Click here to read the paper. Here’s the abstract:
Hydropower has been the leading source of renewable energy across the world, accounting for up to 71% of this supply as of 2016. This capacity was built up in North America and Europe between 1920 and 1970 when thousands of dams were built. Big dams stopped being built in developed nations, because the best sites for dams were already developed and environmental and social concerns made the costs unacceptable. Nowadays, more dams are being removed in North America and Europe than are being built. The hydropower industry moved to building dams in the developing world and since the 1970s, began to build even larger hydropower dams along the Mekong River Basin, the Amazon River Basin, and the Congo River Basin. The same problems are being repeated: disrupting river ecology, deforestation, losing aquatic and terrestrial biodiversity, releasing substantial greenhouse gases, displacing thousands of people, and altering people’s livelihoods plus affecting the food systems, water quality, and agriculture near them. This paper studies the proliferation of large dams in developing countries and the importance of incorporating climate change into considerations of whether to build a dam along with some of the governance and compensation challenges. We also examine the overestimation of benefits and underestimation of costs along with changes that are needed to address the legitimate social and environmental concerns of people living in areas where dams are planned. Finally, we propose innovative solutions that can move hydropower toward sustainable practices together with solar, wind, and other renewable sources.
We need innovative sustainable solutions to meet energy demands, guarantee food security, and ensure water availability around the globe. Over the years, dams have been used for land management and flood control; to store water for irrigation and agriculture; to provide recreation and navigation, and to address management of aquatic resources. There are over 82,000 large dams in the United States alone. In addition, over 2 million small low-head dams fragment US rivers, and their cumulative impacts are largely unknown, since they have escaped careful environmental assessment.
Beginning in the late 19th century, the first hydroturbines were invented to power a theater in Grand Rapids, Michigan and then, to power streetlights in Niagara Falls, New York. Alternating current then made possible the first hydropower plant at Redlands Power Plant, California in 1893. Beginning in the 1920s, the US Army Core of Engineers began to build hydropower plants. The Tennessee Valley Authority in 1933 developed hydropower in the Tennessee River with the clearly stated goal of promoting rural electrification, later widely imitated throughout the country—the most notable being the Hoover Dam in 1937. The New Deal gave an enormous boost to hydropower construction, tripling output in 20 years until it accounted for 40% of electrical use in the United States. Hydropower dams were an important part of North American and European energy development.
Starting in the late 1960s, big dams stopped being built in developed nations, because the best sites for dams were already developed, the costs became too high, and most importantly, growing environmental and social concerns made the costs unacceptable. Since then, the contribution of hydropower to the United States’ electrical supply has steadily declined to 6.1% of energy consumption, and other energy sources, such as nuclear, gas, coal, solar, and wind, began to replace it. 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. European countries with favorable topography and rain patterns, such as France and Switzerland, continue to have hydropower as an important part of their energy mix through technological innovations at existing dams. In contrast, 3,450 dams have been removed to date in Sweden, Spain, Portugal, the United Kingdom, Switzerland, and France (https://www.damremoval.eu). Hundreds of dams were removed in the United States (546 from 2006 to 2014) and Europe at enormous financial cost. This situation contrasts with what is happening in developing countries.
Developing countries, where millions of people are still not connected to the electric grid, have been ramping up hydroelectric dam construction for decades. These often involve megaprojects, which repeat the problems identified with big dams built in the past by the United States and European nations: disrupting river ecology, causing substantial deforestation, generating loss of aquatic and terrestrial biodiversity, releasing large amounts of greenhouse gases, displacing thousands of people, and affecting the food systems, water quality, and agriculture near them. The sustainability of these undertakings is commonly insufficiently scrutinized by those promoting them. The priority in large dam construction is to generate energy to serve growing industries and urban populations—these two things often overwhelm socioeconomic and environmental considerations. Left behind are local communities saddled with socioenvironmental damages and loss of livelihoods. Often, they do not even gain access to electricity, because they are not provided the power from the large dams, and they are not sufficiently compensated for their disrupted lives. All countries need renewable energy, and hydropower should be part of this portfolio. However, there is a need to find sustainable and innovative solutions that combine hydropower development with other energy sources, thus providing benefits that will outweigh, reduce, or even eliminate the negative environmental, behavioral, cultural, and socioeconomic externalities resulting from large dams.
Here, we review the socioeconomic and environmental situation in several major river basins where dams are being built. We examine the proliferation of large dams in developing countries, the lack of attention to climate change in the decision of whether to build a dam, some of the governance and compensation challenges, and the overestimation of benefits and underestimation of costs. We also identify changes that are needed to address the legitimate social and environmental concerns of people living in areas where dams are planned and propose innovative solutions to meet the food, water, and energy needs of citizens in those regions. These solutions have relevance worldwide, as hydropower can also contribute to meeting goals of reducing fossil fuel emissions and building sustainable communities with diversified energy sources.
From the BBC (Matt McGrath):
A new study says that many large-scale hydropower projects in Europe and the US have been disastrous for the environment.
Dozens of these dams are being removed every year, with many considered dangerous and uneconomic.
But the authors fear that the unsustainable nature of these projects has not been recognised in the developing world.
Thousands of new dams are now being planned for rivers in Africa and Asia.
Hydropower is the source of 71% of renewable energy throughout the world and has played a major role in the development of many countries.
But researchers say the building of dams in Europe and the US reached a peak in the 1960s and has been in decline since then, with more now being dismantled than installed. Hydropower only supplies approximately 6% of US electricity.
Dams are now being removed at a rate of more than one a week on both sides of the Atlantic.
The problem, say the authors of this new paper, is that governments were blindsided by the prospect of cheap electricity without taking into account the full environmental and social costs of these installations.
More than 90% of dams built since the 1930s were more expensive than anticipated. They have damaged river ecology, displaced millions of people and have contributed to climate change by releasing greenhouse gases from the decomposition of flooded lands and forests.
“They make a rosy picture of the benefits, which are not fulfilled and the costs are ignored and passed on to society much later,” lead author Prof Emilio Moran, from Michigan State University, told BBC News.
His report cites the example of two dams on the Madeira river in Brazil, which were finished only five years ago, and are predicted to produce only a fraction of the power expected because of climate change.
In the developing world, an estimated 3,700 dams, large and small, are now in various stages of development.
The authors say their big worry is that many of the bigger projects will do irreparable damage to the major rivers on which they are likely to be built.
On the Congo river, the Grand Inga project is expected to produce more than a third of the total electricity currently being generated in Africa.
However, the new study points out that the main goal for the $80bn installation will be to provide electricity to industry.
“Over 90% of the energy from this project is going to go to South Africa for mining and the people in the Congo will not get that power,” said Prof Moran.
“The people that I study in Brazil, the power line goes over their heads and goes 4,000km from the area and none of the energy is being given to them locally.”
“The nice goal of rural electrification has become completely subverted by large-scale interests who are pushing this technology, and governments are open to being convinced by them that this is the way to go.”
The report points our that the large installations on these great rivers will destroy food sources, with 60 million people who live off the fisheries along the Mekong likely to be impacted with potential loss of livelihoods greater than $2bn. The authors also believe that dams will destroy thousands of species in these biodiversity hotspots.
In Brazil, which gets 67% of its electricity from hydropower, the response to reduced water capacity because of climate change is to build more dams.
With the election of Jair Bolsonaro in Brazil, a temporary halt to building new hydro projects is likely to be overturned. Plans for 60 new dams are already in place.
The authors say that with huge pressure on countries to press ahead with renewable energy developments, a mix of energy sources including hydro is the most sustainable approach.
“Large hydropower doesn’t have a future, that is our blunt conclusion,” said Prof Moran.
“To keep hydropower as part of the mix in the 21st Century we should combine multiple sources of renewable energy,” said Prof Moran.
“There should be more investment in solar, wind and biomass, and hydro when appropriate – as long as we hold them to rigorous standards where the costs and benefits are truly transparent.”
The study has been published in the journal Proceedings of the National Academy of Sciences.