Potential Benefits, Impacts, and Public Opinion of Seawater Air Conditioning in Waikïkï

UHERO April 11, 2013

This report provides a summary of an investigation by the University of Hawai‘i Sea Grant College Program into the viability and effectiveness of installing a seawater air conditioning district cooling system in Waikīkī. Seawater air conditioning (SWAC) harnesses the cooling properties of cold seawater to provide cool air for air conditioning purposes. In doing so, SWAC reduces the amount of electricity needed for air conditioning. SWAC is particularly relevant to Hawai‘i for two reasons: first, the proximity of deep, cold, ocean water to areas of high population make Hawai‘i an obvious location for implementing the technology; and secondly, with approximately 90% of its electricity generated from fossil fuels, Hawai‘i is the most fossil fuel dependent state in the nation. Unlike the rest of the U.S., where coal, natural gas, and nuclear power are called upon to meet a substantial proportion of the electricity demand, Hawai‘i relies heavily on residual fuel oil (the by-product of refining crude oil for jet fuel, gasoline, and other distillates). As a result, Hawai‘i has very high electricity prices compared to the rest of the country. SWAC has the potential to both cut the cost of air conditioning and reduce the amount of harmful emissions that are released as a by-product of generating electricity from fossil fuels.

Seawater air conditioning works by pumping cold (44-45°F), deep (1,600-1,800 feet) seawater into a cooling station (Figure 1). Here, the cold seawater is used to chill fresh water flowing in nearby pipes. The chilled fresh water is then piped into hotels for cooling purposes while the seawater (slightly warmed to 53-58°F) is pumped back into the ocean at a shallower depth (120-150 feet).

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Investigating the Potential for Seawater Air Conditioning in Waikiki

UHERO, April 14, 2013

Researchers at the University of Hawai‘i at Mānoa recently concluded a study into the potential for seawater air conditioning (SWAC) in Waikīkī. The study was led by the University of Hawai‘i Sea Grant College Program (UH Sea Grant) in partnership with the the Economic Research Organization at the University of Hawai‘i (UHERO) to investigate various aspects of seawater air conditioning and its applicability to Waikīkī. In examining the appropriateness of SWAC technology, researchers compared SWAC with ‘business as usual’ and various renewable energy and other energy efficiency options. Each option was analyzed in terms of: 1) generation capacity; 2) applicability to existing policy standards; 3) economic factors; 4) environmental and social factors; and, 5) energy and supply security.

According to the findings of the report, while SWAC may be more costly than other efficiency/conservation options, its ability to provide an uninterrupted supply of cool air gives it a solid advantage over the use of more intermittent renewable energy technologies (such as wind and solar power) for air conditioning purposes. For Waikīkī, where demand for air conditioning is constant, SWAC has the potential to decrease the cost of air conditioning and reduce the amount of harmful emissions that are released as a by-product of generating electricity from fossil fuels.

Traditional air conditioning systems require large amounts of energy to cool air to the desired temperature. In contrast, SWAC technology harnesses the cooling properties of cold seawater to achieve the same purpose, reducing the amount of electricity required. SWAC is particularly relevant to Hawai‘i, where the close proximity of deep, cold, ocean water to areas of high population make it an ideal location to implement the technology. In addition, the first seawater air conditioning unit was invented by a UH Sea Grant researcher in the early 1980’s.

When surveyed, 62 percent of O‘ahu residents indicated support for SWAC development in Waikīkī, compared to 8 percent opposed and 30 percent neither supporting nor opposing. Individuals more familiar with SWAC technology were more likely to support its development than those who were not aware of the technology (69 percent in favor compared to 54 percent). Slightly less than half of O‘ahu residents, 46 percent, also supported the use of public funds to help develop SWAC in Waikīkī, versus 26 percent opposed and the remaining 28 percent neither supporting nor opposing.

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