Sustainable use of existing infrastructure for hydrogen storage & transport

In order to close the gaps in the supply of the renewable energies in the future, new and innovative ways of storing the energy produced are needed. The world’s first underground storage facility for green hydrogen planned for the Bad Lauchstädt Energy Park represents a new milestone in this respect. The gas network connected to the Park also means we can transport the green hydrogen to the end customer in line with the general supply situation.

For the first phase of the real-life laboratory, an overground hydrogen storage facility is planned in combination with a gas processing plant and a gas volume measurement system. This complex, just as the facility as a whole, is subject to stringent security standards. Building the storage facility above ground will allow the project to be realised more quickly so that green hydrogen can be used as early as possible.  

In the second phase of the project, the world’s first underground storage facility for green hydrogen is to be built – another important step towards the industrial use and security of supply of green hydrogen. In principle, there are two options for storing gases underground: In pore or cavern stores. Whereas in pore storage facilities the gas is pumped underground and absorbed by sponge-like formations in the rock, cavern storage facilities are artificially created cavities in the ground into which the gas is pumped. As a rule, these are depleted natural gas reservoirs for pore storage or old salt mines for cavern storage. In the case of the Bad Lauchstädt Energy Park, an existing natural gas cavern storage facility is to be converted for the storage of green hydrogen.  

Storage tanks for gases are very safe in principle. Accidents or incidents are ruled out as there is no oxygen or ignition sources in the storage tank, which would be essential for dangerous incidents. Accidents are therefore only possible in the pipework of the surface installation. To prevent such accidents, strict safety standards are adhered to and measuring devices and automatic shutdown systems are installed. Any escaping gas is detected immediately and the system is shut down in the event of danger.

In addition to these safety measures, the location of the gas storage facility was examined in detail as part of the HYPOS research projects H2-UGS and H2 research cavern and was classified as suitable and safe. 

VNG Gasspeicher GmbH (VGS) is responsible for the storage facility. As the third largest storage facility operator in Germany, it can look back on almost 50 years of experience in the storage of gases and gas mixtures containing hydrogen. The VNG subsidiary is an expert in the construction and operation of underground storage facilities and the associated processes.

After conversion, green hydrogen can also be transported in existing steel pipelines that were formerly used for natural gas. The Bad Lauchstädt Energy Park will therefore use the existing gas network to transport the green hydrogen to the end customer. To this end, a 25-kilometre natural gas pipeline leading to the industrial area near Leuna is being converted to transport pure hydrogen. In the future, it will also be possible to transport the green hydrogen produced at the Bad Lauchstädt Energy Park to other regions via connections to the organically growing infrastructure. For example, via the Green Octopus Central Germany (GO!) project, which has been classified as an Important Project of Common European Interest (IPCEI) Towards the west and the LHyVE sub-project, the hydrogen ring around Leipzig, towards the east. These links in the emerging European Hydrogen Backbone also provide access to import points and other hydrogen storage facilities.

The pipeline used for gas transport is part of the network of the transmission system operator ONTRAS, which is responsible for both the conversion of the pipeline and its subsequent operation. ONTRAS operates a 7,700 kilometre gas network in Eastern Germany and has also been transporting green gases (biomethane, synthetic methane and natural gas/hydrogen mixtures) for many years. 

Before commissioning, the natural gas pipeline used for H₂ transport is tested using state-of-the-art diagnostic tools to identify and eliminate any weak points. The pipeline is then disconnected from the natural gas system and integrated into the hydrogen infrastructure. This also requires equipping the pipeline with suitable control, regulation, measuring and monitoring systems to ensure safe operation at all times. 

The hydrogen pipeline is scheduled to come on stream in 2024 and will be operated at a pressure of 30 bar, whereby a maximum pressure of 63 bar would be possible. The decision not to use the maximum pressure reflects the findings from, for example, the European Hydrogen Backbone, according to which pipeline transport at a medium pressure is conducive to an optimal operating regime. Like all ONTRAS lines and systems, this line is monitored and controlled 24/7 from the control centre. The monitoring and maintenance cycles are adapted to the new medium as necessary. Safety-relevant components (e.g. valves and pressure control systems) can also be controlled remotely and can therefore be operated from the ONTRAS control centre without any loss of time if required.

Ensuring the highest purity standards is crucial for the effective utilisation of the hydrogen produced. During storage and transport, however, foreign substances can get into the hydrogen, which must be removed before it can be used. In order to provide customers with green hydrogen of the required quality and purity, specialised gas processing plants are required post-storage and post-transport.

The first gas processing station, which is being built on the premises of VNG Gasspeicher GmbH (VGS), will be constructed and operated by DBI - Gastechnologisches Institut gGmbH Freiberg (DBI). Because it is stored in a cavern, the green hydrogen may contain impurities such as water, oxygen or sulphur compounds, which can form in the cavern as a result of microbial activity. In order to remove these substances, the DBI is building plants for green hydrogen drying and desulphurisation on a 20 m x 30 m site. As part of the scientific support for the real-world laboratory of the energy transition, the DBI is investigating whether new – more efficient and cost-effective – processes can be developed for the preparation of hydrogen.

There is also a risk that green hydrogen through pipelines may be contaminated, for example by natural gas residues that adhere to the converted pipeline. In order to remove such contamination, special adsorbers with several layers (e.g. special activated carbon) are installed at the transfer station between the pipeline and the consumer. ONTRAS Gastransport GmbH will install and operate two such adsorbers at the transfer station to the refinery for the first anchor customer of the Bad Lauchstädt Energy Park, the TotalEnergies refinery in Leuna. The adsorbers each have a height of four metres and a diameter of approx. 1.5 metres.