This Dam Simple Trick is a great green energy gain

Some countries are already making use of this potential. Since 2000, 36 dams in the United States have been retrofitted with turbines, which has added more than 500 megawatts of renewable production capacity. There is even more potential out there: A 2016 report from the U.S. Department of Energy showed that an additional 4.8 gigawatts of electricity could be generated by retrofitting non-powered dams over the next three decades. In places like the United States and Western Europe, where dam construction in the mid-20th century has long since faded, retrofitting may be the only option left for governments looking to extract a little more hydropower. “If there are dams that will remain in place, let’s try to find solutions and work together for the most optimal solution,” says McManamay.

But before anyone starts upgrading all these dams, they might want to take another look at the numbers. It is not easy to predict exactly how much electricity a retrofitted plant will actually produce because it turns out that not all dams are well suited for conversion. Let’s say someone wants to mount turbines in a dam that was built to hold back the water so it can be used to irrigate farmers ’fields. During the growing season, much of that water will usually be directed toward crops instead of flowing over the dam to generate electricity. Or maybe it’s in an area where the water is only high enough to produce electricity part of the year. Suddenly, the retrofitted dams may not seem like such a smart idea.

A recent study of retrofitted dams in the United States, also commissioned by the Department of Energy, found that projections of their power emissions fluctuated toward the optimistic side: on average, these projections were 3.6 times greater than actual production. The study showed that the most successful retrofits tended to be concrete dams originally built to aid navigation. (Dams are often used to widen or deepen waterways to make it easier for boats to pass through.) “This is a complex issue. It is not an easy solution,” says McManamay.

But in countries like Brazil, large dams are still very much on the agenda. “If they are to develop and really raise the standard of living in the country as a whole, they need energy. That’s the long and short of it, ”says Michael Goulding, a senior aquatic researcher at the Wildlife Conservation Society. The country’s latest 10-year energy plan outlines nine new large dams planned to be completed by 2029. Instead of hoping that these dams are not built, it is important to ensure that proper studies are carried out to ensure that they are built in a way that minimizes damage to the environment, says Goulding: “Often the framework for environmental impact is not very good. They will define an area of ​​interest close to the dam, and that area of ​​interest does not include all downstream impacts and upstream impacts as well. “

The Belo Monte dam is a good example of how big an effect large dams have on the surrounding environment. The dam complex diverted 80 percent of Xingus’ flow away from a 62-mile stretch of river known as Big Bend. This part of Xingu also happens to be the only known wild habitat for the Zebra Pleco – an eye-catching striped cat loved by aquarists. “There’s a huge risk that this species will become extinct,” says Thiago BA Couto, a postdoc researcher at Florida International University’s Tropical Rivers Lab. The impact of dams on fish species is well documented elsewhere in the world. In the state of Washington, the Elwha Dam severed the upper and lower Elwha watersheds, reducing the habitat for salmon by 90 percent. Some species locally by the river disappeared completely, while others’ populations – such as the Chinook – dropped to a fraction of their previous levels.

Eventually, however, even large dams can survive their usefulness. In 2014, the last remnants of the Elwha Dam were removed forever. The Chinook salmon, which for decades had been locked behind two dams, is now slowly making its way back upstream. A full recovery is expected to take decades. “Dams don’t last forever,” Couto says. “There are many who are abundant but who do not provide the minimum benefits they should.”


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