Modeling the Adoption of Sea Water Air Conditioning in the Caribbean

Small islands in the Caribbean face many challenges related to sustainability. For instance, they need to improve energy security and at the same time reduce fossil fuel dependence; they need to guarantee economic growth and... [ view full abstract ]

Small islands in the Caribbean face many challenges related to sustainability. For instance, they need to improve energy security and at the same time reduce fossil fuel dependence; they need to guarantee economic growth and fresh water and food supply, ideally with minimum impact in natural resources. Deep ocean water (DOW) is a renewable resource that can provide cooling services, electricity, freshwater and nutrients for food production. Given this, the use of DOW is emerging as an alternative to the sustainability challenges of the Caribbean. One of the most mature DOW technologies is Seawater Air Conditioning (SWAC), which uses cold DOW to provide air conditioning (AC) to a set of buildings through a cooling district. By replacing traditional AC with SWAC, a building could increase its efficiency about 80% and could eliminate the use of fossil fuel for AC generation, which in the long term represents a lower cost than traditional AC. Despite the advantages, the adoption of SWAC in the world, and especially in the Caribbean, is limited. The main reasons are the preliminary stages of SWAC technology, high investment costs, and uncertainty in environmental impacts. The adoption of SWAC is strategic for a sustainable development in the Caribbean, given that it could drive the adoption of other less-mature DOW technologies such as ocean thermal energy (OTEC). Thus, this study aims to understand the dynamics of SWAC adoption and to identify actions and policies that could accelerate SWAC deployment in the Caribbean. We developed a system dynamics model for SWAC adoption, based on the Bass diffusion model for new technologies. The model has three sub-models: DOW supply, demand for AC, and acceptance of SWAC. The integrated model constitutes a tool for testing scenarios and policy incentives. We simulated a business-as-usual (BAU) scenario and performed a sensitivity analysis to validate the model's behavior. With the validated model, we tested the effectiveness of different incentives to increase the installed capacity of DOW supply infrastructure and installed capacity of SWAC in buildings. Simulations show that, similar to other renewables, the adoption of SWAC follows an S-shaped path. Despite the high investment costs the profitability is not a limitation to adopt, since SWAC has a lower levelized cost of energy (LCOE) than traditional AC. A SWAC network provides AC to several buildings, thus the construction of the first system needs to guarantee a minimum AC demand (threshold capacity) to be economically feasible. We found that the main limitation to SWAC adoption is the low technology acceptance, necessary to reach such threshold capacity. Policymakers should design incentives to increase acceptance and reach the threshold capacity, instead of providing incentives to decrease costs, such as tax exceptions. The most effective action to reach 100% acceptance in the Caribbean before 2050 is subsidizing the construction of the first DOW extraction pipeline, and forcing all new buildings to connect to the SWAC district. 

Keywords: Caribbean; cooling district; deep ocean water; technology adoption; OTEC;