In 2015, Stanford University in California swapped out its natural gas-powered energy system with one primarily powered by electricity. The university did this because it recognized that buildings are large energy users and that electrification is a necessary step toward a sustainable energy future. The new system has cut the campus’ greenhouse gas emissions by 65 percent due to efficiency improvements and electricity for the system being partially supplied by solar energy. This is a big step toward Stanford meeting its commitment to be 80 percent carbon-free by 2025, which will also involve electrifying all university vehicles and purchasing 100 percent renewable electricity.
In Stanford’s system, cold and hot water circulate through pipes around the campus to meet cooling and heating needs. As it travels around campus and through buildings, the cold water is heated. At a central facility, heat recovery chillers transfer the excess heat from the cold water to the hot water — thus cooling the cold water and heating the hot water to the appropriate temperatures, a process that meets 80 percent of the campus’ heating needs. These heat recovery chillers are twice as efficient as natural gas heating systems, which leads to significant cost savings — $420 million over 35 years for Stanford’s system.
This system also features tanks that can store the hot and cold water for later use. This allows the university to heat and cool the water in the tanks at night when electricity costs are low and circulate it through the buildings during the day when demand is high.
On very hot or cold days, the heat recovery chillers can extract heat from the ground or Stanford’s lake water irrigation system to meet the additional demand. The campus retains its old natural gas hot water generators as a last back up. This type of system can even be used in cold climates, where excess heat is generated by cooling and humidity control in certain buildings and can also be tapped from the ground or nearby water bodies.