First-ever offshore infrastructure and processing facilities concept for hydrogen storage in offshore caverns have been developed by Tractebel and its partner companies.
Using a scalable offshore platform, Tractebel Overdick GmbH can compress and store up to 1.2 million m3 of hydrogen, according to a new design study released by the company’s offshore experts. The hydrogen produced offshore will be stored and buffered in underground salt caverns before it is transported via pipeline to the onshore grid and finally to consumers and customers via the pipeline network.
Despite the importance of offshore wind energy in the global energy transition, current hydrogen production technologies will only be effective if they can be scaled up. Hydrogen (H2) from renewable sources will be needed to meet future energy needs, and offshore sites are essential to industrial-scale production.. In 2019, Tractebel pioneered an innovative solution to address this demand by developing a unique offshore hydrogen platform concept, followed by an optimized and scalable version the following year. For the first time ever, Tractebel’s experts have designed an offshore infrastructure and processing facility concept for the storage of hydrogen in offshore caverns.
A wellhead platform for the caverns and a series of compression platforms are part of this offshore platform complex that allows for a gradual increase in capacity. Additional modules can be added to the plant at a later date if it is needed. According to the study, a hydrogen production capacity of 2 GW is assumed. At any time, modifications and customizations can be made.
Offshore compression and storage hubs such as these can further increase the flexibility of upcoming offshore hydrogen production. As the compression effort decreases at the wind farms’ electrolysis plants, so too shall the cost for offshore hydrogen production sites in general. “Centralised offshore hydrogen hubs also facilitate the integration of smaller-scale hydrogen production, which is to be expected within the scope of capacity expansions while re-powering offshore wind farms in the future. At the same time, they offer an economically viable option, as the export and compression of hydrogen produced offshore can be bundled. This significantly reduces the overall costs for future projects,” says Klaas Oltmann, Director Business Development at Tractebel Overdick GmbH.
Hydrogen stored in underground salt caverns at 180 bar is processed by newly designed storage and compressor platforms that process 400,000 Nm3/h. As a result, it is possible to design a more cost-effective export pipeline thanks to these storage facilities.
Existing offshore infrastructures can use green hydrogen directly instead of other energy sources for their operations, which is a significant contribution to the sustainability of large underground hydrogen storage facilities. This contributes to the offshore industry’s decarbonization.
The North Sea is well suited for the solution due to its geological conditions and underground rock salt formations. Caverns are leached in these formations to create large storage volumes. The study assumes a total storage volume of up to 1.2 million m³ as a starting value for efficient peak coverage of offshore H2 production rates. “This storage is also necessary in the long term, because it will be an essential building block for the success of the energy transition,” explains Oltmann. “Offshore caverns can buffer the renewable energy produced in the form of hydrogen and therefore balance out the divergence between energy production and demand profiles. In this case, the proposed size of the offshore storage facility is merely a starting point.”
DEEP.KBB GmbH and PSE Engineering GmbH, with their many years of experience, were also involved as important components in the design study alongside Tractebel’s renewable energy and offshore experts. From geology to processing equipment, this forward-thinking alliance of experts helped develop the concept. The offshore hydrogen hub and future H2 projects will be able to build on this foundation of bundled expertise in the long term.
