Over the last few years, hydrogen has become increasingly popular with the general public, and is represented by a multitude of colours depending on its production method: pink for nuclear power, turquoise for methane pyrolysis, blue for steam reforming with carbon sequestration, and green for renewable energies. There are as many colors of hydrogen as there are colors of the rainbow.

In this article, we will clarify the different names for hydrogen by presenting the molecule in terms of the European taxonomy.

First of all, what is hydrogen? Hydrogen is a storage energy, an energy carrier that offers a solution for storing and transporting energy that is stable over time in the form of dihydrogen (H2).

So how is hydrogen produced? There are two main methods of producing hydrogen:

• The “carbon” method, based on the steam reforming of natural gas, coal or oil. This method involves the partial combustion of fossil fuels with the addition of steam or air to extract synthesis gases.
• Methods based on the electrolysis of water, which can be described as “renewable or low-carbon” depending on the origin of the electricity used. This method consists of separating water molecules using an electrolyser and an electric current to recover dihydrogen. The term “low-carbon” can be added if the carbon-based hydrogen production method is coupled with carbon sequestration technologies. The term is also applicable when the production of hydrogen by electrolysis uses electricity from the grid in a country where the energy mix is low in carbon.

At present, hydrogen production is very unevenly distributed, dominated by carbon-based methods, which account for 90-95% of global hydrogen production. The remaining 5% is covered by water electrolysis.

It is important to stress the existence of hydrogen in its natural state, known as native hydrogen, which exists in underground cavities and is the result of chemical reactions between water and various minerals in the deep layers of the Earth’s mantle. However, the relevance of native hydrogen to decarbonisation remains to be demonstrated.

The market for renewable hydrogen is growing rapidly, with the installation of electrolysis capacity expected to reach between 170 and 365 GW by the end of the decade, according to the International Energy Agency. An essential element in the development of the hydrogen economy is the ability to certify the origin and production method of hydrogen through certification mechanisms. These do not use a colour system, but are based on the notion of carbon intensity, which is calculated in kilograms of CO2 equivalent per kilogram of hydrogen (CO2eq/kgH2).

The carbon intensity of hydrogen is strongly influenced by two factors: The presence or absence of CO2 sequestration technology for carbon-based production methods.

The type of electricity used for electrolysis. The energy mix of the producer country has a major impact on hydrogen produced from grid electricity. According to the European regulations currently being drawn up, the carbon intensity of low-carbon hydrogen (blue hydrogen) is below 3 kg CO2eq/kgH2. For renewable hydrogen (green hydrogen), it is below 2 kg CO2eq/kgH2.

First introduced in France in 2015, the Low Emission Zones (ZFE) have taken over from the Restricted Traffic Zones (ZCR). The ZFEs are a territorial scheme managed by local authorities and supported by the State, designed to delimit geographical zones in urban areas where the circulation of certain vehicles can be restricted according to the quantity of emissions of atmospheric pollutants and fine particles.

The legislative framework and objectives are defined in the Mobility Orientation Law (LOM) of 26/12/2019 and the Climate and Resilience Law of 22/08/2021. The main aim of deploying m-FTAs is to improve air quality in urban areas by reducing emissions of atmospheric pollutants and fine particles resulting from road mobility. In the long term, this will lead to a reduction in serious illnesses linked to exposure to fine particles and other atmospheric pollutants.

From a motorist’s point of view, the ZFE-m can have an impact on travel in two ways:

• A partial ban on traffic in urban areas in the event of a pollution peak, where differentiated traffic is decreed by the prefect for the duration of the pollution peak.
• A permanent ban on access to the urban area at times defined by the local authorities.

In France, the Low Emission Zone initiatives are monitored and enforced by a system of air quality certification known as Crit’air. This certification takes the form of a sticker to be affixed to the vehicle’s windscreen. Vehicles are categorised according to their emissions of atmospheric pollutants, fine particles and nitrogen oxides. This summary will focus solely on the classification of diesel and petrol light commercial vehicles.

An exhaustive classification is available in article L.318-1 and R.318-2 of the Highway Code:

• Crit’air 0: Electric or hydrogen.
• Crit’air 1: Petrol, Euro 5 and 6 standard from 01/01/2011; diesel: not eligible.
• Crit’air 2: Petrol, Euro 4 standard between 01/01/06 and 31/12/2010; diesel: Euro 5 and 6 standard from 01/01/2011.
• Crit’air 3: Petrol, Euro 2 and 3 standard between 01/10/97 and 31/12/2005; diesel: Euro 4 standard between 01/01/2006 and 31/12/2010.
• Crit’air 4: Diesel, Euro 3 standard between 01/01/2001 and 31/12/2005.
• Crit’air 5: Diesel, Euro 2 standard between 01/10/97 and 31/12/2000. Not classified: Petrol and diesel: Euro 1 and earlier.

Article R411-19-1 of the Highway Code already provides for a penalty mechanism in the event of non-compliance with the EPZs. Any infringement of the ZFE-m is punishable by a class 3 fine with no loss of points on the driving licence. Fines are set at €68 for light vehicles and €135 for heavy vehicles, with a system of reductions and increases ranging from €45 to a maximum of €450.

In response to these constraints, the State and local authorities are offering a range of schemes to help people living in EPZs to buy cleaner vehicles, with an added bonus.

Here are the details:

• Ecological bonus: up to €4,000 for an electric or hydrogen-powered van.
• Conversion allowance: up to €9,000 for the purchase of an electric or hydrogen-powered vehicle, on condition that an old vehicle is scrapped.
• ZFE bonus: €1,000 extra assistance.
• Local authority ZFE bonus: up to €2,000.

In addition to the aid provided by the State and local authorities, a series of national and local exemptions have been introduced to enable professionals who have no zero-emission alternative to maintain their activity in urban areas. You can find the list of local exemptions on your local council’s website.

Here is the list of permanent national exemptions:

• General interest vehicles as defined in article R. 311-1 of the Highway Code (Gendarmerie, customs, fire brigade, SNCF, GDF, SMUR and other emergency medical services).
• Ministry of Defence vehicles.
• Vehicles carrying a “mobility and inclusion” card bearing the words “parking for the disabled”.
• Low-emission public transport vehicles.
• Vehicles with an equivalent range in all-electric mode in the city of more than fifty kilometres.