Tractebel along with partner companies unveils world’s first offshore hydrogen storage concept

Tractebel Overdick GmbH claims that the design study outlines a revolutionary solution for large-scale hydrogen storage on the high seas: a scalable offshore platform for the compression and storage of up to 1.2 million cubic meters of hydrogen.

Tractebel mentioned that underground salt caverns will be used as storage and buffers for the hydrogen produced offshore before it is transported via a pipeline network to the onshore grid and finally to consumers and customers.

Green hydrogen from offshore wind energy is becoming an important part of the global energy transition. However, existing hydrogen production technologies will only be viable if production rates reach an industrial scale.

According to Tractebel, massive volumes of hydrogen (H2) from renewable sources will be required to meet future H2 energy demands, and offshore sites are critical for industrial-scale production.

Tractebel responded by developing an offshore hydrogen platform concept in 2019, which was followed by an improved, scalable version the following year.

Now, the company claims to have designed the world's first offshore infrastructure and processing facilities idea for hydrogen storage in offshore caverns.

This offshore platform complex includes a wellhead platform for cavern operation and a succession of compression platforms for capacity expansion in stages.

Additional modules can be added to the plant in the future if necessary. The study assumes a capacity of 2GW of green offshore wind power converted to hydrogen. Individual adjustments and extensions are possible at any time.

Offshore compression and storage facilities like this can help future offshore hydrogen production become even more flexible. According to Tractebel, if the compression effort at wind farms' electrolysis plants reduces, so will the cost of offshore hydrogen manufacturing 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." said Klaas Oltmann, Director Business Development at Tractebel Overdick GmbH.

"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”  he added.

The newly constructed storage and compressor platforms process 400,000 Nm3/h of hydrogen, which is kept at a pressure of up to 180 bar in subsurface salt caverns. These storage facilities are supposed to buffer output peaks, improve flow rates, and allow for a more cost-effective export pipeline design.

Existing offshore infrastructures can directly employ green hydrogen instead of other energy sources for their operations, helping to the decarbonization of the entire offshore industry, according to Tractebel. This makes massive underground hydrogen storage facilities more sustainable.

Due to its geological features and subterranean rock salt formations, the North Sea is ideal for the solution. In these formations, caverns are leached to provide vast storage quantities. For optimal peak coverage of offshore H2 production rates, the analysis considers a total storage volume of up to 1.2 million cubic meters as a starting value.

”This storage is also necessary in the long term, because it will be an essential building block for the success of the energy transition,” said 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.”

The technical teams of DEEP.KBB GmbH and PSE Engineering GmbH were also involved in the design research, supporting the concept's comprehensive development, from geology to processing equipment, in addition to Tractebel's renewable energy and offshore experts.

According to Tractebel, this packaged know-how will serve as the cornerstone for additional optimizations of the offshore hydrogen hub and future H2 initiatives.

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