Learn more about AHC
To help you learn more about hydrogen, we have answered some commonly asked questions and explained terminology used by the industry. For a comprehensive list, check out HyFAQ.
Hydrogen is an industrial raw material, and it can be combined with other things to create hydrogen-based fuels and feedstocks. There is already a market in hydrogen for various applications.
When we are talking about the potential for a hydrogen economy, we are talking about hydrogen in its pure form, where it is an energy carrier. Hydrogen stores energy which can be used at later times and can be transported to different places. In this way, hydrogen acts like a battery. However, unlike conventional batteries, hydrogen allows energy to be stored for long periods.
Hydrogen is versatile. It can be produced from a range of sources and physically converted between its gaseous and liquid states. It can displace natural gas for heating and cooking, and it can replace diesel and petrol (and other fuels) for cars, trucks, ships and planes. It can store excess electricity and feed this back into the grid when it is required. It can also be chemically converted into other forms, such as ammonia and methane. Hydrogen can be repeatedly converted across and between its physical forms and chemical forms.
When we combine these features with the possibility of hydrogen being created at scale with renewable or clean energy, we can see the great potential for hydrogen in the new energy ecosystem.
The International Energy Agency has identified around 70 million tonnes per year (MtH2/yr) of demand worldwide for “pure” hydrogen, where this is demand for hydrogen with only small levels of additives or contaminants. Hydrogen of this type is commonly used for refining oil and producing ammonia for fertilizer.
There is a further 45 MtH2/yr of hydrogen used in a mixture of gases, such as synthesis gas, for fuel or feedstock. This hydrogen is mainly used for producing methanol and steel.
Most hydrogen used today is produced from fossil fuels.
Traditionally hydrogen has been more expensive than conventional fuels to produce, store and transport. There are efficiency losses from converting electricity and natural gas to hydrogen, which make the case for hydrogen more challenging. It is also energy intensive to store and deliver.
Technically hydrogen is not an energy source; hydrogen carries energy produced from other sources. The hydrogen used in industry is manufactured through chemical processes: it is split from its bond with oxygen in water or separated from carbon in natural gas and coal.
Electricity is also an energy carrier. However, electricity is made up of electrons only, and hydrogen is composed of molecules and electrons. Hydrogen’s molecular structure is what allows its ability for storage for long periods and its potential to replace the current use of fossil fuels. Electricity is more limited in its uses and in its storage capabilities.
There are energy efficiency losses with conversions between hydrogen’s physical and chemical forms, and these can be significant. While hydrogen’s energy efficiency losses are less than those from processing petrol and diesel, they do make hydrogen less efficient than electricity when we look at the full processing path to its end use. This is one of the reasons why electricity and hydrogen are complementary, not competing, as energy carriers.
Electrolysis is a process where an electric current is used to drive a chemical reaction. In the production of hydrogen, an electrolyser is used to apply electricity to water to split it into its components (hydrogen and oxygen). The hydrogen is collected and the oxygen is allowed to harmlessly escape.
Electrolysis is a well understood process and has been used in various applications for over 150 years. For hydrogen production it is a newer technology, at least for large-scale use. There are different types of electrolysers, with different costs and efficiencies, and these can be expected to improve over time.
‘Clean’ generally means there are very low to zero carbon emissions in the production of the hydrogen. This term covers hydrogen both with and without carbon capture and storage.
The colour terms denote the relative cleanness of hydrogen. Globally these terms are not consistent. In Australia:
Yes, the difference is that a fuel cell vehicle generates electricity as it moves, through the chemical reaction in the fuel cell. A battery electric vehicle carries all of its electricity in a battery.
See here for how a fuel cell car works.
Power-to-X refers to where electricity is converted to other energy carriers or chemicals, and in the hydrogen industry this means through hydrogen produced by electrolysis.
The X refers to the result of the conversion, which can be fuel, heat, and chemicals.
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