A grant-supported district-heating system in Seward, Alaska, that employs six water-source Mayekawa CO2heat pumps is expected to be completed by the end of 2019, according to the energy consultant working on the project.
The heat pumps will provide heating to four municipal buildings in Seward – City Hall, City Hall Annex, the Community Library and Fire Hall.
The heat pumps will be located in the library basement, with oil and electric boilers as a backup, noted Andy Baker, owner of Anchorage, Alaska-based YourCleanEnergy, an energy consultant responsible for this project and a similar one at the Alaska SeaLife Center in Seward.
Hot water will be circulated to the other three buildings through an Alfa Laval heat exchanger to prevent contamination of the heat pumps. Baker projects using the heat pumps for 80%-90% of the heating load in the buildings, and achieving a COP of 2.4, with the temperature of return water reaching 100°F“more consistently with big radiant heat loads in the library.”
Source heat for the project will come from ocean tides in nearby Resurrection Bay, tapped through a 200-ft-deep closed glycol loop and delivered to the library 500 ft away. A nearby hydroelectric energy plant under consideration in Seward could be a future source of waste heat for the district-heating project.
It is estimated that the district heat pump system will save the Seward $25,000 in annual heating costs compared to a fossil-fuel system – another step toward a decarbonized society.