New Renewable Energy Report Released: Seawater Air Conditioning in the Caribbean

– July, 2015

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The study used Makai’s computer model to design district cooling systems in the Caribbean. The above
screenshot shows the model being used to design another SWAC district cooling system in Mauritius
for Urban Cooling. Once a layout is defined by the user, the major system components (deep seawater
pipes, chilled freshwater network, etc.) and operations (pumping power, maintenance, etc.) are then
optimized for a minimum cost of cooling. The Caribbean study suggests that district cooling is a clear
economic and environmental winner versus conventional A/C.

Makai 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 (AFD) 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. The final report that summarizes the study is now available upon request.

Hotels and resorts are large consumers of electrical energy, and conventional air conditioning (A/C) systems account for around 40% of the total energy consumption in such buildings. Energy costs can be very high, especially in tropical and island locations, which creates an opportunity to develop lower-cost district cooling systems. Seawater air conditioning (SWAC) 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 A/C systems, greatly reducing the
electrical consumption and costs of cooling. The benefits of SWAC include:

  • Large energy & cost savings: approaching 90% compared to conventional A/C.
  • Stable costs: almost entirely independent of volatile energy prices.
  • Proven technology: deep seawater systems have operated for over 28 years continuously.
  • Environmentally friendly: reduced greenhouse gas emissions, fuel, and water consumption.
  • Secondary uses: cold, nutrient-rich seawater is available for other applications.

SWAC systems are large renewable energy projects, often with capital costs in excess of $50 million USD. In order to determine the relative economic value of district cooling systems such as SWAC versus a conventional A/C system, Makai uses a sophisticated computer model to compute the “levelized cost of cooling.” The model, called the Makai Economic, Thermal, and Hydraulic Optimization and Design software, or METHOD™ software, takes into account all the major capital and operational costs for both 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.

The METHOD™ software consists of two main components: an engineering and an economic model. The engineering model considers the physical layout, chillers, pump stations, heat exchangers, thermal storage, customer loads, proximity to cooling source, pipe sizes, lengths, flow rates, and power requirements. The economic model considers financial aspects such as cost of electricity, financing, CAPEX, and OPEX for a district cooling project. The economic model is based on the Electric Power Research Institute’s Technical Assessment Guide (TAG), which is an economic analysis method of fairly comparing two alternative energy systems with different capital and operating costs using what is called a “levelized” or “annualized” cost of cooling. METHOD™ has been continuously developed over 25 years, and recently underwent a major overhaul with the help of a U.S. Navy research and development grant. Notably, the cost algorithms were upgraded and now account for 160 various costs applied across a dozen of the key construction steps for district cooling systems.

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. Users can instantly see the effect on levelized cost due to a change in the network. In the case of a SWAC system, METHOD™ includes accurate costs for the offshore seawater pipes that are derived from real construction projects – these are necessary to get an accurate project cost, and are something only a firm with significant offshore pipeline construction experience can offer.

CAF’s recent feasibility study evaluated eight sites for SWAC and then produced two conceptual designs and cost estimates at the most economically attractive locations. The results suggest that SWAC development is likely to be economically attractive in these two locations. Makai presented results at the first Caribbean deep seawater cooling conference, in Santo Domingo in November 2014, organized by CAF. A newly released report summarizing the findings is available upon request.

About CAF

CAF – Development Bank of Latin America is a regional multilateral development agency that promotes a model of sustainable development in Latin America and the Caribbean. CAF has co-financed these studies with the Agence Française de Développement (AFD), a financial institution and the main implementing agency for France’s official development assistance to developing countries and overseas territories. To contact CAF to get the report, please send request to:

About Makai Ocean Engineering, Inc.

Makai Ocean Engineering, Inc. is an innovative ocean engineering and design firm based in Hawaii, USA since 1973. Makai’s expertise includes submarine cable software and services, marine pipelines, Seawater Air Conditioning (SWAC), Ocean Thermal Energy Conversion (OTEC), underwater vehicles, and general marine engineering and R&D. We are not district cooling developers, but rather design engineers who support project developers. Please visit for more.


For more information, contact:
Duke Hartman
Vice President, Business Development
+1 (808) 259-8871

Makai Ocean Engineering
Makai Research Pier
41-305 Kalanianaole Hwy
Waimanalo, Hawaii 96795 USA