St. Paul, MN: District Energy Heating and Cooling Plants

Kellogg Plant: (3D Satellite)

10th Street Plant: (3D Satellite)

Derek Bauer posted three photos with the comment:

NSP's Third Street Plant in St. Paul, MN decked out for the holidays (1920s). 

Originally built in 1906 for district steam heating with electrical generation added the following year. It still operates today for the same purpose with the addition of chilled water for cooling. It now burns biomass instead of coal. 

Turbine hall pictured circa 1920s vs 2019.

 

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The big tank is thermal storage. "Thermal storage refers to a large tank that holds hot water or chilled water and functions as a thermal battery. This technology allows a district cooling system to chill water at night, using off-peak electricity, and then store the water for distribution to customers during the day. At District Energy St. Paul, most of the chilled water provided is produced at night using off-peak electricity and stored in two larger thermal storage tanks, located at the Kellogg and 10th Street plants (respectively – 2.5 million and 4.2 million gallons of capacity)." [DistrictEnergy-storage] This is the Kellogg plant with a 2.5m gallon tank.

3D Satellite

The tank makes it easy to find the plant. This would be the 10th Street Plant. It looks like this one might specialize in chilled water.

3D Satellite

Another view of the Kellogg plant.

3D Satellite

DistrictEnergy-water

DistrictEnergy-how-it-works

In 1979, it started distributing hot water. "The system was developed as one of the first hot water district energy systems in North America." [Central heating districts had used steam.] In 1993, they added the chilled water service, and they added the thermal storage in 1994. They added their combined heat and power (CHP) plant in 2003. This burns tree waste to produce 65mw of heat and 25mw of electricity that they sell to Xcel Energy. [DistrictEnergy-history]

DistrictEnergy-history

The solar power facility:

3D Satellite