(Reuters.) Several industries, including steel and energy, are seeking large-scale hydrogen applications that will help to decrease carbon emissions and prevent global warming.

Hydrogen is the most abundant element of the universe. However, hydrogen can be very rare as a gas. Most gas production methods release large quantities of carbon dioxide.

Although hydrogen is colorless, each type of hydrogen has been assigned a colour to reflect its carbon footprint. The final is green hydrogen. This is made from power generated by renewable energy like wind and solar.

You can find more information about hydrogen in green, grey and blue here:

1. Green hydrogen

This hydrogen can come from renewable sources such as off-shore wind or floating electrolysis plants. You can store, pipe, transport, or carry green hydrogen by tankers to your customers, such as to fill hydrogen stations. It has been mostly used in experimental research.

2. Grey hydrogen

The steam-methane Reforming process, which is the industry standard, extracts grey hydrogen.

3. Blue hydrogen

While blue hydrogen can be produced the same as grey hydrogen, it has CO2 emissions that are stored underground or undersea. This is often used as a transitional method until green hydrogen production can be scaled up.

4. Turquoise hydrogen

This hydrogen is also known as low-carbon hydrogen and is used in very limited quantities. It is produced from natural gas, but is pyrolyzed to produce solid carbon.