Experimental Comparison of Hydrogen Refueling with Directly Pressurized vs. Cascade Method

Abstract

This paper presents a comparative analysis of two hydrogen station configurations during the refueling process: the conventional “directly pressurized refueling process” and the innovative “cascade refueling process.” The objective of the cascade process is to refuel vehicles without the need for booster compressors. The experiments were conducted at the Hydrogen Research and Fueling Facility located at California State University, Los Angeles. In the cascade refueling process, the facility buffer tanks were utilized as high-pressure storage, enabling the refueling operation. Three different scenarios were tested: one involving the cascade refueling process and two involving compressor-driven refueling processes. On average, each refueling event delivered 1.6 kg of hydrogen. Although the cascade refueling process using the high-pressure buffer tanks did not achieve the pressure target, it resulted in a notable improvement in the nozzle outlet temperature trend, reducing it by approximately 8 °C. Moreover, the overall hydrogen chiller load for the two directly pressurized refuelings was 66 Wh/kg and 62 Wh/kg, respectively, whereas the cascading process only required 55 Wh/kg. This represents a 20% and 12% reduction in energy consumption compared to the scenarios involving booster compressors during fueling. The observed refueling range of 150–350 bar showed that the cascade process consistently required 12–20% less energy for hydrogen chilling. Additionally, the nozzle outlet temperature demonstrated an approximate 8 °C improvement within this pressure range. These findings indicate that further improvements can be expected in the high-pressure region, specifically above 350 bar. This research suggests the potential for significant improvements in the high-pressure range, emphasizing the viability of the cascade refueling process as a promising alternative to the direct compression approach.

A review of technologies in the area of production, storage and use of hydrogen in the automotive industry

“…The final test that concludes experimental development work on hydrogen components in vehicles before their market implementation is homologation testing. First of all, they confirm the safety of approved components [13]. Hydrogen vehicles must also have comprehensive approval.…”

“…This is the offer to transport large amounts of hydrogen for bus applications. This amount of hydrogen can be used to refuel twelve 12-metre buses and each of them can travel over 400 km on hydrogen [13,14,15]. GA ZAP is already considering the possibility of refuelling hydrogen buses with grey hydrogen and in the future with green hydrogen.…”

Strategic Model for Yellow Hydrogen Production Using the Metalog Family of Probability Distributions

“…Transport, which refers to using hydrogen passenger cars, buses, and trucks will require distributed sources of hydrogen generation [106]. This means that the refueling stations for low-emission hydrogen, its production in electrolysis processes, and the acquisition of energy from renewable energy sources will have to be located next to each other [107][108][109]. As a result, this will prevent transporting hydrogen on longer routes, which is quite troublesome.…”