Going for a Dip
- By Julie Sturgeon
- November 1st, 2000
Relying on circulated water to cool buildings won’t raise eyebrows in this decade. After all, a Hawaiian company air-conditions several of its high-rises using ocean water. Stockholm, Sweden, businesses rely on the Baltic Sea for similar purposes. Even Cornell University dusted off records that prove it lightly explored this notion in the 1960s and early ‘70s before opting for other solutions.
Now 20 years later, Cornell officials finally concluded this method represents the most economical long-term choice for their future. After three years of analysis and engineering summarized in 1,600 pages of environmental impact studies, the Ithaca, New York-based university today operates a unique piping system that dredges the 39F water from deep in Cayuga Lake to keep 75 of its buildings (including sensitive research labs with special cooling and dehumidifying demands) comfortable -- about 40 percent of the space in its central campus. The actual construction of the lake water and land-chilled water piping systems (the two water loops are separated by a stainless steel heat exchanger) needed only six months to complete by November 1999, but the planning stages occupied nearly five years of Associate Vice President for Facilities Services Henry Doney’s time.
Blame it on CFCs, the banned refrigerant agent Cornell’s chillers required to operate. When the government banned new production and importation, prices on the remaining CFC supplies skyrocketed so, by 1994, Doney knew his chillers’ days were numbered. “Additionally, we needed some new capacity, so combining the $30-million cost to replace the chillers with a lake-based design expected to yield twice the life of the chillers made it economically possible to consider,” he explains. Not to mention an 80 percent reduction in electric use, which would result in significant cutbacks of fossil fuel combustion at regional utility plants that supply the university with electricity.
The advantages weighed heavily on the balance sheet: The water-cooling system taps into a renewable resource while sidestepping the need to generate energy with these nonrenewable fossil fuels. The heat exchangers and piping that comprise the system require fewer maintenance dollars than the complicated water chillers they replace, and engineers assured it should last between 75 and 100 years under normal use. The amount of energy this system returns to the lake each year equals only what the sun accomplishes beating down on the surface in four hours.
Finally, thanks to Cornell’s position on Cayuga Lake’s banks (the water actually lies 450 feet below the campus’s elevation), the system doesn’t need to pump the water uphill when returning to the supply side of this closed loop. “You just have to overcome friction and circulate the water, so that saves a great deal of energy,” Doney points out.
Bottom line: Cornell could expect a positive payback on the $60-million system and lower annual operating costs in a little more than 10 years. The university anticipates chopping its $1.2-million annual expenditure on electricity alone by 80 percent. “It’s really the simplest form of physics,” Doney says. The most challenging technology involved running a 63-in. high-density polyethylene lake-water intake pipe deeper than 250 feet. The project ultimately required building a pipe 10,400 feet long -- a feat the manufacturer had never done previously. As it turned out, it was no big deal in the big picture.
“On the other hand, it is a big civil works project,” he notes. “Anyone who does this should enter knowing there are pitfalls.” Because a water-cooling project interacts with the environment, the Cornell administration left no stone unturned in exploring engineering and environmental impact statements. The ongoing daily, weekly, monthly and annual testing and reporting schedules by an independent monitoring firm to meet the strict requirements of permit for operation granted by the Department of Environmental Conservation in New York cost $100,000 annually. The university also convenes a lake data sharing group to discuss this information on a regular basis with the community.
“I don’t know of any other campus that has ever done anything that offered as much information put out early and had as much buy-in from what we consider identifiable, true environmentalists,” says Doney. “We went everywhere to anyone who would listen to us, told them what we were thinking and invited them to participate in the development of the environmental impact statements.” He cites Cornell’s own professors and Center for the Environment -- an independent consortium of researchers from many disciplines -- as the toughest critics.
“They probably added cost to the project, but that’s okay,” he muses. “They have legitimate concerns, and we covered those carefully and thoroughly.” Still, the university watched progress grind to a halt when a group of well-meaning citizens filed a lawsuit that postponed the campus from using its new system until July 2000. “Some people just have the idea that if you do anything, something could happen and it would be wrong,” Doney explains. “That probably shouldn’t have come as a surprise to us, but I suppose we were lulled into a false sense of security by having the normal group of environmentalists approve of the project throughout the review process.”
However, campuses not near a deep lake (defined as 250 feet so that the water stratifies in summer with warm water on top and cold water below) probably don’t have the resources even to flirt with this option. Doney also chalks up a portion of his campus’ savings to the fact that Cornell’s previous chillers operated on a network to pipe cold water from central generating facilities to the buildings. Two projects -- one involving the City of Toronto and the other an industrial and research complex outside Rochester -- are now beginning to take off on Lake Ontario, both of which began before Cornell launched its project. They have closely watched the university’s success, and now harbor renewed hopes for their drawing-board sketches.
“It takes somebody big to swing this,” Doney emphasizes. “But it’s been a great project for us.”