Albert Lea WWTP

At a Glance
• System Configuration: 4 × C30 Grid Connect Capstone Microturbines with Unison Solutions gas conditioning
• Annual Generation: >800,000 kWh/year (~25% of total plant electrical load)
• Energy Savings: Up to $90,000 / year in reduced utility expenditures
• Thermal Integration: 28 MMBtu/day (1.17 MMBtu/hr) of recovered heat for anaerobic digesters and space heating


The Challenge
Wastewater treatment facilities face continuous operational pressure from high baseload electricity requirements and strict odor-control mandates. At the Albert Lea Wastewater Treatment Facility, the anaerobic digestion process produced significant volumes of low-Btu methane gas. Traditionally, facilities flare this biogas into the atmosphere or burn it passively in boilers, treating it as an environmental liability rather than an energy asset. Facility leaders and city engineers needed a solution to eliminate waste flaring, offset high utility grid power demand, maintain precise temperature control in their digesters, and protect plant operations from power outages.


The Solution
The City of Albert Lea partnered with state energy programs and local utility partners to deploy a 120 kW biogas-fueled Combined Heat & Power (CHP) system featuring four C30 microturbines.
• Biogas-to-Energy Conversion: Treats and conditions raw anaerobic digester gas (removing siloxanes, moisture, and particulates) to fuel four continuous-duty microturbines, generating clean electricity on-site.
• Dual Thermal Recovery: Captures 28 MMBtu/day of high-grade exhaust thermal energy to maintain optimal temperatures for the anaerobic digester process while providing building space heating during cold Minnesota winters.
• Utility Tariff Mitigation: Generates over 800,000 kWh annually, directly displacing approximately 25% of the plant's total grid electricity purchases and hedging against rising industrial utility tariffs.
• Incentive Optimization: Leveraged state and utility Conservation Improvement Program (CIP) grants and rebates to accelerate project payback and maximize public capital efficiency.


The Results
• Up to $90,000 Annual Savings: Converts an ongoing waste product into a continuous financial hedge, significantly lowering municipal operating expenditures.
• 1.5 Million lbs/yr Emissions Reduction: Eliminates open gas flaring, cutting air pollutants and methane emissions to align with municipal environmental targets.
• High Tolerance Fuel Flexibility: Purpose-built microturbine combustion technology handles variable-Btu biogas without the severe engine wear, frequent oil changes, or heavy maintenance associated with reciprocating engines.
• Award-Winning Performance: Recognized with the Governor’s MnGREAT Award for environmental excellence, demonstrating how municipal facilities can turn waste streams into resilient energy assets.


"It gives us the ability to use the methane gas already generated at the plant. We are able to take a waste product and use it for something beneficial."
— Steve Jahnke, City Engineer, City of Albert Lea