Pioneer's innovative Cascade Technology

Offering more hydrogen refills and greater utilisation

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Pioneer Cascade Technology

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There are typically two ways to transfer hydrogen gas from one receptacle to another without using a compressor: This is decant or cascade technology.

Both methods utilise the pressure gradient between a higher-pressure source and the low-pressure target tank to move hydrogen fuel without any external energy requirements.

Decant Technology

A decant system takes a high-pressure system of a certain volume and is connected to the target system also at a certain volume and at a lower pressure.

The systems are opened to one another and the hydrogen flows from high pressure to low pressure. This movement of gas stops when both systems have reached the same pressure. This is known as equalisation.

Pioneer Cascade Technology

The Pioneer Hydrogen Refuelling Station utilises cascading refuelling, which is essentially an automated sequence of individual decants. This technique enables the filling of significantly more vehicle tanks to higher fill pressures & greater hydrogen utilisation from the refueller than through simple decant filling.

A cascade filling system is a multi-bank high-pressure gas cylinder storage system which is used for the refilling of smaller compressed gas cylinders.

Read more on the Pioneer and its innovative low-cost solution here, or contact us now for more information!

Principle of Operation

Decant fill

The simplest hydrogen refuelling method is the decant method, where a large, high-pressure storage vessel (or several small vessels joined together), is connected directly to a user’s vehicle to decant a portion of hydrogen. This works by allowing the pressure in the hydrogen storage vessel to balance with the hydrogen vehicle’s fuel tank.
The decant method has the benefit that it is of minimal complexity, and has a low capital cost for a single fill. However, it is only capable of delivering very few vehicle refuels at high pressure before the cylinders are deemed too empty to give an adequate state of charge.
This can be seen using the game of tower-blocks shown in the animation below.



Cascade fill

A more effective standalone refuelling strategy is the cascade method. This refuelling technology is essentially a sequence of individual decants, in which multiple high-pressure vessels (not necessarily all at the same pressure) are individually, or in small groups, connected to the downstream tank of a hydrogen powered vehicle.
In using this approach, the cascade technology is able to first dispense fuel from its lowest pressure cylinder. Then, when the cylinder source has achieved balance, the next highest-pressure cylinder is connected. This process continues with each successive vessel source to ensure high pressure at every step of the refuelling cycle.
This approach optimises utilisation of hydrogen from a standard source cylinder to achieve a significantly higher rate of vehicle refuels to the target pressure.



Decant Vs Cascade Comparison

This graph indicates the relative performance of the two solutions when filling a bus tank.

A full fill = 20kg for a typical large hydrogen bus application.

The 4 bank cascade method vs 9 bank cascade method demonstrates that a 4 bank system provides faster refuels. A 9 bank system offers better gas utilisation, to which a Pioneer Hydrogen Refuelling Station can be configured.

NanoSUN's Pioneer Hydrogen Refuelling Station's incorporation of innovative cascade technology offers faster refuel times and better hydrogen gas utilisation.

Unlike traditional fixed refuelling stations, cascade refuellers require no external power source or moving parts hence they work well for reliable field and mobile hydrogen refuelling. An additional benefit of the cascade system is the ability to meet the demand of filling several small cylinders in close succession, whereas filling from a traditional compressor with buffer cylinder often has the need for longer intermediate periods during which the buffer cylinder can be recharged.

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The Pioneer Hydrogen Refuelling Station
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