A non-toxic and non-polluting gas, hydrogen is the most abundant chemical element in the universe. Like electricity, it is an energy carrier, and of all combustible fuels it has the highest energy density (roughly three times that of gasoline) combined with a low molecular weight (14 lighter than air). It is a safe chemical energy storage medium capable of storing large quantities of intermittent renewable energy that cannot be absorbed by the electricity grid.
Properties and Application
Hydrogen has been used as an industrial gas for more than 100 years. In 2000, the world production and use of hydrogen was estimated around 500 billion Nm 3 (normal cubic metres, cf. table), about 60 billion Nm 3 of this by the European Union (EU-15). Most of these quantities are ‘captive’ produced in bulk amounts for immediate consumption on site, mainly in chemical and petrochemical plants. On the other hand, road transport by truck to smaller customers is also an everyday business with proven codes of practice.
Due to its low volumetric energy density, hydrogen is stored and transported as a compressed gas (CGH2) or in liquefied state (LH2) at about -253°C. Hydrogen’s low boiling point makes liquefaction very energy intensive.
Most of the hydrogen is used as a raw material for the production of a wide range of substances (i.e. for non-energetic purposes). This is mainly ammonia and methanol synthesis, but also iron and steel production, treatment of edible oils and fats, glass and electronics industry etc.
The main indirect application of hydrogen for energy production is the petrochemical hydration of (conventional) fuels. The introduction of low-sulphur fuels, driven by regulations in North America and Europe (e.g. Clean Air Act and Auto Oil Program), has lead to a rising hydrogen demand in this field.
The direct use of hydrogen for energy purposes is mainly for power and heat generation. Today this sector only plays a minor role. This is likely to change over the coming decades when hydrogen may become an energy carrier as important as electricity to power electric fuel cell vehicles, including buses and other applications.