The distribution of solar energy resources in China and the characteristics of solar energy
China is one of the countries rich in solar energy resources. More than 2/3 of the country’s total area has an annual sunshine time of more than 2000h, and an annual radiation amount of more than 5000MJ/m². According to statistical data analysis, the total amount of solar radiation received by China’s land area each year is 3.3 x 10³ ~8.4 x 10³ MJ/m², which is equivalent to a reserve of 240 x 104 billion tons of standard coal.
According to the standards of the Wind Energy and Solar Energy Evaluation Center of the National Meteorological Administration, China can be divided into the following four types of regions according to the distribution of solar energy resources.
Type I regions (resource-rich zone): the annual radiation amount is 6700 ~ 8370MJ/m², which is equivalent to the heat emitted by the combustion of 230kg standard coal, mainly including the Qinghai-Tibet Plateau, northern Gansu, northern Ningxia, southern Xinjiang, northwestern Hebei, and Shanxi North, southern Inner Mongolia, southern Ningxia, central Gansu, eastern Qinghai, southeastern Tibet and other places.
The second-class area (the resource-rich zone): the annual radiation is 5400 ~ 6700M/m², which is equivalent to the heat emitted by the burning of 180 ~ 230kg standard coal, mainly including Shandong, Henan, southeast of Hebei, southwestern Shanxi, northern Xinjiang, Jilin, Liaoning, Yunnan, northern Shaanxi, southeastern Gansu, southern Guangdong, southern Fujian, central and northern Jiangsu, and northern Anhui.
Three types of regions (general resource belts): the annual radiation is 4200 ~ 5400 MJ/m², which is equivalent to the heat emitted by 140 ~ 180kg of standard coal burning, mainly including the middle and lower reaches of the Yangtze River, Fujian, Zhejiang and parts of Guangdong. Spring and summer It is rainy and the solar energy resources are okay in autumn and winter.
Four types of regions: the annual radiation amount is below 4200MJ/m², mainly including Sichuan and Guizhou provinces, which are the regions with the least solar energy resources in China.
The first and second types of regions, the annual sunshine hours are not less than 2200h, are China’s solar energy resource-rich or relatively rich regions, with a large area, accounting for more than 2/3 of the total area of the country, and have good resource conditions for the use of solar energy.
Compared with other conventional energy and nuclear energy, solar energy has the following characteristics.
- The resources of solar energy are very rich. The solar radiant energy reaching the surface of the earth every year is equivalent to 130 trillion tons of standard coal, the total amount of which is the largest energy that can be developed in the world today.
- Solar power generation is safe and reliable. Estimated according to the current rate of nuclear energy produced by the sun, the hydrogen storage on the sun is sufficient for tens of billions of years to provide long-term and stable energy without suffering the impact of energy crisis or unstable fuel market.
- Solar energy is available everywhere, and it can be supplied nearby without long-distance transmission, which avoids the loss of long-distance power transmission lines.
- Conventional energy sources (such as coal, oil and natural gas, etc.) will emit a large amount of harmful gases when they are burned, and radioactive waste must be discharged when nuclear fuel is working, which will pollute the environment. The use of solar energy does not produce any waste, has no pollution, noise and other public hazards, and has no adverse effects on the environment. It is an ideal clean energy.
- Solar energy does not use fuel, and the operating cost is very low.
- The total radiant energy of solar radiation is very large, but its radiant energy density is small, that is, the incident power per unit area is small. Under standard conditions, the solar radiation intensity received on the ground is 1000 W/m2. If you need to get more power, you must occupy a larger light-receiving area.
- The randomness of solar radiation is relatively large. In addition to being affected by different latitudes and altitudes, the radiation energy will change throughout the year or even within a day. Therefore, when using solar light to generate electricity, in order to ensure the continuity and stability of energy supply, it is necessary to be equipped with a considerable capacity of energy storage devices, such as water storage tanks, batteries, etc.