A 632 km (412 miles) long reservoir was found on the Yangtze River, also called the Three Gorges Dam, because it floods three upstream gorges. Its main reason for installation was to provide hydroelectric power.
To begin with, the advantages of the TDG are numerous. It yields 18 GW of electric power which is the equivalent of a large coal or 18 nuclear power plants. Further, downstream floods are prevented, leading to a boost in agricultural productivity. Moreover, the movement of large ships upstream is enabled, on the one hand, while recreation and commercial fishing is possible, on the other hand. However, the negative ramifications of dam building cannot be belittled. The already extinct dolphin species of the Yangtze River are endangered; at least 1.5 million citizens face displacement, sometimes with little or no compensation; this is in addition to the submergence of canyon wall writings and historical and cultural treasures, and pollution of the river by industrial wastes and contaminated sites during flooding. Even though agricultural productivity has improved downstream, arable land in the upstream region has been submerged, thus, affecting agriculture. More disadvantages are seen into the growing number of waterborne diseases, like schistosomiasis and malaria. The setting up of the dam has not been an easy feat, as getting investors has been mired by lack of clarification on design, construction and effectiveness. Sedimentation of the dam has also proved to be an impediment to reasons for its installation, like irrigation and hydropower.
In order to protect natural resources, animals and plants, the conservationists propose that the government should invest in renewable energy sources (green technology) as the sustainable solution to the energy problem. Such technology includes the solar energy and other indirect solar energy sources like wind, ocean waves and temperature gradients in the deep sea. It is speculated that in the future it may be possible to produce power as a result of ocean temperature gradients. Ocean thermal energy conversion (OTEC) is the technology that will take advantage of the temperature gradient in the deep seas and oceans to cool buildings and produce electricity. A case in point is the ongoing construction of the OTEC plant at Natural Energy Laboratory of Hawaii Authority on the Hawaii islands.