Today, great progress has been made in the utilization of hydrogen energy. Since 1965, the United States began to develop liquid hydrogen engines, various types of jet engines and rocket engines have been successfully developed. The American space shuttle has successfully used liquid hydrogen as fuel.
China's Long March II and III also used liquid hydrogen as fuel. Replacing diesel with liquid hydrogen is also very active in the development of railway locomotives or general motors. Hydrogen cars run on hydrogen fuel and hydrogen fuel cells, which is also an important means to communicate the power system and hydrogen energy system.
Characteristics of hydrogen energy
1, the lightest weight: in the standard state, when the density is 0.0899g/l and the temperature is -252.7℃, it can become a liquid; If the pressure increases to several hundred atmospheres, liquid hydrogen can become metallic hydrogen.
2. The thermal conductivity is the best: it is 10 times higher than most gases.
3. The primary color of the universe: It is estimated that it constitutes 75% of the mass of the universe and is mainly stored in water in the form of compounds. Water is the most extensive substance on the earth. It is estimated that if all the hydrogen in seawater is extracted, the total heat generated is 9000 times greater than that released by all fossil fuels on the earth.
4. Recovery: The only waste discharged by cars using hydrogen energy is water, so hydrogen can be decomposed again and recovered again.
5. Ideal calorific value: except nuclear fuel, the calorific value of hydrogen is the highest among all fossil fuels, chemical fuels and biofuels, which is142,351kj/kg, which is three times that of gasoline.
Refer to the above content: Baidu Encyclopedia-Hydrogen Energy