Renewable energy — energy from natural resources such as sunlight, wind and water — is quickly becoming a critical component of California’s power supply. As a water supplier and a clean energy-conscious agency, the Water Authority is pursuing hydroelectric and solar energy projects as part of its infrastructure and at its offices.
The Water Authority owns and operates the Rancho Peñasquitos in-line hydro generation facility, which has been providing clean, renewable energy to the local power grid since December 2006.
The power is generated using a single 4.5-megawatt horizontal turbine and sold on the California Independent System Operator wholesale energy market. The facility, which operates year round and is controlled by the Water Authority’s central control site, provides 25,000 to 30,000 megawatt-hours (mWh) of renewable energy annually, enough electricity for approximately 5,000 San Diego households.
Rancho Peñasquitos not only reduces the Water Authority’s energy costs and acts as a source of clean energy for San Diego, it also generates approximately $500,000 in annual revenue for the Water Authority, allowing the agency to recover the costs of the facility in approximately seven years. Using hydroelectric power instead of electricity from fossil fuel power plants will also eliminate the equivalent of 60,000 metric tons of carbon dioxide a year.
The Water Authority entered into a power purchase agreement for the installation of photovoltaic solar panels at its headquarters in San Diego, its operations center in Escondido, and at the Twin Oaks Valley Water Treatment Plant.
The power purchase agreement with Borrego Solar Systems enabled the Water Authority to install solar without the use of Water Authority funds for the design, construction or maintenance of the project. Under the power purchase agreement, the Water Authority purchases the solar power under a pre-set price structure, and the provider is responsible for the design, construction, operation and maintenance of the systems.
New solar power systems installed at the Water Authority’s San Diego headquarters and the Escondido Operations Center and Twin Oaks Valley Water Treatment Plant produce an estimated 2.7 million kWh of renewable power each year. The 20-year agreement with Borrego Solar Systems will save the Water Authority approximately $5.6 million over the lifetime of the agreement, and will support the agency’s commitment to sustainability.
The Water Authority has received a $1 million incentive from the California Public Utilities Commission to build an energy storage project that is expected to save the Water Authority nearly $100,000 per year in energy costs by using industrial-sized batteries at the Water Authority’s Twin Oaks Valley Water Treatment Plant.
Installing batteries will help the Water Authority store low-cost power – either excess solar energy or retail energy purchased during off-peak hours – for later use during high-demand periods, maximizing the value of energy generated at the plant. The energy storage project is being carried out through a no-cost Power Efficiency Agreement with Green Charge to install a 1 megawatt/2 megawatt-hour energy storage system at the Twin Oaks plant.
Green Charge will own, operate and maintain the system on Water Authority land for 10 years, after which the Water Authority can choose to extend the agreement, purchase the batteries, or have them removed and the site returned to its original condition.