Which of the following is not a requirement for site selection of hydroelectric power plant?

Question

Examoogle · Accepted Answer

Sedimentation

Explanation: Sedimentation is not a requirement; rather, it is a detrimental process that reduces the effective storage capacity of a reservoir and can damage turbine blades. Site selection for a hydroelectric plant focuses on maximizing water availability, head, and structural stability of the terrain.

Working Principle: Hydroelectric power stations convert the potential energy of stored water ($PE = mgh$) into kinetic energy through penstocks, which then rotates a turbine to drive a generator. Excessive sedimentation leads to reservoir siltation, which decreases the lifespan of the dam and increases maintenance costs, making it a design challenge to be mitigated rather than a site selection requirement.

Key Formulas: $P = \eta \rho g Q H$ — Power output where $\eta$ is efficiency, $\rho$ is density, $g$ is gravity, $Q$ is discharge, and $H$ is head.; $E_p = mgh$ — Potential energy stored in the reservoir.

Key Points: High head availability (H) is essential for efficient power generation.; Rocky land is preferred to ensure a stable foundation for the massive concrete structure of the dam.; A large catchment area ensures reliable water supply throughout the year.; Sedimentation is considered a negative factor that necessitates desilting chambers.

Advantages: High operational efficiency; Long lifespan of infrastructure; Clean and renewable energy source

Disadvantages: High initial capital investment; Risk of siltation and sedimentation; Ecological impact on local habitats

Applications: Base load power plants; Peak load management; Grid frequency regulation

Additional Info: Sedimentation occurs when rivers carry suspended solids that settle in the low-velocity reservoir area.. Effective site selection aims to minimize silt entry through proper dam wall location and spillway design.

Answer: D is correct — Sedimentation is an undesirable geological phenomenon that reduces dam capacity, whereas the other options are essential prerequisites for a viable hydroelectric site.

Exam Tip: Always distinguish between 'site requirements' (beneficial conditions) and 'engineering challenges' (conditions that need mitigation). Sedimentation, evaporation, and seismic activity are typically engineering challenges.

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