Although the process seems fairly simple for generating electricity, one of the bigger challenges will be developing a solid method for pumping large amounts of cold water up from about 1,000m below sea level2. This is one of the main problems that many research facilities dedicated to the development of OTEC are researching such as the OERC. Another disadvantage that OTEC carries s that it is less competitive against non-sustainable energies in terms of cost per-kilowatt hour. OTEC sits currently at about 20 cents per kWhr where as coal sits at about 3 cents per kWhr2.
Another obstacle that OTEC faces is that although it is very efficient in certain places, it primarily relies on areas where the temperature difference is at about 36°F year round such as along the equator. This limits the areas where it is useful.
Areas where OTEC is most reliable are in red1.