Oxy-fuel refers to technology that burns pure oxygen with gaseous fuel. As compared to air, which contains 20.95% oxygen, higher temperatures can be reached using pure oxygen. Approximately the same total energy is produced when burning a fuel with oxygen as compared to with air; the difference is the lack of temperature-diluting inert gases. The most common fuel burned in a torch with oxygen is acetylene; even though it presents special handling problems, it has the greatest heat output.
The process has also been proposed as a method of capturing carbon dioxide from coal-fired electric power plants because the output flue gases from combustion in oxygen as opposed to air have a higher carbon dioxide content fraction. See Oxy-fuel combustion process.