The City of Duluth is leveraging the major investment of Superior Street reconstruction to modernize its energy system, upgrading from steam to hot water distribution. Updating this energy infrastructure provides Duluth the pathway to a modern, resilient system. This transformation will reduce the energy demands of the system and in customer buildings, also creating opportunities to reduce fossil fuel usage, reduce carbon, and integrate renewable energy.
The new closed-loop hot water system will greatly reduce the temperature of the water used to heat buildings along Superior Street. Additionally, energy in a loop can return to the plant in a cycle to get reheated and sent back out to customers. This saves energy and water!
The new closed-loop hot water system will greatly reduce the temperature of the water used to heat buildings along Superior Street. Additionally, energy in a loop can return to the plant in a cycle to get reheated and sent back out to customers. This saves energy and water!
Customer Benefits
Environmental Benefits
The Duluth Energy Systems team and contractors will continue to monitor the COVID-19 situation and adjust our workplan accordingly. We will coordinate work in customer buildings when the risk of the spread of the virus is reduced.
Note: Steam customers whose buildings are outside of the hot water expansion area will continue to have steam services now and into the future. Steam customers that do not have buildings located in the Superior Street project should not anticipate changes to their steam system without additional communications and planning from our team.
Much of Canal Park is already on a hot water distribution system, it serves as a local example of how the hot water system can service a wide mix of buildings.
More information can be found at http://www.duluthenergysystems.com/how-it-works/
Closed-loop hot water systems can operate at a much lower temperature than the existing steam system. The lower the temperature of the heating medium, the lower the heat losses. This is due to the temperature difference between the heating medium and the surrounding air temperature and the rate at which the heating medium cools. The greater the difference, the faster the heating medium will give up heat, which is energy.
In a closed loop hot water system, the hot water from Duluth Energy Systems heats water in your building in an energy transfer station. The hot water that will flow through offices or living spaces in your building is separate from the hot water in the DES hot water loop. Any heat that is not absorbed by your buildings hot water energy transfer system to heat your building is returned to the DES plant to be reheated and pumped back into the hot water loop. The recycling of this water results in water savings. In an open loop steam system, no water or steam is returned to the plant, it is all wasted to the storm or sanitary sewer.
The water that is returned to the plant in a closed loop hot water system is significantly warmer than the make-up water that comes from Lake Superior. This also increases the efficiency of the system as it takes far less energy to bring this water back up to operating temperature than it does to bring the ice-cold water of Lake Superior to operating temperature.
The City’s district heating system was built in 1932, and it was designed as a once-through steam system. Energy in the steam system follows these steps: