Bora-Bora in the South Pacific is known for resorts that make ample use of the surrounding turquoise waters, where snorkelers and scuba divers can stop for therapy at a seawater spa before retiring to over-water bungalows at night.
(Related: Bora Bora Photos)
It only made sense for the French Polynesian island to turn to cooling energy from the sea.
The Intercontinental Bora Bora Resort and Thalasso Spa, located on the coral island of Motu Piti Aau, just off the coast, was the first hotel in the world to rely almost entirely on seawater cooling for air-conditioning and refrigeration.
The system, installed in 2006, draws frigid ocean water from a depth of 3,000 feet (915 meters), where it flows into a thermal exchanger—a kind of radiator made of titanium plates, which are excellent thermal conductors resistant to corrosion. The seawater circulates on one side of the plates, chilling the fresh water that circulates on the other side of the plates. Cool air from the thermal exchanger is then fanned into the hotel, without the need for bulky, noisy compressors.
The seawater is warmed in this process, so it is re-released at a depth of about 200 feet (60 meters) in an effort to avoid damaging fish and coral. It is part of an effort by entrepreneur Richard Bailey, owner of this and three other French Polynesian hotels, to put an environmental stamp on his properties.
Seawater cooling is not a new idea: the city of Toronto cools its main administrative center with water drawn from Lake Ontario, and for 16 years, the city of Stockholm has cooled downtown buildings with a system that relies on cold water from the Baltic Sea. (Related: “The AC of Tomorrow?”)
But the systems have very specific siting requirements, explains Joris Benninga, of RealNewEnergy, in Rockville, Maryland, which is working on a system on the island of Curaçao in the Caribbean.
The Bora-Bora system cost nearly $8 million to construct but saves the equivalent of 660,000 gallons (2.5 million liters) of imported fuel oil and should pay for itself in 11 years, according to a recent report by a hotel consulting firm. Of course, the payback will be faster if the global price of oil increases. The resort's owners are so happy with the results that they are building another system on Tetiaroa, another Tahitian isle. It's for their new resort, The Brando, named after the late actor, Marlon, who “discovered” the island while filming “Mutiny on the Bounty” and purchased a long-term lease to the land from the French Polynesian government. Bailey has been working with Brando’s estate to create an eco-hotel on the atoll.
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(Related: French Polynesia Photos)