The principal method of hydrogen gas production is steam reforming of fossil fuels, especially methane gas. At high temperatures, methane (CH4) reacts with steam in the presence of a metallic catalyst to produce hydrogen gas (H2) and carbon monoxide gas (CO), by the reaction: CH4 + H2O = CO + 3H2.
The venerable Kvaerner process produces hydrogen gas from natural hydrocarbon fuels. In a high-temperature plasma burner, the hydrocarbons are reduced to their essential components, carbon (C) and hydrogen gas, by the general reaction: CnHm + heat = nC +m/2 H2.
For example, methane is reduced as follows: CH4 + heat = C + 2H2.
Coal gasification is a process that produces coal gas, a mixture of carbon monoxide and hydrogen gases, from reaction of coal (essentially carbon) and oxygen (O2): 3C + O2 + H2O = H2 + 3CO.
This reaction is followed by the "shift reaction": CO + H2O = CO2 + H2. The CO2 is stored underground, and the hydrogen is used to power electricity-generating turbines.