SWAC (Sea Water Air Conditioning) is air conditioning obtained from icy water drawn from the depths of the seas. That of the CHPF is the largest in the world. In the Overseas and even in France, it is the only one. A 3.8 kilometer long underwater pipe draws water at 5°C from 900 meters deep. This seawater is then conveyed by pumps to a technical room and through a heat exchanger in which it passes, it cools the fresh water of the air conditioning system of the CHPF. Fresh water and salt water never meet. Fresh water is not returned to nature. Salt water is discharged at 12°C into the ocean, without disturbing the ecosystem. “The volume that is pumped to supply chilled water to the CHPF is a tiny amount compared to the volume that exists in the surrounding area. And when the water at 12°C is discharged into Taaone Bay, the dilution effect of this discharged volume is negligible compared to the surrounding volume. The impact studies that we carried out at the start of the project show us that today, the SWAC has no impact on its environment” says Teumere Mu, head of technical service at the CHPF.
A air conditioning system more efficient and more virtuous for the environment
Air conditioning is essential to the proper functioning of the hospital: “The CHPF has to be cool all the time. Without cold, the majority of our medical activities cannot function. The laboratory chain, operating theatres, MRI, scanners, radiotherapy equipment… The energy share of air conditioning is the most penalizing for the CHPF since it previously represented 40% of the CHPF’s electricity consumption. And the SWAC today brings us a real plus sincewe reduce our energy bill between 35 to 40%“.
Indeed, the installation of the SWAC has made it possible to take a new step in the energy transition for the CHPF: “Before, we produced all our chilled water by chillers which consumed more than 9 million kilowatt hours per year, and thanks to the SWAC, we save 8 million kWh. (…) Polynesia’s energy mix is currently based solely on carbon electricity which is produced from fuel oil, so inevitably, by lowering electricity consumption to such a level, this contributes to the energy transition. and reduce its carbon footprint” says the head of the technical department. The hospital’s old “cold units” which provided air conditioning are still maintained and kept in case of emergency.
Three months after its launch, we can thus say that thanks to the SWAC, the CHPF hardly uses any more fossil fuels to air-condition its hospital which is thehe largest consumer of electricity in Polynesia. “It’s a new equipment that we take in hand. The time to acclimatize with the equipment, to find the best possible settings to optimize its operation… After three months, we have reached a good cruising speed for its operation” says Teumere Mu.
The SWAC made it possible to reduce the electricity needs of the entire island of Tahiti by 2% i.e. 5,000 tons of CO2 in a month or the equivalent of 27 million kilometers traveled by car. It also saves nearly 300 million XPF in electricity. Within 15 years, the project which cost 3.7 billion XPF should be profitable.
Next step in the energy transition of the hospital, the switch to solar for its lighting.
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Three months of commissioning for the CHPF SWAC
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