Hydrogen is a hot topic in the energy, fuel, and sustainability sector. With the necessary financial support from governments and the development of innovative applications, hydrogen has the potential to become the sustainable energy carrier of the future.
As a result, hydrogen pipelines are also in the spotlight. Does the growing interest in hydrogen mean that existing pipelines for natural gas must be modified or replaced? What are the special requirements for gaseous and liquid hydrogen pipelines? What risks are involved in the transport of liquid hydrogen? In this blog, we will answer these questions in detail.
Pipelines for gaseous hydrogen
There are millions of miles of natural gas pipelines around the world. These pipelines transport the gas between regions, cities, or between different countries. Gas pipelines generally have a large diameter and use steel alloys (in the case of high pressure) or, in the case of distribution pipelines, materials such as cast iron, copper, steel, or plastic (PVC or PE).
With increasing sustainability goals and guidelines, the use of natural gas is under pressure. Therefore, pipeline producers, gas producers, and governments are raising the question of whether existing infrastructures for natural gas can also be used for a more sustainable gas: green hydrogen.
Research into the best pipelines for gaseous hydrogen has been ongoing for several years, and it appears that there are options to convert existing infrastructures into safe hydrogen networks.
Gasunie, the company currently responsible for the transport, storage, and conversion of natural gas in the Netherlands, is working on a project that would make the Netherlands the first country where the existing natural gas network is modified to accommodate hydrogen.
“The contiguous national infrastructure will not only connect our ports and industrial clusters to each other and to hydrogen storage sites, but it will also connect them to our neighboring countries. As a result, the Netherlands will become the gateway to Europe for the global hydrogen market.” – Han Fennema, CEO of Gasunie.
That an existing pipeline can be used for hydrogen is, however, not a given. A report by Hydrogen Europe shows that the possibilities certainly exist but that not every infrastructure is the same. It will therefore be necessary to evaluate the extent to which adjustments are needed for each infrastructure.
Where pipelines for gaseous and liquid hydrogen meet
The pipelines we talk about above are used to transport gaseous hydrogen over long distances. But which features should the pipelines to transport liquid hydrogen have? And at what point is gaseous hydrogen converted into its liquid form?
One of the locations where gaseous and liquid hydrogen meet is the Botlek area in Rotterdam. Here, gaseous hydrogen is produced in large reformers and then liquefied with liquefiers. The site contains both pipelines for gaseous hydrogen and transfer lines for liquid hydrogen, through which this cryogenic liquid is routed from storage tanks to tankers for transportation.
As early as 1988, when the infrastructures for hydrogen were built in the Botlek, Demaco was the preferred party for the construction of cryogenic infrastructures for liquid hydrogen. The network of vacuum insulated transfer lines in the Botlek was the first major hydrogen project that our engineers constructed. With success, because hardly any repairs or maintenance was required up until today.
Transfer lines for liquid hydrogen
The transport of gaseous hydrogen is complex; that of liquid hydrogen is, if possible, even more, complicated. In order to avoid waste and ensure optimal safety, transfer lines for liquid hydrogen must be exceptionally well insulated. Liquid hydrogen is at a temperature of -252.9 centigrade, extremely cold.
Safety is essential when transporting liquid hydrogen. In combination with oxygen, the cryogenic liquid can cause explosions. In case ice-cold liquid hydrogen is released due to a leak in the transfer line or due to insufficient insulation, there is a high probability that the surrounding oxygen will condense. The condensed oxygen, in combination with liquid hydrogen, can lead to dangerous situations. For this reason, transfer lines for liquid hydrogen are subject to more stringent requirements than those for liquid oxygen or liquid nitrogen.
Vacuum insulation (VIP) has proven to be the method of choice for optimal insulation of liquid hydrogen transfer lines. A high-vacuum environment is created by insulating pipelines or systems with a double wall and drawing out all the air between these walls. In the vacuum, hardly any molecules remain, which means heat transfer cannot occur from the hot outer tube (vacuum jacket) to the cold inner tube (process pipe). Thus, a vast amount of the surrounding heat is kept out of the system or the pipe.
Vacuum insulated transfer lines have several advantages. First, the high quality of the piping provides very high efficiency, keeping the long-term operating costs for the system lower than those of conventional insulating materials.
Secondly, vacuum insulated transfer lines take up less space than conventional insulation materials (PIR/PUR, Foamglas, Armaflex, Perlite, or Misselon). The double-wall offers an insulation value that is so high that it can only be approached with the above materials when applying many layers of material. This significantly increases the diameter of the pipe while also increasing the chance of oxygen condensation, as conventional insulation is less vapor-tight. A safety concern that does not arise with vacuum insulation.
Finally, one more benefit that we already briefly addressed in our earlier blog on liquid hydrogen. In some specific industries, it is required that liquid hydrogen transfer lines are equipped with double-containment for additional safety (should the process line leak, the double-containment will absorb it.)
While other insulation methods require the construction of an additional wall to meet this requirement, vacuum insulation automatically has two walls. This makes vacuum insulated transfer lines extra safe, extra widely applicable, and by far the best economical choice.