AEven with consideration for people and nature, immense amounts of additional electricity could be generated worldwide by hydropower. This is what researchers write in Journal “Nature Water”after calculating the potential of possible hydroelectric power plants for almost three million rivers.
In addition to the existing hydropower capacities, more than five petawatt hours of electricity could be produced per year. Roughly speaking, this corresponds to one fifth of global electricity generation in 2020. The majority of the capacities are located along the Himalayan mountains, writes the team led by Rongrong Xu from the Southern University of Science and Technology in Shenzhen, China.
In the fight against global warming, it is considered essential to convert power generation to renewable energies as quickly as possible. However, solar energy and wind energy have the fundamental problem that they are dependent on the weather. They can be supplemented by hydroelectric power plants, which can be run up as needed, regardless of the weather. According to the researchers led by Rongrong Xu, 16 percent of the electricity produced worldwide is already generated by hydropower. In some countries, the technology is considered a key element in moving away from fossil fuels.
However, hydroelectric power plants are quite controversial. They disturb the ecosystems of rivers, hinder fish in their migrations, people have to be resettled for reservoirs.
The Hengstey run-of-river power plant on the Hengsteysee in the Ruhr area
Source: picture alliance / blickwinkel/H. blousey
In some cases there are even diplomatic conflicts, for example over a huge dam in Ethiopia, which is said to be the largest in Africa after its completion in 2023. The dam is intended to dam the Blue Nile, protesting the two downstream countries Sudan and Egypt.
The scientists have now analyzed the possibility of additional hydroelectric power plants for 2.9 million rivers around the world. Among other things, they took into account data on the current, possible construction costs, local population and environmental factors. In order to keep negative effects as low as possible, the researchers excluded locations in protected zones, densely populated regions or areas at risk of earthquakes.
On this basis, they identified places where, in their opinion, hydroelectric power plants are not only possible, but also profitable and environmentally friendly. They come to the conclusion that globally, 5.27 petawatt hours of electricity could be produced per year. For comparison, global power generation was according to a Energy report of the mineral oil company BP in 2020 at almost 27 petawatt hours.
The authors of the study expect a lot from dam power plants in which river water is dammed up to form a lake with the help of a dam. The water can be drained from the lake at high pressure as required and drives a turbine.
The researchers’ analyzes showed that, at 85 percent, the vast majority of hydropower potential lies in Asia and Africa, especially in China. In Europe, on the other hand, there is very little room for improvement.
The illuminated dam wall of the Edertalsperre on the Hessian Edersee near Waldeck Castle
Source: picture alliance / imageBROKER/Andreas Vitting
The researchers emphasize that hydroelectric power plants produce extremely little CO₂. If all unused, profitable hydropower capacities were actually expanded, enormous amounts of CO₂ could be avoided compared to fossil fuels, an estimated 3.4 billion tons per year. That corresponds to around 8.2 percent of global man-made CO₂ emissions.
A total of 650,000 people would need to be relocated for all of the possible projects identified by the researchers. Rongrong Xu and his team emphasize that this is only about half as many as the 1.3 million who had to leave their homeland for the Chinese Three Gorges Dam on the Yangtze River. The power plant is the most powerful in the world.
The researchers point out that ongoing climate change could change the suitability of some areas for hydroelectric power plants – both for better and for worse. For example, depending on the region, there could be more or less rain, evaporation and glacial meltwater. “But these changes and their impact on the global potential of profitable hydropower are extremely difficult to measure.”
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