development of underground hydrogen storage

The hydrogen storage location is to be selected after a rigorous siting study of subsurface geology, the proximity to the hydrogen infrastructure (e.g. EU hydrogen backbone), and the proximity to supply and demand centers. The heart of the hydrogen storage project will be a cluster underground caverns created in deep salt formations situated about 600-1500 meters below the ground level. The void will be created by the process of leaching the salt rock by water (solution mining). 

Salt formations have already proven to be the world’s best sealing rocks for natural gas reservoirs. The hydrogen caverns will be sealed by about 300-meter-thick salt layers to ensure leak-free containment of the gas storage. The integrity of the caverns will be additionally tested by a series of Mechanical Integrity Tests (MIT) during development and regularly during operations. The cavern size will be big enough to fit the entire Eiffel Tower inside the cavern, which would be about 300 meters tall and 70 meters in diameter. This will allow for the storage of over 5000 metric tons of hydrogen per one cavern, roughly 500k m3 in size, an equivalent of nearly 200 GWh of energy. A cluster of 10 of such caverns would make up a 2 % of the annual energy consumption of the Netherlands. After connecting with the surface infrastructure such as the hydrogen backbone, the caverns will be ready to be filled with hydrogen and serve its customers.

The underground hydrogen storage project will be developed in 3 phases as outlined below, which will be followed by the cavern operating phase.

The underground hydrogen storage project will be developed in 3 phases as outlined below, which will be followed by the cavern operating phase:

(1) hydrogen storage feed phase (project planning)

• Market pre-commitment – Letters of Intent (LoI) and Master Storage Agreements (MSA) with prospective customers for hydrogen Storage-as-a-Service (STaaS)
• Pre-FEED – tenders for strategic services, site feasibility and pre-requirements studies
• Stakeholders and community engagement
• Regulatory and legal framework
• Geologic site investigation and site acquisition
• FEED – subsurface and surface front-end engineering design
• Permitting – application for salt mining and hydrogen storage

(2) hydrogen storage construction phase (project execution)

• Fresh and brine water disposal facility construction
• Power supply construction
• Connection to existing H2 pipelines infrastructure
• Well drilling and completion
• Cavern leaching operations
• H2 compression and purification system construction

(3) hydrogen storage testing phase (project commmissioning)

• Brine extraction and buffer gas injection (30% of total cavern capacity)
• Cavern Mechanical Integrity Tests (MIT)
• Surface infrastructure integrity checks