ITHACA, NY — In searching for cooling options for Cornell University, a team of New York engineers turned to the “cold, deep water of Cayuga Lake.” Applying lake source cooling eliminated the use of refrigerant-based chillers, reducing energy use by 86%. It also saves more than 20 million kWh per year.

“Use of lake source cooling provides a passive and technologically simple cooling option for Cornell University, using a natural, non-polluting, and renewable source,” said W.S. “Lanny” Joyce, project manager. “It is designed and operated with great care to protect the lake.”

The 20,000-ton capacity chilled water district cooling system is one of two projects that will be awarded a first-place American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Technology Award during the society’s 2002 Winter Meeting, January 12-16, in Atlantic City, NJ.

The ASHRAE Technology Awards recognize outstanding achievements by members who have successfully applied innovative building design in the areas of occupant comfort, indoor air quality, and energy conservation. Performance is proven through one year’s actual, verifiable operating data.

The lake source cooling project was designed and constructed by a team of engineers led by Joyce, who will accept the award in the alternative and/or renewable energy use category on behalf of the team. He is manager of utility engineering, planning, and energy management, Cornell University Department of Utilities and Energy Management.

In the depths of Cayuga Lake, the water temperature remains a constant 39 degrees F. A 63-in.-dia by 10,400-ft-long intake pipe made of high-density polyethylene carries water from a from a depth of 250 ft to a heat exchange facility at the lake’s shore. Here, the cold water is pumped through a bank of stainless steel heat exchangers where heat is absorbed from a second, separate flow of water coming from the campus.

This second flow of water, cooled to 42 to 45 degrees, is pumped back to the campus three miles away to cool laboratories and other building spaces. The lake water is warmed to 48 to 56 degrees and returned to the lake about 500 ft from shore through a specially designed diffuser.

According to Joyce, the environmental savings have been significant as well. They include:

  • Reduced electricity use equivalent to 2,500 homes;
  • Elimination of the burning of over 19 million lbs of coal annually in regional power plants along with the associated impacts of mining, transportation, and ash removal;
  • Carbon dioxide emissions reduced by over 56 million lbs per year, sulfur oxides reduced by over 645,000 lbs per year, nitrogen oxides reduced by over 55,000 lbs per year; and
  • Accelerated elimination of 40,000 lbs of CFC refrigerants and reduced reliance on HFC refrigerants.
The long-term financial savings for the project’s initial premium over conventional chillers are generated by the 86% reduction in energy use, an expected life more than twice that of chillers, and reduced maintenance, Joyce said.

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Publication date: 12/24/2001