Hydropower

What are the Disadvantages?

• Disrupt ecosystems through altering gas composition of the water flow which traps organisms in the reservoir water [8]
• Damages surrounding vegetation, rivers, communities, wildlife
• Displaces residents in that area
• Vulnerable to silt build up (silt is a granular material with the size between sand and clay with a mineral origin of quartz and feldspar) which can cause issues with the capacity and equipment involved with the plant
• Reliant on rain and snow
• Expensive up front

Types of Hydroelectric Plants

Impoundment

• • Impoundment is the most common type of hydroelectric power plant. It uses a dam to store river water in a reservoir where the water is then released into a turbine, spinning it, which activates a generator to produce electricity [5].

Diversion

• • Diversion is sometimes called run-of-river. It channels a portion of river through a canal or penstock so a dam is not always required [5].

Pumped Storage

• • Pumped storage works like a battery. By pumping water uphill to a reservoir that is at a higher elevation than the first one, it can store the electricity generated from other resources. When there is a high electrical demand, the water is released back into the lower reservoir, turning the turbine which will generate electricity [5].

What do you Need to Consider Before Building a Hydro Plant?

Availability of Water

• • Water is the primary requirement for a hydro-electric power station so there must be an availability of water that can provide huge quantities at a time [10].

River Path

• • Best location for a hydroelectric power plant should be along the path of a river, preferably at the river canyon or a place in the river where it starts to narrow. If the plant’s goal is to store maximum water on the dam, the volume of the basin located way above the dam should be calculated to ensure that the dam does not suffer from insufficient water supply [11].

Storage of Water

• • Due to this type of power plant being dependent on water, water must be stored through dams. The location of where this power plant is placed is dependent if a dam can fit within that area as well [10].

Cost and Geological Structure

• • The initial cost and type of land must be reasonably priced and can bear the capacity of a power plant (i.e. the ground should be able to withstand the weight of heavy types of equipment) [10]. If the dam’s walls are built on top of the rock’s structure, the walls should have the capability of holding and sustaining both visible and invisible forces (regardless if it’s man-made or natural) as well as be waterproof. The rock should be able to withstand an earthquake and block water leaking in, since this weakens the dam [11].

Transportation Facilities

• • Area selected must be accessible on transport facility so heavy machinery can be easily transported to the station [10].

Dam Materials

• • The materials used to construct the dam will determine whether it will last for long or effectively serve its purpose. The materials for the walls of the dam should be able to hold the force of water. Materials often used are cement and ballast. Using high-quality materials prevent disasters (e.g. water flooding) [11].

Technologies to Help Solve Hydropower Plant Problems

Hydropower Flexibility

• • Currently under development, these technologies are to help increase unit flexibility and operating range of a hydroelectric plant: stabiliser fins, an adjustable diaphragm installed in the draft tube cone, J-grooves, air injection/admission, axial water injection with high/low velocity and low/high discharge, tangential water injection at a cone wall, axial water injection with a counter-flow tangential component, ejector power plants for the excess flow rate, two-phase air-water injection along the axis, hydroelectric energy storage solutions, battery hybrids, and smart modelling and control solutions [12].

Hydropower Digitalization

• • Collecting and processing real-world data to adjust the working conditions of a hydropower turbine can provide advanced grid supporting services without compromising the station’s reliability and safety. By implementing this technology, the increase can lead to lower annual operational costs as well as significantly reduce the greenhouse gas emissions [12].

Generation with Current-Controlled Rotors

• • Novel power electronics with current-controlled power supplies can ensure better control of electrical machines (e.g. start and stop phases). An example is the hydropower plant Frades II plant in Portugal which is equipped with two pump-turbines, and an AC-excitation system controls the rotor power of the induction-motor generator [12].

Novel Small-Scale Hydropower Technologies

• • Benefits mini-grid and rural electrification strategies. Currently, the novel designs of gravity hydraulic machines, turbines, advanced designs, and operation strategies for pumps as turbines are being introduced [12].

Fish-Friendly Hydropower Technologies

• • Fish-friendly turbines include Archimedes hydrodynamic screws, water wheels and Vortex turbines for low head applications, the Alden turbine and the minimum gap runner turbine for higher heads [12].