The City of Santa Rosa, California, is collaborating with Trane, a leading global provider of indoor comfort solutions, and services and a brand of Ingersoll Rand, to execute an innovative project that will increase energy independence at the city’s Laguna Wastewater Treatment Plant which is managed by the city’s water department, Santa Rosa Water.
Trane chose Santa Rosa’s Laguna Wastewater Treatment Plant for the project to implement a $5 million grant from the California Energy Commission, the state’s primary energy and planning agency. The project team, which represents companies contributing $2 million in technology development funding, includes, among other companies, Alstom Grid, the world’s leading power-transmission company.
“Being selected for this grant is a great example of our commitment to our community’s future,” said David Guhin, director of Santa Rosa Water. “Santa Rosa strives to find innovative and cost-effective solutions that improve energy efficiency, optimize energy production, and reduce greenhouse gas emissions, making this project a huge win.”
The Laguna Treatment Plant is responsible for treating wastewater from the California communities of Santa Rosa, Sebastopol, Cotati, Rohnert Park, and other areas of Sonoma County. The project will transform the plant into an advanced microgrid and also will decrease dependence upon the traditional energy grid by incorporating additional renewable energy.
Anticipated benefits of transforming the plant into an advanced microgrid include stabilizing energy costs, providing additional revenue sources, and delivering the grid services needed to allow increased use of renewable energy, including solar and wind. The microgrid is anticipated to be operational in late 2016.
“We’re leveraging existing technology to support better regional energy management by making our operations more efficient and putting available energy back onto the grid for other consumers to use,” said Michael Day, utility solutions vertical market leader for Trane in California, and the principal proposal author. “The project also will support the use of more solar and wind renewables.”
An Efficient Operation Means Available Energy for Other Users
The microgrid will pull power from the main grid when excess energy is available, allowing Santa Rosa to easily switch back and forth to help balance power on the main grid.
To treat wastewater from approximately 230,000 customers, the treatment plant recycles approximately 17.5 million gallons of water per day, which requires approximately four megawatts of energy. Roughly 30 percent of this energy is generated on-site by beneficially using digester gas to run engine-driven generators. The other 70 percent of energy demanded for treatment currently comes from the main electrical grid and costs up to $3.5 million a year.
The project team selected the treatment plant for the upgrade from among more than 60 wastewater treatment plants statewide based on its strong infrastructure and its size: neither too large nor too small.
Energy upgrades will contribute to a low-carbon future at the wastewater treatment plant, and will also include integrated solar power and energy storage. Implementation will also include an advanced distributed energy management software system, an innovative microgrid controller and smart inverter systems provided by Alstom Grid.
The project team plans to decrease dependence on the grid and increase the amount of energy generated onsite by reusing the digester gas and combining it with renewable energy sources. This will reduce the overall carbon footprint of the wastewater plant, leaving more energy available for commercial users in the region and potentially generating a revenue stream for the city.