Study criticises Brazil’s dam construction, saying that more economically and ecologically viable alternatives already exist
Dams are hugely controversial, especially in the Amazon Rainforest. Their proponents, flashing green credentials, have dammed the tributaries of the Amazon for decades. However, there is a rising backlash against the huge economical, environmental, and sociological costs dams bring. A paper led by Dr. James Randall Kahn from Washington and Lee University is the latest in this volley.
Published in Energies, the study is based on a simple principle – that developmental projects should not be pursued if the future damages they cause (even if measured in terms of decades) outweigh the original benefits. In the case of dams in the Brazilian Amazon, the authors believe that this threshold was crossed a long time ago. Their paper thus dismantles the economic justifications for Amazonian dams, while also highlighting the huge damages brought about by these projects.
Their argument can be broken into two parts: flawed governmental analyses and the existence of more effective alternatives to sustainable energy.
The authors note several issues with studies undertaken by the authorities in dam proposals. First among them is the tendency to declare areas where dams are planned to be “without environmental constraints” before ecological studies were conducted. Such locations include the Rio Negro basin, among the least-studied and most pristine environments in the Amazon. Somewhat astonishingly, the areas with acknowledged environmental constraints will be subjected to 90 percent of future dam construction.
Secondly, the benefits of dams diminish significantly after completion. Dams are especially problematic in tropical and topologically flat areas, which typify the Amazonian basin. Converting shallow lake and river areas into deep reservoirs drowns and kills the terrestrial forest, destroying carbon sinks and leading to the atmospheric release of greenhouse gases through decomposition.
The Balbina Dam in Brazil’s Amazonas state, implemented in 1989, has been heavily criticized for environmental destruction and greenhouse gas emissions that were the result of the reservoir created by the dam. Despite being 4,438 square kilometers (1,714 square miles) in area, the dam has a meager capacity of 250 megawatts. Photos by: James Randall Kahn.
Ominously, the paper calculates that should all the proposed reservoirs in the Amazon be constructed, 785 million metric tons of methane and carbon emissions would be released. In comparison, the carbon dioxide emissions from fossil fuel combustion in Brazil in 2010 totalled 453.87 million tons, 1.73 times less than projected emissions from the planned reservoirs.
The ability of dams in the Amazon basin to generate electricity is also compromised by subsequent sedimentation and the fact that water flow in Amazonian rivers is predicted to diminish due to climate change. Furthermore, the areas that need the power generated by these dams most are often situated thousands of kilometers away. Considering that dam capacity diminishes by approximately 20 percent for every 1,000 kilometers (620 miles) the electricity travels through conventional power lines, this represents a significant waste of energy.
Choose the real sustainable energy sources
Brazil is not stuck with hydropower, write the authors, as the country has much potential for other sources of alternative energy, such as solar, wind and biogas. Photovoltaic and wind power costs have been declining rapidly and continue to do so, and are already more efficient than hydropower. For instance, the costs of solar power range from 35-40 percent less per watt than hydropower, and considering the high amounts of sunlight Brazil gets, it is in the perfect location to harness this type of energy.
Biogas, Kahn said, is another promising alternative. A cheap and effective source of energy that has been in used for centuries, it is created from organic waste that is burned, leaving rich fertilizer behind.
“Most of the sewage in Brazil is untreated and it needs to develop proper treatment,” he said. “While it makes an investment there it could also invest in routing that sewage through biogas facilities and producing electricity. A real advantage is that you have the sewage in the place where you have the demand for it.”
When one factors in the local environmental and social costs dams cause, it is hard to argue in favor of them, say the authors. Their construction can block fish migration and sediment flow, lower oxygen levels both below and above the dams, fragment entire aquatic ecosystems, and displace rural and indigenous communities.
Raising the precautionary principle—the concept that an action with high a potential for harm should not be carried out unless it is proven to be safe—the authors believe any short-term benefits that dams may bring in the Amazon are simply not worth the havoc they will wreak on the environment. Rather, they maintain Brazil needs to – and can – rely on a combination of alternative fuel sources to meet the increasing energy demands of its continuing development. All that is needed is the political will and changing of old paradigms.
“The real key between now and the more distant future is to minimize the damage we do to the planet,” Kahn said. “We don’t want to make choices over the next ten or twenty years that have implications for the next 100 years… We need to aggressively go after the newer technologies.”
- Kahn, J. R., Freitas, C. E., Petrere, M., 2014. False Shades of Green: The Case of Brazilian Amazonian Hydropower. Energies, 7, 6063-6082
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