How deep sea aircon could cut the heat of climate change

Until the 1960s, when jet travel brought mass tourism to Hawaii and skyscrapers began sprouting from Waikiki to Pearl Harbor, Honolulu was a city of widely spread-out low buildings shaded by giant monkeypod trees naturally cooled by the strong trade winds that prevail 2000km north of the equator.

Today, however, a forest of concrete structures that not only trap heat but emit it through air-conditioning have turned the city center into a heat island and have become a drain on the state’s over-extended power-generation system.

In the next few months, work will begin on a project to make Honolulu the first city in the world to have its heart cooled by seawater pumped from the deep. This will save building owners money in several different ways and at the same time cut greenhouse emissions, according to an environmental impact statement published last fall.

The technology is already used in parts of Toronto and Stockholm to balance temperatures inside large buildings, notably to cool areas with computer servers and telephone exchanges during the summer months. But, says William M. Mahlum, president of Honolulu Seawater Air Conditioning LLC, which is undertaking the $240-million project,...

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