Janesville WWTP

At a Glance
• System Configuration: Multi-unit array featuring 4 × C65 and 1 × C200 Capstone Energy+ Microturbines, Unison Solutions gas conditioning skid and controller
• Capital Efficiency: Over 90% of recent upgrade costs covered through combined federal Investment Tax Credit (ITC) benefits, a DOE ITAC grant, and local utility incentives
• Financial & Thermal Impact: ~$100,000 / year in energy savings; delivers 2.5 MMBtu/hr (2,500,000 BTU/hr) of recovered waste heat for digester loop heating
• Waste-to-Energy Output: Generates >3,000 MWh/year of clean baseload electricity from treated anaerobic digester gas (~25 ppmv H_2 S)
• Operating Profile: Grid-parallel continuous baseload operation supporting a 13–19 MGD regional wastewater treatment facility


The Challenge
The Janesville Wastewater Treatment Plant—serving a 13–19 MGD municipal network—had utilized digester gas for on-site power generation since 1985. However, legacy reciprocating engines suffered from high maintenance overhead, frequent downtime, and reduced efficiency when burning raw, unconditioned biogas. To maintain mesophilic (98^∘ "F" ) and thermophilic (130^∘ "F" ) anaerobic digestion temperatures and offset rising utility electricity rates, the city needed a low-maintenance, ultra-reliable CHP technology capable of turning corrosive waste gas into high-value energy with minimal staff intervention.


The Solution
Building on a partnership established in 2010, the City of Janesville systematically phased out legacy engines in favor of an oil-free, air-bearing Capstone microturbine system managed and maintained by Veristar Energy.
Phased Modular Generation: Scaled to a 460 kW site capacity utilizing four C65 (65 kW) microturbines and one C200 (200 kW) unit, ensuring high part-load efficiency across seasonal biogas production swings.
• Advanced Biogas Conditioning: Treats raw digester gas to remove moisture, siloxanes, and hydrogen sulfide down to ~25 ppmv H_2 S, protecting downstream generation assets.
• Thermal Process Integration: Captures microturbine exhaust waste heat to deliver 2,500,000 BTU/hr of hot water directly to the plant's sludge pre-heating and anaerobic digester loops.
• Incentive-Driven Capital Execution: Veristar facilitated system upgrades in 2024–2025 using DOE ITAC grants, ITC direct-pay options, and local utility rebates to offset over 90% of capital project expenditures.


The Results
• $100,000 Annual Utility Offset: Reduces plant operating expenses by replacing grid power and natural gas boiler fuel with on-site biogas generation.
• 90%+ External Project Funding: Delivered critical energy infrastructure upgrades with near-zero financial friction for local taxpayers and city utility budgets.
• Decade-Plus Reliability: Demonstrates exceptional asset longevity, with original 2010 microturbine units operating seamlessly alongside new 2024/2025 expansion modules.
• Turnkey Operational Simplicity: Requires minimal day-to-day oversight from resource-constrained municipal staff, backed by Veristar's ongoing service and maintenance support.