About the Chilled Water Plants
The campus chilled water system is made up of three central plants with two large refrigeration machines and a chilled water thermal storage tank and a deep lake water based non-contact cooling plant connected to a buried network of recirculated chilled water. The chilled water moves the heat entering the buildings to the central plants which then reject the heat to the environment.
Staff
Ed Wilson
Central Heating and Chilled Water Plant Manager
Introduction
The Cornell University Chilled Water System made district cooling history when it was originally constructed and continues make history today. In 1959 and 1960, engineers in Cornell's Department of Buildings and Properties became concerned that the University owned water filtration plant would not be able to keep up with demand for potable water that was used in air conditioning systems throughout the campus. To solve this problem, a closed loop district cooling system, sized to meet the present and future loads, was constructed. Originally commissioned in 1963 with two 1,200 ton Carrier model 19C centrifugal chillers, this plant was one of the earliest commissioned in the United States and was considered state of the art. Today, Cornell's system is recognized as one, if not the, most efficient district cooling systems in the world. The current system can provide up to 20,000 tons of peak cooling capacity using a renewable resource and is a continuation of the leadership that Cornell University has continuously strived for in the district energy field.
The Cornell district cooling system distributes cold water to campus facilities where unwanted waste heat is transferred to the water, returned to the cooling plant and then rejected to the atmosphere.
The Cornell district cooling system operates year round, with summer chilled water supply and return temperatures at a maximum of 45ºF and 60ºF. Winter chilled water supply and return temperatures are typically 40ºF and 50ºF. The chilled water system produces approximately 30 million ton-hours of cooling each year for research processes as well as for general air conditioning of laboratory space, computer rooms, lecture/teaching areas and common spaces. The system serves 75 buildings totaling over 4 million square feet of air conditioned space, about 40% of the core campus. The system delivers more than 18,000 tons of cooling capacity at peak demand, circulating about 28,000 gallons per minute. The underground piping network consists of over fifteen (15) miles of underground direct buried piping with a volume of approximately 3.0 million gallons. A 4.5 million gallon stratified thermal storage tank increases the total system volume to 7.5 million gallons.
The original (pre 2000) Cornell district cooling system was nationally recognized as one of the most efficient of its kind with an annual operating efficiency of 0.75 kWh/ton-hour (1.0 kWh/ton-hour for a typical district cooling system). With the commissioning of Lake Source Cooling in July 2000, the annual efficiency has dropped to 0.10 kWh/ton-hour. CWP1and CWP2 will be decommissioned as will Chiller-4 at CWP3. Chiller-7, Chiller-8, the Thermal Storage Tank and free cooling at CWP1 will remain for system back up and peak shaving when the system peak demand outgrows LSC. LSC is considered a landmark achievement for optimizing energy costs using a renewable resource. The annual benefits of LSC are as follows:
- Reduced electricity use equivalent to 2,500 homes (over 20 million kWh/yr).
- The burning of over 19 million pounds of coal annually in regional power plants is eliminated along with the associated impacts of mining, transportation and ash removal (based on a peaking local plant).
- Carbon Dioxide pollution is reduced by over 56 million pounds per year.
- Sulfur Dioxides is reduced by over 645 thousand pounds per year.
- Nitrogen Oxides is reduced by over 55 thousand pounds per year.
- Accelerated elimination of 40 thousand pounds of CFC refrigerants that are known to deplete the ozone and act as a greenhouse gas.
- Reduced reliance on HFC's which are known greenhouse gases and potentially have unknown environmental impacts.
