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Hydropower: Truly Clean?

Updated: Nov 26, 2022

By: Hung-Yeh Lee

Image Courtesy of Unsplash


Hydropower is one of the biggest renewable energies produced world wide. It is the largest renewable source of energy in the world as it accounts for 16% of electricity produced globally in 2019; for comparison around 5% of electricity produced globally came from wind power. In the United States it is the second largest renewable source of energy which accounts for 6.3 % of the total U.S electricity. As climate change becomes an increasingly urgent topic for officials to address, there have been discussions and actions to increase U.S hydropower generation capacity. The Department of Energy proposed that the U.S has the potential to increase its hydropower power production through upgrading old dams and plants and adding hydropower function to them. This proposal gained support in last year’s infrastructure law where $2.3 billion in dam funding and a portion of that funding would go towards adding hydropower to nonpowered dams. Despite the potential for the development of hydropower, there are problems that need to be addressed.


Hydropower, despite its seemingly green and renewable nature, can be harmful towards the environment and specifically climate change. Recent studies have shown that reservoirs created by dams emit considerable amounts of carbon dioxide and methane into the atmosphere, and hydropower facilities could make it worse. Methane in particular is more dangerous in causing global warming as it is 80 times more potent than carbon dioxide in the first 20 years of its release. Methane comes from decomposing vegetation and other organic matter, and when the area is flooded as the result of forming a reservoir methane from these organic matter will be released into the atmosphere. Thus it is important to measure and monitor the amount of greenhouse gasses when planning to expand the hydropower capacity to new and old dams.


There are several options to reduce the amount of greenhouse gasses released from the reservoir. First, installing an aerating device inside the reservoir could help increase the oxygen in the water. Oxygen is needed to dissolve methane into carbon dioxide, but as global warming causes temperature to rise up, it causes the depletion of oxygen in the reservoir. An aerating device to help pump the oxygen into the reservoir so methane can be dissolved into carbon dioxide and in turn reduce the lethality of the emitted greenhouse gasses.


Second, a thorough analysis of the reservoir’s impact on nearby environments and potential greenhouse gas emissions would help determine if the dam project is greenhouse gas cost effective. Despite its complexity, it is possible to estimate the increase of greenhouse gasses should the hydropower plant be built. Thus it is important to do thorough research prior to the construction so the impact on environment and greenhouse emission would not outweigh the benefit of hydropower.


Lastly, it is possible to recover the methane produced by the reservoir and use it as an alternative energy option. A study in the past has shown that it is possible to recapture the methane release from the reservoir and use it as an energy source. The methane can be stored up and burned by gas turbines to generate electricity or purified so it could be used in transport applications. This is an interesting way to capture and change the methane into a new form of renewable energy as well as lowering the greenhouse gas emissions from the reservoir.


As hydropower becomes an essential part of the equation in combating climate change, it is important to mitigate the impact of the reservoir's greenhouse gas emission released into the atmosphere. Without careful planning hydropower cannot achieve its full potential in reducing the overall carbon footprint produced by humankind. But when everything is done correctly and carefully, hydropower will be a crucial weapon in our fight against climate change.

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