Hydropower has been definitely the leading renewable energy source that supplies 71% of all renewable electricity globally [1]. The scale can be huge also–over 20,000 MW–especially compared to other renewable sources. However, as Lester Brown wrote in his 2015 book The Great Transition that “for most of the world, the era of large dam building is over [2],” the potentials of hydropower utilizing dams have almost reached the peak in most of the countries around the world, and many are demolishing the existing dams due to environmental impacts they caused. So, one might wonder about the future of hydroelectricity.
Currently, China stands at the front in hydropower utilization; it produces some 856.4 billion kWh per annum, which is double the amount produced by the world’s second hydropower giant, Brazil. Next comes Canada and the U.S., followed by Russia, Norway, India, Venezuela, Sweden and Japan [3]. In these countries, hydropower is considered a consistent and flexible renewable source that is capable of meeting base load requirements as wells as unexpected electricity demands [1].
Even though hydropower is a “clean” energy source that uses natural resources and does not contribute to greenhouse gases emissions, there are concerns about it because it often leads to other environmental impacts including destroyed wildlife habitats and ecosystems, flood risks, and water unavailability. Moreover, the massive upfront costs are often viewed as a roadblock.
Recently, a Belgium company named Turbulent Hydro introduced a new type of hydropower, so-called “Damless Hydro.” This run-of-river method can generate electricity without changing the course of river. This type of hydro power plants are in line with the more recent energy trends of decentralization of grids and connected devices. In 2017, the company created its first 15 kW hydropower turbine that could be installed into any flowing water with a small height difference [4].
Turbulent Hydro – Youtube video
Since the technology is in an early stage, it is not clear whether it can be an alternative to the conventional hydropower. It actually shares similar problems with solar and wind; it does not work with the demand, is sensitive to the location and does not always guarantee reliability. However, considering the current state of hydropower, it would be one important element in discussing the future of hydropower.
[1] World Energy Council, retrieved from https://www.worldenergy.org/data/resources/resource/hydropower/ [2] Lester R. Brown, 2015, The Great Transition. [3] World Economic Forum, retrieved from https://www.weforum.org/agenda/2015/10/which-countries-produce-the-most-hydroelectric-power/ [4] https://www.azocleantech.com/article.aspx?ArticleID=694
hoon's blog on energy and climate change 
Not only the environment, hydroelectric dams also affect the local communities that have been living near the river bed for generations. Their homes are lost in the process of constructing dams. That is why, construction of dams have faced stiff public resistance.
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