Hydropower Faces the Future Challenge of Extreme Weather?

Warnings Against Hydropower Expansion
Meanwhile, many hydropower plants already in operation around the world are facing another problem — aging. According to a United Nations University study, dams reach the end of their useful life 50 to 100 years after construction. The more these structures weather, the study notes, the more likely dam failure becomes.

From as early as 25-35 years into a dam’s lifetime, the measures needed to maintain it significantly increase the operating costs, the authors said.

With that in mind, it would be disastrous to invest in more hydropower plants while phasing out fossil fuels, says Thilo Papacek from CounterCurrent, a German NGO that campaigns for socially and environmentally responsible foreign involvement from German organizations abroad.

Hydropower plants don’t only interfere with the surrounding ecosystem, but because they prevent sediment from being carried downstream, they can also become hazards for people, Papacek told DW. 

“Without sediment accumulation on the riverbanks, the river burrows deeper and narrower into the landscape behind the dam. It can then develop tremendous force during heavy rains, especially if water also has to be released from the reservoir,” he said, adding that it increases the risk of flooding in nearby settlements. 

Mega-Dam Alternatives
“It’s true that we won’t be able to do without hydropower in the future,” said Klement Tockner, director general of the Senckenberg Society for Nature Research and a professor of ecosystem science at Goethe University in Frankfurt. 

“But the question is: Where do we build them, how do we build them and how do we operate hydropower plants in the future?”  

He believes they should not be built in existing protected areas where there are still sufficient free-flowing rivers and says that where appropriate, measures should be put in place to offset the negative impacts of hydropower plants on ecosystems — such as the restoration of impaired waterways and the removal of dams. New plants need to be built in such a way that rivers are still as permeable as possible — both to let fish and sediment to travel up and downstream, and to allow the flow of large volumes of water during floods. 

“That means the flow velocity must not be impacted too much, and the river must retain enough residual water as well as floodplains,” explained Stefan Uhlenbrook, a hydrologist at the International Water Management Institute (IWMI). “If necessary, sediment must be mechanically returned to the river channel,” he told DW.  

He says large plants are likely to become increasingly ineffective due to climate change, and that the focus should be on smaller plants and a decentralized supply.

Technology Alone Is Not Enough
There are alternatives to mega-dams. Instream turbines, for example, are suspended in the middle of the river and generate electricity from the velocity of the flowing water. These don’t require extensive construction work and can still operate when water levels dip. But while they are suitable for remote regions, they cannot supply metropolitan areas. 

Another example is the shaft hydropower plant, located at the Technical University of Munich (TUM), which was designed to accommodate for flood safety and longevity. A pilot plant in the southern German state of Bavaria supplies electricity to around 800 households.

But innovative technology alone won’t protect against severe and long-lasting droughts.

“We can mitigate the effects of droughts by using the land differently,” said ecosystem scientist Tockner. “Semi-natural forests and wetlands store a lot of water, which they then release during periods of drought — we have to look at how we can reduce both droughts and floods using nature-friendly measures.” 

But, he added, given the increase in extreme weather events, it’s clear that “hydropower will no longer be a reliable source of energy to the same extent.”  

For hydrologist Uhlenbrook, there’s another aspect in the energy debate that is often overlooked: “Above all, we must focus on saving as much energy as possible in the future.”

Jeannette Cwienk is a freelance writer.This article is published courtesy of Deutsche Welle (DW).