Energy securityCan Hydropower Survive in a Future of Extreme Weather?

By Jeannette Cwienk

Published 13 September 2021

Hydropower has long been seen as a reliable renewable energy source. But during drought and heavy rain, hydropower plants often come to a standstill. Will climate change spell the end for this clean energy alternative?

For many years, the thinking around the use of hydropower as a clean energy source has been that once built, a plant can reliably generate electricity at any time.  As recently as 2019, more than half the world’s renewable electricity was generated from hydropower.

But as the climate changes, so does the potential of this water-powered source of energy. This year, droughts made more frequent and severe by rising temperatures have caused the biggest drops in hydropower generation recorded for decades. 

Losses in Power Generation Worldwide
At Lake Mead, not far from the US metropolis of Las Vegas, the Colorado River feeds the Hoover Dam, which supplies water to more than 140 million people in America. But right now, the vast reservoir is just one-third full.  

Declining levels mean the dam’s power plant produced 25% less electricity this July than would usually be the case. They have also prompted the US federal government to announce water cuts to towns downstream of the dam starting in January 2022. 

In South America, it’s a similar situation. The Parana River, which flows through Brazil, Paraguay and Argentina, is experiencing extremely low levels of water. Southern Brazil, where the Parana rises, has been in the grip of severe drought for three years.  

According to local reports, levels in reservoirs in central and southern Brazil have dropped by more than half the average of the past 20 years, and are currently at just under a third of their capacity. As Brazil generates about 60% of its electricity from hydropower, continued low dam levels could lead to blackouts.  

A Return to Fossil Fuels
To prevent that from happening, Brazilian authorities have begun reactivating natural gas power plants, which is causing electricity prices, as well as greenhouse gas emissions, to rise.

A similar scenario is playing out back in the United States. In drought-ridden California, the state government has permitted industries and ships to use diesel generators for the electricity they cannot access from renewable sources. Natural gas power plants are also being permitted to burn more gas to generate electricity. 

But it’s not only drought that can cripple hydroelectric power generation. Heavy rain and flooding can also pose major problems. In March 2019, severe flooding following Cyclone Idai, which struck western Africa, damaged two major plants in Malawi, cutting off power to parts of the country for several days.  

Hydropower on the Way Out in Africa?
In several African countries, including the Democratic Republic of Congo, Ethiopia, Malawi and Mozambique, hydropower accounts for more than 80% of electricity generation, according to theInternational Energy Agency (IEA). Overall, hydropower accounted for about 17% of electricity in Africa at the end of 2019. That figure is forecast to rise to more than 23% by 2040. 

But according to the IEA, most new plans for hydropower plants in Africa do not adequately take into account the potential hazards of climate change, if they consider them at all.