastewater plant using 2 megawatt/480 kilowatt-hours of battery energy storage, a microgrid controller integrated into the supervisory control and data acquisition system of the plant for controllable loads, a 126-kilowatt carport solar photovoltaic array, and the modification of two existing 1.1 megawatt combined heat and power Cummins engines with selective catalytic reduction that are used as dispatchable resources for load reduction. The microgrid project will improve plant operations and grid resiliency for Santa Rosa and the surrounding region.

The microgrid is connected to the Pacific Gas and Electric distribution grid at 69 kilovolts through a computer-controlled circuit breaker and is designed to operate autonomously. The project experienced many hurdles during construction. In October 2017, the Tubbs fire caused major damage to the areas surrounding Santa Rosa. The fire caused delays in the project approvals, while the city dealt with a major catastrophe in the area. Several critical suppliers at the beginning of the project such as Alstom and Tesla quit the project. Nuvation Energy and Parker Hannifin replaced them. Despite project difficulties, the California Energy Commission granted a project extension to March 31, 2019, due to these circumstances, and the project was completed.