According to the basic form of energy, energy can be divided into primary energy and secondary energy.Primary energy refers to the energy resources existing in the original form in nature and not processed and converted, also known asNatural energy, such as coal, oil, natural gas, hydropower, etc[1]。
According to the basic form of energy, energy can be divided into primary energy and secondary energy.Primary energy, i.e. natural energy, refers to the existing energy in nature, such as coal, oil, natural gas, water energy, etc[1]。Secondary energy refers to energy products processed and converted from primary energy, such as electricity, gas, steam and various petroleum products.Primary energy can be divided into renewable energy (hydropower, wind energy and biomass energy) and non renewable energyRenewable energy(coal, oil, natural gas, oil shale, etc.).All energy that can be continuously supplemented or regenerated in a short period of time is called renewable energy.Wind energy, hydro energy, ocean energy, tidal energy, solar energy and biomass energy are renewable energy;The energy that has been formed over hundreds of millions of years and cannot be recovered in a short time is called non renewable energy.Such as coal, oil, natural gas, etc.With large-scale exploitation and utilization, their reserves are getting less and less, and they will always be exhausted[1]。Geothermal energy is basically non renewable energy, but from the perspective of the huge reserves in the earth, it has the nature of regeneration.The new development of nuclear energy will make the nuclear fuel cycle have the nature of proliferation.The energy of nuclear fusion is 5~10 times higher than that of nuclear fission. The most suitable fuel for nuclear fusion, heavy hydrogen (deuterium), is also abundant in seawater, which can be described as "inexhaustible".Nuclear energy is one of the pillars of the future energy system.Appeared in the 1970senergy crisisSince then, all countries have attached great importance toNon renewable energyAnd accelerate the research and development of renewable energy.
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Secondary energyIt refers to the energy obtained after processing and conversion of primary energy, includingelectric energy, gasolinediesel oil、Liquefied petroleum gasandHydrogen energyEtc.Secondary energy can also be divided into "process energy" and "energetic energy". Electric energy is the most widely used process energy, while gasoline and diesel are currently the most widely used energetic energy.
The secondary energy can also be explained as the energy used again from the primary energy, for example, the steam generated by coal combustion can drive the generator, and the generated electric energy can be called the secondary energy.
Or, after being used, electric energy is converted into wind energy through electric fans. At this time, wind energy can also be called secondary energy. There must be a certain degree of loss between secondary energy and primary energy.
The secondary energy is different from the primary energy. It is not directly taken from the nature, but can only be obtained after the processing and conversion of the primary energy. Therefore, strictly speaking, it is not "energy", but should be called "secondary energy".energy crisisRenewable energy does not involve secondary energy.
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coal
Coal is an ancient plant body buried underground due to crustal movement and evolved over a long period of time in an appropriate geological environment. Its carbon content is generally 46%~97%.Coal is an important fuel andchemical industryRaw materials.Coal is abundant on the earth.Coal is the coal reserves in major regions of the world today, which are decomposed from organic matter - plant debris growing in marshes or river deltas. The proportion of non Europe, Asia and Oceania, and North America is the highest. On the whole, the current coal reserves are estimated to be available for us for 200 years.
Coal is composed of organic matter and inorganic matter.Organic matter in coal is mainly composed of four elements: carbon (C), hydrogen (H), oxygen (O) and nitrogen (N), while some elements are composed of inorganic matter in coal, mainly including sulfur (S), phosphorus (P) and rare elements.In China, coal resources are mainly distributed in Shanxi, Shaanxi, Inner Mongolia, Heilongjiang, Liaoning, and Shandong provinces. The famous large coal mines include Datong Coal Mine, Dongsheng Coal Mine, Shenfu Coal Mine, etc.
petroleum
Oil is generally believed to be the organic matter "oil matrix" in the stratum, which is generated bit by bit and floated in the stratum after long-term refining at the ground temperature.Due to the buoyancy, the oil in the water slowly moves upward along the stratum or fault every year until it is blocked by the impermeable closed stratum.When there is more and more oil in this enclosure.
Petroleum is the fossil fuel next to coal. It is a natural yellow, brown or black flowing or semi flowing viscous flammable liquid hydrocarbon mixture.Oil is also called "crude oil".It can be processed into various fractions, including natural gas, gasoline, naphtha, kerosene, diesel, lubricating oil, paraffin and many other derivatives. It is the most important liquid fuel and chemical raw material.
natural gas
Natural gas is a kind of hydrocarbon, which is mostly produced with the exploitation of crude oil in the mining area. In the past, it could not be transported across the ocean, so it can only be used locally. If there is any surplus, it has to be burned and scrapped, which is a pity.If the natural gas is stored in artificial construction facilities, it is very likely to be dangerous in case of external damage such as earthquake, fire, etc.
Natural gas is another important primary energy besides coal and oil.It has a high calorific value when burning, and has less pollution to the environment. It is also an important chemical raw material.The generation process of natural gas is similar to that of oil, but it is easier to generate than oil.
Natural gas is mainly composed of methane, ethane, propane, butane and other hydrocarbons, of which methane accounts for 80%~90%.Natural gas can generally be divided into pure natural gas, oil associated gas, condensate gas and mine gas.
Hydroenergy
Water energy is a primary energy widely existing in nature.It can beHydropower stationConvenient conversion to high-quality secondary energy——electric energy。 "Hydropower" is both widely used conventional energy and renewable energy.Moreover, hydropower has no pollution to the environment, so hydropower is an inexhaustible high-quality energy among the world's many energy sources.
The utilization of water resources (commonly referred to as water conservancy development) is to make full and reasonable use of surface and underground water sources in rivers and waters to obtain the highest comprehensive benefits.Water energy utilization is a systematic project. Its task is to draw up the optimal water resource utilization scheme based on river planning and power system planning according to the needs of national economic development and water resource conditions.China has a vast land, many rivers, abundant runoff, huge drop, and rich hydropower resources.It is estimated that the theoretical reserves of China's river water energy resources are 676 million kW, and the annual power generation is 5920 billion kW · h. China ranks first in the world in terms of both the theoretical reserves of water energy resources and the potential hydropower resources to be developed.
The development mode of water resources is selected according to the concentrated drop, and there are roughly three basic modes, namely dike type, diversion type and hybrid type.However, these three development methods should also apply to certain natural conditions of the river reach.Hydropower stations built according to different development modes have different hydro junction layout and building composition, so they can be divided into three basic types: dike type, diversion type and hybrid type.
solar energy
Solar energy is both primary energy and renewable energy.It is rich in resources, which can be used for free, without transportation, and without any pollution to the environment.But solar energy also has two main disadvantages: one is low energy flow density;Second, its strength cannot be maintained constant due to various factors.These two shortcomings greatly limit the effective use of solar energy.
The use of solar energy has a long history.Solar energy utilization mainly includes solar energy heat utilization and solar energy light utilization.Solar heat is widely used, such as solar hot water, heating and cooling;Solar drying of agricultural and sideline products, medicinal materials and wood;Solar desalination of seawater;Solar thermal power generation, etc.Solar energy is mainly used for photovoltaic power generation and hydrogen production.
Wind energy
The sunlight shines on the atmosphere from top to bottom to make it warm up.Due to the rotation and revolution of the earth, uneven heating occurs everywhere near the ground, and the atmospheric temperature difference changes, causing air flow.Wind is formed when air flows horizontally.Since wind has a certain mass, speed and temperature, it has energy.About 2% of the solar radiation to the earth is converted into wind energy.Nevertheless, the amount of wind energy is still large.It is equivalent to more than 1000 times of the global annual coal consumption.
The use of wind energy has a long history. China is one of the first countries in the world to use wind energy.Wind energy is the use of wind turbines to convert wind energy into electrical energy, thermal energy, mechanical energy and other forms of energy for power generation, water lifting, navigation assistance, cooling and heating.
geothermal energy
The planet we live on is like a huge "thermos", which is cool outside and hot inside, and the more inside it is, the higher the temperature is.The heat energy contained in the earth's interior is called "geothermal energy".The earth continuously transports the heat energy contained in it to the ground through volcanic eruption and hot spring overflow.The hot spring, which is often said by modern people, is a kind of geothermal energy that human ancestors began to use long ago.However, the large-scale development and utilization of geothermal energy by human beings can be said to have just started.Therefore, geothermal energy is a new type of energy with great development potential.
At present, there are about 120 countries and regions in the world, and more than 7500 geothermal springs and wells have been discovered and exploited.At present, the development and utilization of geothermal energy are mainly in heating, power generation, breeding, greenhouse cultivation and bathing.The utilization of geothermal energy can be divided into geothermal power generation and direct utilization.
Ocean energy
The ocean is a huge treasure house of energy. Only the kinetic energy such as waves, tides and currents in the ocean and the energy storage of ocean temperature difference and salinity difference are astronomical.These marine energy sources are inexhaustible and renewable.Marine energy usually refers to the renewable natural energy contained in the ocean, mainly including tidal energy, wave energy, ocean current energy (tidal energy), seawater temperature difference energy and seawater salt difference energy.In a broader sense, ocean energy also includes wind energy over the ocean, solar energy on the ocean surface, and marine biomass energy.The causes are that the tidal energy and tidal current energy are derived from the gravitational changes of the sun and the moon on the earth, and the rest are derived from solar radiation.
The reserves of ocean energy in the total ocean water body are huge, but the energy per unit volume, unit area and unit length is small.That is to say, if you want to get large energy, you must get it from a large amount of seawater.It is renewable.Ocean energy comes from the universal gravitation between solar radiation energy and celestial bodies. As long as the sun, moon and other celestial bodies coexist with the earth, this energy will be renewable and inexhaustible.
Bioenergy
Bioenergy is an energy form of solar energy stored in biology in the form of chemical energy. It is an energy carried by biomass, which directly or indirectly comes from the photosynthesis of plants. Among various renewable energy sources, biomass energy is unique. It is the stored solar energy, but also the only renewable carbon source, which can be converted into conventional solid stateLiquid and gaseous fuels.
Biomass is the fourth largest energy source after coal, oil and natural gas, and plays an important role in the whole energy system.Biomass energy has always been one of the important energy sources for human survival. In terms of its energy equivalent, it ranks fourth only after coal, oil and natural gas. In the world energy consumption, biomass energy accounts for 14% of the total energy consumption, but more than 40% in developing countries.
nuclear energy
Nuclear energy, also known as atomic energy, is an efficient and lasting energy source.Nuclear power generation is to use the fission chain reaction of uranium 235 to release a large amount of heat energy, turn water into steam, and use the steam to drive the generator to generate electricity.There are many methods of nuclear power generation. Boiling water nuclear power generation and pressurized water nuclear power generation are used in Taiwan.In addition to power generation, nuclear energy has many applications in agriculture, medicine, industrial science and technology, etc.Such as agriculture: use it to keep vegetables and fruits fresh, improve varieties, prevent diseases and pests and other functions;In medicine, it can be used to kill cancer cells, treat cancer and other functional nuclear power plants. The investment amount of nuclear power plants is huge, the construction time is time-consuming, and the site suitable for construction is difficult to find.The biggest disadvantage is the disposal and safety of radioactive nuclear waste.The advantages are easy access to nuclear fuel, convenient transportation and storage of raw materials, low demand, and low expenditure on safety stock.
There are two methods for the practical use of nuclear energy: one is the heavy nuclear fission method that has reached the practical stage, which isFission reactorPrinciple of;The second is the light nuclear fusion method, which is still in the research and test stage. This is the principle of nuclear fusion reaction.
