Environment: Assessing the world’s unused hydropower potential

Africa and Asia account for 85% of the world’s unused profitable hydropower, according to a global assessment published in Nature Water. The findings may help countries formulate hydropower development strategies that consider environmental and social impacts.

Hydropower is a relatively cost-effective energy source, expected to play a key role in the transition of some nations to decarbonized energy systems. However, the development of hydropower is controversial because of its environmental and societal implications. Hydropower plants can disrupt river ecosystems, exacerbate flood risk, degrade land during construction, and displace people.

Zhenzhong Zeng and colleagues analysed the global unused hydropower potential of 2.89 million rivers worldwide. The authors synthesized river flow data, reservoir data, demographic and environmental variables, and cost considerations, to determine locations where new hydropower plants could be established. Their analysis excludes sensitive locations, for example in heritage areas, biodiversity hotspots, earthquake-prone zones, and densely populated regions, and considers how hydropower stations can maintain downstream river ecosystem integrity. The authors indicate that the global unused profitable hydropower potential is 5.27 petawatt hours (about 5.27 trillion kilowatt-hours) per year, and that Asia and Africa account for 85% of this total. They suggest that most unused hydropower potential exists in Asia, with two-thirds of the global total located in the Himalayas. Africa’s unused hydropower potential ranks second and the authors propose that most African countries, including the Democratic Republic of Congo, Ethiopia, Mauritania, Zambia, and Namibia, would be able to meet their current electricity demand if their unused profitable potential was developed.

The authors suggest their analysis offers a path to sustainably develop global hydropower, enabling hydropower to play a larger role in future energy resources while reducing negative impacts on the environment and societies.