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.
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.
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.
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.
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.
The following resources explain the fundamentals of geothermal cooling technologies:
International District Energy Association: Serves as a resource for central heating and cooling applications, including deep water cooling.
U.S. Department of Energy Geothermal Technologies Program: Provides research and resources on geothermal heating and cooling technologies and applications.