The encasing of wind turbines in a duct to enhance performance is not new. A ducted wind turbine produces more power than an unducted wind turbine of the same parameters. A number of approaches in studying the effects of diffusers and other wind concentrating devices have been done and have resulted in a number of prototypes produced but without any commercialization. The aim of this paper is to investigate the failure of commercialization of ducted turbines. A technical and economic analysis of a ducted turbine is also presented. The work shows that traditional economic methods used to evaluate ducted wind turbines are erroneous; they do not account for external effects of power generation and individual and community benefits derived from this technology. Failure to penetrate the market is due to negative publicity as a result of the erroneous evaluation undertaken and lack of appropriate engineering techniques to protect ducted wind energy systems in extreme wind conditions. 1. Introduction The quest for sustainable and environmentally friendly methods of electric generation and the oil crisis experienced in late 1973 have fueled the shift to renewable energy sources. This has seen a tremendous growth in renewable energy technologies. Global power capacity from renewables increased by 75% between 2004 and 2008 [1]. The total power capacity from renewables as in 2008 was 280？GW and of this 121？GW is from wind power. Wind power has been the fastest growing renewable energy sector. This exponential growth in wind power is a result of its low cost which is relatively low when compared with other renewable energy sources [2]. South Africa’s energy intensive economy depends greatly on fossil fuels for energy generation and consumption with almost 90% coal based electricity generation and is ranked among the top 20 emitters of greenhouse gasses in the world and as the largest emitter in Africa [3]. However, South Africa is endowed with abundant renewable resources. Besides the vast solar resource characteristic, South Africa has more than a thousand kilometer long coastline with abundant wind resource potential. The wind speeds along the coastline are greater than or equal to 4？m/s at 10？m and 8,5？m/s at 50？m. The rest of the country is characterized by wind speeds between 3 and 4？m/s and further north wind speeds are as low as less than 3？m/s [4]. Most rural locations are situated in these low wind speed areas and in most cases have no access to national grid electricity. Supplies of other nonrenewable sources of energy are also either unavailable,
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