Resumo

Hydroelectric plants have been the main alternative for energy supply in Brazil, representing 64% of the Brazilian energy matrix. Most enterprises focus their sustainability programmes on environment compensations, impacts reduction and support the socioenvironmental development of the region. However, considering the dependency of hydroelectric power plants on the ecosystem services, sustainability programs should account its value for conciliating and optimizing the relation between generating revenue and preserving the reservoir.

This research aims to measure the ecosystem service of regulation of soil erosion for the Itaipu hydroelectric plant. It is understood that the protection zone vegetation prevents sediments from being dumped into the reservoir, maintaining its operation conditions. Measuring the value of these ecosystem services is an opportunity to comprehend the risks caused by the shortage of natural resources (water and soil), as well as to dimension and evaluate the magnitude of investments (costs and benefits) and act preventively in areas of interest, aiming to maintain the lifespan of the venture.

It was based on the discussion about the role of hydroelectric plants and reservoirs, which can lose storage capacity when sediments accumulate in streams that maintain them, impacting their operation and longevity. Soil erosion regulation was considered as a relevant ecosystem service, for its impact in the operative and economic life of a power plant and even in the water provision. Finally, an investigation on how this approach has been used in the electricity sector was conducted.

The research topic was the Sustainability Programme of the Itaipu Hydroeletric plant. The methodology included documents assessment, study, simulation and evaluation exercise based on the literature, considering the reposition costs, the expenses that would be necessary to recover the reservoir due to sediment dumping. Finally, the valuation of the eventual non-disbursed revenue due to the accumulation of sediments was proceeded, using the average value of the cubic meter of water used in power generation as a reference unit.

Considering the average daily water consumption and revenue, the value of the cubic meter was estimated. Evaluating the sum of the average annual investments of the hydroelectric plant focused on activities that directly impact the maintenance of the vegetation and the soil conservation, revealed that it represents approximately 13% of the lowest avoided annual cost due to dredging, and 0.011% of the average annual revenue. It allowed the conclusion that for each US$ 1 dollar invested in these activities, expenses from US$ 8 to US$ 520.65, with the process of dredging, are avoided.

The annual costs avoided for removing sediment from the reservoir were estimated. It confirmed, monetarily, the economic viability of maintaining the developed actions, which are considered decisive and represent an investment in the preservation of the storage capacity of the reservoir. The evaluation exercise presented points out relevant data to support the organization´s decision-making process, since it expands the understanding of risks arising from sedimentation and scarcity of water; allows the dimensioning of investments and the opportunity to act preventively in areas of interest.

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