Other Routes to Clean Energy

Seawater Air Conditioning


In August 2013, the Ulupono Initiative invested $1 million in Honolulu Seawater Air Conditioning (HSWAC) for development of its seawater air conditioning cooling system. The goal is to help HSWAC begin construction in 2014 "on one of the largest energy-efficiency projects in Hawaii," according to the Ulupono Initiative, which was created by Honolulu resident Pierre Omidyar to encourage energy and food self-sufficiency for Hawaii.

Seawater air conditioning does not create energy. It offsets or replaces the electricity needed to cool buildings with a clean, renewable technology. It is our best immediate opportunity to take advantage of the ocean's energy potential.

Conventional air conditioning systems consume four to 12 times more electricity than equivalent seawater A/C systems.

Honolulu Seawater Air Conditioning, LLC, is currently developing a 25,000-ton seawater air conditioning system for downtown Honolulu.  The company reports it has commitments from future customers totaling more than half the first system's capacity.

Hawaiian Electric is one company that has made a commitment to use seawater A/C at our headquarters building at 900 Richards Street.  Hawaiian Electric has also given the company a letter to share with potential customers urging them to consider joining the system.

How Does it Work?

Cold seawater is pumped from deep offshore to a cooling station located near the buildings. There the cold sea water chills fresh water. The system is designed to prevent sea water from mixing with fresh water.

The chilled freshwater is then pumped through a loop to buildings that will use the chilled water for cooling.  The slightly warmed sea water is returned to the ocean at a level where it will match the ambient temperature of the water.

Possible areas for expansion include Waikiki, Kapolei, Kakaako and the University of Hawaii at Manoa. A modified system using deep well water is already in use at the University of Hawaii John A Burns School Of Medicine in Kakaako, reducing the electric use for A/C in that complex by about 25%

Seawater A/C systems provide numerous environmental, economic development and customer benefits.

Environmental benefits:

  • reduces the electrical usage with a renewable resource significantly
  • reduces use of ozone-depleting chlorofluorocarbon (CFC) refrigerants
  • reduces reliance on fossil fuels and emission of greenhouse gases

Customer benefits:

  • price-competitive service with stable energy cost to consumer
  • model of sustainability with fuel dollars staying in the local economy
  • eliminates the need for chillers or cooling towers
  • saves space in the mechanical room
  • equipment built to last 75 to 100 years is easy to operate and maintain

See http://www.honoluluswac.com for more information.