Every few weeks an article will appear about an automaker designing a hydrogen engine to replace the EV. I’m not a big supporter of hydrogen passenger cars or hydrogen in combustion engines in general. While the concept is noble, and it works in theory, hydrogen combustion engines are not well suited for on-road vehicles in today’s world. I’m not even going to get into the challenges of production, storage, and dispensing, as they have been addressed before.
The drivers, pardon the pun, behind the push for new technologies in transportations are sustainability and cost. The alternatives to gas and diesel are EVs (including hybrids), hydrogen fuel cell electric vehicles, and hydrogen combustion engines.
Conventional thinking is that it will be less expensive to convert an existing ICE to run on hydrogen. While it’s possible to convert some existing vehicles to run on hydrogen, in the long run, an electric engine will be less expensive to make than a combustion engine vehicle, be it gas or hydrogen.
The real cost benefit is in the operation of the vehicle. The energy to run an EV vs. a hydrogen vehicle is dramatic. The electricity cost for a passenger car is about $5/100 miles. A hydrogen combustion engine would be more like $40/100 miles. This difference is staggering.
Comparing hydrogen combustion engines and hydrogen fuel cells also reveals a significant difference as hydrogen combustion engines are far less efficient. The overall system efficiency of a FCEV is 34-57%, compared to 25-40% for a hydrogen combustion engine. This translates into more fuel being consumed for the same distance traveled. Using the comparison above, the FCEV would cost about $25-$30/100 miles. This efficiency advantage highlights why fuel cell electric vehicles (FCEVs) are considered a superior technology for most applications involving hydrogen.
All three technologies produce no CO2 at the tailpipe, but that is where the environmental similarities end. The Hydrogen ICE does produce Nitrogen Oxides (Nox) as part of the combustion process. Nitrogen oxides, primarily nitrogen dioxide (NO₂) and nitric oxide (NO), are pollutants produced by all combustion engines. Exposure to NOx has significant health implications, including respiratory impact, cardiovascular effects, and cancer risk.
Children, the elderly, and individuals with pre-existing health conditions are particularly vulnerable to the adverse effects of NOx exposure. Reducing NOx emissions from combustion engines is crucial for improving air quality and public health and is a more urgent and pressing matter than carbon emissions.
This is not to say that there is no place for hydrogen in transportation. The niche for hydrogen is with fuel cells in high use and heavy-duty equipment. Dedicated and tethered fleets are the most attractive targets. I believe Hydrogen is the Diesel Killer.
I see EVs as the superior choice for passenger cars and medium duty trucks and FCEV for high use and heavy-duty vehicles. Hydrogen combustion engines do not fit into the mix.
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