The hydrogen leaves the electrolyzer at 400 to 500 psi and flows into a large distribution tank. When the distribution tank is nearing capacity, the hydrogen is pumped to smaller primary vessels and pressurized to 10,000 psi for storage. The primary vessels are designed to provide enough hydrogen storage for nighttime energy use and use when other renewables are incapable of providing energy due to extended weather events.
Each of these primary vessels are equipped a series of check valves and robotic valves to maintain security and safety in the event of a hydrogen leak. Should that occur, the operator is notified by series of sensors that detect any loss in high pressure. With that information, the operator can make the necessary valve closures and adjustments to operations to ensure the safety of the plant.
The use of a number primary vessels is necessary to avoid a process called embrittlement. Embrittlement occurs when hydrogen is under high pressure inside the container vessel. The hydrogen molecules being much smaller than the Ferrous molecules actually penetrates the surface of the container vessel. Over time, this can cause the wall of the container vessel to weaken and possibly rupture. This problem is easily solved by allowing each primary vessel to be periodically emptied of nearly all stored hydrogen to pressures near one bar. This allows the hydrogen molecules embedded in the vessels surface to be squeezed back out into the hydrogen atmosphere. In the field of storage tanks through this process at least one tank would be near empty at all times.