Water is consumed when hot water passes through the cooling towers. These cooling towers use evaporation to remove heat from the hot water and release the wastewater into the sewerage system. During the evaporation process, a large amount of water will be evaporated into the atmosphere, so additional water needs to be added in order to maintain consistent volumes of water in the system. Along with this, if there are leaks in the pipes that distribute this water throughout campus, there is a lot of water going to waste. The UIUC plant is currently undergoing a process, starting in 2008 with an end-goal of 2025, in which the water loss due to leaks in pipes across campus will be diminished by 40%. After surveying the 63 miles of pipes running under UIUC Campus in 2013, nearly twenty leaks were found. After fixing this issue, roughly 35,000 kilo-gallons were saved each day. If regular surveying is done, pre-existing and worsening leaks can be prevented, thus losing less water in the cycle, making the chiller plant more environmentally friendly. According to UIUC iCAP, the annual water consumption of chiller plants is approximately 1.25 Billion Gallons, which accounts for 33% of all campus water usage. However, water usage in chiller plants varies throughout the year. Water usage is much greater in the summer compared to winter, because during the summer, the temperature is higher, so the water is easier to evaporate than in the winter.

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            The Oak Street Chiller Plant uses the vapor-compression refrigeration cycle to cool down water. During the process, electricity is used in the process of compressing the R134a refrigerant into the condenser. According to Mr. Larson’s Chiller Plants Presentation, roughly 30,000 gallons of water are pumped into condenser every minute, which is about 1895 kilograms of water per second. With the calculation, the compressor has an output power of 40.477kW. Similar to water usage, electricity usage also varies throughout the year. In the summertime, when cooling power is required at maximum, all six of the chillers are used, while in the wintertime, only one chiller is used. Therefore, in the summer the output power of electricity would be 242.86kW, while only 40.48kW in the winter.

 

            The campus chiller plant uses R134a as the refrigerant. If properly used in the plant, there is no emission of the chemical compound and the refrigerant never has to be replaced, unless it leaks or lacks purity. However, the carbon footprint left by chiller plants, in general, is substantial. The amount of energy derived from various carbon combustion methods has a profound impact on carbon emissions. The Oak Street Chiller Plant uses steam-driven York chillers, York electric centrifugal chillers, and variable speed York electric centrifugal chillers. In the steam-driven chillers, natural gases are typically burned in order to produce steam, with roughly 80% efficiency when heating. UIUC has recently signed the American College and University Presidents' Climate Commitment, which has a goal of carbon neutrality by 2050. It's important to consider where the power is generated from. Some of the chillers at UIUC use steam produced from the Abbot Power Plant, which has made efforts to reduce their carbon footprint by roughly 30% through co-generation. However, in 2015, about .87 pounds of carbon dioxide were produced by the Abbott Power Plant for every kilowatt/hour. While this is under the 1.00 limit for the EPA restrictions, there is still much room for improvement, and it's vital to consider that this is where the chiller plant is receiving steam from. With Illinois being one of the top states with large quantities of coal, UIUC has a large source of coal. Along with this, there are efforts being made to switch from coal to natural gas. Biomass is soon to be considered at UIUC, after efforts have been made at other colleges in the Midwest, however, the carbon emissions aren't much of an improvement.