The standard air density of 1.225？kg？m？3 is often used in determining the energy output of a wind turbine although the energy output is dependent on a site's air density. By using measurements of temperature, dew-point temperature, and pressure, we calculate the monthly air density of moist tropical climates at two sites in the small-island state of Trinidad and Tobago. In addition, we calculate the energy output of a BOREAS 30？kW small wind turbine using the 10？m level wind speed distribution extrapolated to hub height. The average air densities at Crown Point and Piarco were 1.156？kg？m？3 and 1.159？kg？m？3, respectively, and monthly air densities at both sites were at most 6% less than standard air density. The difference in energy output of the BOREAS 30？kW calculated using standard air density over that using the local site's air density could provide electrical energy for the continuous monthly operation of 6 light bulbs rated at 50？W at Crown Point and 4 light bulbs at Piarco. Thus, communities interested in implementing wind turbine technologies must use the local air density of the site when sizing a wind turbine system for its needs. 1. Introduction The Fourth Assessment Report of the Intergovernmental Panel on Climate Change has recognized that small-island states are vulnerable to the effects of climate change, sea level rise, and extreme events [1]. Adverse stresses to coral and marine ecosystems, destruction of forested areas due to increases in cyclones or storms, reduced water supply and its impact on agriculture, reduced tourism due to coastal erosion, flooding, and increases in the incidence of vector-borne diseases have been projected with high confidence. Trinidad and Tobago, a twin small-island state located northeast of Venezuela in the Caribbean Sea, like other Caribbean islands, faces not only these potential climatic change impacts but also issues of energy security. Unlike most small-island states, Trinidad and Tobago is a net exporter of oil and gas. However, the increasing electricity demand [2] and carbon dioxide emissions [3], coupled with the 10-year lifetime of gas reserves [4], indicate a need to diversify the energy mix to include renewable energy (RE) sources for long-term sustainability [2, 3]. At present, wind energy is the most suitable source of renewable energy for bulk electricity generation in Trinidad and Tobago [2] and has the potential to reduce greenhouse gas emissions substantially [5]. In the 2010 budget allocations of the Republic of Trinidad and Tobago, tax incentives and programs were offered to assist in
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