Intro Climate change poses one of humanity's greatest threats now and in the future. Changes in global weather patterns, sea level rises, and more intense storms threaten our safety and prosperity. These threats will continue to loom over us until we reduce or eliminate our need to burn fossil fuels. Countries and organizations around the world recognize the threat of climate change and have invested more and more in renewable energy sources to help ween ourselves off from fossil fuels. In March 2018, Portugal produced enough renewable energy to power the entire country. Then in April 2018, the UK went 44 hours without burning coal for the first time since the beginning of the Industrial Revolution (1760). In the same month, Apple Inc., the largest company in the world by market capitalization, announced that their company operations now run on 100% renewable energy. Unfortunately, Portugal, Apple, and the like are the exceptions. Better put on your shades. The future is bright. The majority of countries and companies still depend heavily on burning fossil fuels. Coal and natural gas stations generate most of our electricity, and nearly all our vehicles, airplanes, and ships run on oil. The latest advances in renewable technologies have yet to be distributed to most of the world, and the infrastructure to make full use of them are still limited to the most industrialized nations. Humanity has made massive strides to fight our addiction to fossil fuels, but the journey has just begun.

Hydropower Hydropower is the largest source of renewable energy in the world. Hydropower stations, the majority of which are dams, are among the largest electricity generating facilities in the world in terms of total capacity. In 2016, hydropower contributed to 54.3% of all renewable electricity generated. Hydropower is also the most commonly adopted form of renewable energy. More than 150 countries, including many less developed countries, use some form of hydropower. In contrast, adoption of other renewable energy sources like solar, wind, and geothermal is still limited to a few countries. Hoover Dam | Image by Andrew Parnell / CC BY Outlook Although hydropower is globally the largest source of renewable energy, it is not growing as fast as other renewable energy sources like solar and wind. In 2016, hydropower capacity grew by 25 GW for a total of 1,096 GW, an increase of just 2.33%. In comparison, solar power capacity grew by 75 GW for a total of 303 GW, an increase of 32.89%. Wind power capacity grew by 54 GW for a total of 487 GW, an increase of 12.47%. There are at least three reasons why hydropower will not be the main driver of renewable growth in the near future. One, hydropower is growing from a larger and more developed base. Compared to other sources of renewable energy, many of its low hanging fruits have already been picked. Nonetheless, it's estimated that only about 1/4 of the world's hydropower potential has been developed, so there is still room for further growth. Two, there is growing concern around the negative social and environmental impacts of developing hydropower. Large dams in particular can alter human and natural landscapes in a profound way. For example, the construction of the Three Gorges Dam, the largest dam in the world, displaced 1.3 million people, flooded archaelogical and cultural sites, and disrupted the habitats of endangered species like the Baiji Dolphin. Three, as the technology around solar power and wind power continues to improve, both solar power and wind power offers a cost competitive and more flexible solution for renewable energy. In addition, both solar power and wind power facilities have a smaller ecological impact than hydropower sources like dams. Despite these challenges, companies and governments around the world are still making investments to better harness the power of the world's water. In highly developed countries where opinions on large dams have soured, new hydropower facilities take on smaller forms like run-of-the-river hydroelectricity, which generate electricity without creating large reservoirs. Furthermore, the technology around dams have not stagnated and continue to improve so that existing dams can be upgraded to become more efficient. El Atazar Dam, Community of Madrid, Spain. | Image by Carlos Delgado / CC-BY-SA Largest Hydropower Station in the World The world's largest hydropower station is the Three Gorges Dam in Central China. The massive dam has a total electricity generating capacity of 22,500 MW, twenty times more than Hoover Dam. That means the Three Gorges Dam can generate enough electricity to power approximately 15,000,000 homes. The Three Gorges Dam also happens to be not only the largest hydrostation but also the largest power producing facility of any kind in the world. And it's not even close. The next largest power facility in the world is the Itaipu Dam, which only has a total capacity of 14,000 MW, around 50% less than the Three Gorges Dam. The Three Gorges Dam on the Yangtze River, China. | Image by Rehman / CC BY References The Three Gorges Dam Project Environmental Impacts

List of largest hydroelectric power stations

Three Gorges Dam

https://en.wikipedia.org/wiki/Renewable_energy#Hydropower

https://en.wikipedia.org/wiki/Renewable_energy#Hydroelectricity