Hydrogen can be stored physically as either a gas or a liquid. Storage of hydrogen as a gas typically requires high-pressure tanks (350–700 bar [5,000–10,000 psi] tank pressure). Storage of hydrogen as a liquid requires cryogenic temperatures because the boiling point of hydrogen at one atmosphere pressure is −252.8°C.

Hydrogen can also be stored in other gases, as a medium term storage solution, such as ammonia. Ammonia can be liquefied under mild conditions (room temperature, pressure of 8-10 bar), this means that it can be stored in a simple and inexpensive pressure vessel. It is also considered to be a safer transport option than hydrogen as, although toxic, its smell can be detected at low levels. Ammonia also has a lower flammable range than hydrogen and is considered to be non-flammable when being transported, whereas hydrogen burns with an invisible flame. 

Hydrogen is distributed from the point of production to the point of use either via pipelines, by road in cryogenic liquid tanker trucks or gaseous tube trailers, or internationally via shipping. Pipelines are deployed in regions with substantial (hundreds of tons per day) long-term demand.

Road transportation of hydrogen is deployed when the use-case requires a set quantity of liquid hydrogen over a shorter period of time. This could be as a means of producing energy or being used in a hydrogen refuelling station. Hydrogen producing countries generally transport to other countries with a demand for the gas via ships.

It should be noted that, currently, hydrogen is only being shipped for short term voyages, and is instead being converted to ammonia for medium to long voyages. This is because ammonia is a better carrier of hydrogen and there is already a large amount of existing infrastructure and legislation to support the movement of ammonia.

Industrial uses of hydrogen makes up the majority of hydrogen use today, as it is used widely in the production of materials such as cement, steel and glass.

As hydrogen’s role in the global energy transition continues to grow, other uses of hydrogen are likely to grow.

Hydrogen Power and Hydrogen Heating

Hydrogen fuel cells use the chemical energy of hydrogen to generate electricity.

Hydrogen can also be used to heat our homes and businesses. Whilst a switch to 100% hydrogen is not currently viable, the UK government intends to sanction hydrogen blending in 2023 and we could see the UK using a 20% blend by 2027.

Hydrogen Vehicles

Hydrogen fuel cells can also be used to power vehicles, with hydrogen buses already seeing use across the world.

The three key colours of hydrogen are green, blue and grey.

Grey hydrogen is hydrogen produced using fossil fuels, such as natural gas, and is the most commonly-produced form of hydrogen in the world today.

Blue hydrogen is produced in the same way as grey hydrogen. Unlike grey hydrogen, the greenhouse gases produced are captured through the process of carbon capture and storage (CCS), therefore blue hydrogen is considered to be a carbon neutral form of hydrogen.

Green hydrogen is considered the cleanest form of hydrogen and is produced using electricity to power an electrolyser that separates hydrogen from the water molecule producing oxygen as a by-product. Excess electricity can be used by electrolysis to create hydrogen gas that can be stored for the future.

Crowcon’s molecular property spectrometer (MPS™) sensor technology offers the best solution for hydrogen gas detection. Requiring reduced maintenance and zero calibration for five years along with the elimination of sensor poisoning, the shortfalls of traditional sensing technology are eliminated with MPS. As well as driving up safety in areas where flammable gases pose a risk, MPS™ technology generates significant savings on total cost of ownership, and reduced interaction with the unit drives down occupational risk for operators.

When dealing with hydrogen, as with any gas, health and safety is paramount. Hydrogen has a wide flammable range (4%–74% vol. in air), so even small quantities of H2 can cause explosions when mixed with atmospheric air. Just a spark of static electricity from a person’s finger is enough to trigger an explosion when hydrogen is present, and in many locations where hydrogen is used, spark ignition from electrical components or maintenance activities is an ever-present risk.

Hydrogen is non-toxic, but in indoor environments like battery storage rooms, hydrogen may build up and cause asphyxiation by displacing oxygen. In fuel cell stacks, hydrogen is prone to leak from seals present at process connections near the H₂ storage cylinders.

Another concern around hydrogen flammability and detection is that hydrogen flames are pale blue in color and nearly invisible to the human eye. Hydrogen flames also emit low radiant heat, so people may not feel that heat until they are very close to the flame. Flame detectors are therefore used to complement point gas detectors, as they cover a wide area. Hydrogen flame can be detected using multi-spectrum infrared detectors.

These dangers are present across the hydrogen value chain from production and storage to distribution and use, with gas detection representing the first line of defence against hydrogen leaks.

Whilst there is a range of regulation on gases generally, there is a lack of legislation which applies specifically to Hydrogen.

In the UK, the Office of Gas and Electricity Markets (Ofgem) regulates the gas market and requires anyone engaging in the supply, shipping or transportation of gas to have a license to do so under the Gas Act.

There is also a number of health and safety laws which relate to hydrogen, including the Gas Safety (Management) Regulations, Pipeline Safety Regulations, Hazardous Substance Regulations and the Dangerous Substances and Explosive Atmosphere Regulations.

ISO 22734-1:2019 specifies that a hydrogen gas detection system that initiates ventilation at 0.4%v/v (100%LEL) hydrogen must be installed close to the hydrogen generator.