SEPTEMBER 2024AUTOTECHOUTLOOK.COM9"One can imagine how the alphabet soup of compliance laws creates a difficult business environment in which OEM strategies are difficult to maintain and flexibility must be exercised.""Initially, JCB had designed an excavator that used a hydrogen fuel cell. But after extensive testing, JCB decided fuel cell technology was not the best option for their customers, and they decided to move toward a hydrogen-combustion solution."Later, Youngs concludes, "FCEVs and HICEs do not compete with one another...Ultimately, it's not a matter of which technology is better but which is more suitable for an end user's conditions, applications, and needs.Note that these OEMs are leaning on the same carbon-free energy source and the ICE for future applications in these working-class vehicle sectors. Fortunately, the EPA accommodates H2-ICE as a zero GHG option in the Phase 3 proposed draft. Finally, hydrogen is very attractive, offering abundant fuel for millennia.Although H2 appears to be a panacea fuel for solving GHG emissions, it presents a double-edged sword called combustion flame speed. The high combustion flame speed of hydrogen is a friend of both the Diesel (Compression Ignition) and Otto (Spark Ignition) cycles. Significant efficiency improvements can theoretically be realized if we can harness the flame speed and induce a near-constant volume pressure rise in the Otto cycle. Furthermore, Westport Fuel Systems' David Mumford reported that with an HPDI fuel system, 51.5% efficiency was achieved with a late injection Diesel cycle (H2 Technology Expo Houston, June 28, 2023). On the other hand, hydrogen's flame speed produces an astonishing amount of heat release over a short amount of time, and combustion pressure rises approaching engine-knock accelerations. There are a couple more hydrogen combustion characteristics that are risky to ignore. The lower flammability limit of hydrogen allows the combustion wave to propagate near enough to the cylinder wall to combust the lubricant. Also, after hydrogen combustion, the in-cylinder environment is void of ions (unlike gasoline), and the ignition system builds a capacitive charge that waits to pre-ignite the next air/fuel mixture as it enters the combustion chamber. Sometimes called "ghost sparking," this produces negative work and can potentially damage engine components.Finally, regardless of fuel type, combustion charge air contains 78 percent N2, and NOx is produced. This criteria pollutant is a precursor to ozone and acid rain and is regulated. Abatement technologies exist to address NOx beyond 2027 regulations.The hydrogen combustion characteristics may seem daunting, but not as daunting as producing a battery to drive working-class vehicles. The industrial engine developer must tackle these concerns, or their engines will not go to market. Fortunately, early engine testing has identified these concerns, and viable solutions are emerging.Stronger piston materials and designs, durable self-lubricating ring coatings, ignition systems designed to mitigate ghost sparking, and exhaust after-treatment systems designed to function directly after start-up are currently under test or in production and ready for hydrogen fuel applications. The full functionality of hydrogen fuel is challenging but only requires special design considerations (not a technological perturbation). H2-ICE seems to occupy that functional "sweet spot," meeting emissions regulations and customer demands. OEMS must find suppliers who enable them to achieve their goal of employing hydrogen in blue-collar vehicles. In addition to the cited references, the author wishes to thank Tenneco technology experts Dmitri Konson, Dr. Steffen Hoppe, Dr. Frank Doernenburg, and Dr. Volker Scherer. Stronger piston materials and designs, durable self-lubricating ring coatings, ignition systems designed to mitigate ghost sparking, and exhaust after-treatment systems designed to function directly after start-up are currently under test or in production and ready for hydrogen fuel applications
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