Winona WWTP

At a Glance
• System Configuration: 2 × C65 Grid Connect Capstone ICHP Biogas Microturbines with controls
• Annual Generation: >1,000 MWh/year of clean, renewable electricity
• Thermal Output: 860,000 BTU/hr of recovered hot water for anaerobic digester process heating
• Financial Impact: ~$100,000 / year in direct energy savings; over 90% of project upgrade costs funded via federal ITCs and DOE grants
• Fuel Source: Cleaned, conditioned anaerobic digester biogas
• Long-Term Partnership: Original C65 unit surpassed 100,000 runtime hours over 15+ years; City of Winona made a repeat purchase with Veristar Energy to double capacity in 2025


The Challenge
The City of Winona Wastewater Treatment Plant in Minnesota treats up to 9.6 million gallons per day (MGD) using a trickling filter and activated sludge system, handling high-strength commercial and industrial flows. Operating a C65 microturbine since 2008, the facility achieved over 100,000 hours of continuous runtime on by-product digester gas. To replace the aging legacy unit, double its renewable generation capacity, and eliminate reliance on fossil-fuel natural gas boilers, the city needed an affordable, highly reliable system expansion that could capture time-sensitive federal grant and tax incentives.


The Solution
Building on a 15-year track record of reliability, the City of Winona turned to Veristar Energy to supply two Capstone C65 ICHP microturbines and controller to double its on-site biogas-to-energy plant output while optimizing system visibility and maintenance dispatch.
• Expanded Waste-to-Energy Generation: Converts by-product digester gas into over 1,000 MWh of clean electricity annually, offsetting expensive utility power purchases across the 9.6 MGD facility.
• Digester Process Heating Integration: Captures 860,000 BTU/hr of exhaust waste heat to maintain optimal anaerobic digester temperatures, replacing legacy natural gas boiler burn.
• Smart Remote Monitoring: Features a Veristar controller to deliver real-time system visibility, predictive maintenance tracking, and continuous operational optimization.
• Creative Capital Funding: Leveraged federal Investment Tax Credits (ITC) and a Department of Energy (DOE) Industrial Training and Assessment Center Implementation Grant to cover over 90% of total project costs.


The Results
• $100,000 Annual Utility Savings: Delivers direct, recurring operational cost reductions for the municipal budget while generating clean, low-cost power.
• 90% Capital Cost Offset: Maximized federal funding opportunities to modernize critical public infrastructure with minimal impact on local municipal taxpayers.
• Doubled Renewable Output: Maximizes digester gas utilization to reduce greenhouse gas emissions and support long-term citywide sustainability benchmarks.
• Trusted Repeat Customer: Demonstrates the value of a 15+ year relationship, with Winona entrusting Veristar Energy once again to deliver its next-generation clean energy infrastructure.