How we can save hydropower

The way we’ve historically generated energy from water is not good for the environment. Here’s how that’s changing.

The take-away

  • Dams disrupt the ecosystems within and around rivers, reduce biodiversity and mess with water quality
  • Solutions to make them more sustainable include using fish-friendly turbines or lowering their height. In some places, turbines are even put directly into rivers, streams and the ocean.

Hydropower is the world’s third largest source of electricity and provides around 70% of the world’s renewable energy. However, dams – the traditional way we’ve harvested energy from water – are not as sustainable as you might think, disrupting the ecosystems within and around rivers, reducing biodiversity, and messing with water quality. Now, researchers are trying to find a way to make hydropower more environmentally friendly.

“It’s only recently that people have started to realize that these dams fill up with sediment, that they are structurally unsound, some of them, and that something needs to be done with them,” says Carlos Garcia de Leaniz of Swansea University in Wales.

But the world needs energy, and compared to other forms of renewable energy, hydropower is both flexible and predictable. Dams can store surplus energy generated when the sun is shining and the wind is blowing, and, unlike solar and wind, hydropower is fairly consistent. “There is no surprise tomorrow what amount of water will be in the Rhone or in the Rhine rivers,” says Anton Schleiss, who until the end of 2018 was president of the International Commission on Large Dams.

That’s why, despite their downsides, for the past 20 years large dams have still been built across the world at a steady rate. According to Schleiss there are around 320 to 350 of them higher than 60m under construction at any one time. While some countries in Europe may be running out of places to build very large dams, others, such as those in the Balkans, are still building.

Roselend Dam, France

Huge dams can disrupt the ecosystems within and around rivers, reduce biodiversity and mess with water quality.

Fish-friendly dams

Though large dams can be tracked, there are currently no reliable estimates of smaller ones across rivers in Europe, says Garcia de Leaniz. He is co-ordinator of the Amber project which, with the help of citizen scientists who upload photos, intends to map river barriers across the continent. Once Amber has been able to identify priorities, dams that are no longer in use can be dismantled to restore the waterway to its previous state, and those that remain useful can be rehabilitated to provide hydropower in a more sustainable way.

That’s where the second part of the Amber project comes in. The plan is to use “adaptive management” to maximise the benefits of a dam, while paying attention to and minimising environmental impacts over time. This can be done, for example, by using turbines that are more efficient or fish friendly, or by lowering the height of dams. Electricity production can even be stopped at crucial times to help fish pass upstream.

When it comes to making hydropower fish-friendly, another European project FITHydro, co-ordinated by the Technical University of Munich, is also looking into which of these techniques work best in different scenarios. As well as helping fish, the wider local ecosystem can be taken into account when designing dams. “They can be built in a way that, for example, flat wetlands can be restored as a compensation measure, and in many projects this already done,” says Schleiss.

Garcia de Leaniz points to the Poutès Dam on the River Allier in France as a success story. The dam has been responsible for a dramatic decline in the local wild salmon population. But in recent years a compromise has been struck between energy company EDF, environmentalists, scientists and local government, which will see the height of the dam lowered and the size of its reservoir reduced. These and other adaptations should allow fish to begin to flourish again, and still allow the energy company to generate electricity. “I think it’s very important to realise that we need to strike those compromises in the future because we really still need dams,” he says.

Going with the flow

For those hoping to eschew dams altogether, there is another way to generate hydropower. Companies like Smart Hydro Power in Germany are pioneering new technologies to put turbines in rivers and streams in order to generate electricity without disrupting the flow of water. Similarly to turbines inside dams, kinetic energy from the water is converted into kinetic energy in the turbine, which drives a generator to make electricity. “We are just tapping this opportunity,” says Karl Kolmsee, CEO of the company.

Others hope turbines in the ocean harvesting tidal energy can contribute a significant amount of renewable energy in the future. EnFAIT, a European project led by Nova Innovation in Scotland, is hoping to show that tidal energy can be an “abundant, economically viable and predictable source of power”, says John Meagher, director of business development at Nova Innovation.

Theoretically, these less-invasive methods provide hydropower without the environmental repercussions of dams – although some have argued that they can still disrupt fragile ecosystems and should not be considered a “green panacea”.

Either way, these new technologies won’t be able to entirely wean us off dams any time soon. With hydropower such an important energy source worldwide, and the EU requirement that its member states get 20% of their electricity from renewable sources, dams, in one form or another, are here to stay.

But that doesn’t mean we can’t look after the environment, too, says Garcia de Leaniz: “It’s very important that the criteria that are used for building dams in the 21st century is not the criteria that was used for building dams a hundred years ago.”

PNAS, Carlos Garcia de Leaniz (Chair Aquatic Biosciences, Swansea University), Anton Schleiss (Professor Emeritus, Laboratory of Hydraulic Constructions, EPFL), AMBER, FITHydro, Smart Hydro Power, EnFAIT, New Scientist