How can a drop of water be reused 19 times? An article reveals the mysteries of hydroelectric power generation
For a long time, hydroelectric power generation has been an important means of electricity supply. The river flows for thousands of miles, containing enormous energy. The development and utilization of natural water energy into electricity is called hydroelectric power generation. The process of hydroelectric power generation is actually an energy conversion process.
1、 What is a pumped storage power station?
Pumped storage power stations are currently the most technologically mature and stable high-capacity energy storage method. By constructing or using the existing two reservoirs, a drop is formed, and surplus electricity from the power system during low load periods is pumped to high places for storage. During peak load periods, electricity is generated by releasing water, known as the “super power bank”
Hydropower stations are facilities that use the kinetic energy of water flow to generate electricity. They are usually built at high falls in rivers, using dams to intercept water flow and form reservoirs, which then convert water energy into electricity through water turbines and generators.
However, the power generation efficiency of a single hydropower station is not high because after the water flows through a hydropower station, there is still a lot of remaining kinetic energy that is not utilized. If multiple hydropower stations can be connected in series to form a cascade system, a drop of water can be activated multiple times at different heights, thereby improving power generation efficiency.
What are the benefits of hydropower stations besides power generation? In fact, the construction of hydropower stations also has an important impact on the local economic and social development.
On the one hand, the construction of hydropower stations can drive local infrastructure construction and industrial development. The construction of hydropower stations requires a large amount of manpower, material resources, and financial investment, which provides local employment opportunities and market demand, drives the development of related industrial chains, and increases local fiscal revenue. For example, the total investment of the Wudongde Hydropower Station project is about 120 billion yuan, which can drive regional related investments of 100 billion yuan to 125 billion yuan. During the construction period, the average annual increase in employment is about 70000 people, forming a new driving force for local economic growth.
On the other hand, the construction of hydropower stations can improve the local ecological environment and people’s well-being. The construction of hydropower stations should not only follow strict environmental standards, but also carry out ecological restoration and protection, breed and release rare fish, improve river landscapes, and promote biodiversity. For example, since the establishment of the Wudongde Hydropower Station, more than 780000 rare fish fry such as the split belly fish, white turtle, long thin loach, and bass carp have been released. In addition, the construction of hydropower stations also requires the relocation and resettlement of immigrants, which provides better living conditions and development opportunities for the local people. For example, Qiaojia County is the location of the Baihetan Hydropower Station, involving the relocation and resettlement of 48563 people. Qiaojia County has transformed the resettlement area into a modern urbanization resettlement area, improved infrastructure and public service facilities, and improved the quality of life and happiness of the immigrant population.
A hydropower station is not only a power plant, but also a benefiting plant. It not only provides clean energy for the country, but also brings green development to the local area. This is a win-win situation that deserves our appreciation and learning.
2、 Basic types of hydroelectric power generation
The commonly used methods of concentrated drop include dam construction, water diversion, or a combination of both.
Build a dam in a section of the river with a large drop, establish a reservoir to store water and raise the water level, install a water turbine outside the dam, and the water from the reservoir flows through the water conveyance channel (diversion channel) to the water turbine at the lower part of the dam. The water drives the turbine to rotate and drive the generator to generate electricity, and then flows through the tailrace channel to the downstream river. This is the way to build a dam and build a reservoir for power generation.
Due to the large water level difference between the water surface of the reservoir inside the dam and the outlet surface of the hydraulic turbine outside the dam, a large amount of water in the reservoir can be used for work through a large potential energy, which can achieve high water resource utilization rate. The hydropower station established by using the method of concentrated drop in dam construction is called a dam type hydropower station, mainly consisting of dam type hydropower stations and riverbed type hydropower stations.
Establishing a reservoir to store water and raise the water level in the upper reaches of the river, installing a water turbine in the lower reaches, and diverting the water from the upstream reservoir to the lower water turbine through the diversion channel. The water flow drives the turbine to rotate and drive the generator to generate electricity, and then passes through the tailrace channel to the lower reaches of the river. The diversion channel will be longer and pass through the mountain, which is a way of water diversion and power generation.
Due to the large water level difference H0 between the upstream reservoir surface and the downstream turbine outlet surface, a large amount of water in the reservoir works through a large potential energy, which can achieve high water resource utilization efficiency. Hydroelectric power plants that use a concentrated head of water diversion method are called diversion type hydropower stations, mainly including pressure diversion type hydropower stations and non pressure diversion type hydropower stations.
3、 How to achieve “19 times reuse of a drop of water”?
It is understood that the Nanshan Hydropower Station was officially completed and put into operation on October 30, 2019, located at the junction of Yanyuan County and Butuo County in Liangshan Yi Autonomous Prefecture, Sichuan Province. The total installed capacity of the hydropower station is 102000 megawatts, which is a hydroelectric power project that comprehensively utilizes natural water resources, wind energy, and solar energy. And the most eye-catching thing is that this hydropower station not only generates electricity, but also achieves the ultimate efficiency of water resources through technological means. It repeatedly uses a drop of water 19 times, creating an additional 34.1 billion kilowatt hours of electricity, creating multiple miracles in the field of hydropower generation.
Firstly, the Nanshan Hydropower Station adopts the world’s leading hybrid hydropower generation technology, which comprehensively utilizes natural water resources, wind energy, and solar energy, and achieves systematic optimization and collaboration through technological means, thus achieving sustainable development.
Secondly, the hydropower station introduces cutting-edge technologies such as big data analysis, artificial intelligence, and the Internet of Things to finely manage various aspects such as unit parameters, water level, head, and water flow, in order to improve the operational efficiency of the hydropower station. For example, by establishing a constant head pressure automatic tracking and regulation technology, the water turbine generator unit maximizes the utilization of water resources while ensuring safe operation, achieving the goal of optimizing and increasing power generation through head optimization. At the same time, when the reservoir water level is low, hydropower stations establish a dynamic management system for the reservoir to slow down the rate of water level decline, improve recycling efficiency, and effectively increase power generation capacity.
In addition, the excellent design of Nanshan Hydropower Station is also indispensable. It adopts a P-M water turbine (Pelton Michel turbine), which is characterized by the fact that when water is sprayed onto the impeller, the cross-sectional area of the nozzle and the flow rate towards the impeller can be adjusted by rotation, so as to match the direction and speed of the water spray with the rotation direction and speed of the impeller, maximizing the efficiency of power generation. In addition, advanced technologies such as multi-point water spraying technology and the addition of rotating sections have been adopted, greatly improving power generation efficiency.
Finally, the Nanshan Hydropower Station also adopts exclusive energy storage technology. A set of emergency water level drainage facilities have been added in the water deposition area. Through the water storage reservoir, water resources can be divided into different time periods, achieving multiple functions such as water production and power transmission, and ensuring the economic and safe utilization of water resources.
Overall, the reason why Nanshan Hydropower Station has achieved the goal of “reusing 19 times a drop of water” is due to various factors, including the world’s leading hybrid hydropower generation technology, the application of cutting-edge technology, efficient management mechanisms, excellent design, and unique energy storage technology. This not only brings new ideas and models for the development of the hydropower industry, but also provides beneficial demonstrations and inspirations for the sustainable development of China’s energy industry.
Post time: Aug-14-2023
