About District Cooling

The Cool. Green. Clean. Solution

While seawater air conditioning (SWAC) is relatively new, it is a proven technology and systems in operation in the U.S., Canada, the Netherlands, and Sweden have achieved impressive economic and environmental results.

A number of studies have been conducted to evaluate the potential of SWAC in Hawaii, and there is an operating system at the Natural Energy Laboratory of Hawaii Authority (NELHA) at Keahole Point, Hawaii.  These studies all show that there is significant potential for SWAC in Hawaii.  SWAC is suitable for coastal developments with a large air conditioning demand and reasonable access to deep, cold seawater. Notable areas in Hawaii include southern Kauai, several areas of Oahu, and the southern 60 percent of the Big Island.

More recent studies show that combining SWAC with thermal energy storage and auxiliary chillers further increases the cost effectiveness and applicability of such systems.

Main factors that influence the economic viability of a SWAC system are:

• Distance offshore to cold water in the 39˚F-45˚F range
• Size of the air conditioning load
• Concentration of the air conditioning load; i.e., size of the onshore distribution system
• Utilization of the air conditioning system (during days, nights, weekends, etc.)
• Local cost of electrical power and water

A sustainable solution – The alternative that goes above and beyond.

As Hawaii’s most abundant natural resource, seawater can reduce electricity consumption used for air conditioning by up to 75%. When used for district cooling, it will efficiently produce chilled water at a plant with a capacity of 25,000 tons – equaling 12.5 million square feet of air conditioned area. The chilled water is then piped to air conditioning systems in individual buildings, resulting in the elimination of chillers and other expensive equipments.

Benefits at a glance.

District cooling provides numerous benefits for our customers, for our community, and for our environment.

  • A ton of cooling is the equivalent of melting one ton of ice over 24 hours
  • Deep water air conditioning uses only the cold from the water, not the actual water
  • There is enough cold deep seawater to provide air conditioning to the current world's population for more than 177,900 years
  • Deep cold seawater is replenished every 1,000 years, or so
  • Each year, enough cold, deep seawater is produced to operate the downtown Honolulu SWAC system for more then 23 million years, or to provide air conditioning to the current world's population for nearly 178 years