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I see I get to have this conversation several times.
I looked it up, hydrogen fuel cells can attain about 60% efficiency from the energy potential in hydrogen, when converting to electricity. So I'm not wrong, we're talking about different numbers.
You're referring to the efficiency of the whole system from generation (via solar panels) to conversion to hydrogen (I assume by electrolysis?) to conversion back to electricity by fuel cell (~50-60% efficiency), then any losses getting the electricity to the wheels. That's a very different number than what I was saying.
AFAIK, no real progress has gone into electrolysis for decades. But we can usually also do natural gas reclamation, which is the process of removing the carbon from CH4, and producing pure hydrogen, which, I believe is a much more energy efficient process.
It becomes an entire discussion to figure out how you're producing hydrogen for the system, which is not an easy topic to tackle in a limited written medium like this one. I decided to forego that and focus on the efficiency of the hydrogen fuel cell vs the energy potential in hydrogen directly. I was still off, I'll give you that, but not so far off to make ICE look like a good option compared to FCVs.
BEVs are great short trip vehicles, daily commuters and all around daily driver vehicles. Even with current battery technology, I'm not disputing that. The fact is that the batteries will cause the cars life to end long before anything else wears out that could potentially cause the car to get scrapped. It's cycle life which is the primary issue, but if we get super long cycle life at the cost of energy density, we generally won't switch (see LiFePO4). If the c rate is too low (significantly lower than current tech), then acceleration and charging time will suffer, and we will equally reject the technology as viable for the purpose. So it needs to beat out lithium/cobalt on cycle life, but come close to, or do the same or better than lithium/cobalt in terms of C rate and energy density.
If anyone finds something that is identical to lithium/cobalt for energy density, and C rate, and just has an improved cycle life while all other factors are the same.... Then IMO the entire industry would pivot so fast your head will spin.
Cycle life is the core of the battery problem. Other factors are nice, but the cycle life is where we need to improve before we can really get rolling on EVs. If that problem can be solved, I don't think that ICE cars will even be built anymore. It will end the consumer petrol market within a decade of such a breakthrough. Of course, there's more uses for gasoline and diesel than vehicles so there will still be gas stations, but there will be a LOT fewer of them, and many will likely be replaced by EV charging points.
If you are looking at the pure engine efficiency, we are now looking at >97% for most EV motors (class IE4). However, the point of the entire transition away from fossil fuels is preventing or delaying climate collapse. For this purpose lowering emissions and reducing energy use go hand in hand, hence the overall efficiency is critical.
Hydrogen is less strongly bound to Carbon than Oxygen, however in this process we produce more CO2 again.
There is a theoretical upper bound for the efficency of water electrolysis, depending on the temperature. While current electrolyzers can surely be improved, since we are already making electricity, we might as well use it directly. Some applications (aircraft, rockets, ...) need the higher energy density of chemical fuels. But: Working with liquid or gaseous hydrogen is terrible: Cyrogenic liquids are not easy to handle, let alone store. Hydrogen will embrittle any metal exposed to it and when inadvertenly mixed with air forms a highly explosive gas. Even the rocket people try to avoid using hydrogen unless they really need the ISP.
So far we have seen EV batteries not degrade a lot due to good BMS. For most cars the battery will last at least 10 years before performance is seriously impacted and even then the battery can be reused for storage (home or grid scale). Most EVs have >40kWh batteries, homes usually need 5-10kWh storage. So one chewed up EV battery could be reused for multiple stationary battery systems.
I do agree that current battery tech is... not great. Having less spicy cells that are easier to recycle or recondition would be a massive gain and more research needs to be a core focus. However Li-Ion and LiFePo are already good enough to work for most people most of the time. Pair this with a lot of wind and solar energy generation and you have mostly sustainable traffic. This can be done right now and it has to be done right now. I argue a lot against hydrogen because it seems like a technology that is not there yet and allows many old players in the energy market to delay a transition which is not beneficial to them.