Air Conditioning With Deep Seawater: A Reliable, Cost Effective Technology

Deep, cold seawater has long been recognized as a valuable energy resource, and early studies in the 1970's, motivated by the energy crisis, identified its advantages for coastal air conditioning.',' Air conditioning with seawater uses only a small fraction of the electrical power required for conventional air conditioning. At the time of these studies, however, the cost of the seawater air conditioning system was uncertain because pipelines had not been built to the water depths required and heat exchangers had significant unknowns relative to corrosion, fouling and costs. This has now changed. Over the last decade, research on Ocean Thermal Energy Conversion (OTEC) has brought the development of reliable, moderately sized pipelines suitable for cold water air conditioning and the development of low cost aluminum heat exchangers compatible with deep, cold seawater. Air conditioning with seawater for some areas is now a reliable, cost-effective technology. This paper summarizes the operation of an air conditioning system using deep, cold seawater and identifies the primary conditions under which a system can be cost effective. The primary factors impacting the economic success of such a system is the size of the air conditioning load, the accessibility to deep cold water, the percent utilization of the air conditioning system and the local cost of electricity. This paper provides data and graphs that are suitable for an initial assessment of the economic pay back period based on these site-specific conditions.