The San Diego County Water Authority will save approximately $100,000 per year with commercial-scale batteries installed at the agency’s Twin Oaks Valley Water Treatment Plant near San Marcos. The energy storage system is designed to reduce operational costs at the facility by storing low-cost energy for use during high-demand periods when energy prices increase. The batteries were installed at no charge to the Water Authority as part of an agreement with Santa Clara-based ENGIE Storage, a division of ENGIE North America, formerly known as Green Charge.