“This project is a win-win. It will achieve substantial savings for Central San’s ratepayers, while also reducing our climate footprint and furthering our mission to protect the environment.”
Central San Resource Recovery Program Manager Melody LaBella
Background
Central Contra Costa Sanitary District (Central San) is a wastewater utility serving nearly 500,000 residents and over 15,000 businesses in central Contra Costa County.
One of Central San’s key objectives, identified in its Comprehensive Wastewater Management Plan, is to optimize energy production and use while minimizing greenhouse gas emissions.
Central San hired ARC Alternatives to explore avenues for expanding its solar photovoltaic (PV) footprint and identify energy efficiency opportunities at its facilities. This would, in part, help Central San facilitate saving opportunities for its customers.
The Solution
Working with ARC Alternatives and Central San, REC Solar designed, engineered, procured and constructed a 2.2 MW ground mount solar array on a repurposed portion of a 48-acre buffer property near Central San’s Martinez wastewater treatment plant. Central San and REC Solar worked closely with the existing tenant and the surrounding community to ensure the project had minimal disruption to the land and was not visible to the neighboring residents.
The low-profile, fixed-tilt ground mount array, designed to be optimal in both production and cost, offsets most of the annual grid demand of Central San’s treatment plant and major pumping stations through PG&E’s Renewable Energy Self-Generation Bill Credit Transfer (RES-BCT) program.
As part of the RES-BCT program, the solar array’s energy generation is injected locally onto the PG&E grid, providing offsets to the various electrical meters across Central San’s operation. This allows for optimization of a local, centralized generation source that can provide benefit to the distributed infrastructure operated by Central San.
Financed as a 25-year Power Purchase Agreement (PPA) through REC Solar, Central San was able to shift the project from a costly capital expense to a predictable monthly payment with no price escalation. As part of the agreement, REC Solar will continue to own, operate and maintain the solar array over the life of the PPA.
The array is estimated to generate nearly $6 million in net electricity bill savings over the next 25 years.
Benefits
Predictable monthly payments with no price escalation
No maintenance, ownership or operating risks
Nearly $6 million in estimated net utility bill savings
Elimination of 1,865 metric tons of carbon dioxide emissions annually