New ways to model fuel cell performance could greatly improve technology, says Hyzon CTO Shinichi Hirano
Hydrogen Economist, Vincent Lauerman interviewed Hyzon’s chief technology officer, Shinichi Hirano, to help ascertain the state of competition between hydrogen fuel cells and batteries in the heavy-duty truck market, as well as the outlook for its G3 Titan Stack. Hirano is 30-year veteran of automotive fuel cell technology, and led the Ford-Daimler fuel cell alliance during his 17 years with vehicle manufacturer Ford Motor Company.
When are heavier duty vehicles better suited to run on hydrogen than batteries and why?
Hirano: Hydrogen fuel cell electric vehicles (FCEVs) show a significant advantage over battery power for heavy-duty and mid-duty truck applications. Hydrogen is significantly more energy dense than batteries, which is an advantage that allows for longer driving range and heavier payloads. For example, a hydrogen fuel cell powertrain is more than 2t lighter than a battery powertrain for a 500-mile range truck.
Additionally, the refuelling time of hydrogen is significantly shorter than battery charging time. This makes it appropriate for highly utilised vehicles, which run 2-3 shifts per day, leaving little downtime to charge. A hydrogen FCEV will take minutes—up to 15 minutes for a Class 8 truck—to refuel, while an EV takes hours to recharge.
Lastly, FCEVs are less sensitive to cold temperatures than battery electric vehicles (BEVs). At cold temperatures, the range of BEVs can be greatly reduced.
What is the lifespan for fuel cells compared with batteries?
Hirano: The expected lifetime for fuel cells is about 20,000 hours for a less aggressive usage profile such as steady-state operation, but fuel cell life is highly dependent on the operational profile. Hyzon is working to achieve a lifetime of 20,000 hours under a more realistic operation profile. It is difficult to make an apples-to-apples comparison with battery life, as these are measured in number of charging cycles.
Do their end-of-life issues differ? If yes, how so?
Hirano: The end-of-life issues do differ. In fuel cells, the main issue is performance degradation, which gradually lowers the maximum power and efficiency of the fuel cell. A typical cause of degradation is catalyst degradation, including platinum catalyst dissolution.
Hyzon is taking multiple technical approaches to improve the lifetime of fuel cells. We are working to make our materials more robust and durable, and deploying a systemic mitigation strategy to account for stress factors and ultimately improve the lifetime without using exotic materials.
Batteries, on the other hand, lose capacity over time. In some instances, the energy density at a battery’s end-of-life is approximately half of its original density.
Are there potential game-changing developments in the technology on the horizon?
Hirano: Yes. Nano-scale visualisation of fuel cells through synchrotron x-ray tomography and computational fluid dynamics techniques allows for the accessibility of detailed behaviour at the fuel cell reaction site, which is used to design the structure and material property of electrodes. This high-fidelity model-based engineering could become a game-changing advancement.
Another potential game-changer could be the adoption of artificial intelligence devices, which enable model-based control and the prediction of the future state of hydration to optimise operational conditions to avoid failures—and eventually improve lifetime and performance.
At the present time the capital cost of hydrogen FCEVs is substantially higher than diesel-powered ones. What will it take to close the gap?
Hirano: Customers of commercial vehicles are conscious of the total cost of ownership (TCO) rather than the capital cost of vehicles. That TCO is primarily driven by fuel costs over the lifetime of the vehicle. Hyzon is developing fuel cell vehicle technology and access to low-cost hydrogen through local, technology agnostic production and distribution.
How does your G3 Titan Stack support that effort?
Hirano: G3 is Hyzon’s next generation fuel cell technology and is designed to improve efficiency, durability and power density, to provide a carbon-neutral solution and TCO benefits to our customers. It has the highest priority in Hyzon’s R&D work.
Our G3 technology supports the fuel cell stack, cell system architecture and system controls. Utilising G3, Hyzon’s system design will be able to achieve higher power (200-310kW) at lower cost.
What technological developments have allowed the G3 to achieve the world’s highest power density for a PEM fuel stack?
Hirano: Hyzon is aiming for not only the world’s highest power density but also to produce maturity—specifically reliability, durability and system efficiency in the G3 technologies. In addition to other innovations, G3 uses titanium metallic plates to make the cell thinner and lighter. Titanium is both corrosion-resistant and adhesive to our coating material, making it a key enabler to improve density.
SOURCE: Hyzon Motors