Dam and blast: big hydro infrastructure needs a major rethink

Researchers call for big changes to hydropower and dam design to meet the challenges of climate change and social disruption. Nick Carne reports.

Large dams such as this one on the Jinsha River, a tributary of the Yangtze River in Yunnan Province, China, may not be able to cope with warming temperatures.

Large dams such as this one on the Jinsha River, a tributary of the Yangtze River in Yunnan Province, China, may not be able to cope with warming temperatures.

shan.shihan/Getty Images

Hydropower needs to be significantly rethought if it is to provide benefits rather than becoming even more of an environmental and social burden, according to a new US report.

In short, says a team of geographers, engineers and environmental scientists from Michigan State University, big dams just aren’t sustainable any more – at least not on their own.

Planners and policy-makers must start incorporating climate change into considerations of whether to build them, say the researchers, while recognising “the unsustainability of current common practices”.

Hydropower still provides around 70% of the world’s renewable power, but is increasingly less important in developed countries, some of which are dismantling many more dams than they are building. A total of 3450 have been decommissioned in Sweden, Spain, Portugal, the UK, Switzerland and France, for example.

In contrast, many new large dams being built and planned in developing countries, particularly in the basins of the Amazon, Congo and Mekong rivers.

The problem is that “socioeconomic and environmental damages in these river systems are even greater than the early costs in North America and Europe,” Emilio Moran and his colleagues write in a paper published in the journal Proceedings of the National Academy of Sciences.

The issues include disrupting river ecology, deforestation, losing aquatic and terrestrial biodiversity, displacing thousands of people or altering their livelihoods, and affecting the food systems, water quality and agriculture near them.

There are problems in developed countries, too. Reduced water volume associated with climate change means many dams are unlikely to produce the energy for which they were designed, yet they contribute to climate change by releasing greenhouse gases from decomposition of flooded forests.

Others are just worn out. “Dam removal rather than construction has become the norm in North America and Europe, because many that were built before 1950 are at the end of their useful lives, they would be too costly to repair, many no longer serve their initial purpose, and their social and environmental negative externalities became unacceptable,” the researchers write.

There are exceptions. Hydropower remains an important part of the energy mix in countries with favourable topography and rain patterns, such as France and Switzerland, “through technological innovations at existing dams”.

That last caveat is important.

The authors report the development of in-stream turbine technology that protects fish, and prioritises energy delivery to local communities and which, they say, could be an integral part of a large sustainable energy generation portfolio when combined with solar, wind, and biomass energy production.

“The most important advantage of hydropower in contrast to other renewable energy sources, like wind and solar, is that it can be dispatched quickly at any time, enabling utilities to balance load variations on the electric distribution system,” they write.

“As we move forward in the 21st century, electric companies need to diversify their energy projects even more than they have. The cost of solar and wind is dropping, efficiencies are up, and increasingly, they are price competitive for the energy produced.

“Hydropower can be part of a sustainable future if it moves away from big dams and toward a combination of instream turbines and diversified energy sources in ways that do not disrupt stream ecology and fisheries and the lives of people on the great rivers of the world.”

The researchers note, however, that we will still need to consider the “governance and compensation challenges”.

  1. http://www.pnas.org/cgi/doi/10.1073/pnas.1809426115
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