Hydropower against weather extremes
Reliable, cheap and low carbon — since coming into use over a hundred years ago, hydropower has become a vital clean energy source, today providing more electricity than all other renewables combined. But recent power shortages in Ecuador and Colombia have highlighted its vulnerability in the face of climate change.
A drought fueled by the El Nino weather phenomenon has reduced reservoir water levels in hydropower plants, which both countries rely on for most of their electricity. This has led Ecuador to declare a state of emergency and institute power cuts. In neighboring Colombia, water has been rationed in the capital and the country has halted electricity exports to Ecuador. Hydropower functions by harnessing the movement of water flowing through a turbine, which generates electricity as it spins. “Hydropower is dependent on water so clearly if there is no water at all then hydropower cannot be used, disrupting energy production and stressing energy systems,” said Matthew McCartney, expert on sustainable water infrastructure with the International Water Management Institute, based in Sri Lanka.
Droughts — and sudden floods which can also damage dams — made more frequent and severe by climate change, are therefore an “increasing concern” for hydropower, he added.
Hydropower plants are built to respond to changes in the weather — storing water in the rainy season to use when it becomes dry, explains Luz Adriana Cuartas, a hydrologist at the Brazilian Center for Monitoring and Early Warning of Natural Disaster.
But Colombia and Ecuador have seen surging temperatures and low rainfall last year, says Cuartas. “And this is why regulation [of hydropower] is becoming more challenging.” The problem in the region has been exacerbated by a simultaneous increased demand for energy and water as people turn on air conditioners and taps, she adds. Ecuador and Colombia are not isolated cases. While hydropower remains the world’s largest renewable source of electricity and had been increasing by 70% over the last two decades, in the first half of 2023 its global output saw a historic drop, according to Ember, a UK based energy think tank. Their findings say drought — likely exacerbated by climate change — drove an 8.5% drop in hydroelectricity around the world during this period. China, the world’s largest hydroelectricity generator, accounted for three quarters of the global decline. In 2022 and 2023 droughts led to Chinese rivers and reservoirs running dry, causing power shortages and forcing the country to ration electricity.
Just over a quarter of all hydropower dams are in regions that are projected to have medium to extreme risk for water scarcity in 2050, according to one 2022 study.
Countries with a high dependence on hydropower are particularly vulnerable to climate impacts, says Giacomo Falchetta, researcher at the International Institute for Applied Systems
Analysis. In Africa, where his research has focused, hydropower accounts for over 80% of electricity generation in the Democratic Republic of Congo, Ethiopia, Malawi, Mozambique, Uganda and Zambia — many of which are also struggling with severe droughts.
“On top of that [high dependence], they have limited installed capacity for alternative power generation and limited transmission infrastructure to import power,” said Falchetta. The solution for these countries is to diversify their power sources by incorporating other renewable technologies — such as wind and solar — into their energy mix, said Falchetta. He highlighted Ghana and Kenya as two countries that are successfully moving from high reliance on hydropower towards a more “robust portfolio of technologies”.