Seawater Air Conditioning Studied in the Caribbean

August 6, 2015 By Linda Hardesty

oceanMakai Ocean Engineering has completed a feasibility study of a district cooling system that uses deep cold seawater, known as seawater air conditioning (SWAC). The study was commissioned by CAF Development Bank of Latin America, with co-financing from the Agence Française de Développement and used Makai’s recently upgraded district cooling software. Eight locations in the Caribbean were analyzed for SWAC development, which were then down-selected to two sites considered to be most promising: Montego Bay in Jamaica, and Puerto Plata in the Dominican Republic.

Seawater air conditioning is a district cooling technology that uses deep cold seawater for cooling that can be as cold as 5°C or 41°F, even in the tropics. SWAC replaces the chillers used in conventional air conditioning systems, greatly reducing the electrical consumption and costs of cooling.

The benefits of SWAC include:

  • Energy and cost savings approaching 90 percent compared to conventional air conditioning.
  • Stable costs that are almost entirely independent of energy price fluctuations.
  • Environmentally friendly technology with reduced greenhouse gas emissions, fuel and water consumption.

SWAC systems are large renewable energy projects, often with capital costs in excess of $50 million. In order to determine the relative economic value of district cooling systems such as SWAC versus a conventional A/C system, Makai uses a computer model to compute the “levelized cost of cooling.” The model, called the Makai Economic, Thermal, and Hydraulic Optimization and Design, or METHOD software, takes into account all the major capital and operational costs for both physical and economic systems and the complex interplay between the sub-system designs and operational costs. This enables an “apples-to-apples” economic comparison of district cooling versus an equivalent conventional A/C system. Other financial metrics, such as payback period and rate of return of the district cooling system, are also computed.

In order to reduce the costs of a district cooling system, METHOD is used to design and optimize components to minimize the overall levelized cost of cooling. The software is particularly useful for providing quick and cost-effective “what if” analyses to help the developer decide between possible design variations early in the project, such as evaluating whether or not to add a nearby A/C customer to the network.

Hotels and resorts are large consumers of electrical energy, and conventional air conditioning systems account for around 40 percent of the total energy consumption in such buildings. Hotels in tropical and island locations could especially benefit from seawater district cooling systems.

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