[ storage ] appropriate solution , but otherwise , liquefaction is a costly and energy-intensive approach .
Unique underground solution
Vertical hydrogen storage housed below ground presents a new storage solution for quantities of hydrogen ranging from 1 to 100 metric tons . In such a system , hydrogen is pressurized and injected into long pressure vessels made of pipe assemblies . Each pipe is 12 meters long , and , depending on needs , varying numbers of pipes can be assembled using threaded connections to reach the desired depth . These pipe strings are inserted into excavated ground between 5 and 10 meters in diameter and up to 100 meters in depth .
Significantly lower footprint
One of the principal concerns that an underground vertical storage solution addresses is the footprint required for hydrogen storage . Using a vertical underground system can occupy up to 30 times less surface area than alternative above-surface solutions . It utilizes existing underground civil works technologies , such as ventilation shafts and access wells , and applies existing knowledge from the energy sector for the assembly of steel pipes .
Housed below ground , the storage system is nearly invisible – helping with acceptance from surrounding communities and meeting permitting requirements . The vertical solution also means hydrogen is much less exposed , improving security by limiting access .
Optimal safety
Vertical storage brings numerous gains in terms of safety . Firstly , the cavity is inert . With no oxygen in the space between pipes , it prohibits the potential for an explosion , minimizing risk in the underground part of the storage . The solution also provides passive ventilation . In the unlikely event of a leak , hydrogen is unable to accumulate . It would dissipate and rise to the surface , where it would be detected , and the leak would be quickly
The Delphy demonstrator in France is representative of all the main functions and steps in the value chain and will run tests until Q3 2024 .
dealt with . In the theoretical event of an explosion , energy would be directed upwards , away from equipment and personnel onsite .
On top of this , the storage system is equipped with rigorous safety features . Drawing on state-of-theart instrumentation and automation , the solution provides optimal leak detection , fire detection , and fire safety . Piping and instrumentation are connected in the upper part of the assembly in an accessible chamber , as is the automation that controls the system – including leak detection and sensing methods , infrared and hydrogen sensors .
The materials selected have been explicitly engineered and validated for hydrogen applications . This includes qualified hydrogenresistant tubes and hydrogen-tight connections to ensure a metal-to-metal seal , withstand hydrogen-induced embrittlement , and prevent any
Hydrogen Tech World | Issue 17 | August 2024 19