Hydrogen, which is the most abundant and lightest element in the universe, is a clean energy that can be made with water, and then becomes water again after use.

Hydrogen is a secondary energy that can be produced in various ways by using primary energy. Typical methods of producing hydrogen include fossil fuel reforming, byproduct hydrogen utilization, and water electrolysis.

Natural gas is a naturally occurring mixed gas that accumulates underground. It is a gaseous fuel that is either directly collected from a gas field or vaporized from liquefied natural gas. It is categorized as PNG and LNG depending on the method of distribution from production to supply.