Hydrogen Storage for Heavy Duty Trucks: Challenges and Solutions

Hydrogen is a promising alternative fuel for heavy duty trucks supporting decarbonization of transportation and participating to cleaner mobility: up to Zero Emission in the case of FCEV. However, hydrogen storage poses several technical and economic challenges that need to be addressed. In this article, we present some of the aspects of hydrogen storage for heavy duty trucks, based on the experience of FORVIA, one of the companies involved in the RHeaDHy project and design expert in hydrogen storage systems.

Storage capacity

One of the main challenges of hydrogen storage for heavy duty trucks is to maximize on-board H2 quantity to reach the optimal range of operation. Within RHeaDHy, we work with a storage capacity of 100 kg of H2 in line with objectives of H2 refueling station of 100kg refueling in 10 minutes. This is an ambitious goal as no such system is available on the market today.

Most of the trucks manufacturers are still at the prototype or small fleet phase, with some architecture limitations. Vehicle constraint for Hydrogen storage system integration are important due to the fact that on-road vehicles size is limited, that energy volumetric Density of CGH2 70 MPa is lower than Diesel fuel or Battery, and that market trend is maximization of driving range. Today, most H2 truck programs aim to install 60-80 kg systems.

Constraints

Another challenge of hydrogen storage for heavy duty trucks is to design a system that can fit with vehicle packaging constraints and comply with the safety and performance requirements. A unique 100 kg tank would be approximately 3.5 m long and have a 1 m diameter (inner dimensions). Most of the current European trucks can’t integrate such a volume. Forvia faced several constraints for designing such a system, such as:

• Integration within the vehicle: With current European heavy-duty trucks architecture, H2 capacity is limited. The tanks are usuallly installed behind the cabin or in the vehicle wheelbase, EU regulation about maximal vehicle dimensions then limit the available space and tank length.,.
• System architecture design: The system consists of multiple tanks with different sizes and shapes (as depicted on Figure 1), leading to different thermal behavior The system also includes valves, piping, sensors, and other components that need to be optimized and integrated.

Figure 1: Two different H2 storage architectures designed by Forvia to equip trucks.

Forvia is developing type IV tanks in line with the current standards and norms. These tanks are made of a plastic liner and a carbon fiber composite mechanical structure. This type of tank offers the best weight-to-capacity ratio and need tooling and process adaptations. Moreover, new refueling protocols standards (SAE J2601-5) are designed for tanks not larger than 800 L, meaning ~32 kg of H2. This assumption is based on the outcomes of a survey sent to the industry stakeholders, including vehicle manufacturers, CHSS manufacturers, and hydrogen station manufacturers and operators.

Models

To overcome these challenges, Forvia relies on advanced correlated modelling and simulation tools that can predict the behaviour of the hydrogen storage system under various conditions. Forvia is able to do:

• 3D and 1D fluidic/thermal simulation, to evaluate the hydrogen flow, temperature, and pressure inside the tanks and the system.
• 3D FEA (finite element analysis) to model the mechanical stress of the tank to ensure the structural integrity and safety of the tank under different load cases.
• 3D FEA simulation for mechanical stress on a system level, to optimize the system architecture and integration.

Test

In addition to modelling and simulation, Forvia also performs experimental testing to validate and demonstrate the performance and reliability of the hydrogen storage system. Forvia is developing a dedicated test bench for RHeaDHy project, which must be modular so that tests can be done on the full 100 kg capacity and also potentially less. The test bench must also comply with the R134 certification limitations, which means testing with tanks gas temperatures in a range going from -40°C to +85°C and pressure going up to 875 bar at +85°C. Nothing going out of the R134 boundaries will be tested during RHeaDHy testing phase.

The test bench will allow Forvia to perform refuelling and defuelling tests, as well as durability and safety tests, to evaluate the system performance and robustness. The test results will provide valuable feedback and data for the system improvement and optimization.

Forvia is confident that the hydrogen storage system developed for the RHeaDHy project will meet the expectations and requirements of the heavy duty truck market,and will contribute to the deployment and adoption of hydrogen mobility in Europe.

Authors: Loïc GOUBIN and Sullivan ICARD (FORVIA), and Jean HERISSON (Benkei)