Amazon hydropower plant causes global warming

Monika R, PSG College of Technology, Coimbatore

Amazonian forests harbour the world’s richest tropical biodiversity but have been relentlessly cleared and fragmented over the last four decades. This is mainly because over the decades, hydropower complexes have been built in several hydrographic basins of Brazil including the Amazon. Hydroelectric power generation is the most vital source of electrical energy in Brazil (about 80% of electricity). The Brazilian government and foreign capital have invested heavily in building hydroelectric dams, mainly in Amazonia, to provide cheap energy supplies for urban and industrial development. An increased need for energy to sustain economic development has boosted governmental plans to expand hydropower in Amazonia. 

In addition to the prominent potential for hydropower resources to provide “clean” electricity for Brazil, however, they’re been considerable, with loss of habitat and biodiversity, which ends up in the conflict between human needs for socio-economic development and conservation of nature with the protection of biodiversity. Therefore, it’s necessary to understand the effects of these constructions on the environment and native communities.

Do Amazon hydropower plants cause greenhouse gas emissions?

Emission of Greenhouse gas from hydroelectric dams are often portrayed as non-existent by the hydropower industry and have been largely ignored in global calculations of emissions from land-use change. Research conducted by Faria et al proves that “Tropical dams considered as ‘clean’ emissions-free energy sources” could be a myth. Tropical hydroelectric dams have significant greenhouse gas emissions. Although this has now been known for over two decades, it’s yet to have any perceptible effect on dam-building decisions. 

Amazon hydropower plant and global warming

Substantial emissions of greenhouse gases have been seen from hydroelectric dams in tropical forest areas. The Amazon has warmed up around 1⁰C in the last century because of global warming associated primarily with the rise of greenhouse gas emissions. The projections for temperature increase for this century range from 1.8⁰C to 5.1⁰C. 

Dams emit carbon dioxide (CO₂), but only a part of this emission may be a net contribution to global warming because the CO₂ emitted is removed from the atmosphere through plants in the reservoir. But when the tropical forest is flooded and killed, there’s a loss of an annual uptake of carbon by the standing forest and also the CO₂ which comes from non-renewable sources contributes to global warming. Tropical dams also emit methane (CH₄), which has far more impact on global warming per ton of gas emitted than CO₂. Oxygen within the bottom water is quickly exhausted, and decomposition of organic matter must therefore end with the formation of CH₄ instead of CO₂. Each ton of methane encompasses a very large effect on global warming relative to CO₂ while it remains in the atmosphere. 

These gases are emitted from above-water decay, the reservoir surface, turbines, and spillway of the hydropower plant. The frequent drawdowns in reservoir management may be expected to end in greater CH₄ release through bubbling. Flooding of habitats covered by vegetation also causes the discharge of CH₄ and CO₂. 

Going forward, predictive models to estimate the GHG emissions of future reservoirs are indispensable to maneuver towards more sustainable energy generation processes.

Study

Bertassoli et al conducted a study to measure greenhouse gas emissions. The locus of this study was Belo Monte Hydropower Plant, built-in Amazonia, and holds the biggest installed capacity among other power plants worldwide. It also has been generating major environmental impact and social conflict. 

Bertassoli’s team studied CH₄ and CO₂ emissions during Belo Monte’s first two years of operation. The global warming potential (GWP) of the Belo Monte reservoirs represented up to a threefold increase in greenhouse gas emissions when compared to nuclear power plants/other renewable sources like photovoltaic and wind power plants. This quarrel favors avoiding hydropower expansion in Amazonia.

Other impacts of Amazon hydropower plant

Amazon forest has been threatened by several drivers like land use, forest degradation and fragmentation, global climate change, and the increase of extreme droughts and floods. But of these impacts are interconnected with hydropower plant because of the following reasons:

• They are current drivers of habitat loss across Amazonian forests, disturbing the hydrological balance that controls the structure and performance of those environments.
• It has created large archipelagos (fragmentation) of upland forest in Amazonia.
• Under habitat loss and fragmentation, local species extinctions are accelerated, and this disrupts essential ecosystem functions.
• Disruption of indigenous and riverine communities is seen, and this results in forest degradation and loss of biodiversity.
• Alteration of the natural “flood pulse” by altering the hydrology of rivers negatively affects the ecological dynamics of downstream floodplain ecosystems. 
• The impacts of huge dams on freshwater biota are relatively well-known. However, the effects of small hydropower plants are still not well understood and have a high risk of producing MeHg (methylmercury) contamination.

To avoid hydropower expansion in Amazonia

Hydropower is commonly promoted by government authorities as a ‘clean’ source of energy, in contrast to fossil fuels. While fossil fuel contributions to global warming are well known, hydroelectric dams don’t seem to be freed from impact. Hydroelectric dams in tropical forest areas emit greenhouse gases like CO₂ and CH₄.

Emissions from various sources were ignored in previous estimates for Amazonian reservoirs. At present, due to emerging consciousness in our society, the environmental impact assessment of great hydropower projects has been vehemently discussed among scientists, governments, the business community, NGOs and has well-versed multi-stakeholder processes to succeed in an innovative partnership to license hydroelectric plants.

In the Amazon, the effects of tropical hydropower dams are enormous, and these effects can reach distant areas. This framework has to change, and therefore the available science must be considered to support decision-making. For those dams already constructed, enforcing hunting and logging restrictions within forest islands is recommended.

“Tropical dams: not to build or to build?” remains a controversial topic. Together with all other social and environmental costs of Amazonian reservoirs, we may urge decision-makers to think about alternatives for energy generation that avoid green gas emission and other deadly impacts.

Also read: The invention of an improved Nanotech OLED electrode

Source:

• Bertassoli, D, J., Sawakuchi, H, O., Araújo, K, R., Camargo, M, G, P., Alem, V, A, T., Pereira, T, S., Krusche, A, V., Bastviken, D., Richey, J, E., Sawakuchi, A, O. (2021). How green can Amazon hydropower be? Net carbon emission from the largest hydropower plant in Amazonia. Sci. Adv. 7, eabe1470. doi: http://10.1126/sciadv.abe1470
• Fearnside, P. M. (2016). Greenhouse gas emissions from Brazil’s Amazonian hydroelectric dams. Environmental Research Letters, 11(1), 011002. doi:http://10.1088/1748-9326/11/1/011002
• Alho, J, R. (2011). Environmental effects of hydropower reservoirs on wild mammals and freshwater turtles in amazonia: a review. Oecologia Australis, 15(3), 593-604, doi: http://10.4257/oeco.2011.1503.11

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About the author: Monika R is an enthusiastic Biotech student aspiring for an opportunity to develop skills and grow professionally in the research field. Extremely motivated and possess strong interpersonal skills and the ability to understand concepts quickly.