District Energy Plant
The University of Idaho uses a district energy system for the heating and cooling needs of campus. District energy systems produce utilities such as steam, chilled water, and compressed air for use in multiple buildings. The District Energy Plant at the University of Idaho (often referred to as the steam plant or energy plant) distributes utilities to campus buildings through miles of tunnels located under sidewalks and roads. By using a centralized location, energy can be distributed at a lower cost than producing it in every building. This eliminates the need for redundant, low-efficiency equipment throughout buildings that need to be maintained.
The U of I energy plant is located on campus at the corner of 6th and Line Street in Moscow, Idaho. Originally built in 1926 to use coal, the plant has undergone many changes over the years as coal was slowly phased out in favor of natural gas. As the university sought to further reduce greenhouse gas emissions in the 1980’s and secure a long-term, sustainable fuel source, an agreement was made with the local wood products manufacturing industry where the companies would invest in the installation of a new wood chip fueled boiler at the energy plant. This would provide the university with the sustainable fuel source it desired while providing lumber mills a means of removing waste in an environmentally friendly manner. In 1986, the new biomass boiler was installed and the last coal boiler was converted to burn natural gas.
To ensure that environmental impacts are minimized, the steam plant requires all woody biomass to be managed in accordance with industry/sustainability best practices for the use of mill residues/waste products, including requiring that biomass must not be sourced from the forest floor. Additionally, potential suppliers must have the proper certifications to ensure that sustainable forest management practices and standards are being met. Besides ensuring that wood chip fuel is sourced responsibly, the wood chip trailers operated by U of I use biofuel produced on campus, instead of diesel.
Just like any other sustainable energy source, biomass energy is most effective when near the source. Solar PV technology requires sunlight, wind turbines should be sited in windy areas, and biomass is more effective when near lumber mills. The U of I energy plant demonstrates the potential success for woody biomass as a sustainable fuel source by reducing long-term emissions compared to fossil fuels, while reducing the risk for catastrophic forest fires. The wood boiler at the energy plant reduces the cost of higher education and supports the local lumber mills by reducing their operating costs, benefiting the local communities economically, and improving the health of the Coeur d’Alene, St. Joe, Kaniksu, Clearwater, and Nez Perce National Forests.
Campus Chilled Water
Chilled water is produced using a combination of electric vapor compression chillers and absorption chillers at two central locations on campus. The North Campus Chiller Plant (NCCP) is located inside the District Energy Plant. The South Campus Chiller Plant (SCCP) is located above the Kibbie Dome, next to the Golf Course. The system provides chilled water for process cooling loads such as servers and environmental room conditioning in a reliable and cost effective manner. This has allowed for many worn out and inefficient building chillers to be eliminated, and allows new buildings and major remodels of older buildings to be constructed without separate chillers, further reducing costs.
Besides the chillers, the University of Idaho operates a 2 million gallon chilled water Thermal Energy Storage (TES) tank. The university uses the TES to meet peak load demands during the day without running additional chillers, increasing system efficiency. By discharging the tank when cooling loads are highest, then recharging it at night, the university lowers the peak demand for electricity it purchases from the utility, reducing operating costs significantly while also improving system performance.