Trane and Alstom Pair to Build Wastewater Treatment Plant Microgrid in California

Sept. 10, 2015
Trane and Alstom Grid have paired to build a wastewater treatment plant microgrid, designed to incorporate renewable energy and create a revenue stream for the City of Santa Rosa, California.

Santa Rosa, California to create innovative wastewater treatment plant microgrid. Credit: Wikimedia Commons

Trane and Alstom Grid have paired to build a wastewater treatment plant microgrid, designed to incorporate renewable energy and create a revenue stream for the City of Santa Rosa, California.

The Laguna Wastewater Treatment Plant microgrid will include solar, energy storage, an advanced distributed energy management software system, a microgrid controller and smart inverter provided by Alstom Grid.

Trane, a brand of Ingersoll Rand that will serve as project lead, expects the microgrid to be operating by late 2016.

The California Energy Commission will supply a $5 million grant that Trane won for the project. An additional $2 million will come from the project team.

The team selected Laguna for the upgrade from among more than 60 wastewater treatment plants in California. Laguna won based on its strong infrastructure and its size: neither too large nor too small, according to Trane.

“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 microgrid is expect to increase energy independence at the plant, which is managed by the city’s water department, Santa Rosa Water.

Trane is describing the project as a low carbon microgrid that will stabilize the plant’s energy costs, provide additional revenue sources, and deliver grid services to allow increased use of renewable energy, including solar and wind.

The wastewater water treatment plant 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.

“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.”

The plant uses 4 MW to recycle about 17.5 million gallons of water per day for about 230,000 customers in the California communities of Santa Rosa, Sebastopol, Cotati, Rohnert Park, and other areas of Sonoma County.

Roughly 30 percent of the plant’s energy comes from an on-site digester gas that runs engine-driven generators.  The central grid provides the other 70 percent of the plant’s energy at a cost of up to $3.5 million a year.

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. It also will leave more energy available for commercial users in the region and potentially generate revenue for the city, according to Trane.

Separately, Trane equipment is being used in the Fort Collins Zero Energy District (FortZED) in Colorado, which includes a micogrid with mixed distributed resources. The project’s customers include the New Belgium Brewery, InteGrid laboratory, City of Fort Collins facilities, Larimer County facilities, and Colorado State University.

FortZED aims to reduce peak load by 20 to 30 percent on two distribution feeders, increase the penetration of renewables, and deliver improved efficiency and grid reliability, according to the Microgrids at Berkeley Lab, a project of the U.S. Department of Energy. Johnson Controls and Trane building automation systems are being used to  reschedule heating, cooling, and ventilation for demand response.

The DOE awarded FortZED  $6.3 million, and partners  contributed $4.7 million, among them Eaton, Advanced Energy, and Brendle.

Meanwhile, Alstom was one of seven companies last year to win $8 million in microgrid RD&D funds from the DOE. Alstom was awarded the $1.2 million to research and design community microgrid systems for the Philadelphia Navy Yard.

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About the Author

Elisa Wood | Editor-in-Chief

Elisa Wood is the editor and founder of She is co-founder and former editor of Microgrid Knowledge.