*2.3. Positive Signs of Harnessing Wind Energy*

Wind turbines mounted on buildings appear to be feasible for reducing carbon emissions by contributing significantly to energy requirements in buildings. The aggregate electricity generated from these wind turbines range from 1.7 to 5.0 TWh per year and reduce carbon emissions by from 0.75 million to 2.5 million tons per year [21]. An energy company, Royal Dutch Shell, and an operator of oil tankers, Maersk, are also attempting to use wind power to cut tankers' fuel bills. They try to install the oil tanker with two 'rotor sails' to propel the vessel, which is one of other ideas of supplying energy to the oil tanker such as solar-powered sails and kites [22].
