Honolulu Seawater Air Conditioning, LLC (HSWAC) is currently developing a 25,000-ton SWAC district cooling system for downtown Honolulu.  This system is designed to serve buildings in the downtown core.  Customer response to this project has been outstanding.  HSWAC also plans to develop a similar SWAC system for Waikiki and possibly for other areas in Hawaii.

As a tropical island state, Hawaii has a year-round, relatively uniform need for air conditioning.  Conventional air conditioning systems are energy intensive and represent 35 to 45 percent of energy use in typical office and hotel buildings in Hawaii.  Hawaii also has some of the highest electricity rates and air conditioning costs in the country.  And, Hawaii relies on expensive imported fossil fuels for more than 90 percent of its energy needs.  At the same time, all islands have some shorelines that have good access to deep, cold seawater used in a SWAC system.

SWAC is suitable for coastal developments with a large air conditioning demand and reasonable access to deep, cold seawater.  Notable areas are southern Kauai, several areas of Oahu and the southern 60 percent or more of the Big Island.

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

The HSWAC downtown project is essentially a chilled water distribution system with the cold, deep water of the Pacific Ocean as its primary energy source.  The downtown customer market has a potential of more than 30,000 tons of cooling load.  Potential customers currently operate their on-site, primarily oil dependent, electric air conditioning systems with ever escalating 20-year fuel operating expenses.

The HSWAC downtown project changes a customer’s on-site profile of approximately 25 percent fixed costs and 75 percent fuel and other variable costs to 80 percent, 20-year, fixed capital costs and only 20 percent variable costs.  Establishing a reliable district cooling system that operates on over 80 percent fixed costs would greatly benefit downtown building owners, managers and operators.