What are the three main types of gas?

The three main common types of gas are natural gas, manufactured gas, and liquefied petroleum gas (LPG). Natural gas is a mixture composed of low-molecular-weight hydrocarbons, with sources including gas field gas, associated petroleum gas, condensate field gas, coalbed methane, and shale gas. Manufactured gas is a combustible gas produced by converting solid raw materials such as coal and coke, or liquid raw materials such as heavy oil and light oil, and must comply with relevant national standards. Liquefied petroleum gas is a by-product of oil extraction and refining processes, whose main components are propane, propylene, butane, and butene. It is gaseous at normal temperature and pressure, but easily liquefies when pressurized or cooled, making it convenient for storage and transportation. These three types of gas each have their own characteristics in the field of energy applications: natural gas is widely used due to its cleanliness and environmental friendliness; manufactured gas was once the main type of gas in the early days; and liquefied petroleum gas is often used for domestic cooking and small industrial purposes.