Hydropower is the paradox of renewable energy. Hydroelectric plants offer a relatively cost-effective source of fossil fuel-free electricity, but they can increase flood risk, obstruct fish migration, disrupt river ecosystems, and displace people.
But it does not have to be this way. An international team of researchers looked at data from about three million rivers across the world to figure out where hydroelectric dams could be sited with minimal environmental impact.
Their analysis, published in the new journal Nature Water, shows that 124,761 potential locations meet the strict environmental requirements. Over 4,600 of these hydroelectric dams could generate an additional 5.27 Petawatt-hours of energy per year, which is a fifth of the world’s present electricity use, while being profitable
Two-thirds of global unused hydropower potential that the researchers calculated is distributed across the Himalayas. And Africa’s unused profitable and environmentally sound hydropower resource is four times larger than what the continent has developed so far. This study could help countries better plan their hydroelectricity strategies while considering environmental and societal impact.
In 2020, hydroelectricity produced about 17 percent of the world’s power. It is the third-largest source of electricity, after coal and natural gas, and the single largest source of renewable electricity. It has fallen out of favor recently because of its environmental damage, prompting removal in America and much of Europe.
But hydropower is expected to play a key role as developing nations transition to decarbonized energy systems. Hundreds of dams are being built or planned in many parts of the world. Planning this development so it minimizes environmental and society impact will be essential.
Last year, scientists used AI to analyze how to build dams on the Amazon river that maximize power generation and minimize environmental damage. But reports on global estimates unused profitable hydropower potential with strict environmental constraints have been rare, researchers write in the new paper.
“Hydropower can bring major benefits reducing the demand on coal or gas fired plants which are contributing to climate change,” said Joseph Holden, a professor of geography at the University of Leeds and a co-author on the paper, in a press release. “With careful planning and development, hydropower can make an important contribution to electricity generation. This major piece of work identifies where those sites are in the world.”
Holden and colleagues started with a reconstruction of naturalized river flows in 2.89 million rivers around the world to calculate where hydropower plants could be built. They considered the two main hydropower systems: a dam that creates a reservoir from where water is channeled through a turbine to generate electricity; and diversion, where a river’s waterflow is rerouted to run a generating plant further downstream.
The researchers set strict criteria to limit environmental and social impacts. They excluded dam development in heritage areas, biodiversity hotspots, forests, peatlands, earthquake-prone zones, densely populated areas, and locations with existing dams and reservoirs. They also required that a new hydropower station not block the environmental flow needed to support river ecosystem health and water availability downstream, especially in dry seasons.
Small hydropower plants that divert tributary streams would be appropriate in the Himalayas and the Andes because the steep slopes there provide enough fall heights to generate electricity efficiently, the researchers say.
Asia and Africa together had about 85 percent of the world’s unused hydroelectric potential, the study found. These locations were mostly in China, Myanmar, India, Pakistan and Nepal in Asia; and in the Democratic Republic of the Congo, Ethiopia and Zambia in Africa. “Most African countries could potentially fully meet their current electricity demand if they were to develop their unused profitable potential, which would significantly improve Africa’s infrastructure and energy situation,” the team writes in the paper.
Source: Xu, R., Zeng, Z., Pan, M. et al. A global-scale framework for hydropower development incorporating strict environmental constraints. Nat Water, 2023.