Analysis shows that the campus can recover up to 70 percent of the heat now discharged from the cooling system to meet at least 80 percent of simultaneous campus heating demands, significantly reducing fossil fuel and water use in the process. Based on this finding, Stanford will replace the current natural-gas powered cogeneration plant with an electricity powered Heat Recovery plant or the new Replacement Central Energy Facility.
Today, an intertwined system of steam and chilled water meet the simultaneous demand for heating and cooling of campus buildings. Steam from the Central Energy Facility enters the building, and through heat exchangers, produces both warm air for space conditioning and hot water for restrooms, kitchens, and laboratories. Afterwards, the steam changes into condensate, and returns to the Central Energy Facility to be reheated back into steam and then sent out to buildings again. Simultaneous to the steam system, chilled water enters the building, and through a different heat exchanger, provides cold air to cool the building. After collecting waste heat, the chilled water is then piped back to the Central Energy Facility for re-cooling.
New Heat Recovery Design
In the new heat recovery design, the waste heat collected from buildings via the chilled water loop will be captured by new heat recovery chillers and moved to a new hot water loop. The new hot water loop will replace the current steam system for delivering heat to the campus. Due to the significant heat recovery and lower line losses of hot water, compared to steam, the new system is 70 percent more efficient that the combined heat and power process provided by the current cogeneration plant.