Hydroelectric energy is the use of running water to generate electricity or power. Generally, water flowing from a waterfall is used to generate hydro energy on a large scale and provide electricity to cities, towns, etc. Humanity used this for millennia. There have been records of the same concept being used in ancient Greece about two thousand years ago, where people used this flowing water to rotate a wheel that turned ground wheat into wheat flour. More than 15% of the world’s electricity is generated from hydropower in this current day and age, and this value is set to increase by 3.1% every year for the next two decades.
The working principle behind hydroelectricity is that hydroelectric plants have a water reservoir, and a gate or valve is connected to the reservoir to adjust the flow of water coming from the reservoir, and a place the water ends up after it is released from the reservoir. By doing this process, water will be gaining potential energy before it is spilled from the dam, and then this water with potential energy is then converted into kinetic energy as the water flows down. Then, the blades of the turbine at the bottom are rotated by this water which is connected to a generator and thus electricity is generated.
There are 3 types of hydroelectric power plants and they are impoundment facility, diversion facility, and pumped-storage facility. Among these three types, an impoundment facility is the most common hydroelectric power plant. In an impoundment facility, the dam controls the water flow that is stored in a reservoir or a water pool. This water is released accordingly to the power requirements. Then, gravity pulls the water down, and this water, which has kinetic energy, rotates the turbine, which in turn powers the generator. A diversion facility doesn’t require a dam but uses canals to direct the water flow towards the turbines which power the generator. Speaking about a pumped-storage facility, it should be noted that, firstly, energy from other sources like wind, solar, and nuclear is collected and stored. By using this energy, water from a lower elevation is pumped into a higher elevation. Then, when there is an electricity demand, this water is then released back into the lower elevation, which rotates the turbines to generate more electricity.
There are a lot of advantages of hydroelectric power. First, since the fuel for rotating the turbine is water, which is a very clean fuel source, there will be no pollutants to pollute the environment, unlike fossil fuels, coal, or natural gas that pollute the environment. Moreover, most of the countries have water bodies, so they don’t need to rely on other countries for importing fuel. The energy created from hydropower is reliant on the water cycle, which is controlled by the sun, thus making it a renewable power source. So, it is better than fossil fuels as they won’t be depleted if used wisely and replenishes over time. Hydroelectric plants can immediately power the grids, so they can shift quickly from zero to maximum output. This provides a good backup in cases of electric outages or any power disruptions in the grid. Also, they have many other benefits like irrigation, water supply, and flood control. And the last advantage is that the places where there are hydroelectric plants also offer some recreational activities like boating, swimming, fishing, etc.
Despite all the benefits, there are some disadvantages of hydroelectric power as well. Firstly, the construction of a hydroelectric plant requires the usage of a lot of resources like money, time and construction, and land. Also, suitable places for the construction of hydroelectric plants are already taken. As water is the main force that drives the hydroelectric plant, it is dependent on precipitation levels that fluctuate year to year causing instability. Hydroelectric plants also cause minor to major changes in the water present in the reservoir, or the overall quality of it, or even changes in the temperature of the water. These changes would affect native plants and animals in the river. And as hydroelectric plants require a lot of land, people initially living in that area might be displaced from their homes.
Though there are some negative impacts like damaging the ecosystem due to hydroelectric power plants, they still are and will be a major contribution in the generation of energy as the energy produced is clean and better than fossil fuels. Also, as a long-term measure, we can practice watershed management, which involves soil conservation and catchment restoration that will reduce erosion and also the inflow of sediments into the reservoir. Other ways like sluicing, dredging, flushing, and also hydro suctioning can reduce the sedimental deposit to some extent in the reservoirs. The effect mostly will be concentrated in a particular area, unlike burning fossil fuels which affects the whole world, which is the lesser evil among the two.
As long as water tables are maintained normally, hydro energy will be a sustainable source for generating electricity as the Earth is filled with oceans, rivers, ponds, lakes, etc.