The name hydrogène (from ancient Greek ὕδωρ - water and γεννάω - I give birth) - “giving birth to water.”

Hydrogen is a chemical element; it has symbol H and atomic number 1. Hydrogen is the most abundant chemical substance in the universe, constituting roughly 75% of all normal matter. Stars such as the Sun are mainly composed of hydrogen in the plasma state. Most of the hydrogen on Earth exists in molecular forms such as water and organic compounds.

Hydrogen is the lightest gas: it is 14.5 times lighter than air. The smaller the mass of the molecules, the higher their speed at the same temperature. As the lightest, hydrogen molecules move faster than the molecules of any other gas, due to which they can transfer heat from one body to another faster. It follows that hydrogen has the highest thermal conductivity among gaseous substances. Its thermal conductivity is approximately 7 times higher than the thermal conductivity of air.

The hydrogen molecule is diatomic - H2. Under normal conditions, it is a colorless, odorless, and tasteless gas. Density 0.08987 g/l (n.s.), boiling point −252.76 °C, slightly soluble in water - 18.8 ml/l at n.s. The solubility of hydrogen in water increases with increasing pressure and decreases with increasing temperature.

Hydrogen is highly soluble in many metals (Ni, Pt, Pd, etc.), especially in palladium (850 volumes of H2 per 1 volume of Pd). The solubility of hydrogen in metals is related to its ability to diffuse through them; Diffusion through a carbon alloy (for example, steel) is sometimes accompanied by destruction of the alloy due to the interaction of hydrogen with carbon (so-called decarbonization). Practically insoluble in silver.

What are the isotopes of hydrogen ?

We choose to name elements according to their atomic number. Anything that has an atomic number of 1 we can call a type of hydrogen. The atomic number is the number of protons. A neutrally charged atom has the same number of electrons as protons. (We will ignore charged atoms, ions, and we won’t bother with excited electronic, much less nuclear, states.). The chemical properties of an atom are mostly determined by the number of electrons, which is why we ended up naming elements according to atomic number instead of something else like atomic weight. We can say, then, that any type of hydrogen has one proton and one electron per neutral atom, and the different types will behave very similarly from a chemical perspective. So what’s the difference between the different types? The number of neutrons in an atom of a particular type is the difference. We choose to call atoms that differ only in the number of neutrons isotopes.

These isotopes have their own chemical symbols: protium - H, deuterium - D, tritium - T.

H-1 is often called protium (H). H-1 has 1 proton and no neutrons. It is by far, by more than 1000-to-1, the most abundant naturally occurring isotope. H-1 is the smallest atom in the universe. It is stable, meaning that, left alone, it will remain H-1.

H-2 is often called deuterium (D). It has one proton and one neutron. It is the second most abundant naturally occurring type of hydrogen. It is stable. Even though it is rarer than H-1, if you are holding a cup of water, you are holding more than a trillion-trillion deuterium atoms. When a water molecule has two deuterium atoms and one oxygen, we call it heavy water, which is about 10% heavier than regular water and has a particularly important role in nuclear reactors.

H-3 is often called tritium (T). It has one proton and two neutrons. It is the least abundant form of naturally occurring hydrogen, and it is extremely rare in our world: about 1-trillionth-trillionth of the abundance of H-1. Tritium is unstable: it is mildly radioactive. It decays by emitting a beta particle (fast electron) and an electron-neutrino, turning one of its neutrons into a proton, and becoming an atom of helium. The decay is very slow; it takes an average of more than 12 years for half of a starting amount of tritium to convert to helium (>12 years half-life for tritium). Tritium decays just fast enough to illuminate things like watch numbers and other self-illuminating items. After 12 years, the illumination in those items will be reduced by half. It has other significant roles that we’ll leave alone.

H-4, 5, 6, and 7 are very short-lived types of hydrogen (half-lives of around 10E–23 to 10E–22 seconds). They have 3, 4, 5, and 6 neutrons respectively (but still just 1 proton). We can create them in a laboratory but they don’t occur at detectable levels in nature. They decay by kicking out excess neutrons, generally producing tritium or deuterium via a single decay event.

In summary, there are 7 different types of hydrogen that we have observed/detected. Only two are stable Only three are detectable as naturally occurring, and only those same three matter in everyday life. The structural differences in the 7 different types are in the numbers of neutrons in each atomic nucleus.

Natural molecular hydrogen consists of H2 and HD (deuterium hydrogen) molecules in a ratio of 3200:1. The content of pure deuterium D2 molecules in it is even less; the ratio of HD and D2 concentrations is approximately 6400:1.

Spin isomers of molecular hydrogen

Molecular hydrogen exists in two spin forms (modifications): orthohydrogen and parahydrogen. Modifications differ slightly in physical properties, optical spectra, and also in neutron scattering characteristics. In the molecule of orthohydrogen o-H2 (English o-H2) (mp -259.10 °C, bp -252.56 °C) the spins of the nuclei are parallel, and in parahydrogen p-H2 (English p -H2) (mp. −259.32 °C, bp. −252.89 °C) - opposite to each other (antiparallel). An equilibrium mixture of o-H2 and p-H2 at a given temperature is called equilibrium hydrogen p-H2 (English e-H2), and a mixture of 75% ortho-hydrogen and 25% para-hydrogen is called normal hydrogen n-H2 (English n- H2).

Molecules of pure protium, deuterium and tritium can exist in two allotropic modifications (differing in the mutual orientation of the spins of the nuclei) - ortho- and parahydrogen: o-D2, p-D2, o-T2, p-T2. Hydrogen molecules with a different isotopic composition (HD, HT, DT) do not have ortho- and para modifications.

Geological hydrogen

There are potentially huge reserves of geological hydrogen in the world (also called native hydrogen). It is found literally everywhere, which means it has an almost inexhaustible supply and the ability to be extracted from a wide range of substances. The potential of natural hydrogen in the Earth's interior has not been evaluated until now and has not attracted much attention of researchers because of the existing prejudice that free hydrogen in nature is rare and in low concentrations due to the fact that it diffuses rapidly and easily chemically combines with other elements and molecules, which makes it difficult to keep it in a gaseous state below the surface. Furthermore, hydrogen, hydrogen sulfide and methane are consumed in hydrothermal vents to provide food for microbes. 

However, in recent years, free, chemically unbound natural hydrogen is known to be found in the form of diffusion seeps and underground accumulations intersected by drilling wells. These known accumulations are located in a wide variety of geological environments, suggesting that there may be different mechanisms for the production of natural hydrogen. Proposed sources or mechanisms include, but are not limited to: 

Serpentinization 

Radiolysis 

Rock Fracturing (Cataclasis) 

Magma Degassing 

Crust Weathering 

High-Temperature Basalt Alteration 

Lava–Seawater Interaction 

Crystallization 

Pyrite Formation 

Decomposition of organic matter 

Natural seeps 

High hydrogen fluxes in drillholes and mines 

Adsorbed Hydrogen 

Hydrogen in Inclusions

Emanations of Hydrogen have been observed in many places. Many hydrogen emergences have been identified on mid-ocean ridges. Geological hydrogen degassing is distributed between mid-ocean ridges and faults with account 90% , 2% by volcanoes and 8% by ring structures.

Biomass of hydrogen-oxidizing microorganisms

Hydrogen-oxidizing microorganisms, in some sources they are called hydrogen bacteria, are a group of microorganisms that include not only bacteria, but archaea that use the oxidation of molecular hydrogen to produce energy. 

The number of microorganisms capable of oxidizing hydrogen is enormous. Hydrogen is an attractive substrate for growth because it contains a large amount of energy. Hydrogen oxidation is a chemosynthesis reaction and is one of the important inorganic energy sources capable of releasing a relatively large amount of energy (237 kJ/mol-h2). Therefore, hydrogen oxidizing organisms play a key role in the ecosystem. The flow of molecular hydrogen as it leaves the Earth significantly affects the properties of soils, marine silt, sedimentary rocks, etc. 

Currently, microorganisms that oxidize hydrogen attract much attention due to the use of biotechnologies in different directions.

Hydrogen explosions 

Hydrogen gas (dihydrogen or molecular hydrogen) is highly flammable. The enthalpy of combustion is 286 kJ/mol. Hydrogen gas forms explosive mixtures with air in concentrations ranging from 4 to 74%. The auto-ignition temperature in air is 500 °C (932 °F). Essential to the consideration of accidental consequences is the estimation of hazards and hazard levels, e.g., overpressures, thermal radiation, and the estimation of the damage level or the vulnerability of the receiving objects. In chemical explosions, which are usually exothermal oxidation reactions, a great portion of the combustion energy is carried by the developing blast wave which is uniformly distributed in all directions. Depending on the various types of combustion processes (slow deflagration or fast turbulent flame or detonation), the pressure history will be different. It is characterized by the peak overpressure and the pressure increase/decay rate. This effect is strongest at ground level (hemispherical) explosions where due to reflection the respective yield ratio can be twice as high as for a spherical explosion.

Deflagration and detonation differ in peak overpressure, in the duration of the impulse (time-integrated pressure), in the steepness of the wave front, and in the decrease of overpressure with propagation distance. Secondary blast wave parameters are the peak reflected pressure, peak dynamic (blast wind) pressure, shock front velocity, and blast wave length.

Deflagration

In a deflagration with flame speeds of 1-10 m/s, the volume expansion of the gas acts like a piston displacing the unburnt gas. The deflagration pressure wave in a confined space is characterized by a slow increase of pressure and fluid velocity in the region preceding the flame front. The pressure in the vessel is independent of the location and mainly determined by the fraction of burnt gas. The static pressure loading in slow deflagration processes is described by the “adiabatic, isochoric, complete combustion” (AICC) pressure representing an upper bound in a confined space. A mitigation of the AICC pressure is given by incomplete combustion, venting, radiation/conduction heat losses, or the addition of diluents. Therefore the maximum static pressure will be generally lower than the AICC pressure. On the other hand, initial turbulence increases the degree of combustion and thus the pressure. The peak pressure in a closed vessel for most hydrocarbon mixtures is in the order of 0.8 MPa, sufficient for many buildings to exceed their failure limits. For a hydrocarbon-oxygen mixture, it is even 1.6 MPa. A hydrogen-air mixture, initially at NTP, will reach a pressure of 0.815 MPa; its volume will increase by a factor of 6.89 (BakerWE:1983).

The pressure buildup depends on the flame propagation and the degree of confinement. Particularly hazardous configurations are those, which are heavily confined like tubes, pipes, or channels, where – if long enough – even in insensitive methane-air mixtures, high flame speeds and pressures can be reached. Venting can reduce the pressure.

Inside a spherical vessel, the pressure rise following the ignition of a flammable mixture is proportional to the cube of the burning velocity. In pipes with no obstacles, the transition distance increases with increasing diameter (example: 8 m for propane-air mixture in a 50 mm diameter pipe) (MoenIO:1993). The effective burning velocity must be as high as ~ 100 m/s to produce significant blast overpressures of 10 kPa. Comparing explosion tests in tubes and in spherical vessels, it was observed that pressures are generally lower in a spherical propagation of the gas mixture (unconfined) than in a planar propagation. The pressure behind the flame front is decaying away from the flame, since wave energy dissipates.

The combustion of a hydrogen-air mixture in an unconfined vapor cloud explosion (UVCE) typically liberates only a fraction of 0.1-10 % of its thermal energy content, in most cases less than 1 % (LindCD:1975). Depending on the combustion mode (deflagration/detonation), the explosion is connected with a more or less destructive pressure shock wave.

Fast deflagration

In the intermediate stage of a fast deflagration with the flame front still traveling at subsonic speed, a preceding shock wave is developing in the still unburnt mixture. The peak overpressure is lower, the pressure drop, however, takes place over a longer period of time. This means that the impulse, i.e., the integral of pressure over time, which is a measure for the load upon a structure, is about the same in both cases. The peak overpressure increases with increasing flame speed. Transient pressures can be locally higher than the AICC pressure. Inhomogeneities can result in local detonations decaying to deflagrations. When the shock wave leaves the cloud, it turns into an expanding decaying wave. In the long-distance range, the pressure wave for both deflagration and detonation exhibits about the same shape decaying with 1/r.

Local explosions like from jet flames result in locally high pressures and can also result in high flame speed in less confined areas and may even trigger a detonation wave.

Detonation

In contrast, the detonation is a combustion mode with the flame traveling at supersonic speeds in the order of 2000 m/s. The flame front proceeds by shock wave compression of the unburnt gas. It is characterized by a distinct pressure spike and a subsequent almost exponential decrease. The shock wave, which is at the same time the flame front, is followed by the reaction zone, in which a pressure discontinuity is observed where the pressure even drops to values lower than atmospheric pressure (“molecular collapse”) due to the much denser oxidation product (water) upon hydrogen combustion. The essential parameters are peak overpressure and positive/negative phase of the specific impulse depending on the liberated explosion energy. The combustion process is completed without an expansion of the gas cloud. Peak overpressures in the near field are typically in the range of 1.5-2 MPa. The pressure wave gradually decays and eventually turns into an acoustic wave.

In geometries which allow the transition from deflagration to detonation, pressures near the location where detonation takes place, may be much higher than the CJ (Chapman-Jouguet) pressure of a stabilized (and idealized) detonation wave, which is due to a pre-compression effect by the propagating shock wave (VanWingerdenCJM:1999).

In confined spaces, peak pressures can range between “normal” deflagration peak pressure and very high pressures following DDT. Worst case is considered the DDT on a reflected shock wave produced by a fast flame with an estimated peak pressure to be by a factor of 10 higher than the detonation pressure. The transfer of a detonation wave into adjacent mixtures is possible and has been observed for planar clouds, whereas in spherical clouds, fast deflagrations are more likely to occur.

An explosion in a vessel which is connected by a small opening to another vessel creates a peak overpressure and a pressure increase rate much higher than in a single vessel explosion, a phenomenon known as “pressure piling”. A pressure of more than 3.5 MPa was measured in a two-chamber geometry for a stoichiometric hydrocarbon-air mixture, where 0.8 MPa were expected for the explosion in a single vessel. Unlike the length of the interconnecting tube, its diameter is pertinent for the peak overpressure.

Hydrogen gas cloud

In reality, a gas cloud shows the typically expected features of a non-premixed, inhomogeneous concentration distribution, air entrainment at the boundaries, and stratification if evolving from a pool of liquefied gas. Furthermore in case of an explosion, a real gas cloud is not an “ideal” explosion source due to a larger-than-infinitesimal volume and a lower energy density and energy deposition rate, thus leading to non-ideal blast waves. Deviations from the ideal situation are able to either enhance or to attenuate the pressure buildup. Non-stoichiometry as well as ignition at the cloud edge will certainly have a damping effect on the pressure buildup. The maximum blast impulse, which becomes larger with increasing shock duration, is not near the explosion center, but about 13-15 charge radii. A near-ground flat long-stretched cloud of heavy gases or vaporized cryogens may experience multi-point ignition connected with a sequence of pressure peaks, and more turbulence-generating terrain roughness or obstacles in the flow path, both effects of which lead to an enhancement of the pressure buildup.

Unlike a heavy gas cloud which would be of a pancake form, a hydrogen vapour cloud would soon cover an area, which is larger than that of a hemispherical cloud with the same explosive inventory. Only in case of just vaporized LH2 after a large-scale spill, the cold gas cloud would travel and stretch near ground, until sufficient air has entrained from the outside to make the gas positively buoyant and develop soon to a vertically stretched cloud shape.

The flame spreading in a non-spherical cloud is spherically until it reaches the cloud edge at some point; then it continues in the direction, where still gas can be found. The pressure is decreasing immediately behind the flame front because of the upward expansion of the combustion products.

Technological features of hydrogen fuel

In 1874, science fiction author Jules Verne set out a prescient vision that has inspired governments and entrepreneurs in the 145 years since. In his book The Mysterious Island, Verne wrote of a world where “water will one day be employed as fuel, that hydrogen and oxygen which constitute it, used singly or together, will furnish an inexhaustible source of heat and light, of an intensity of which coal is not capable”.

Hydrogen or dihydrogen, is carbon dioxide free, and it has long been touted by some as a fuel source for clean energy. Hydrogen is an ideal source of energy and an environmentally friendly fuel.The specific heat of combustion of hydrogen is approximately 140 MJ/kg (upper) or 120 MJ/kg (lower), which is several times higher than the specific heat of combustion of hydrocarbon fuels (for methane - about 50 MJ/kg).

Yet, shifting society towards a hydrogen energy-based one requires overcoming some significant technical issues.

Hydrogen is the most dangerous gas from the point of view of explosiveness. It makes explosive mixture with air. It burns without color. It tends to leak. It has no odor. When leaking it tends to self-ignite (it will ignite when leaking from pipe or tank without external spark). It is super hard to work with. Gaseous one require very high pressure to keep significant amount of hydrogen in practical volume. When leaking, it tends to be captured in buildings near the ceiling and then explode when minimum amount for explosive mixture is reached.

Liquid one is super cold and is very hard to pump because its very not dense and have very low boiling temperature (thus its very prone to cavitation), plus liquefaction is not easy either. Temperature of liquid hydrogen is so low that air turns to ice on contact with tank containing liquid hydrogen (if its not thermally isolated by special foam).

An essential is structural and functional materials that produce, store, transport and preserve hydrogen. To develop advanced materials for hydrogen-related applications, a fundamental understanding of how hydrogen behaves in materials is crucial. Hydrogen embrittlement (HE) has been studied for decades, yet the complex nature of HE phenomena. Detecting atomic state hydrogen – the smallest atom in the universe – with X-rays or lasers is challenging due to its unique characteristics.

First Hydrogen Standards

There are numerous interfaces between hydrogen standards and those from other fields, like pressure vessels, vehicles, etc. Work on hydrogen standards cannot be carried out in isolation, but only in collaboration between various standardization committees, regulators and key strategic partners.

Some organizations participating in the development of regulatory documents on the use of hydrogen:

• IEC (IECEX, IECQ, IECRE, IECEE)

• ISO

• OIML

• World Trade Organization

• UNECE ( WP.6, H2 Task Force Sustainable Energy Division)

• Hydrogen Council (IPHE, UNIDO)

• Hydrogen TCP IRENA

In 2023, at the UN Climate Change Conference COP28, the International Organization for Standardization (ISO) unveiled a new technical specification (ISO/TS 19870) as a framework for harmonization, safety, interoperability and sustainability in the hydrogen value chain.

Also, based on the results of the conference, the following conclusions were made:

Lead outcomes:

• Declaration of the intent on mutual of certification schemes for hydrogen and its derivatives,

- Covers 80% of future Global market (Declaration endorsed by 40 countries representing prospective importers and exporters)

- Promotes reliability and trust (Certification schemes key to evidence the sustainability attributes of hydrogen and its derivatives)

- Advances interoperability (Mutual recognition of certification schemes is an instrumental to avoid market fragmentation)

- Lays out implementation pathway (IPHE & IEA H2 TCP to lead technical implementation and report progress at G20/CEM in Brazil)

• ISO Methodology for GHG emissions assessment for Hydrogen on an LCA basis,

- Covers multiple production and transportation pathways (Including electrolysis- and CCS-enabled production and transportation as LH2, ammonia and LOHC)

- Provides full life-cycle assessment (Covers all stages of the life-cycle analysis from cradle to delivery gate, including production, conversion/conditioning, and transport)

- Converse methane emission (Includes upstream methane emission for hydrogen produced from methane)

- Sets the basis for a suite of standards for production, conditioning / conversion, and transport of hydrogen)

• Public-Private Action Statement on unlocking trade corridors

Platform outcomes:

• SDG Compass for the Hydrogen Economy

• Diversity, Equality and Inclusion Platform for Hydrogen

International Organization for Standardization ISO

The following official documents have been published by various technical committees of the ISO

Technical Committee : ISO/TC 197 “Hydrogen technologies”

ISO/TR 15916:2015 Basic considerations for the safety of hydrogen systems (This standard was last reviewed and confirmed in 2023. Therefore this version remains current.)

ISO 13984:1999 Liquid hydrogen — Land vehicle fuelling system interface (This standard was last reviewed and confirmed in 2023. Therefore this version remains current.)

ISO 13985:2006 Liquid hydrogen — Land vehicle fuel tanks (This standard was last reviewed and confirmed in 2021. Therefore this version remains current.)

ISO 14687:2019 Hydrogen fuel quality — Product specification (Expected to be replaced by ISO/DIS 14687 within the coming months.)

ISO 16110-1:2007 Hydrogen generators using fuel processing technologies Part 1: Safety (This standard was last reviewed and confirmed in 2021. Therefore this version remains current.)

ISO 16111:2018 Transportable gas storage devices — Hydrogen absorbed in reversible metal hydride

ISO 17268:2020 Gaseous hydrogen land vehicle refuelling connection devices (Expected to be replaced by ISO/DIS 17268-1 within the coming months.)

ISO 19880-1:2020 Gaseous hydrogen — Fuelling stations Part 1: General requirements

ISO/DIS 19880-2 Gaseous hydrogen — Fuelling stations Part 2: Dispensers and dispensing systems

ISO 19880-3:2018 Gaseous hydrogen — Fuelling stations Part 3: Valves

ISO 19880-5:2019 Gaseous hydrogen — Fuelling stations Part 5: Dispenser hoses and hose assemblies

ISO/DIS 19880-7 Gaseous hydrogen — Fuelling stations Part 7: Rubber O-rings

ISO 19880-8:2019 Gaseous hydrogen — Fuelling stations Part 8: Fuel quality control (Expected to be replaced by ISO/DIS 19880-8 within the coming months.)

ISO/PRF 19880-9 Gaseous hydrogen — Fuelling stations Part 9: Sampling for fuel quality analysis ISO/AWI TS 19880-10 Gaseous hydrogen — Fuelling stations Part 10: Mobile fueling stations

ISO 19881:2018 Gaseous hydrogen — Land vehicle fuel containers (Expected to be replaced by ISO/DIS 19881 within the coming months.)

ISO 19882:2018 Gaseous hydrogen — Thermally activated pressure relief devices for compressed hydrogen vehicle fuel containers (Expected to be replaced by ISO/DIS 19882 within the coming months.)

ISO/AWI 19884-1 Gaseous Hydrogen - Pressure vessels for stationary storage Part 1: Part 1: general requirements

ISO/AWI TR 19884-2 Gaseous Hydrogen - Pressure vessels for stationary storage Part 2: Material test data of class A materials (steels and aluminum alloys) compatible to hydrogen service

ISO/AWI TR 19884-3 Gaseous Hydrogen - Pressure vessels for stationary storage Part 3: Pressure cycle test data to demonstrate shallow pressure cycle estimation methods

ISO 19885-1:2024 Gaseous hydrogen — Fuelling protocols for hydrogen-fuelled vehicles Part 1: Design and development process for fuelling protocols

ISO/AWI 19885-2 Gaseous hydrogen — Fuelling protocols for hydrogen-fuelled vehicles Part 2: Part 2: Definition of communications between the vehicle and dispenser control systems

ISO/AWI 19885-3 Gaseous hydrogen — Fuelling protocols for hydrogen-fuelled vehicles Part 3: High flow hydrogen fuelling protocols for heavy duty road vehicles

ISO 26142:2010 Hydrogen detection apparatus — Stationary applications 

Technical Committee: ISO/TC 197/SC 1 “Hydrogen at scale and horizontal energy systems”

ISO/TS 19870:2023 Hydrogen technologies — Methodology for determining the greenhouse gas emissions associated with the production, conditioning and transport of hydrogen to consumption gate

ISO/FDIS 19887 Gaseous Hydrogen — Fuel system components for hydrogen fuelled vehicles

ISO/AWI 19888-1 Hydrogen Technologies — Aerial Vehicles Part 1: Liquid Hydrogen Fuel Storage System

ISO 22734:2019 Hydrogen generators using water electrolysis — Industrial, commercial, and residential applications (Expected to be replaced by ISO/DIS 22734-1 within the coming months) 

Technical Committee: ISO/TC 207/SC 7 “Greenhouse gas and climate change management and related activities”

ISO 14067:2018 Greenhouse gases — Carbon footprint of products — Requirements and guidelines for quantification 

Technical Committee: ISO/TC 207/SC 5 “Life cycle assessment”

ISO 14040:2006 Environmental management — Life cycle assessment — Principles and framework 

Technical Committee: ISO/TC 85 “Nuclear energy, nuclear technologies, and radiological protection”

ISO 19443:2018 Quality management systems — Specific requirements for the application of ISO 9001:2015 by organizations in the supply chain of the nuclear energy sector supplying products and services important to nuclear safety (ITNS)

Technical Committee: ISO TC 22 “Road Vehicles”

ISO TC22 “Road Vehicles”is also a key hydrogen standard developer through its sub-committee SC 37 “Electrically propelled vehicles”. The following official hydrogen related document has been published:

ISO 23273:2013, Fuel cell road vehicles — Safety specifications — Protection against hydrogen hazards for vehicles fuelled with compressed hydrogen

International Electrotechnical Commission IEC

The following white papers have been published by various technical committees of the IEC

Technical Committee: IEC TC 105 “Fuel Cells”

IEC 62282-2-100:2020 Fuel cell technologies - Part 2-100: Fuel cell modules - Safety

IEC 62282-3-100:2019 RLV Fuel cell technologies - Part 3-100: Stationary fuel cell power systems - Safety

IEC 62282-3-200:2015, Fuel cell technologies - Part 3-200: Stationary fuel cell power systems - Performance test methods

IEC 62282-3-300:2012 Fuel cell technologies - Part 3-300: Stationary fuel cell power systems - Installation

IEC 62282-5-100: 2018 Fuel cell technologies - Part 5-100: Portable fuel cell power systems - Safety

IEC 62282-6-200:2016 Fuel cell technologies - Part 6-200: Micro fuel cell power systems - Performance test methods

IEC 62282-6-100:2010+AMD1:2012 CSV Fuel cell technologies - Part 6-100: Micro fuel cell power systems - Safety 

Project: IEC 63341-3 ED1 IEC 63341-3 ED1Railway applications - Hydrogen and fuel cell systems for rolling stock - Part 3: Performance test methods for fuel cell power system (Current Status PRVC) 

Technical Committee: IEC TC 1 “Terminology”

IEC 60050-485: 2020, International Electrotechnical Vocabulary (IEV) - Part 485: Fuel cell technologies 

Technical Committee: IEC TC 111 “Environmental standardization for electrical and electronic products and systems”

IEC 62430:2019, Environmentally conscious design (ECD) - Principles, requirements and guidance

IEC 63372 ED1 Quantification and communication of Carbon FootPRINT and GHG emission reductions/avoided emissions from electric and electronic products and systems – Principles, methodologies, requirements and guidance (Current Status CCDV). 

Technical Committee: IEC TC 9 “Electrical equipment and systems for railways” 

Project: IEC 63341-1 ED1 Railway applications - Hydrogen and fuel cell systems for rolling stock - Part 1: Fuel cell system (Current Status PRVC) 

To develop IEC 63341-2 Railway applications - Rolling stock - Fuel cell systems for propulsion - Part 2: Hydrogen storage system

Other regulatory documents

Also, in the case of using hydrogen, other regulatory documents should be followed, for example: 

Leak tightness of the system parts in accordance Annex B EN 1127-1:2019 Explosive atmospheres - Explosion prevention and protection - Part 1: Basic concepts and methodology, developed by the CEN/TC 305 “Potentially explosive atmospheres - Explosion prevention and protection” 

IEC 31010:2019 Risk management - Risk assessment techniques, developed by the IEC TC 56 “Dependability” 

ISO 12100:2010, Safety of machinery — General principles for design — Risk assessment and risk reduction, developed by the ISO/TC 199 “Safety of machinery“ 

Hydrogen pipelines in accordance with ASME B31.12 - 2023 Hydrogen Piping and Pipelines and ASME STP-PT-006 Design Guidelines for Hydrogen Piping and Pipelines developed by the ASME (The American Society of Mechanical Engineers) 

Also, the requirements for hydrogen pipelines are as follows in Amendment 1: Complementary requirements for the transportation of fluids containing carbon dioxide or hydrogen ISO 13623:2017/Amd 1:2024 Petroleum and natural gas industries — Pipeline transportation systems, developed by ISO/TC 67/SC 2 

There are numerous interfaces between hydrogen standards and those from other fields, like pressure vessels, vehicles, etc. Work on hydrogen standards cannot be carried out in isolation, but only in collaboration between various standardization committees.

Sources of Hydrogen Impurities

The presence of impurities in hydrogen depends on the feedstock and the production process. Hydrogen produced by electrolysis of water may routinely include trace oxygen and water, which must be usually be removed prior to use. Hydrogen produced by reforming of hydrocarbons is produced as a mixture with a stoichiometric mixture with carbon dioxide and carbon monoxide which must be separated, additionally trace impurities from the feedstock such as sulphur compounds may be present in the final hydrogen supply. Impurities may also be introduced during storage, distribution, dispensing or as a result of equipment malfunction. Examples of this include distribution of hydrogen through repurposed gas networks which may be contaminated with a range of impurities or malfunctioning of equipment at refuelling stations. Some impurities may be added deliberately, for example odorants to aid detection of gas leaks.

How many types of hydrogen are produced currently, and what are the differences ?

The term “produce” isn’t really right for hydrogen. Hydrogen is the most plentiful element in the universe (by far). You cannot really make hydrogen, only collect it from the environment (and separate it from compounds it may have formed).

ISO/TS 19870:2023 Hydrogen technologies - Methodology for determining the greenhouse gas emissions associated with the production, conditioning and transport of hydrogen to consumption gate. ISO 14067:2018 Greenhouse gases - Carbon footprint of products - Requirements and guidelines for quantification.

The color label assigned to it relates to how the hydrogen is sourced or created and if the production process itself results in lesser carbon emissions than conventional methods of generating the gas.

Thresholds, Labels (Colors) are defined by public policies or by the market.

ISO/TS 19870:2023 is NOT defining what is acceptable in a given jurisdiction for the purpose of a specific public policy !

Green Hydrogen

Green Hydrogen is hydrogen that not only meets the low-carbon threshold but is generated using renewable energy sources such as solar or wind.

Yellow Hydrogen

Yellow hydrogen is hydrogen produced by electrolysis using mixed-origin electricity. For example, purchased electricity on the electricity exchange of the European Energy Exchange (EEX).  

Geological

White hydrogen

White hydrogen  refers to naturally occurring reserves of underground hydrogen. There are potentially huge reserves of geological hydrogen in the world. But the issues of how to find large accumulations of geological hydrogen have not been resolved. Using stimulated mineralogical processes could lead to the production of more underground hydrogen, which could become a significant source of clean energy.

It is hydrogen that is primarily considered as the fuel of the future, because it is an almost inexhaustible resource due to continuous and abundant hydrogen degassing of the Earth, otherwise it is also called "Hydrogen Breath of the Earth".

Hydrogen degassing is the phenomenon of hydrogen release in a mixture with other fluid gases (most often hydrocarbons, helium and radon) in rift zones, during volcanic eruptions, from crustal faults, kimberlite pipes, some mines and wells. In many cases earthquakes of tectonic origin are accompanied by an increase in the hydrogen content in the air at the epicentre and adjacent areas.

The potential of natural hydrogen in the Earth's interior has not been evaluated so far due to the existing prejudice that free hydrogen in nature is rare and in low concentrations and therefore has not attracted much attention of researchers. But in recent years, there are known cases of detection of free, not chemically bound, natural hydrogen on the continental land, usually in the areas of crustal fracture. We are talking about hydrogen in the composition of gases found in the form of free gas outlets in the water areas of reservoirs (gas griffins, bubble outlets), in gas-liquid inclusions in various rocks, in water-dissolved, oil-dissolved and other types of gases. In addition, there is a large amount of data on elevated hydrogen content in gas jets at the bottom of oceans.

Golden Hydrogen

Golden hydrogen is given specifically to hydrogen produced by microbial activities in depleted oil wells and gas wells. Golden hydrogen has a particularly unique production method. This type of hydrogen is extracted from depleted oil and gas wells. These wells contain residual oil and gas hydrocarbons that cannot be profitably extracted in their current form. To produce golden hydrogen, proprietary mixes of nutrients and bacteria are pumped into the depleted wells. The bacteria then break the oil residue down into hydrogen and CO2. This process can bring new life to wells with existing infrastructure. However, ensuring that the CO2 is captured from the wells is a priority in order to ensure this type of hydrogen is carbon neutral. Through this method, golden hydrogen allows for oil and gas companies to make “second use” of old oil and natural gas assets, extending the profitability of drilling projects. Process will revolutionize biomining and subsurface biomanufacturing. Under the right conditions, depleted oil reservoirs can be transformed into subsurface hydrogen biorefineries. To have enough bacteria to extract enough hydrogen and carbon dioxide from depleted oil and gas wells, bioreactors are used to rapidly breed genetically modified microbes that can feed on hydrocarbons. For this process, the genes and enzymes of microorganisms in bioreactor systems are changed. As a result, microorganisms acquire new properties that allow them to become more tolerant of the harsh conditions of oil and natural gas reserves and acquire new abilities, such as removing heavy metals or producing ethylene.

Orange Hydrogen

Orange hydrogen is hydrogen produced by injecting a CO2-enriched aqueous solution into reactive, iron-rich rocks. Orange hydrogen combines hydrogen generation with CO2 sequestration by creating a chemical reaction in iron-rich geological formations. Water, including saltwater, is charged with CO2 and injected into the target formation where it reacts with the iron ore, leaving the CO2 behind and enriching the material with hydrogen that can then be extracted. This is, in effect, artificially creating the conditions for white hydrogen development, all while sequestering CO2, giving it a net-negative emissions profile. 

Nuclear

Pink Hydrogen/Purple Hydrogen/Red Hydrogen is it is one that is produced from the energy of nuclear reactors. Electrolysis or thermochemical processes are used to produce hydrogen.

Pink Hydrogen

Pink Hydrogen is produced by electrolysis of water using electricity from a nuclear power plant.

Purple Hydrogen

The very high temperatures of nuclear reactors are used to produce Purple Hydrogen, produce steam for more efficient electrolysis, or steam reforming of fossil gas-based methane. Water electrolysis occurs at relatively low temperatures (80°C to 120°C), while steam electrolysis occurs at much higher temperatures and is therefore more efficient. Steam electrolysis may be ideal for integration with modern high-temperature nuclear power plants, since the process requires a coolant supply temperature of 700°C to 950°C.

Red Hydrogen

Thermochemical processes produce Red Hydrogen through chemical reactions with certain compounds at high temperatures that break down water molecules. Advanced nuclear reactors, capable of operating at very high temperatures, can also be used to produce heat for these processes. Hydrogen production using the sulfur-iodine cycle in particular has great potential for scaling up applications for sustainable, long-term operation.

Methane

Turquoise Hydrogen

Turquoise hydrogen is produced by splitting natural gas through methane pyrolysis (as opposed to steam methane reforming) into hydrogen and solid carbon. The difference is that this process is carried out by heat generated through electricity, rather than by burning fossil fuels. • The release of carbon in solid form (rather than CO2) means that there is no need for Carbon Capture, Utilization, and Storage (CCUS), and the carbon can even be used for other purposes, such as soil improvement or the production of certain goods such as tires. Where the electricity driving the pyrolysis is renewable, the process is zerocarbon, or even carbon negative if the feedstock is bio-methane rather than fossil methane (natural gas).

Blue Hydrogen

Blue Hydrogen is hydrogen that meets the low-carbon threshold but is generated using non-renewable energy sources, with carbon capture where applicable. Hydrogen production through steam reforming of methane is obtained from natural gas or biomass with the application of Carbon Capture, Utilization, and Storage (CCUS). Hydrogen is considered blue whenever the emission generated from the steam reforming process are captured and stored underground via industrial Carbon Capture, Utilization, and Storage (CCUS), so that it is not dispersed in the atmosphere. That is why Blue hydrogen is often considered a carbon neutral energy source, even though “low carbon” would be more accurate since around 10-20% of the generated CO2 cannot be captured.

Grey Hydrogen

Grey Hydrogen is hydrogen produced from steam reforming of methane obtained from natural gas without using Carbon Capture, Utilization, and Storage (CCUS). Grey hydrogen – the most popular route for hydrogen production. Currently this accounts from roughly 95% of the hydrogen produced in the world today. This process emits a great deal of CO2 to the atmosphere. Due to the predominance gray hydrogen in the global hydrogen economy, there is a need to decarbonize the route production.

Coal

Black and brown hydrogen are the least environmentally friendly types of hydrogen to produce because they are obtained from fossil fuels. To obtain them, they use the gasification method, the fossils are heated very strongly with steam and oxygen, after which the chemicals inside the fossils react, forming the so-called synthesis gas (syngas), consisting of carbon dioxide (CO₂), carbon monoxide (CO), methane, ethylene , a small amount of other gases and, in fact, hydrogen. The first two of these gases have no use in generating electricity. This makes the process very polluting compared to other methods. However, chemical companies can distill the hydrogen from this mixture.

Small city gas plants produced hydrogen from coal for hundreds of years, but back then it was called "City Gas" or "Lighting Gas".

Black Hydrogen

Black hydrogen is formed by the gasification of black (bituminous) coal or oil.

Brown Hydrogen

Brown hydrogen  is formed by the gasification of brown coal, which is still quite rare.

Biomass

Hydrogen from biomass

Hydrogen is obtained from biomass by thermochemical or biochemical methods. 

With the thermochemical method, biomass is heated without oxygen to a temperature of 500–800 °C (for wood waste), which is much lower than the temperature of the coal gasification process. As a result of the process, H2, CO and CH4 are released.

In the biochemical process of nitrogen fixation, hydrogen is produced by various bacteria, for example Rodobacter speriodes.

Hydrogen fuel quality

The impact of impurities varies with the specific equipment used and on the physio-chemical nature of the impurity. For example, hydrogen boilers that combust hydrogen will generally tolerate higher concentrations of impurities than a vehicle using a polymer electrolyte membrane fuel cell (PEMFC) and inert impurities such as nitrogen are usually less harmful than reactive species such as hydrogen sulphide.

As the specific impurity matters it is not sufficient to rely on normal metrics of gas purity, often reported using nines (e.g. >99.9990% or 5.0N), as this does not provide adequate information about which impurities may be present at trace levels. Instead, standards have been developed that provide more detailed requirements on fuel purity for specific applications. The international standard ISO 14687:2019 «Hydrogen fuel quality — Product specification»  specifies maximum permissible concentrations for many key impurities depending on use. This document specifies the minimum quality characteristics of hydrogen fuel as distributed for utilization in vehicular and stationary applications.

Hydrogen fuels are classified according to the following types and grade designations:

1. Type I (grades A, B, C, D and E): gaseous hydrogen and hydrogen-based fuel.

2. Type II (grades C and D): liquid hydrogen.

3. Type III: slush hydrogen.

The quality requirements for hydrogen depend on its applications and are divided into three application categories:

• Hydrogen for use in PEM fuel cell road vehicles (Type I grade D, Type II grade D);

Hydrogen fuel index (minimum mole fraction) is 99,97 %, It is determined by subtracting the "total non-hydrogen gases", expressed in mole percent, from 100 mole percent. Maximum total non-hydrogen gases is 300 μmol/mol. Maximum particulate concentration is 1 mg/kg. Particulate matter includes solid and liquid particles, including oil mist. Coarse particulate matter can cause problems with vehicle components and should be limited with a filter.

• Hydrogen and hydrogen-based fuels for PEM fuel cells of stationary applications (Type I grade E category 1, 2, 3);

— Type I grade E category 1(hydrogen-based fuel; high efficiency/low power applications) and  category 2 (hydrogen-based fuel; high power applications).

Hydrogen fuel index (minimum mole fraction) is 50 %. Maximum mole fraction total non-hydrogen gases is 50 %. Maximum particulate concentration is 1 mg/kg. Maximum particle diameter is 75 μm.

 — Type I grade E category 3 (gaseous hydrogen; high power/high efficiency applications). Hydrogen fuel index (minimum mole fraction) is 99,9 %. Maximum mole fraction total non-hydrogen gases is 0,1 %. Maximum particulate concentration is 1 mg/kg. Maximum particle diameter is 75 μm.

• Hydrogen for applications other than PEM fuel cell road vehicle and stationary applications (Type I grade A, B, C, Type II grade C, Type III) 

— Type I grade A

Hydrogen fuel index (minimum mole fraction) is 98 %. 

The hydrogen shall not contain dust, sand, dirt, gums, oils or other substances in an amount sufficient to damage the fuelling station equipment or the vehicle (engine) being fuelled. 

— Type I grade B

Hydrogen fuel index (minimum mole fraction) is 99,90 %. 

— Type I grade C

Hydrogen fuel index (minimum mole fraction) is 99,995 %. 

— Type II grade C, Type III

Hydrogen fuel index (minimum mole fraction) is 99,995 %. Para-hydrogen (minimum mole fraction) 95,0 %.

Fuel Cell Electric Vehicles

Fuel cell electric vehicles commonly use polymer electrolyte membrane fuel cells (PEMFC) which are susceptible to a range of impurities. Impurities impact PEMFC using a range of mechanisms, these may include poisoning the anode hydrogen oxidation reaction catalysts, reducing the ionic conductivity of the ionomer and membrane, altering wetting behaviour of components or blocking porosity in diffusion media. The impact of some impurities like carbon monoxide, formic acid, or formaldehyde is reversible with PEMFC performance recovering once the supply of impurity is removed. Other impurities, for example sulphurous compounds, may cause irreversible degradation. 

Efforts to assess the compliance of hydrogen supplied by hydrogen refuelling stations against the ISO 14687 standard have been performed. While the hydrogen was generally found to be 'good' violations of the standard have been reported, most frequently for nitrogen, water and oxygen.

Combustion Engines and Appliances

Combustion applications are generally more tolerant of hydrogen impurities than PEFMC, as such the ISO-14687 standard for permissible impurities is less strict. This standard has itself been criticised with revisions proposed to make it more lenient and therefore suitable for hydrogen distributed through a repurposed gas network.