The theoretical potential of hydroelectric power, setting aside all other considerations than what can hypothetically be produced from all sources on the planet, is estimated to be about 2,800 gigawatts. However, a lot of that potential must remain undeveloped due to environmental and economic concerns. Hydroelectric power is a renewable energy source and contributes no greenhouse gases or other pollutants. All of its environmental impact is local rather than global and results from the effect on wildlife and local ecosystems from damming rivers. That impact is nonetheless considerable, and substantial environmental opposition sometimes arises to large-scale hydroelectric projects which can drown wildlife habitats and severely impact migratory fish populations. The Union of Concerned Scientists details the environmental drawbacks of hydroelectric power, as well as those of other forms of renewable energy, in this article. Overall, hydroelectric power currently accounts for 21% of global energy production.
The largest actual and potential producer of hydroelectric power is China. The country’s installed hydropower capacity exceeds 100 GW. China’s hydroelectric potential is estimated to be more than 400 GW. It’s expected that China will continue to aggressively develop this potential energy source as it has done in the past, given the rapidly increasing demand for energy in the country as industrialization proceeds.
Canada is the second-largest producer of hydroelectric power and still has substantial potential to develop more. Brazil is the largest potential hydroelectric producer in the Western Hemisphere. In the United States, most potential large-scale hydroelectric production has already been developed and some may have to be reduced due to environmental concerns. However, there is still some potential in the United States for small-scale hydroelectric power.
Most of the world’s remaining hydroelectric potential is found in developing countries. This is only logical, as the technology to produce energy from water flow is not new, and the advanced world has tapped a great deal of its potential hydroelectric power already. Besides Brazil and China, substantial development is in progress in India, Russia, and parts of Europe, as well as Southeast Asia and other well-watered areas of the developing world.
One reason why hydroelectric power is likely to play such a large role in the transition to renewable energy that the world must undertake is that it is relatively cheap. At less than 5 cents per kilowatt-hour (including construction, operation, and maintenance costs), hydroelectric power is cheaper than either wind or solar power, and also cheaper than non-renewable energy from nuclear, coal, and natural gas. It’s likely for this reason that a developing country will prefer to meet its energy needs from hydroelectric power as much as it can, and use other sources of energy to meet demand that hydroelectric capacity cannot supply.