What is Hydrogen?
Features of Hydrogen
Hydrogen (chemical formula: H2) is a colorless, odorless, and non-toxic substance.
Its melting point is -259.14℃, its boiling point is -252.87℃, and it exists as a gas at room temperature.
Hydrogen has a molecular weight of 2.016 and is the lightest gas on Earth.
How hydrogen is produced
- Steam reforming
- This is a method of producing hydrogen from the hydrocarbons contained in fossil fuels and natural gas. When hydrocarbons such as methane (CH4) and naphtha are chemically reacted with steam, hydrogen, carbon monoxide, and carbon dioxide are produced. The method of refining hydrogen using this chemical reaction is called steam reforming. Steam reforming is a method that has long been used as an industrial method of producing hydrogen.
- Hydrogen Production from Coal
- It is a method of producing hydrogen by pyrolyzing coal. Coal is gasified by heating it in the presence of oxygen and steam. This coal gas further reacts with water and oxygen to produce hydrogen and carbon monoxide. The carbon monoxide produced then reacts with water to form hydrogen and carbon dioxide. By refining the gases generated through these processes, hydrogen can be extracted.
- Method of Producing Hydrogen by Water Electrolysis
- Water is decomposed into oxygen and hydrogen by passing an electric current through it. This phenomenon is utilized to produce hydrogen. Since pure water does not undergo electrolysis, water with dissolved electrolytes such as potassium hydroxide is used. Electrolysis requires a large amount of electricity.
Safety of hydrogen
Hydrogen is a flammable gas. However, it does not burn by itself; combustion occurs only when oxidizing gases such as oxygen are present. The concentration range at which hydrogen can explode in air is said to be between 4.0% and 75%.
Research and development of hydrogen
Hydrogen Fuel Cell
A hydrogen fuel cell is a battery that utilizes the reverse reaction of water electrolysis, using the electricity generated from the reaction between hydrogen and oxygen. The only byproduct of this reaction is water, meaning no carbon dioxide is produced, making it a clean energy source that reduces environmental impact. In the automotive field, hydrogen fuel cells are being developed as a new power source to replace internal combustion engines, and they are being used in electric vehicles such as passenger cars and buses. Additionally, hydrogen fuel cells have already been commercialized for use in household power generation systems.
Hydrogen Engine
In the automotive field, the development of hydrogen engine vehicles that use hydrogen instead of petroleum as fuel for internal combustion engines is also progressing. Like hydrogen fuel cell vehicles, hydrogen engines have the characteristic of not producing carbon dioxide.
Hydrogen Embrittlement of Metals
Hydrogen embrittlement and hydrogen erosion are two well-known phenomena involving hydrogen-related damage to metals. Both can lead to brittle fracture of metals. Hydrogen is easily absorbed into steel and has high diffusivity, making hydrogen-induced embrittlement a longstanding issue for industries dealing with metals. Consequently, the analysis of hydrogen content in metals has become one of the crucial research topics in the metal industry.
