Duluth Steam Hot Water

Duluth Steam to Hot Water Project

Steam to Hot Water on a Legacy System

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 operated and managed 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, Ever-Green’s master planning effort identified advancement of the steam distribution system as the primary opportunity to improve efficiency, reliability, and provide customers and the city with security for the system’s future.

About the Project

The system provides heating, hot water, and cooling to over 165 downtown Duluth and Canal Park buildings, including service to both major hospital complexes and related clinics. The system primarily uses natural gas, with coal as a peaking fuel, to generate high pressure steam and hot water that is distributed by an underground network of pipes.

The majority of the system customers are currently served by steam, which limits the efficiency and flexibility of the overall system. There are 50 customers along Superior Street, comprising 30% of the system’s total capacity, who are being converted to hot water. The system upgrade will reduce energy losses at the plant, while also reducing losses within the Duluth buildings. Water usage will also be greatly reduced by approximately 25 million gallons per year with a commensurate reduction in water treatment at Western Lake Superior Sanitary District, and CO2 and fossil fuel usage will be reduced as well.

The steam to hot water conversion for this major segment will be complete in 2020. By 2024, more than 50% of the system will have transitioned from steam to hot water services.

Ever-Green’s Role

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, make practical investments to keep the business competitive, and align with local policy and environmental initiatives. Our team has led 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, the steam to hot water transition, and future renewable integration.

See the full scope of Ever-Green’s work at Duluth Energy Systems in the utility operations profile.

About The City Of Duluth

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.