Geothermal Heat Pump System for Ice Arena Geothermal Project

From Open Energy Information

Last modified on July 22, 2011.

Project Title Geothermal Heat Pump System for Ice Arena
Project Type / Topic 1 Recovery Act – Geothermal Technologies Program: Ground Source Heat Pumps
Project Type / Topic 2 Topic Area 1: Technology Demonstration Projects
Project Description The city of Eagan is proposing a retrofit for the city’s ice arena. The basis for the retrofit is to improve energy efficiency and lower the energy costs. The centerpiece of the savings is based around a central geothermal heat pump system. The geothermal heat pump system will produce chilled water/glycol to create and maintain the facilities two sheets of ice. An additional set of centralized geothermal heat pumps will be used to produce heating hot water and domestic hot water for the facility.

In addition to the centralized heat pump system, other system improvements will be made to the mechanical system. These improvements will help to minimize the size of the geothermal heat pump system and well field. These improvements include:

1. Low Emissivity Ceilings over the ice rinks. These ceilings reduce the radiation load on the ice, thus lowering the chilled water/glycol demand allowing for a smaller heat pump system. 2. Direct Digital Controls. The proposed geothermal heat pump system will be controlled via a central direct digital control system 3. The Addition of a Dry Fluid Cooler. The fluid cooler will allow the system to perform “free cooling” in the cold winter months by circulating the chilled water/glycol solution through the fluid cooler.

The central heating and cooling plant is sized based on the building’s cooling load (ice making and air conditioning) since the cooling load is larger than the heating load, system. The centralized water-to-water system operates to produce the greater of the two loads on the system at any one time. Most often this will be the chilled water/glycol, because the loads to maintain the sheets of ice are large. A byproduct of producing the chilled water/glycol is hot water. Typically, most conventional systems reject this heat to the outdoors. The proposed geothermal heat pump system instead uses this heat directly within the facility, stores it in the ground, or boosts the temperature of the fluid with another set of centralized heat pumps. This is essentially a “free byproduct” which is where most of the system energy savings come from.

The energy reductions will result in an annual energy cost savings of $140,653. The savings over the 25-year life of the system is $3,096,336. The incremental cost for the proposed geothermal heat pump system is $2,676,505. This translates into a Return on Investment (ROI) of 6.9%.

In addition to energy savings, the proposed geothermal heat pump system will reduce carbon dioxide emissions by 795 metric tons or the equivalent of burning 1,848 barrels of oil as calculated by

State Minnesota
Objectives The proposed centralized heat pump system will reduce energy consumption for the central plant equipment for the renovated building and new expansion by 64% compared to a traditional system.
Awardees (Company / Institution) City of Eagan
Awardee Website
Partner 1 TRAK International

Funding Opportunity Announcement DE-FOA-0000116
DOE Funding Level (total award amount) $1,338,000.00
Awardee Cost Share $1,338,000.00
Total Project Cost $2,676,000.00

Principal Investigator(s) City of Eagan

Targets / Milestones Working with the city of Eagan, TRAK International a division of Harris Companies intends to provide a highly energy efficient mechanical system design and installation for the facility renovation. The design and construction work for the renovation will also provide the ability to expand the central geothermal heat pumps system, should the city wish to expand the facility.

Location of Project Eagan, MN
44.8042°, -93.1669°

Impacts This is a very innovative application of GHP technology, using the loop to provide space conditioning, hot water, and support ice maintenance. Good potential for transferrability to similar facilities.
Funding Source American Recovery and Reinvestment Act of 2009
References EERE Geothermal Technologies Programs[1]


  1. EERE Geothermal Technologies Programs