Seven questions about hydrogen transmission through natural gas pipelines

By 2030, the Netherlands wants to have reduced its carbon emissions by 55% compared to 1990. Industry in the Netherlands is responsible for a large part of national carbon emissions, and electrification makes sustainability possible only to a limited extent. Industry also needs green gases, like hydrogen for example. With green hydrogen as a feedstock or fuel, industrial emissions can be reduced significantly. Hynetwork Services (a fully-owned subsidiary of Gasunie) has been commissioned to build a national hydrogen network. This network will ensure that sufficient hydrogen ends up in the key industrial clusters. This Dutch hydrogen network will be ready in 2030 and can also be connected to the German network and to trans-European networks. The national hydrogen network will largely comprise repurposed natural gas pipelines.

Absolutely. Hydrogen is a gas that can be transported by pipeline, just like natural gas. In the province of Zeeland, the first natural gas pipeline in the Netherlands to be repurposed already started transporting hydrogen gas in late 2018. 
Although the properties of natural gas and hydrogen are different, both energy carriers can, with a number of adjustments, be safely transported through the existing natural gas pipelines. So, when developing the national hydrogen network, we mainly use existing pipelines that will no longer be needed for the transport of natural gas.

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Over the coming years, the Netherlands will see a decrease in the transmission of natural gas. The reason for this is twofold: gas extraction is being phased out in Groningen and the Netherlands is using energy sources ever more efficiently while also increasing sustainability through the use of alternative energy carriers. Now that the transmission of natural gas is on a downward path, part of the gas network is becoming available for the transmission of hydrogen.

In the coming years, a hydrogen network stretching out over some 1,200 kilometres will be developed in the Netherlands. Of this, 1,000km will consist of repurposed natural gas pipelines. That’s 85%. With this approach, we will be contributing significantly to making the energy transition affordable.

These are the steps needed to make a natural gas pipeline suitable for the transmission of hydrogen:

• Inspecting the natural gas pipeline. Natural gas pipelines are safe to operate and are inspected regularly. When we switch to hydrogen, we record the latest condition of the pipeline. 
• If the condition of the pipeline is good, we divert the flow of the natural gas. The pipeline is decommissioned and we reduce the pressure in the pipeline.
• We feed nitrogen into the pipeline to keep air from entering.
• Specially designed valves for hydrogen are installed. Because hydrogen molecules are smaller than natural gas molecules, the existing valves along the natural gas pipeline are not suitable for the hydrogen pipeline. So, these valves are removed and, where necessary, replaced by a section of pipeline or a new valve.
• After installing the new valves, the pipeline is connected to the hydrogen producers, customers and/or the network. Next, in a closely controlled process the nitrogen is displaced in the pipeline by feeding in hydrogen.

In the Netherlands, we have a long history of safe and secure construction and management of natural gas pipelines and transmission of natural gas. Strict safety standards also apply when it comes to hydrogen. These are set and monitored by the Dutch government. Hynetwork Services applies the same strict safety requirements and uses the knowledge and experience of its parent company Gasunie.

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Maintaining hydrogen pipelines does not differ that much from when working with natural gas. This has emerged from various safety studies and field tests. An example is the field test under the HyTap project involving welding on a pipeline filled with hydrogen. During this field test, the main activities that would normally be carried out on an in-service natural gas pipeline were tested extensively with the aim of seeing whether these same activities could still be carried out safely on a pipeline filled with hydrogen. And that proved to be the case. The field test showed that activities such as welding, tapping and installing a sealing component (‘stoppling’) on an in-service hydrogen pipeline do not differ much from when working with natural gas.

Read more about the HyTap project