Study Weighs the Benefits of Hydropower Developments Against Their Negative Impacts

In recent decades, although a majority of the developed countries have minimized the construction of large dams for electricity generation, developing countries, such as Brazil, have started constructing even more enormous hydropower plants.

These countries have failed to consider the impacts of large dams on the environment, such as the loss of biodiversity and deforestation, or the social impacts, including the displacement of thousands of people and the economic damages they suffer. It is necessary for these impacts to be computed in the total cost of such projects. Even worse is the fact that these projects do not account for the context of climate change, which will result in the reduction of availability of water for storage and electricity generation.

Through an article published in Proceedings of the National Academy of Sciences of the United States of America (PNAS), scientists at Michigan State University in the United States give a warning.

Emilio Moran, a visiting professor at the University of Campinas (UNICAMP) in São Paulo State, Brazil, is the lead author of the article as well as the principal investigator of a research project supported by FAPESP under the São Paulo Excellence Chair program (SPEC), designed to analyze the social and environmental effects of Belo Monte hydropower development near Altamira, Pará state.

“We argue that if the construction of large dams in developing countries is to continue, it must always be preceded by a painstaking assessment of their real cost, including the environmental and social impact they have,” Moran told Agência FAPESP.

“When a large dam is built, the result is a downstream loss of a great many fish species that are important to riverine populations. These communities will have to continue somehow making a living despite dwindling fish stocks for 15 or 20 years, for example, and the costs of these projects don’t take such economic and social losses into account.”

The authors of the article consider that hydropower is the principal source of renewable energy across the globe, making up for nearly 71% of the total in 2016.

From 1920 to 1970, developed countries in North America and Europe constructed thousands of dams; however, they stopped the constructions since the ideal sites had already been developed and the environmental and social concerns rendered the costs unaffordable.

Currently, several large hydropower plants in these countries are nearing the end of their service lives, and more dams are being decommissioned than constructed in North America and Europe. According to the article, between 2006 and 2014, a total of 546 dams were dismantled in the United States alone.

The cost of removing a dam once its useful life is over is extremely high and should be taken into account when computing the total cost of a new hydro development. If the cost of removal had to be included, many dams wouldn’t be built. It would be far more expensive to produce a kilowatt hour of electricity via a hydro complex with a useful life of 30-50 years like those under construction in Brazil.

Emilio Moran, Professor, Michigan State University.

Local impact

Moran stated that the first dams were also constructed in North America and Europe to provide power supply to rural areas and to supply water for irrigation systems. “These projects had a social purpose,” he noted.

On the other hand, the dams being built at present along the rivers of the Amazon basin in South America, on the Mekong River in Southeast Asia, and on the Congo River in Africa are chiefly built to provide power supply to steelmaking companies, for instance, without no benefits to local communities.

The most representative case is the proposed Grand Inga Dam on the Congo River at Inga Falls, which is the largest waterfall in the world by volume. The dam could increase the total power generated in Africa by more than one-third and will export electricity to South Africa for use by the mining companies there.

“The people affected by these projects reap no benefits, such as access to electricity or a cheaper power supply. In the case of Belo Monte, the transmission line passes over the heads of the people affected and takes the electricity generated straight to the south and southeast, two of Brazil’s wealthiest regions,” stated Moran.

The article discusses not only the case of Belo Monte but also Santo Antonio and Jirau, which have recently been constructed on the Madeira in the western Amazon; the electricity bills for the locals have increased rather than decreasing. In addition, the majority of jobs promised to the neighboring communities when the construction started went to outsiders and vanished within a period of five years.

The inhabitants of Altamira supported the construction of Belo Monte before it began because they thought it would bring the town huge benefits. No one supports it now because hydro development has destroyed their peace and quiet. It has brought only problems for most people. Belo Monte has been chaotic and has affected the lives of the inhabitants so profoundly that plans to build more large dams in the Amazon basin are being revisited.

Emilio Moran, Professor, Michigan State University.

Apart from the problems caused by the dams to downstream communities, severe environmental impacts are also being brought about by the new dams being built in Africa, South America, and Southeast Asia.

In the Amazon basin, within an area of 6 million square kilometers (km²) 147 dams have been proposed, including 65 in Brazil; these hydropower developments have had major impacts on fish populations and dynamics in an area with about 2320 species of fish. There was a 25% reduction in the number of fishes in the Tocantins, draining into the Atlantic close to the mouth of the Amazon, following construction of dams along the river, for instance.

The article reports that in the Tucuruí dam region, which is also located in the Brazilian Amazon, there was a 60% reduction in the fish yield almost immediately following the construction of dam, and over 100,000 people who lived downstream were affected by the loss of flood recession agriculture, fisheries, and other natural resources.

“Most fish species in the Amazon basin are endemic [unique to the region]. The disappearance of these species represents a huge loss to world biodiversity,” stated Moran.

Impact of climate change

The article also notes that climate change will have a strong influence on the dams constructed in the Amazon basin in the recent past.

It is anticipated that the Jirau and Santo Antonio dams on the Madeira, which were completed in the last five years, will produce only a small proportion of the 3 GW they were each designed to produce due to climate change and the limited storage capacity of their run-of-the-river reservoirs.

The article also states that the Belo Monte dam on Xingu, which was completed in 2016, will generate lesser electricity due to climate variability, insufficient water levels, and a comparatively small reservoir, producing just 4.46 GW as against its 11.23 GW design capacity even under the best-case scenario.

The most worrying fact is that a majority of the climate models have predicted lower rainfall and higher temperatures in the Tapajós, Xingu, and Madeira basins.

Depending on water as the main source of power in a future when we’ll have less of this natural resource looks like an unreliable strategy. To reduce its vulnerability with regard to energy in the context of global climate change, Brazil must diversify its energy mix. It’s still too dependent on hydroelectricity. It needs to invest more in other renewable sources, such as solar, biomass and wind.

Emilio Moran, Professor, Michigan State University.

The authors of the study reiterate the fact that similar to the impacts of climate change, the impacts of changing land use on power production potential are often overlooked by dam builders.

They said that research by another research team demonstrated that the power produced in the Xingu Basin, where Belo Monte is located, could be reduced by less than 50% of the installed capacity as a result of deforestation in the region. This is due to the fact that deforestation hinders rainfall and leads to decline in groundwater in tropical rainforest areas.

It is predicted that around half of the rainfall in the Amazon basin is due to internal moisture recycling. Hence, deforestation will result in less precipitation in the area besides the anticipated decrease owing to global climate change, said the authors.

“Hydro is only one of several solutions to avoid blackouts in Brazil. The best approach is to diversify energy sources and develop innovative solutions that reduce the environmental and social impact of dams,” stated Moran.

The authors propose in-stream or submerged turbine technology, also called “zero head,” as a substitute to conventional dams since it doe not requires any height differential or damming.

This solution could ensure steady supply of power to riverine communities at a reduced cost and is considerably more environment-friendly. Furthermore, it does not involve the relocation of local inhabitants or the other social costs of dams.

This technology could be used throughout Brazil wherever there are relatively small watercourses with discharge rates in excess of 1 cubic meter per second. Small turbines can also be installed near dams to supplement power generation and eliminate the need to build more dams.

Emilio Moran, Professor, Michigan State University.