1、 Water energy resources
The history of human development and utilization of hydropower resources dates back to ancient times. According to the Interpretation of the Renewable Energy Law of the People’s Republic of China (edited by the Law Working Committee of the Standing Committee of the National People’s Congress), the definition of water energy is: the heat of wind and sun causes the evaporation of water, water vapor forms rain and snow, the fall of rain and snow forms rivers and streams, and the flow of water produces energy, which is called water energy.
The main content of contemporary hydropower resource development and utilization is the development and utilization of hydropower resources, so people usually use water power resources, hydraulic power resources, and hydroelectric power resources as synonyms. However, in reality, hydropower resources include a wide range of content such as hydro thermal energy resources, hydro energy resources, hydro energy resources, and seawater energy resources.
（1） Water and thermal energy resources
Water and thermal energy resources are commonly known as natural hot springs. In ancient times, people began to directly utilize the water and heat resources of natural hot springs to build baths, bathe, treat illnesses, and exercise. Modern people also use water and thermal energy resources for power generation and heating. Iceland, for example, had a hydroelectric power generation of 7.08 billion kilowatt hours in 2003, of which 1.41 billion kilowatt hours were generated using geothermal energy (i.e. water thermal energy resources). 86% of the country’s residents have used geothermal energy (water thermal energy resources) for heating. The Yangbajing power station with an installed capacity of 25000 kilowatts has been built in Xizang, which also uses geothermal (water and heat energy resources) to generate electricity. According to experts’ prediction, the low-temperature energy (using groundwater as the medium) that can be collected by the soil within nearly 100 meters in China every year can reach 150 billion kilowatts. At present, the installed capacity of geothermal power generation in China is 35300 kilowatts.
（2） Hydraulic energy resources
Hydraulic energy includes the kinetic and potential energy of water. In ancient China, the hydraulic energy resources of turbulent rivers, waterfalls, and waterfalls were widely utilized to construct machinery such as waterwheels, water mills, and water mills for water irrigation, grain processing, and rice husking. In the 1830s, hydraulic stations were developed and utilized in Europe to provide power for large-scale industries such as flour mills, cotton mills, and mining. The modern water turbines that directly drive centrifugal water pumps to generate centrifugal force for water lifting and irrigation, as well as water hammer pump stations that use water flow to generate water hammer pressure and form high water pressure for water lifting and irrigation, are all direct development and utilization of water energy resources.
（3） Hydroelectric energy resources
In the 1880s, when electricity was discovered, electric motors were manufactured based on electromagnetic theory, and hydroelectric power plants were built to convert the hydraulic energy of hydroelectric power stations into electrical energy and deliver it to users, ushering in a period of vigorous development and utilization of hydroelectric energy resources.
The hydropower resources we are referring to now are usually called hydroelectric resources. In addition to river water resources, the ocean also contains enormous tidal, wave, salt and temperature energy. It is estimated that the global ocean hydropower resources are 76 billion kilowatts, which is more than 15 times the theoretical reserves of land-based river hydropower. Among them, tidal energy is 3 billion kilowatts, wave energy is 3 billion kilowatts, temperature difference energy is 40 billion kilowatts, and salt difference energy is 30 billion kilowatts. At present, only the development and utilization technology of tidal energy has reached a practical stage that can be developed on a large scale in the utilization of marine hydropower resources by humans. The development and utilization of other energy sources still need further research to achieve breakthrough results in technical and economic feasibility and achieve practical development and utilization. The development and utilization of ocean energy that we usually refer to is mainly the development and utilization of tidal energy. The attraction of the Moon and Sun to the Earth’s sea surface causes periodic fluctuations in the water level, known as ocean tides. The fluctuation of seawater forms tidal energy. In principle, tidal energy is a mechanical energy generated by the fluctuation of tidal levels.
Tidal mills appeared in the 11th century, and in the early 20th century, Germany and France began building small tidal power stations.
It is estimated that the world’s exploitable tidal energy is between 1 billion and 1.1 billion kilowatts, with an annual power generation of approximately 1240 billion kilowatt hours. China’s tidal energy exploitable resources have an installed capacity of 21.58 million kilowatts and an annual power generation of 30 billion kilowatt hours.
The largest tidal power station in the world at present is the Rennes tidal power station in France, with an installed capacity of 240000 kilowatts. The first tidal power station in China, the Jizhou Tidal Power Station in Guangdong, was built in 1958 with an installed capacity of 40 kilowatts. The Zhejiang Jiangxia Tidal Power Station, built in 1985, has a total installed capacity of 3200 kilowatts, ranking third in the world.
In addition, in China’s oceans, the reserves of wave energy are about 12.85 million kilowatts, tidal energy is about 13.94 million kilowatts, salt difference energy is about 125 million kilowatts, and temperature difference energy is about 1.321 billion kilowatts. In summary, the total ocean energy in China is about 1.5 billion kilowatts, which is more than twice the theoretical reserve of 694 million kilowatts of land river hydropower, and has broad prospects for development and utilization. Nowadays, countries around the world are investing heavily in researching technological approaches to develop and utilize the enormous energy resources hidden in the ocean.
2、 Hydroelectric energy resources
Hydroelectric energy resources generally refer to the use of the potential and kinetic energy of river water flow to discharge work and drive the rotation of hydroelectric generators to generate electricity. Coal, oil, natural gas, and nuclear power generation require the consumption of non renewable fuel resources, while hydroelectric power generation does not consume water resources, but utilizes the energy of river flow.
（1） Global Hydroelectric Energy Resources
The total reserves of hydropower resources in rivers worldwide are 5.05 billion kilowatts, with an annual power generation of up to 44.28 trillion kilowatt hours; The technically exploitable hydropower resources are 2.26 billion kilowatts, and the annual power generation can reach 9.8 trillion kilowatt hours.
In 1878, France built the world’s first hydroelectric power station with an installed capacity of 25 kilowatts. So far, the installed hydropower capacity worldwide has exceeded 760 million kilowatts, with an annual power generation of 3 trillion kilowatt hours.
（2） China’s hydropower resources
China is one of the countries with the richest hydroelectric energy resources in the world. According to the latest survey of hydropower resources, the theoretical reserves of river water energy in China are 694 million kilowatts, and the annual theoretical power generation is 6.08 trillion kilowatt hours, ranking first in the world in terms of hydropower theoretical reserves; The technically exploitable capacity of China’s hydropower resources is 542 million kilowatts, with an annual power generation of 2.47 trillion kilowatt hours, and the economically exploitable capacity is 402 million kilowatts, with an annual power generation of 1.75 trillion kilowatt hours, both ranking first in the world.
In July 1905, China’s first hydroelectric power station, the Guishan Hydroelectric Power Station in Taiwan Province, was built with an installed capacity of 500 kVA. In 1912, the first hydropower station in Chinese Mainland, Shilongba Hydropower Station in Kunming, Yunnan Province, was completed for power generation, with an installed capacity of 480 kilowatts. In 1949, the installed capacity of hydropower in the country was 163000 kilowatts; By the end of 1999, it had developed to 72.97 million kilowatts, second only to the United States and ranking second in the world; By 2005, the total installed capacity of hydropower in China had reached 115 million kilowatts, ranking first in the world, accounting for 14.4% of the exploitable hydropower capacity and 20% of the total installed capacity of the national power industry.
（3） Characteristics of Hydroelectric Energy
Hydroelectric energy is regenerated repeatedly with the hydrological cycle of nature, and can be continuously used by humans. People often use the phrase ‘inexhaustible’ to describe the renewability of hydroelectric energy.
Hydroelectric energy does not consume fuel or emit harmful substances during production and operation. Its management and operation costs, power generation costs, and environmental impact are much lower than those of thermal power generation, making it a low-cost green energy source.
Hydropower energy has good regulation performance, fast start-up, and plays a peak shaving role in the operation of the power grid. It is fast and effective, reducing power supply losses in emergency and accident situations, and ensuring power supply safety.
Hydroelectric energy and mineral energy belong to resource-based primary energy, which is converted into electrical energy and called secondary energy. Hydroelectric energy development is an energy source that completes both primary energy development and secondary energy production simultaneously, with dual functions of primary energy construction and secondary energy construction; No need for a single energy mineral extraction, transportation, and storage process, greatly reducing fuel costs.
The construction of reservoirs for hydropower development will change the ecological environment of local areas. On the one hand, it requires the submergence of some land, resulting in the relocation of immigrants; On the other hand, it can restore the microclimate of the region, create a new aquatic ecological environment, promote the survival of organisms, and facilitate human flood control, irrigation, tourism, and shipping development. Therefore, in the planning of hydropower projects, overall consideration should be given to minimizing the adverse impact on the ecological environment, and hydropower development has more advantages than disadvantages.
Due to the advantages of hydropower energy, countries around the world are now adopting policies that prioritize the development of hydropower. In the 1990s, hydropower accounted for 93.2% of Brazil’s total installed capacity, while countries such as Norway, Switzerland, New Zealand, and Canada had hydropower ratios of over 50%.
In 1990, the proportion of hydroelectric power generation to exploitable electricity in some countries in the world was 74% in France, 72% in Switzerland, 66% in Japan, 61% in Paraguay, 55% in the United States, 54% in Egypt, 50% in Canada, 17.3% in Brazil, 11% in India, and 6.6% in China during the same period.
Post time: Sep-24-2024
