No. Our system utilizes ground-source heat pumps to deliver geothermal energy to the buildings serviced on campus.

While our system is dependent on externally-provided electricity, our use of that energy has been reduced by over 50% since the geothermal system was brought online. In addition, our carbon-dioxide emissions have been reduced by 25,000 tons per year and annual water consumption was cut by over 25,000 CCF, or 18 million gallons.

645 wells have been installed for the three main geothermal plants.  144 wells have been installed for the Bullman geothermal project.  The total number of wells installed is 789.

The wells range in depth from 400 to 440 feet. Average depth of the wells is about 430 feet.

The groundwater temperature in this area is approximately 60°F. As the year progresses from predominantly cooling season to heating season, the temperature of the water circulating in the closed geothermal loop will vary from 90°F to 100°F in the early fall to 40°F to 45°F in the spring.

Ground source heat pump technology has been around for many years, but only one other university has completed a project of this scale.

McClure Engineering offered consulting while Physical Facilities was evaluating feasibility.

A heat recovery chiller (HRC) operates on the principles of a refrigeration cycle: the same basic cycle that is used for refrigerators, air conditioners, and heat pumps you find in your homes. It is designed to provide both useful cooling and heating energy from the system. The work (energy) put into the machine through the compressor is used to simply transfer heat from evaporator to the condenser, which makes the design a more efficient use of energy than combusting fuel for heat.

As seen in the diagram below, refrigerate is first compressed using a screw-type compressor. This hot gas is then condensed to a liquid as it travels in a circuit through the condenser, where heat is transferred to the water flowing through the condenser tube bundle. Our system uses R-134a refrigerant as a thermal transfer medium.

The pressure and temperature of the refrigerant are reduced as it flows through the throttling valve. Next, the refrigerant passes through the evaporator where it absorbs heat from water flowing through the evaporator tube bundle. Then the cycle repeats as the refrigerant goes back to the compressor. The refrigerant is confined inside of the heat recovery chiller for the entire process.

The geothermal system provides heating in the winter and cooling in the summer. If needed, the system may also operate in a dual-production mode and provide simultaneous heating and cooling.

Heating Water Production

Water from the campus heating water return lines flows through the condenser of the heat recovery chiller (HRC) where it is heated to a nominal 120 degrees Fahrenheit for distribution back to campus. Heat is transferred from water flowing through the evaporator tube bundles, which has been circulated in the geothermal loop and warmed by the well fields.

Chilled Water Production

Water from the campus chilled water return lines flows through the evaporator of the HRC where it is cooled to a nominal 44 degrees Fahrenheit for distribution back to campus. Heat is transferred to water flowing in the condenser tube bundles, which has been circulated through the geothermal loop and cooled by the well fields.

Simultaneous Heating and Cooling

As before, water from the campus hot water return lines flows through the HRC and is heated to a nominal 120 degrees Fahrenheit. In this case, water from the campus cold water return lines provides the necessary heat transfer as it flows through the HRC evaporator and is cooled to a nominal 44 degrees Fahrenheit. Geothermal loop water is mixed as needed through either the condenser or evaporator tube bundles to balance the loads on the chiller.