Publish Date:

February 27, 2022

Hydroelectric and clean energy

Hydroelectric produces ¾ of the world’s renewable energy. As we’ve entered the 21st century and the need for renewable energy grows as we realize the limits of fossil fuels, hydro will take center stage once again. On a larger scale, hydropower generates 16% of the world’s total electricity. This number could be tripled if all available river and lake resources were harnessed, resulting in an annual output of approximately 15,000 TWh.

Growing concerns about fossil fuels—especially their potential contributions to pollution and global warming—have individuals and governments around the globe looking for alternative sources of power.

For the last 150 years, hydroelectric dams have been built on all five continents, creating large lakes, regulating floods and harnessing the power of rivers to generate electricity. Along the way, we’ve discovered several serious drawbacks to this form of energy. One of them is their environmental impact.

Damless hydro is an interesting development in which only a portion of a river is diverged and then sped into a naturally-occurring vortex that spins a turbine, with the outflow channel reconnecting to the river. This allows fish to swim up- and downstream at ease, since its not a dam it does not create lakes and thereby the surrounding natural environment remains intact.

Another issue is the upfront cost. Furthermore, researchers at the University of Oxford found that prices of large dam projects ran 57% over their initial estimate on average. This makes hydro prohibitively expensive for many poorer countries and cash-strapped communities. New technologies are making the process more affordable. Modular hydro plants can be constructed off-site at cheaper costs and then simply transported to the project site for easy construction.

Another economic option is to power up the many non-powered dams already in existence. In the United States (US) alone, powering up the country’s 100 largest non-powered dams would bring in an estimated 45 TWh of electric energy annually.

Hydroelectricity is an industry that is especially vulnerable to changes in global temperatures. We are living in a climate change reality where extreme weather events are becoming more common, rainfall precipitation fluctuates wildly between years and water is becoming increasingly more scarce in some regions.

Hydropower has a unique double relationship with climate change; on one hand, it is a very clean source of energy that helps reduce emissions of CO2 and other harmful substances, on the other hand, it can cause havoc on natural environments.


Right now, in the United States, hydroelectric power is the largest source of renewable energy and responsible for around 7 percent of all national energy production. 

Hydropower is also a popular source of renewable energy internationally, especially in China, which is one of the world’s largest producers of hydroelectric energy. There, dams—including the Three Gorges Dam, the largest power station in the world by installed capacity—produce more than 15 percent of the nation’s total energy.

The annual growth of hydroelectric power has slowed over the past few years. Governments have either reconsidered fossil fuels or looked to other renewable energy sources—like wind and solar—that have less of an impact on the environment than dams.

Hydroelectric power generation will likely continue to grow significantly in the near future; however, it may soon be eclipsed by other renewable energy sources that are experiencing much faster rates of growth.


There are challenges that may discourage the further development of hydroelectric power. Ecological and social concerns have slowed or prevented the construction of new dams. By limiting water supply and creating large reservoirs, hydroelectric dams are naturally disruptive to communities and ecosystems upstream. In the Columbia River basin, dams have blocked over 55 percent of the spawning and rearing habitat previously available to steelhead and salmon.

One possible solution to these problems is damless hydropower plants, sometimes called run-of-the-river plants, which generate power using the natural flow rate of water rather than needing water to fall a large distance. Because they don’t create a reservoir or redirect flow when constructed, these plants typically cause less environmental disruption than dams. 

At the moment, these damless plants can’t produce nearly as much electricity as a dammed plant. Their energy production may also be less predictable, due to seasonal and year-to-year variation in the speed of river flow.

At the same time, new weather patterns caused by climate change have the potential to make hydropower too unreliable to be worth using. In some areas, shifts in rainfall patterns and chronic droughts are already causing river flow shrinkage and draining lakes, resulting in significantly reduced output from all hydroelectric power facilities.


Hydropower is increasingly seen as a potential renewable replacement for greenhouse gas–producing fossil fuels. 

However, there are a few difficulties that may prevent the power source’s widespread adoption. Hydroelectric dams can be disruptive to both communities and ecosystems, and their energy output may become less consistent as the weather grows more extreme in the coming years. These are obstacles that must be overcome before widespread use becomes more prevalent

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