While such projects have been few in number, their results have been considerable. Use of lake source cooling in Ithaca, N.Y., resulted in 87% energy savings, while a 75% reduction is anticipated in a Canadian project.
"Cornell University uses lake source deep water supplying over 18,000 tons of cooling for its campus," Alex Sleiman, District Energy St. Paul Inc., St. Paul, Minn., said. "The city of Stockholm uses the Baltic Sea to supply over 70,000 tons of cooling to its district-heating customers. The city of Toronto is in the process of implementing an extension to its district cooling system to supply deep water cooling from Lake Ontario."
Energy use reduction and environmental benefits of deep water usage will be discussed in a seminar chaired by Sleiman at the ASHRAE 2004 Winter Meeting. The meeting takes place January 24-28, 2004Anaheim, CA. The seminar will be held from 8-10 a.m. January 25. It is sponsored by ASHRAE's technical committee on district energy.
A lake source cooling project at Cornell University, which earned an ASHRAE Technology Award in 2002, replaced central campus refrigeration based chillers with a new source based on the cold deep waters of nearby Cayuga Lake.
"The system was a $58 million investment made by the university to reduce the future cost of cooling facilities, reduce energy use, eliminate the use of CFC refrigerants, reduce system complexity and maintenance, reduce environmental impact associated with energy use, and extend the life of the system," speaker W.S. "Lanny" Joyce, P.E., Cornell University, Ithaca, N.Y., said.
Since its start-up in July 2000, the project has averaged greater than 85 % reduction in energy use delivered to the buildings, and the system's ease of operation has exceeded original expectations, he said.
Deep water cooling and heat pump cooling systems using lakes and seas as a heat sink have been used successfully in Scandinavia for more than 15 years, according to speaker Mark Spurr, FVB Energy Inc., Minneapolis.
He will discuss a system in Sweden that includes aquifer storage. During the winter, cold seawater from a bay of the Baltic Sea is stored in the aquifer to reduce the warmer temperature of the seawater during summer. For another system in Stockholm, the Baltic Sea is used in combination with heat pumps to supply over 70,000 tons of cooling for downtown Stockholm.
Deep lake water cooling is expected to use up to 75 % less electrical energy than conventional electric chillers, according to speaker Vladan Veljovic, Enwave District Energy Ltd., Toronto, ON, Canada.
Such cooling is based on using year-around cold water from the depths of Lake Ontario, which can provide a permanent source of natural cooling for much of downtown Toronto. The use of cold deep ocean water for seawater air conditioning in the Hawaiian Islands also holds significant promise to increase energy efficiency and renewable energy use.
"Seawater air-conditioning systems exhibit very low operating energy costs, but relatively high capital cost," speaker John Andrepont, The Cool Solutions Co., Lisle, IL, said. "The integration of thermal energy storage with seawater air conditioning reduces total capital cost per ton of peak load served, thus enhancing the commercial potential for deep water source cooling."