Utilization of solar radiant energy, wind energy and small hydropower energy


① As a kind of energy, solar radiant energy has its own unique characteristics compared with coal, oil, natural gas, nuclear energy, etc. Its advantages can be summarized as follows.

a. Universal. The sun is shining on the earth, and solar energy is everywhere, which can be used on the spot. There is no need to search everywhere, let alone trains, ships, cars and other non-stop transportation day and night. This has great advantages in solving the energy supply in remote areas, villages and islands with inconvenient transportation.

b. Harmless. Using solar energy as energy, there is no waste residue, waste, waste water, exhaust gas, no noise, no harmful substances to the human body, so it will not pollute the environment, and there is no public hazard.

c. Long-term. As long as the sun exists, there is solar radiant energy. Therefore, the use of solar energy as energy can be said to be inexhaustible and inexhaustible.

d. Huge. The total amount of solar radiation energy that reaches the ground within a year is tens of thousands of times larger than the total amount of various energy sources currently consumed on the earth each year.

Its disadvantages are as follows.

a. Dispersibility. That is, the energy density is low. At noon on a clear day, on the ground perpendicular to the direction of sunlight, the solar energy that can be received by an area of ​​1m2 is only about 1kW on average. As an energy source, this energy density is very low. Therefore, in actual use, a set of solar energy collection equipment with a considerable area is often required. This makes the equipment occupies a large area, uses more materials, has a complex structure, and increases costs, which affects popularization and application.

b. Randomness. The direct solar radiant energy that reaches a certain ground is extremely unstable due to factors such as climate and seasons. This adds a lot of difficulties to large-scale utilization.

c. Intermittent. The direct radiant energy of the sun that reaches the ground changes with the alternation of day and night. This makes most solar equipment unable to work at night. In order to overcome the difficulties caused by the absence of direct solar radiation and weak scattered radiation at night, it is necessary to research and equip energy storage equipment to collect and store solar energy for use at night or on cloudy and rainy days.

②Wind energy. It is solar radiation that causes uneven heating of various parts of the earth, causing differences in temperature and air pressure in various places, and energy generated by air movement. Use wind turbines to capture wind energy, which can then be converted into electrical energy, mechanical energy, and thermal energy for use. The main forms of wind energy utilization are wind power generation, wind water lifting, wind heating, and sailing aids.

③Small hydropower. The so-called small hydropower usually refers to the general name of small hydropower stations and their supporting power grids. The Second International Conference on Small Hydropower held by the United Nations in 1980 determined the following three types of small hydropower capacity ranges: small hydropower stations (small), 1001~12 000k; small hydropower stations (mini), 101~1 000kW; micro hydropower stations (micro) ), below 100kw. According to the current regulations of my country’s National Development and Reform Commission, power stations with a total capacity of less than 50,000 kilowatts are small; those with a total capacity of 50,000 to 250,000 kilowatts are medium-sized; and those with more than 250,000 kilowatts are large-scale ones. Since the 1970s in my country, small hydropower generally refers to small hydropower stations with a single station capacity of less than 12,000 kilowatts and their supporting small power grids. However, with the development of the national economy, the capacity range of small hydropower has been increased to 50,000 kilowatts per station since 1996. Most of the small hydropower stations operated below the village level in rural my country are currently micro hydropower stations with a capacity of about 100 kilowatts. The development methods of small hydropower can be divided into three types: diversion type, dam type and mixed type according to the method of centralized water head.