From renewable hydrogen to carbon-hydrogen: a gas whose carbon footprint varies

Hydrogen: a gas that does not emit CO₂ when used.

Ecological transition is a key issue for decades to come. In this context, hydrogen presents a number of arguments. When used, it produces no pollutants or greenhouse gases. Its combustion produces only water. This is why it is called hydrogen (hydro = water/ gene = product).

Hydrogen is also the most abundant element in the universe. Unlike fossil fuels, it is therefore available in large quantities.

Carbon footprints vary depending on how hydrogen is produced

If driving a hydrogen vehicle does not emit CO₂, we must not forget to take into account how the hydrogen in its tank is produced! Indeed, the methods of production of this molecule vary, as does the electricity used to produce it. Hydrogen is, therefore, more or less clean depending on how it is produced.

The law now defines more precisely the categories of hydrogen: fossil fuel hydrogen, low-carbon hydrogen, renewable hydrogen. This infographic will help you understand better.

Fossil fuel hydrogen

Fossil fuel hydrogen is produced by one of the following processes:

• Steam reforming of natural gas
• Gasification of coal
• Electrolysis of water using fossil fuel electricity

For every 1 kg of hydrogen (H₂) produced, 11 to 20 kg of CO₂ is emitted.

Low-carbon hydrogen

Low-carbon hydrogen is produced from:

• Electrolysis of water using grid electricity produced with the energy mix of the area (nuclear, gas, coal)
• Electrolysis of water with CO₂ capture using grid electricity combined with methods of CO₂ capture

For every 1 kg of hydrogen (H₂) produced, between 4 and 10 kg of CO₂ are emitted.

Renewable hydrogen

Renewable hydrogen is produced from:

• Electrolysis of water using renewable grid electricity
• Recycled waste
• Biomass thermolysis

For every 1 kg of hydrogen (H₂) produced, between 2 and 4 kg of CO₂ are emitted.

Lhyfe’s renewable hydrogen, a 100% ecological hydrogen

Lhyfe green hydrogen is produced from a process of electrolysis of water using a direct connexion with a renewable energy production site. Where a direct connection is not possible, the H₂ production is synchronized with local renewable energy production, in partnership with the energy producer.

For every 1 kg of hydrogen Lhyfe produced, less than 1kg of CO₂ is emitted.

Green, blue, or grey hydrogen?

In media or social networks, hydrogen is given colors: it can be green, blue, or grey. Even if there is no official definition of these colors, here is some information to help understand:

• Grey hydrogen is manufactured from natural gas using a steam reforming process
• Blue hydrogen means it is produced by steam reforming as grey hydrogen but the CO₂ emissions from its production are captured
• Finally, green hydrogen is produced mainly by electrolysis of water from renewable electricity

How do you know if you’re using renewable hydrogen?

Like for electricity, it is possible to merely purchase a Guarantee of Origin separately from the hydrogen produced (e.g. you can buy a guarantee of origin for green electrons produced in Denmark six months ago). Hydrogen can be mixed with another type of hydrogen or gas.

It is therefore important to verify the traceability guarantee, which is transferred at the same time as the hydrogen produced. This ensures a real guarantee that the purchased hydrogen is not mixed with another gas.

The hydrogen produced by Lhyfe offers this guarantee of traceability. Indeed, its production is 100% ecological, because it is directly connected to the local renewable energy source.

Source: www.afhypac.org