With the increasing consumption of fossil fuels and the decreasing reserves of fossil fuels, there is an urgent need for mankind to find a new and abundant energy source that does not depend on fossil fuels. Hydrogen energy has become a pivotal energy source on the world energy stage. Hydrogen energy is a kind of secondary energy. It is produced by using other energy sources through certain methods. Unlike coal, oil and natural gas, which can be directly mined from the ground, it is an extremely superior new energy source. The main advantages of hydrogen energy are: high calorific value of combustion, the heat of combustion per kilogram of hydrogen is about 3 times that of gasoline, 3.9 times that of alcohol, and 4.5 times that of coke. The product of hydrogen combustion is water, which is the cleanest energy source in the world
The chemical element hydrogen, at the top of the periodic table, has an atomic number of 1, and it is the smallest of all atoms. The usual elemental form of hydrogen is hydrogen (H2), which is a colorless, odorless, and extremely flammable diatomic gas. Hydrogen is the lightest gas. It is gaseous at normal temperature and pressure, and liquid at ultra-low temperature and high pressure. At 0 degrees Celsius and one atmosphere of pressure, hydrogen weighs only 0.0899 grams per liter—just two-twentieth the weight of the same volume of air. Hydrogen is the most common element in the universe, and the most common element on Earth after oxygen. The abundant element, hydrogen and its isotopes, accounts for 84% of the total mass of the sun, and 75% of the mass of the universe is hydrogen. Hydrogen is non-toxic, and when it burns in the air, it produces a small amount of nitrogen oxides. It can be approximated that only water vapor is produced, which causes much less pollution than when other fuels are burned. It can basically be achieved when used in fuel cell electric vehicles” zero emission". The heat energy released per unit weight of hydrogen is about 3 times that of fossil fuels; the thermal efficiency is 10%-15% higher than that of conventional fossil fuels. Hydrogen has high volatility and high energy, and is an energy carrier and fuel. At the same time, hydrogen is also widely used in industrial production. Industry now uses 550 billion cubic meters of hydrogen per year, along with other substances to make ammonia and fertilizers, as well as gasoline refining processes, glass polishing, gold welding, weather balloon detection, and the food industry. Liquid hydrogen can be used as rocket fuel because hydrogen liquefies at -253°C. More importantly, hydrogen energy is a kind of renewable circulating fuel that can be transported and stored.
As an ideal new energy source, hydrogen energy has the following characteristics:
(1) Among all the elements, hydrogen is the lightest element and is safe and reliable. In the standard state, its density is 0.0899g/l; at -252.7°C, it can become a liquid. If the pressure is increased to hundreds of atmospheres, liquid hydrogen can become metal solid hydrogen. The molecular weight of hydrogen is 2, which is 1/14 lighter than air. Therefore, hydrogen leaking into the air will automatically escape from the ground and will not form agglomeration. And other fuel gas will gather on the ground and constitute a flammable and explosive hazard.
(2) Among all gases, hydrogen has the best thermal conductivity. Hydrogen has a thermal conductivity 10 times higher than that of most gases, making it an excellent heat transfer carrier in the energy industry.
(3) Hydrogen is the most common element in nature. It is estimated to make up 75% of the mass of the universe, and in addition to hydrogen in the air, it is mainly stored in the form of compounds in water, the most widespread substance on Earth. It is estimated that if all the hydrogen in seawater is extracted, the total heat it produces is 9,000 times greater than the heat released by all the fossil fuels on the earth.
(4) Hydrogen is an ideal calorific value, high temperature and high energy. Except for nuclear fuels, the calorific value of hydrogen is the highest among all fossil fuels, chemical fuels and biofuels, at 142,351kJ/kg, which is three times the calorific value of gasoline. The calorific value of 1kg of hydrogen is 34000Kcal, which is three times that of gasoline. The temperature of the oxyhydrogen flame is as high as 2800 degrees, which is higher than that of conventional liquid and gas. Hydrogen has the characteristic of changing temperature, and the flame temperature can be adjusted according to the melting point of the heated object.
(5) Hydrogen has good combustion performance, ignites quickly, has a wide flammable range when mixed with air, and has high ignition point and fast combustion speed. The flame of the oxyhydrogen flame is straight, the heat loss is small, and the utilization efficiency is high. Moreover, hydrogen is an active gas catalyst, which can be mixed with air to catalyze combustion of all solid, liquid and gaseous fuels. Accelerate the reaction process, promote complete combustion, and achieve the effect of increasing flame temperature, energy saving and emission reduction.
(6) Hydrogen itself is odorless and non-toxic, and compared with other fuels, hydrogen burns the cleanest. In addition to the production of water and a small amount of ammonia gas when hydrogen is burned, it will not produce environmentally harmful pollutants such as carbon monoxide, carbon dioxide hydrocarbons, lead compounds and dust particles, and will not cause human poisoning. A small amount of ammonia will not pollute the environment after proper treatment, and the water generated by combustion can continue to produce hydrogen, which can be recycled repeatedly.
(7) There are many forms of hydrogen energy utilization. It can not only generate heat energy through combustion, generate mechanical work in a heat engine, but also can be used as an energy material for fuel cells, or converted into solid hydrogen as a structural material. Substituting hydrogen for coal and oil does not require major modifications to existing technical equipment, and current internal combustion engines can be used with a little modification.
(8) Hydrogen can exist in various forms. Hydrogen can appear in gaseous, liquid or solid metal hydrides, which can adapt to the different requirements of storage and transportation and various application environments.
(9) Less hydrogen consumption. Long-distance high-voltage power transmission can be canceled, and long-distance and short-distance pipeline hydrogen transmission can be replaced, the safety is relatively improved, and the ineffective energy loss is reduced.
(10) The utilization rate of hydrogen is high. Hydrogen eliminates the noise source of internal combustion engines and hidden dangers of energy pollution, and the utilization rate is high.
(11) Hydrogen comes from a wide range of sources. Hydrogen can be produced by electrolysis of water, which is inexhaustible, and 1860 liters of hydrogen-oxygen gas can be prepared per kg of water; It is set to supply gas on demand and does not store gas; it has a wide range of applications and is suitable for all places where gas is required.
(12) Hydrogen can reduce the greenhouse effect. Replacing fossil fuels with hydrogen can minimize the greenhouse effect.
(13) The hydrogen transportation is convenient. Hydrogen can reduce the weight of the fuel and increase the payload of the vehicle, which can reduce the transportation cost. Considering the overall benefit of the whole process, the total social benefit is superior to other energy sources.