Figure 3 Principal sketch of a hydrogen filling station downstream gaseous hydrogen supply. Sketch taken from http://www.electrolysers.com
The produced hydrogen will after being dried and purified, be transferred to the compression unit where it will be compressed to about 450 bar (typical for the CUTE stations). The compressor(s) are expected to be located inside a container or some type of weather shed, see. Figure 1.
The produced and compressed hydrogen will be transported in a pipeline to high pressure storage vessels. The vessels are divided into several vessel banks, called the high pressure bank, the medium pressure bank and the low pressure bank to be able to carry out a three stage "cascade filling" of the vehicles. A two stage cascade filling system combined with a booster compressor, or a multiple stage cascade filling system with more than three pressure banks are other options. This is to ensure that the on-board vehicle storage tank reaches the optimum fill pressure within the required time. Each vessel bank is equipped with it's own pressure relief devices and pressure monitoring instruments
Typical storage pressure today is in the order of 350 – 450 bar, but it is expected that the storage pressure may be significantly higher in the near future (600 – 900 bar).
The storage cascades will be filled from the production side, one at a time, and the produced hydrogen will first flow to the high pressure bank, then to the medium pressure bank, and the low pressure bank will be the last filled vessel bank. This is to increase the efficiency of the filling process.
The storage and refuelling system assumed is based on cascade filling and high pressure storage. There may also be other alternatives.
The Fuel Gas Dispenser is a "stand-alone" unit, which provides the mechanical interface between the hydrogen fuel station storage tanks and the vehicle together with safety features and metering equipment. The dispenser consists of a small enclosure where regulation and control valves are located. The filling sequence may be based on cascade filling or cascade