Principle of hydropower generation and analysis of current situation of hydropower development in China

It has been 111 years since China started the construction of shilongba hydropower station, the first hydropower station in 1910. In these more than 100 years, from the installed capacity of shilongba hydropower station of only 480 kW to the 370 million KW now ranking first in the world, China’s water and electricity industry has made remarkable achievements. We are in the coal industry, and we will hear some news about hydropower more or less, but we don’t know much about the hydropower industry.

01 power generation principle of hydropower
Hydropower is actually the process of converting the potential energy of water into mechanical energy, and then from mechanical energy into electrical energy. Generally speaking, it is to use the flowing river water to turn the motor for power generation, and the energy contained in a river or a section of its basin depends on the water volume and drop.
The water volume of the river is controlled by no legal person, and the drop is OK. Therefore, when building a hydropower station, you can choose to build a dam and divert water to concentrate the drop, so as to improve the utilization rate of water resources.
Damming is to build a dam in the river section with large drop, establish a reservoir to store water and raise the water level, such as the Three Gorges Hydropower Station; Diversion refers to the diversion of water from the upstream reservoir to the downstream through the diversion channel, such as Jinping II hydropower station.
02 characteristics of hydropower
The advantages of hydropower mainly include environmental protection and regeneration, high efficiency and flexibility, low maintenance cost and so on.
Environmental protection and renewable should be the biggest advantage of hydropower. Hydropower only uses the energy in water, does not consume water, and will not cause pollution.
The water turbine generator set, the main power equipment of hydropower generation, is not only efficient, but also flexible in start-up and operation. It can start the operation quickly from the static state in a few minutes and complete the task of increasing and decreasing the load in a few seconds. Hydropower can be used to undertake the tasks of peak shaving, frequency modulation, load standby and accident standby of power system.
Hydropower generation does not consume fuel, does not need a lot of manpower and facilities invested in mining and transporting fuel, has simple equipment, few operators, less auxiliary power, long service life of equipment and low operation and maintenance costs. Therefore, the power production cost of hydropower station is low, which is only 1 / 5-1 / 8 of that of thermal power station, and the energy utilization rate of hydropower station is high, up to more than 85%, while the coal-fired thermal energy efficiency of thermal power station is only about 40%.

The disadvantages of hydropower mainly include being greatly affected by climate, limited by geographical conditions, large investment in the early stage and damage to the ecological environment.
Hydropower is greatly affected by precipitation. Whether it is in dry season and wet season is an important reference factor for thermal power plant’s power coal procurement. Hydropower generation is stable according to the year and province, but it depends on the “day” when it is detailed to the month, quarter and region. It cannot provide stable and reliable power like thermal power.
There are great differences between the South and the north in the wet season and the dry season. However, according to the statistics of hydropower generation in each month from 2013 to 2021, on the whole, China’s wet season is about June to October and the dry season is about December to February. The difference between the two can be more than doubled. At the same time, we can also see that under the background of increasing installed capacity, the power generation from January to March this year is significantly lower than that in previous years, and the power generation in March is even equivalent to that in 2015. This is enough to let us see the “instability” of hydropower.

Limited by objective conditions. Hydropower stations can not be built where there is water. The construction of a hydropower station is limited by geology, drop, flow rate, residents’ relocation and even administrative division. For example, the Heishan Gorge water conservancy project mentioned at the National People’s Congress in 1956 has not been passed because of the poor coordination of interests between Gansu and Ningxia. Until it reappears in the proposal of the two sessions this year, it is still unknown when the construction can start.
The investment required for hydropower is large. The earth rock and concrete works for the construction of hydropower stations are huge, and huge resettlement costs have to be paid; Moreover, the early investment is not only reflected in capital, but also in time. Due to the need for resettlement and coordination of various departments, the construction cycle of many hydropower stations will be much delayed than planned.
Taking Baihetan Hydropower Station under construction as an example, the project was initiated in 1958 and included in the “third five year plan” in 1965. However, after several twists and turns, it was not officially started until August 2011. Up to now, Baihetan Hydropower Station has not been completed. Excluding the preliminary design and planning, the actual construction cycle will take at least 10 years.
Large reservoirs cause large-scale inundation in the upper reaches of the dam, sometimes damaging lowlands, river valleys, forests and grasslands. At the same time, it will also affect the aquatic ecosystem around the plant. It has a great impact on fish, waterfowl and other animals.

03 current situation of hydropower development in China
In recent years, hydropower generation has maintained growth, but the growth rate in recent five years is low
In 2020, the hydropower generation capacity is 1355.21 billion kwh, with a year-on-year increase of 3.9%. However, during the 13th Five Year Plan period, wind power and Optoelectronics developed rapidly during the 13th Five Year Plan period, exceeding the planning objectives, while hydropower only completed about half of the planning objectives. Over the past 20 years, the proportion of hydropower in the total power generation has been relatively stable, maintained at 14% – 19%.

From the growth rate of China’s power generation, it can be seen that the growth rate of hydropower has slowed down in recent five years, basically maintained at about 5%.
I think the reasons for the slowdown are, on the one hand, the shutdown of small hydropower, which is clearly mentioned in the 13th five year plan to protect and repair the ecological environment. There are 4705 small hydropower stations that need to be rectified and withdrawn in Sichuan Province alone;
On the other hand, China’s large hydropower development resources are insufficient. China has built many hydropower stations such as the Three Gorges, Gezhouba, Wudongde, Xiangjiaba and Baihetan. The resources for the reconstruction of large hydropower stations may only be the “big bend” of the Yarlung Zangbo River. However, because the region involves geological structure, environmental control of nature reserves and relations with surrounding countries, it has been difficult to solve before.
At the same time, it can also be seen from the growth rate of power generation in recent 20 years that the growth rate of thermal power is basically synchronized with the growth rate of total power generation, while the growth rate of hydropower is irrelevant to the growth rate of total power generation, showing the state of “rising every other year”. Although there are reasons for the high proportion of thermal power, it also reflects the instability of hydropower to a certain extent.
In the process of decreasing the proportion of thermal power, hydropower has not played a great role. Although it develops rapidly, it can only maintain its proportion in the total power generation under the background of the large increase of national power generation. The reduction in the proportion of thermal power is mainly due to other clean energy sources, such as wind power, photovoltaic, natural gas, nuclear energy and so on.

Excessive concentration of hydropower resources
The total hydropower generation of Sichuan and Yunnan provinces accounts for nearly half of the national hydropower generation, and the resulting problem is that areas rich in hydropower resources may not be able to absorb local hydropower generation, resulting in a waste of energy. Two thirds of the waste water and electricity in major river basins in China comes from Sichuan Province, up to 20.2 billion kwh, while more than half of the waste electricity in Sichuan province comes from the main stream of Dadu River.
Worldwide, China’s hydropower has developed rapidly in the past 10 years. China has almost driven the growth of global hydropower with its own strength. Nearly 80% of the growth of global hydropower consumption comes from China, and China’s hydropower consumption accounts for more than 30% of the global hydropower consumption.
However, the proportion of such huge hydropower consumption in China’s total primary energy consumption is only slightly higher than the world average, less than 8% in 2019. Even if not compared with developed countries such as Canada and Norway, the proportion of hydropower consumption is far lower than that of Brazil, which is also a developing country. China has 680 million kilowatts of hydropower resources, ranking first in the world. By 2020, the installed capacity of hydropower will be 370 million kilowatts. From this perspective, China’s hydropower industry still has great room for development.

04 future development trend of hydropower in China
Hydropower will accelerate its growth in the next few years and will continue to increase in the proportion of total power generation.
On the one hand, during the 14th Five Year Plan period, more than 50 million kilowatts of hydropower can be put into operation in China, including Wudongde, Baihetan Hydropower Stations of the Three Gorges group and the middle reaches of Yalong River hydropower station. Moreover, the hydropower development project in the lower reaches of the Yarlung Zangbo River has been included in the 14th five year plan, with 70 million kilowatts of technically exploitable resources, which is equivalent to more than three Three Gorges hydropower stations, which means that hydropower has ushered in great development again;
On the other hand, the reduction of thermal power scale is obviously predictable. Whether from the perspective of environmental protection, energy security and technological development, thermal power will continue to reduce its importance in the power field.
In the next few years, the development speed of hydropower still cannot be compared with that of new energy. Even in the proportion of total power generation, it may be overtaken by the latecomers of new energy. If the time is prolonged, it can be said that it will be overtaken by new energy.

Post time: Apr-12-2022

Leave Your Message:

Send your message to us:

Write your message here and send it to us