FAQ on transport & storage
The existing infrastructure of gas pipelines and underground storage facilities can be used to a large extent for the transport and storage of hydrogen. A hydrogen core network with around 9,700 kilometres of pipeline is to be created in Germany by 2032. In this section, we answer the most important questions about the safety of these technologies. Your question is not included? Send us an e-mail to info@get-h2.de
Transport over long distances is usually carried out through underground pipelines. Existing pipelines that are currently part of the natural gas transmission network are mainly used for this purpose. These pipelines can be converted for the transport of hydrogen.
The GET H2 Nukleus project, for example, largely utilises existing pipelines. Over a total distance of around 130 kilometres, 115 kilometres of existing pipelines that currently transport natural gas will be converted to transport hydrogen. Evonik is building 15 kilometres of partial new pipeline between Marl and Gelsenkirchen-Scholven.
The hydrogen core network, which will be gradually built in Germany by 2032, will comprise around 9,700 kilometres of pipelines. Around 65% of these are existing pipelines, while the rest will be newly built.
The pipelines of the natural gas transmission network are made of steel. The type of steel used is generally suitable for transporting hydrogen. In Germany, there are already some regionally limited hydrogen networks that have been operated by industrial companies for decades. Their pipelines are also made of steel and are comparable to those of the long-distance pipeline network. The suitability of the pipelines that are being converted for the transport of hydrogen as part of the GET H2 Nukleus project has already been confirmed in comprehensive tests.
Hydrogen is transported in its molecular form (H2) in the pipes, not in its much smaller atomic form. Steel is used for the pipes, which is not attacked by molecular hydrogen - unlike high-alloy steel or titanium, for example, which are used in the automotive industry.
Weld seams are no more susceptible than other surfaces in the pipe. The prerequisite for an embrittling effect here is also the occurrence of atomic hydrogen in combination with defects on the inner wall of the pipe. Atomic hydrogen can penetrate the metal lattice through a defect and recombine there into H2. Over time, this can lead to a reduction in the bonding energy of the metal lattice of the conductor. To prevent this, defects in conductors are eliminated.
To ensure that hydrogen networks can be operated safely under all circumstances, network operators calculate the service life very conservatively. Nevertheless, realistic operating periods typically extend over several decades. Therefore, the safe and economical operation of a hydrogen network is assured.
The age of pipelines says nothing about their condition. The condition of the pipeline network is regularly checked in accordance with the DVGW (German Technical and Scientific Association for Gas and Water) regulations. If defective sections are discovered, they are replaced.
In the run-up to the changeover, a technical review is carried out by independent experts. Depending on the outcome of the expert reports, the necessary technical adjustments are implemented. An official authorisation procedure is carried out in parallel. Only when the suitability for safe transport has been established at all levels can the conversion to hydrogen take place.
No. Transporting hydrogen through pipelines is a well-established technology. In Germany and many other countries, private hydrogen networks have been in place for decades and are operated safely, e.g. by Air Liquide in the Rhineland and Ruhr region, by BASF in Ludwigshafen or by Linde in Leuna. The operation and monitoring of the pipeline system is carried out professionally and carefully. Thus, continuous care is taken to minimise all possible dangers.
Leaks can be caused by damaged pipes or defective fittings. The systems and pipelines of the gas networks are subject to strict safety requirements during planning, construction and operation. During operation, the hydrogen pipelines are subject to regular inspections using hydrogen detection by helicopter. A central control centre monitors and controls the gas flow in the pipeline 24/7, 365 days a year. A drop in pressure caused by leaks can be recognised immediately. The affected pipeline section is then immediately shut off and depressurised, and damaged pipeline sections are replaced. If a pipeline is damaged, e.g. by a construction site, a team trained in dealing with critical situations is called in immediately. In coordination with the safety authorities, this team initiates the necessary measures to ensure safety at all levels.
The quantities of hydrogen that can escape into the air through defective fittings or damaged pipes as part of normal wear and tear are very small. Hydrogen is lighter than air and escapes upwards immediately. It also disperses into the air four times faster than natural gas. Hydrogen also does not explode or burn on contact with the air. This would require an open flame, as is the case with the oxyhydrogen test that many people are familiar with from school.
A danger can only arise if a very large quantity of hydrogen escapes at once. This can only happen if a pipe under high pressure (e.g. 60 bar or more) is massively damaged, e.g. by a building site. There is usually only a risk of the hydrogen igniting if there is an open flame or flying sparks at the point of discharge. If this is the case, an explosion can occur - as with other flammable substances. As with the transport of natural gas, the pressure in the system is continuously measured. If a massive gas leak occurs, the pressure drops and this is noticed immediately.
Hydrogen can ignite on contact with oxygen if an ignition spark is present at the same time. The risk of an explosion depends on the hydrogen concentration in the air mixture. If an air mixture has a hydrogen concentration of between 4-77 mol %, there is a risk of explosion. Since the pipeline network transports 100% hydrogen, an explosion inside the pipeline network can be ruled out. As the hydrogen in the pipework system is also under significantly higher pressure than the ambient air, no oxygen can enter the pipework and change the hydrogen concentration.
In the GET H2 Nukleus project, large industrial sites are to be supplied with hydrogen. This will be done through the existing long-distance pipeline network and additional sections that are being built that do not pass through residential areas.
According to the current DVGW (German Technical and Scientific Association for Gas and Water) regulations, the pipelines of the natural gas transmission network are at least one metre below ground level. This will also be the case for hydrogen pipelines.
For the existing pipelines that are being converted, modifications to valves and compressors in the existing systems are necessary. These are carried out locally at the individual locations. For the GET H2 Nukleus project, for example, this affects twelve locations along the 115 kilometre route.
There are two options for new construction projects, which do not differ from the construction of pipelines for natural gas: Either the pipeline is laid open - i.e. laid in a previously excavated pipeline trench with the help of excavators. Or it is laid as a tunnel bore, which is done, for example, when crossing under rivers and canals, roads and railway tracks or landscape and nature conservation areas.
The project will largely utilise existing pipelines. The construction measures are mainly focused on work on the RWE power plant site in Lingen and on the partial construction of a new pipeline by Evonik, which is to run from the Marl Chemical Park to Gelsenkirchen-Scholven (approx. 15 kilometres of pipeline). This section is planned to be realised together with an already planned replacement of existing pipelines so that no additional burdens arise. The cost and impact will therefore be several times lower than for a completely new gas pipeline.
When building a new pipeline, the aim is always to minimise the impact on people and the environment. This is always taken into account when planning the route, which is determined in a complex process with the relevant authorities and sometimes with the involvement of the public. This may mean that green cuttings and clearances have to take place. For each construction project, it is determined in detail how interventions can be minimised and how compensation can be provided, e.g. through replacement planting. Once the lines have been laid, keeping them clear is a safety aspect. Pipelines must be quickly accessible in the event of damage; roots can also cause damage to the pipeline.
efore the conversion, the relevant lines have to be tested for hydrogen compatibility. The respective supervisory authority must approve the conversion and thus the operation with hydrogen.
The rights of way granted for the transport of natural gas also apply to the transport of hydrogen. This was adopted in the amended Energy Industry Act (EnWG) in June 2021.
According to Section 113a EnWG, the existing rights of way for natural gas pipelines also apply equally to hydrogen pipelines. Since the conversion of an existing natural gas pipeline to transport hydrogen does not change the depth of the laid pipeline or the size of the protective strip in which construction work is not possible, we assume that the value of the property will not change either. In case of the construction of a new pipeline, no generalised statements can be made about property values. These are individual cases that are negotiated with the landowners when a new pipeline is built.
No. The project partners are pursuing the goal of converting existing natural gas pipelines so that they can be used to transport 100% hydrogen. This has several advantages: Firstly, it is significantly cheaper than building a new pipeline, and secondly, it is also significantly faster and, of course, much more environmentally friendly. The cost and the impact on the population and the environment are therefore many times lower than if hydrogen pipelines or high-voltage lines were built from scratch. Furthermore, this approach enables rapid implementation.
The industrial and mobility sectors are generally dependent on a supply of pure, unmixed hydrogen. If green hydrogen is added exclusively to natural gas, the project partners will not be able to realise the potential for reducing CO2 emissions in these sectors.
Even if there is a network in which 100% hydrogen is transported, the addition of hydrogen to natural gas remains a theoretical option for reducing the consumption of fossil fuels. However, most experts expect that the cost of climate-neutral hydrogen will be so high that blending it with natural gas will not be worthwhile.
Just as there is only one electricity grid for conventionally generated electricity and electricity from renewable sources, there can only be one hydrogen grid in which hydrogen is transported regardless of its origin. The long-term goal is to feed only green hydrogen into this grid.
Yes, only those parts of the natural gas pipeline network that have been approved by the Bundesnetzagenur (Federal Network Agency) will be converted since they are not necessary to maintain the security of supply of natural gas. The same applies to the cavern storage facilities that are being converted for hydrogen.
So-called cavern storage facilities are mainly used for this purpose. These are usually underground salt caverns that have been used safely for decades to store natural gas and are being modified to store hydrogen. In addition, new salt caverns can be made ready for the storage of hydrogen.
The majority of existing natural gas storage facilities and planned hydrogen storage facilities are located in north-west Germany. Almost 90% of all potential cavern storage facilities in Europe are located in East Frisia, the Oldenburg region and Münsterland. The first hydrogen storage facility, which is to be connected to the GET H2 Nukleus project in 2026, is located in Gronau-Epe.
Tubular storage tanks or gas tanks can also be used on a smaller scale. In general, only proven and safe technologies are used.
GET H2 partner Linde already operates cavern storage facilities for hydrogen. The experience gained has been summarised in a case study, which can be downloaded here.
Hydrogen can be stored and transported in gaseous form under pressure, in liquid form or bound to ammonia, methanol or liquid organic hydrogen carriers (LOHC) such as benzyltoluene. Depending on the technology used, there are different requirements for the storage and transport infrastructure. Each technology has its advantages and disadvantages - there is no single solution that is ideal for all applications.
Cavern storage facilities are cavities created in salt domes. The surrounding salt forms an impermeable boundary. The impermeability of the salt to hydrogen was tested and confirmed in advance so that the hydrogen cannot escape from the cavern into other layers of soil or into the groundwater.