Seawater Air Conditioning

At Simply Air conditioning London we’re always interested in new innovations that help make a greener planet, while new advances in technology really excite us. That’s why we were interested in the new Honolulu Seawater Air Conditioning project, which is utilising piped seawater in an effort to cut down on energy usage in downtown Honolulu. The project will cost some $250 million.

The system will use a thick pipe about five feet across placed, in the deep water about four miles offshore. It will be able to stand up to deployment stresses and withstand the largest storm surf and hurricane waves throughout its lifetime.

The pipe will be in water close to 2000 feet deep. Cold water is sucked up and transported via the pipe into a system that feeds the downtown area.

Sea Water Air Conditioning (SWAC) takes advantage of available deep cold seawater to replace energy-intensive central refrigeration systems that cool chilled water to provide air conditioning in one or more buildings. Such a system can also utilise cold lakes or river water as the cold source.

The cold from the seawater is transferred to a separate loop filled with freshwater. Freshwater is then pumped to individual buildings. The water will be pumped back via a cooling plant and through a heat exchanger returning the seawater back to the ocean. The water, at this stage around 10 degrees warmer, will dissipate quickly to minimise impact on marine life.

“Clean, cool, and green” is how Honolulu Seawater Air Conditioning describes the technology.

Seawater air conditioning systems tap into a significant and highly valuable natural energy resource available at many coastal points. The potential benefit of using colder seawater or lake water for air conditioning include:

  • Large energy savings approaching 90%
  • Proven technology
  • Short economic payback period
  • Positive environmental attributes
  • Costs are almost independent of any future price increases in energy
  • No evaporative water consumption
  • There is availability of cold sea water for other applications

The Honolulu plan calls for driving about 100 piles about a quarter to a half mile offshore. The piles will secure the pipes to the floor in a surf zone where the pipe is subject to movement. Marine life could be impacted by vibration, but marine life, like dolphins and whales will be monitored by marine mammal experts and scientists that the Honolulu Seawater Air Conditioning will have on board at all stages of the project.

While the amount of seawater that can be taken from the ocean is limited, there is still capacity to power forty large sized buildings in the downtown area. The energy savings that will result as the outcome of this project, brings hope to advancement of more eco friendly methods of energy usage. Although the investment is substantial, the long-term benefits may be worthwhile.

Although it’s only possible in certain areas of the world, it is great to see the seawater air conditioning innovation being utilised where possible and we hope to see many more similar innovations in air conditioning and the world in general to help us push towards a greener planet.


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