It’s basically emissions free and a cornerstone of today’s global renewable energy supply. But many hydro-electric plants destroy rivers and the communities that live in and around them. Are hydropower’s intrusive dams the price we have to pay for carbon neutrality? Paul Hockenos reports

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Renewable energy enthusiasts, of which I am one, tend to have little patience when it comes to “not in my back yard” (NIMBY) protesters who object to the likes of transmission lines and wind turbines obscuring their view.

It’s obvious to us that the clean-energy transition must have the highest priority. Otherwise, there will be no lovely landscapes and bountiful rivers left to appreciate. Climate change is already wreaking lethal havoc on the world of flora and fauna, just look at Australia’s wildfires.

So does that justify all forms of renewable energy?

No, all renewable energy sources are neither equal nor welcome. Just because an energy source is zero or low emissions doesn’t mean that it’s intrinsically good for the enviornment – take nuclear power, for instance, which many countries (rightly) deem much too dangerous and its waste an unsolvable environmental hazard.

Like nuclear power, hydro can be a potent means to generate voluminous green power, as it currently does around the world. Hydropower accounts for 16% of the world’s electricity generation. And pumped hydroelectric energy storage is a valuable means to store energy.

Yet hydropower stations can inflict quite severe environmental trauma on ecosystems as well as human communities – and exacerbate geopolitical tensions, too. In terms of the natural world, these impacts include the extinction of fish populations, a loss of aquatic habitats, the erosion of riverine and coastal land, and sinking groundwater levels. The worst sort of hydropower plants turn rivers upstream into fake lakes and downstream into drainage ditches.

The larger impoundment dams are the most pernicious offenders. While the gargantuan, mega dam projects in China and the Amazon are well-known, the most recent such vast, old-school hydro project is less familiar. Turkey’s Ilısu Plant on the Tigris River, which goes into full-scale operation this year, has displaced 80,000 and will drown the 10,000-year-old town of Hasenkeyf, one of the oldest sites of stationary human habitation, as well as many others.

The Ilisu dam on the Tigris River – which is part of a much broader hydropower expansion strategy across all of Turkey – will likely further fuel resentment downstream in Syria, Iraq, and Iran, which already suffer from ever lower levels of the storied river that they, too, like the Turks, live from. The last thing that this highly instable region needs is another factor roiling tensions.

Such massive dam projects are so intrusive and destructive that some states rule them out; in the EU, water access legislation is meant to effectively ban them. But globally ever more are being built and labeled as green energy.

In Europe, small and medium-sized hydropower plants are being constructed at rapid-fire pace. In western Europe, even though most rivers are already dammed to the hilt, another 8,700 are planned or under construction, according to estimates from the World Wide Fund for Nature. It reported 21,387 existing plants.

The plans have conservationist groups up in arms. Many of these new projects will be in the Balkans and threaten some of Europe’s last free-flowing rivers, such as Albania’s Vjosë and Aoös Rivers, which flows from northern Greece through southwestern Albania into the Adriatic Sea. Many of the power stations are so small that they produce negligible amounts of energy – but nevertheless defile the rivers.

What’s so heart-rending and irrational about the plans is they’re not necessary. Indeed, today other, better renewable energy sources exist, such as solar and wind power, as well as bioenergy and geothermal. Studies show that in places such as Turkey and the Balkans, these other, less intrusive renewables could flourish and produce enough electricity to meet all of domestic demand – and probably enough surplus to export.

The hydropower plants already in place and generating a decent minimum of electricity should be left where they are or replaced with less invasive hydropower technologies — as there is significant difference between hydropower technologies. In low-lying regions, for instance, “run-of-the-river” plants, which use partial or no damming, tend to have the least negative impact on their environment.

“A well-designed and well-managed hydropower plant that fits into the local ecosystem and is operated with an eye on fish and other wildlife, can make a great contribution to the energy transformation with relatively small impact,” says R. Andreas Kraemer of Ecologic Institute, a Berlin think tank.

According to a recent study by Institute for Sustainable Futures of the University of Technology Sydney, the global community can hit the Paris summit’s global 1.5C scenario through an aggressive buildout of renewable energy, among other measures. This, though, must include a minimal amount of new hydropower, as well as the refurbishment of all existing hydro plants. The report rules out the construction of more large dams such as those in Brazil, China, and Turkey, which among other negatives often wipe out vast areas of forest area.

“We factored in the refurbishment of all currently productive hydro power plants, which can increase generation capacity by 5% to up to 15%,” the Sydney Institue’s research director Sven Teske told Energy Transition.

Teske says that the world community needs to use about 10% of the total hydropower potential available to achieve the 1.5C scenario. It need not be more.

Hydropower can be destructive and lethal in its worst form. Yet when sustainibility is the measure, not profit, and other renewables are employed when at all possible, low-impact hydro can be the last-option alternative.

Perhaps there’s a compromise with the conservation groups, who call for tighter regulations on hydropower in Europe and the decommissioning of old, obsolete plants, which generate very little power. For every new, modern dam built, one of the low-productivty out-of-date plants be removed – at the cost of the hydropower industry – and a free-flowing river restored to life.