Thanks for the insight, M.M. I agree that FCEV will have a complementary role to BEV. But the Clarity FC is already a HEVFC (no P), with the only problem being the battery capacity is very low. It is very analogous to FC equivalent of Prius, but with an electric engine instead of an ICE. I think Clarity FC has a 1KWh(?) capacity battery, and I can see the battery capacity changing as I drive, similar to the old Prius hybrid display.
One may suggest that the battery size be increased and a plug added to match Clarity PHEV, but FC already takes care of ZEV commuting. I think this idea makes commercial sense only if Hydrogen cost stays very high and daily charging at home is a lot cheaper.
Youre correct that the Clarity (and all FCVs) are really hybrids. It would be unnecessarily and unreasonably expensive to size the fuel cell to handle acceleration loads when a much smaller stack with a battery will provide better performance at much lower cost.
But as I said, presuming that all energy is eventually produced from renewable sources, the very large round trip efficiency loss inherent in using hydrogen for storage gives battery storage an significant edge in terms of energy efficiency.
Basically, you would need 3 times the PVs or wind turbines to generate the same number of miles driven in a FCV versus a BEV.
That trade off is worth it for long-range driving or emergency backup, but for daily short range commuting (which averages something like 20 miles in the US) it’s unnecessary. You’re building an electric drivetrain hybrid vehicle regardless, why not increase the size of the pack somewhat and add a plug.
The only caveat is that hydrogen can more easily be produced during periods of excess renewable generation, making its effective energy cost cheaper (though with a smart charging infrastructure you can do some of that with BEVs as well).
Is the creation of Hydrogen the same cost whether it is made from water, methane or other source? If it is overall cheaper to make from biomass, natural gas, etc. than say, water, then that is one consideration based on local resources.
No, the cost of production varies widely. But while hydrogen reformed from natural gas is relatively cheap, the emissions aren’t much different from an ICE, they’re just in a different location.
Hydrogen from electrolysis is always much less efficient than using the electricity directly, although as noted there may be times when that electricity is in excess and therefore very cheap.
Biofuels are an unknown. We did some bench scale research on catalytically producing hydrogen from carbohydrate solutions (which could be algae, agricultural waste, etc, and could be quite efficient), and it does work, but how viable that is at industrial scale is an unknown.
Hypothetically though you could end up with a source of cheap industrial hydrogen from vast algae farms or waste digesters.
Is the inherent energy stored in H2 pretty much zero? In other words, is the energy needed to create H2 (electricity) merely being stored and there is no inherent chemical energy of H2 (as in the case of gas)? What this means is that the Electricity->H2->Electricity is purely a storage of energy conversion with significant losses. This storage development may still benefit other industries such as energy grids where too much power may be generated by solar/wind at some times and instead of wasting it, may be stored with a recovered efficiency of ~50%, which is still better than 0%, if FC costs are less than the benefit of recovered energy, smoother power grid, etc.
Yes, H2 is
only an energy storage medium.
In technical terms hydrogen does have inherent chemical energy, but as far as what you’re talking about you need to put more energy in to produce it than it contains, whether that energy comes from a wind farm into an electrolyzer, or from a different chemical (methane, methanol, etc) plus some additional input to process it.
And yes, there are times, particularly with renewables, when you generate more than you have anything to do with, and the effective price is low or negative. Industrial electrolysis is one solution to this. I was on a research study looking into exactly this a couple years ago.
The potential issues are currently that the electrolyzer and transportation infrastructure are so expensive that the cheap energy use means you might only be running your plant at 30% of capacity, which isn’t economically viable. On a national scale were you to try to produce most of your transportation fuel this way you also get into relative scale questions—only so much electricity is needed, and the overproduction available is probably nowhere near sufficient to handle a major fraction of all transportation fuel needs.
Fundamentally, there probably is not one right answer, just many different, and complementary, ways of getting people from point A to point B.