Deep Water Cooling

Research campuses that are located near a deep lake or deep, cold ocean currents can use this water directly to cool conditioned spaces with small climate impact.

The following links go to sections that explain how deep water cooling may fit into a climate action plan for your research campus.

Considerations
Sample Project
Related Links

Deep water cooling involves using water from a deep lake or cold ocean current with heat exchangers to provide chilled water for cooling buildings.

Infrastructure costs for deep water cooling systems are significant, but may be appropriate for district cooling systems for large campuses near a suitable thermal sink. Once installed, a deep water cooling system will operate inexpensively and with extremely low climate impact for many years.

Considerations for Campus Deep Water Cooling Installations

Is it located within a few miles of a deep lake or cold ocean currents?
Is there an ongoing and large cooling load?
Do you need to replace refrigerant chillers?
Do you need to build or expand a district cooling?

Research campuses should consider the following before undertaking a deep water cooling assessment or installation.

Ocean or Deep Lake Resources

For direct applications of deep water cooling, water sources must be 45°F or cooler. These temperatures are typically present in the ocean or deep lakes, especially in the Great Lakes region of the United States. The Hawaiian Islands have cold ocean currents passing close to shore. Read more about cold ocean currents in the report "Ocean Energy Technology Overview," published by the U.S. Department of Energy.

Cooling Load

Because installation costs for deep water cooling systems are high, obtaining a good return on the initial investment requires a consistent demand for cooling. Many institutional buildings experience cooling loads year-round. However, engineers should ensure cooling loads are steady and sustained over a long time before a campus considers such an investment.

Map of the Great Lakes region in the United States and Canada.

One of the best opportunities for deep water cooling in North America is in the Great Lakes, which are made up of some of the deepest and coldest fresh water lakes in the world.

Refrigerant Chiller Replacement

Replacing large chillers for district cooling systems can be very costly. The best time to explore options such as deep water cooling is before undertaking a chiller replacement.

Expanding Chilled Water Systems

Campuses with district cooling systems have the distribution piping needed to leverage deep water cooling systems. Another good time to examine the pros and cons of deep water cooling is when you are preparing to expand a district cooling system or develop a new campus.

Leading Example: Cornell University Lake Source Cooling

The Lake Source Cooling System at Cornell University in Ithaca, New York, is a unique example of geothermal cooling through local water resources. The system has a cooling capacity of 18,000 tons, which is large enough to cool the entire Cornell University campus. In service since 2000, the system uses no refrigerants and consumes energy at the rate of 0.1–0.15 kilowatt-hour per ton-hour of delivered cooling. This represents an 86% reduction of energy consumption compared with that of the previous chillers.

Aerial photo of a building next to a lake with a sailboat in front near the shore.

Diagram of the Cornell University deep water cooling system. The diagram shows the campus on top of a hill, 450 feet above Lake Cayuga, which is 250 feet deep. It shows a loop of underwater pipe running 10,000 feet from shore where the water if 39–41°F. It also shows a chilled water loop going from the lake into the university at 45°F and returning to the lake at 60°F.

This Heat Exchange Facility on the shore of Cayuga Lake provides extremely efficient cooling to the entire campus of Cornell University. The electricity required for cooling the campus is a small fraction of the requirement of a conventional chiller plant.
Credit: Cornell University

This installation has been highly successful and has won many state, national, and international awards. The university has conducted an extensive environmental impact study and continuously monitors lake conditions. Design details and nearly 10 years of performance data are available on the Cornell website.

Additional examples of research campus geothermal cooling projects include:

Toronto District Cooling System: This system uses water from Lake Ontario to provide cooling for businesses in commercial buildings, municipal buildings, city schools, and hospitals.
Natural Energy Laboratory of Hawaii Authority (NELHA): This laboratory houses some of the world's preeminent authorities on deep water cooling and ocean energy. Additional information on the NELHA Gateway Energy Center can be found at the NELHA Gateway website.