Duluth Energy Systems is the city-owned energy system that provides heating and cooling service to the city’s downtown and Canal Park. Ever-Green Energy has served the system since 2012 and works closely with the City of Duluth to provide exceptional service and advance the system to better serve the community.
Shortly after taking over operations and management responsibilities, Ever-Green completed a system master plan to:
During planning, Ever-Green identified the distribution system as a major opportunity to improve operations and made plans to transition 16 blocks of the steam distribution system to hot water, concurrent with a major public works project.
Ever-Green is now leading system advancement, including design of the new hot water distribution system, customer building conversions, plant conversion, and construction management.
The steam to hot water conversion for this major segment was completed in 2020. By 2024 more than 50% of the system will have transitioned from steam to hot water services.
Another major initiative has been the natural gas pilot that has significantly reduced the amount of coal used for heating. Since 2012, coal usage has been reduced by nearly 98%. The coal reduction and efficiency efforts have reduced greenhouse gas emissions by 20% in that timeframe. Additional renewable integration is under consideration for the next phase of system advancement.
Ever-Green serves as the system operator and manager. Ever-Green works closely with the City of Duluth to determine the strategic direction of the system, practical investments to keep the business competitive, and align with local policy and environmental initiatives. Our team has guided the system through enhancements to the system’s operational and maintenance processes, including inventory management, operating and maintenance crew structure, work planning, performance monitoring, and trending of key parameters. Ever-Green reviewed the debt financing of the system and recommended changes, which enabled the system to enter into long-term contracts with customers and use revenue bonds for future debt financings.
Recent areas of technical focus have included customer development, efficiency improvements, carbon reduction (through reduction of coal and plant and distribution improvements), a steam to hot water transition, and future renewable integration.
The City of Duluth is a port on Lake Superior in Minnesota with a population of about 86,000 people. The City has made its energy future a priority and has seized opportunities to work within the community, with its utilities, and in collaboration with experts from around the country to integrate state-of-the-art technology and international best practices for an efficient, cost-effective, and environmentally advanced system.
Ever-Green supported the City in its effort to gain community support and state funding for system upgrades. This project has engaged experts and supporters from within and beyond Duluth, including state commissioners, city councilors, and executives from the business, energy, environmental communities who believe in Duluth’s grand energy vision.
|Buildings served with district Steam||164 Buildings|
|FY 2015 energy sales||111,870 MWh|
|Total Building Area Served||5.6 million square feet|
|Two coal boilers||25 MW ea|
|Two Coal / Gas boilers||28 MW ea|
|Pipe Diameter||1-inch to 20-inch|
|Pipe Length||59,000 feet|
|Supply Pressure||150 psi|
HOT WATER SERVICE DATA
|Buildings served with district hot water||6 Buildings|
|FY 2015 energy sales||17,360 MWh|
|Current billed demand||2.65 megawatts|
|Total Building Area Served||0.5 million square feet|
|Exhaust steam from auxiliary turbines|
(augmented by main steam as required)
|Pipe Diameter||4-inch to 12-inch|
|Pipe Length||6,900 feet each, supply and return|
|Supply Temperature||190-220 degrees F|
|Return Temperature||160-190 degrees F|
|Supply Pressure||40 psi|
|Buildings served with district cooling||5|
|FY 2015 Energy Sales||366,382 ton-hours|
|Building Area Served||0.53 million sq. ft.|
|Chiller Plant 401 W First Ave|
|One Steam Absorption Chiller||800 tons|
|Pipe Diameter||4-inch to 12-inch|
|Pipe Length||4,800 feet each, supply and return|
|Volume of distribution system||15,600 gallons|
|Supply Temperature||42 degrees F|
|Return Temperature||56 degrees F|
|Supply Pressure||30 psi|
|Minimum pressure differential||15 psi|