Assessment and statistics of Brazilian hydroelectric power plants: Dam areas versus installed and firm power (2007)

Avaliação e estatísticas de usinas hidrelétricas brasileiras: áreas de barragens versus potência instalada e firme

Antonio Carlos Caetano de Souza

ABSTRACT

The Brazilian relief, predominantly composed by small mountains and plateaus, contributed to formation of rivers with high amount of falls. With exception to North-eastern Brazil, the climate of this country are rainy, which contributes to maintain water flows high. These elements are essential to a high hydroelectric potential, contributing to the choice of hydroelectric power plants as the main technology of electricity generation in Brazil.

Though this is a renewable source, whose utilized resource is free, dams must to be established which generates a high environmental and social impact. The objective of this study is to evaluate the impact caused by these dams through the use of environmental indexes. These indexes are ratio formed by installed power with dam area of a hydro power plant, and ratio formed by firm power with this dam area.

In this study, the greatest media values were found in South, Southeast, and Northeast regions respectively, and the smallest media values were found in North and Mid-West regions, respectively. The greatest encountered media indexes were also found in dams established in the 1950s. In the last six decades, the smallest indexes were registered by dams established in the 1980s. These indexes could be utilized as important instruments for environmental impact assessments, and could enable a dam to be established that depletes an ecosystem as less as possible.

Keywords: Hydroelectric power plants; Dam area; Environmental index; Brazil

RESUMO

O relevo brasileiro, predominantemente composto por pequenas montanhas e planaltos, contribuiu para a formação de rios com grande quantidade de quedas d’água. Com exceção do Nordeste do Brasil, o clima deste país é chuvoso, o que contribui para manter os fluxos de água elevados. Esses elementos são essenciais para um alto potencial hidrelétrico, contribuindo para a escolha de usinas hidrelétricas como a principal tecnologia de geração de eletricidade no Brasil.

Embora esta seja uma fonte renovável, cujo recurso utilizado é gratuito, barragens devem ser estabelecidas, o que gera um alto impacto ambiental e social. O objetivo deste estudo é avaliar o impacto causado por essas barragens através do uso de índices ambientais. Esses índices são a razão formada pela potência instalada com a área da barragem de uma usina hidrelétrica e a razão formada pela potência firme com a área da barragem.

Neste estudo, os maiores valores médios foram encontrados nas regiões Sul, Sudeste e Nordeste, respectivamente, e os menores valores médios foram encontrados nas regiões Norte e Centro-Oeste, respectivamente. Os maiores índices médios encontrados também foram encontrados em barragens estabelecidas na década de 1950.

Nas últimas seis décadas, os menores índices foram registrados por barragens estabelecidas na década de 1980. Esses índices poderiam ser utilizados como instrumentos importantes para avaliações de impacto ambiental e poderiam permitir a construção de uma barragem que esgotasse o mínimo possível um ecossistema.

Palavras-chave: Hydroelectric power plants; Dam area; Environmental index; Brazil

Introduction

Various electricity generation technologies are available, and their priorities depend on potentialities of a determined region or country. In 2005, in Brazil, 83.4% of generated electricity, and 76.06% of installed power came from hydroelectric power plants, being that 68.76% of installed power was provided by hydropower plants, cited in this work (with an overall installed capacity of 64.05 GW [1]. The priority devoted to this technology is due to high flow of water in almost all Brazilian river basins. As much as 12% of all fresh surface water disposed all over the world is available in Brazil due to high rain level in its territory [2].

Brazilian plateaus, which are largely distributed in its territory, also contribute to an enormous hydroelectric potential due to presence of hills and mountains, which are responsible by altitudes variation of rivers and hence, formation of falls. Most of these plateaus are in altitudes that vary between 200 and 1000 m high, where most of Brazilian population and industries are encountered.

Even if Brazilian hydroelectric potential is relatively high, the medium rate of utilization is solely 27.24% (taking into account that hydroelectric potential accounted all over Brazil is 260.09 GW), varying dramatically depending on the state and river basin, while in countries such as USA, Japan, and EU countries where about 70% of its potential has been utilized [1].

In Northern Brazil, due to the small population, low industrialization level, and the high installation expenditure of transmission and distribution systems due to large distances between hydropower plants and customers, the medium rate of utilization of its hydroelectric potential is small compared with other Brazilian regions. Due to these and other motives that, the electricity supply in this region is based mainly upon diesel-powered engines.

With the ever-increasing environmental restrictions, the trend is to avoid the installation of hydropower plants in plain regions such as in the center of Amazonas River basin, where Balbina and Samuel hydropower plants were installed. The operation of these plants started in late 1980s, however assessments carried out before their installations did not take into account their high environment impacts (large forestry areas were inundated). Their projects were conceived in the 1970s and their operation started at following decade. The future projects of hydro power plants for this region concern with native population and high environment and social impacts that installation of transmission and distribution grids could to cause.

Contrary to Northern Brazil, the hydroelectric potential is mostly took advantage in Southeast, South, and Northeast regions, respectively. To supply electricity to the most populous and industrialized states (such as São Paulo state), hydropower plants have been installed in more distant regions such as some regions of state of Minas Gerais, Southern and Mid-Western Brazil. This fact has also been stimulated due to the introduction of transmission lines with fewer losses (such as direct current and higher tension technologies).

As previously explained, one of the main environmental problems caused by hydropower plants is formation of dams, which substitute the previously existent landscape which could be native vegetation, urban zones, farms, etc. Not solely environmental problems generally appear but some economic activities could be also affected. Due to environmental problems caused by these plants, older projects have been modified to mitigate environment, economic and social problems becoming possible, inclusively, to decrease the overall expenditure of this installation. One example that could be cited is Belo Monte hydropower plant, whose project has been modified with objective to diminish the dam area (the previous dam area was three times as much as the area determined by current project).

Various works and technical reports have been published to focus on impacts caused due to installation and operation of hydropower plants, especially about the formed dams [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], and some actions that could be performed to mitigate them [15], [16], [17], [18]. Other impacts must be also considered, such as greenhouse gases production and pollution of water due to decomposition of organic matter [19].

About 2000 dams were established in Brazil, being that more than 1500 are out of use, inclusively at conditions that are not been known. Optimization of the use of water in a river basin could help to a major electricity generation [20], [21], [22].

Despite the problems caused by hydropower plants during their installation, this technology is largely suggested whether cautions are taken into account [24].

Section snippets

Large hydroelectric power plants in Brazil

Most of the electricity produced in Brazil is provided by large power plants. The installed capacity by this power source is as high as 71 GW [23]; and considering all power plants cited in this work about 64 GW¹ was amounted. Some of the cited plants have been run since 1950s due to development of newer technologies of generation, transmission and distribution. At last 

Analysis of findings of cited plants

The relief, and water flows of rivers and their variation during a determined period has rough differences depending upon studied region.

Table 2 focuses on the largest hydropower plants, the installed power, the formed dam areas, and its environmental indexes. These indexes are ratios of installed power or firm power of a hydropower plant with the lake area formed by it. It could be used as a decision-making tool to evaluate the possibility to install a hydropower plant with low environment,

Conclusions

Findings such as environment indexes are important decision-making tools to evaluate the possibility to install a hydropower plant. Of course, the determination of its construction depends largely on other items such as economic, social, financial, and politic factors.

By a study of tables and figures focused on this study, it was possible to obtain some conclusions about the type of power plant and its environmental impact.

Firstly, it was observed that most of the hydroelectric power plants are 

References (60)

• M.J. Kuby et al.A multiobjective optimization model for dam removal: an example trading off salmon passage with hydropower and water storage in the Willamette basinAdv Water Resourc(2005)
• ANEEL. BIG 2005. Available on-line 6 February 2007…
• ECOTERRA. Águas do Guarani. Available on-line 9 February 2007…
• Ministério de Minas e Energia. Balanço Energético Nacional 2005. Available on-line 9 February 2007…
• Ghilardi Junior R. Sustentabilidade de grandes barragens: Adequação das recomendações da comissão mundial de barragens…
• M.A.R. AndreazziImpactos de hidrelétricas para a saúde na Amazônia(1993)
• Cortes RM, Ferreira MT, Pinheiro AN. Efeitos de pequenas obras transversais sobre os ecossistemas fluviais: Os casos…
• R. GoodlandEnvironmental assessment of the Tucuruí Hydroelectric Project, rio Tocantins, Amazonas(1977)
• ELTRONORTE/CENEC. UHE Kararaô—Estudos de impacto ambiental. Technical report. Brasília, Brazil; 1998….
• Ferreira EJG. Relatório final dos estudos e levantamentos do impacto ambiental da UHE da Cachoeira da Porteira….
• G.M. SantosImpactos da hidrelétrica Samuel sobre as comunidades de peixes do rio Jamari (Rondônia, Brasil)Acta Amazôn(1995)
• B. Merona et al.Les efets immédiats de la fermeture du barrage de Tucurui (Brésil) sur l′ichtyofaune en avalRev Hydrobiol Trop(1987)
• D.M. FigueiredoMonitoramento Limnológico da Qualidade da Água e Hidrossedimentológico—AHE Jauru(2003)
• Couto RCS. Hidrelétricas e Saúde na Amazônia: Um Estudo sobre a Tendência da Malária na Área do lago da Hidrelétrica de…
• A.M. Grimm et al.Estudo comparativo do clima local da área do reservatório de Itaipu
• Oldani N, Baigún C, Delfino R. Fishway performances in South American regulated rivers. In: Wetlands engineering and…
• Bernacsek GM. Guidelines for dam design and operation to optimize fish production in impounded river basins (based upon…
• H.P. Godinho et al.Ecology and conservation of fish in southeastern Brazilian river basins submitted to hydroelectric impoundmentsActa Limnol Brasil(1994)
• P. FearnsideHydroelectric dams in the Brazilian Amazon as sources of greenhouse gasesEnviron Conserv(1995)
• Rodrigues JF, Creppe RC. Considerations about electric generation model by hydroelectricity in the Brazil. In: V Latin…
• Silva RM, Carneiro AAFM. Evaluation of the optimized operation of hydroelectric power plants. In: V Latin American…
• Ćarneiro AAFM, Filho DS. Análise de desempenho da operação a reservatório para a Usina Hidrelétrica de Itaipu. In: II…
• Furtado RC. O uso do potencial energético da Amazônia versus outras opções. In: II Latin American congress: electricity…
• A. MartelliAmazônia: Nova dimensão do Brasil(1969)
• Mariotoni CA, Badanhan LF. Potencial energético das pequenas centrais hidrelétricas analisando sob a óptica ambiental…
• ANEEL. Resolução no. 394, Available on-line 6 February 2007…
• CNDPCH. Centro nacional de desenvolvimento de PCH, Available on-line 7 February 2007…
• Santos CMP. A modernização do parque hidrogerador do Noroeste do Brasil. In: II Latin American congress: electricity…
• Bianchi I, Souza TM. Recapacitation and re-powering small hydro power plants out of use or in use in the São Paulo…
• Bermann C. A perspectiva da sociedade brasileira sobre a definição e implementação de uma política energética…

There are more references available in the full text version of this article.