Yesterday I published an article on the efficiency disadvantage of the H2 cycle. A couple friends pointed out two issues with the schematic represented in the chart:
- many electrolyzers are NOT built right next to a photovoltaic or wind farm, so transport losses should accrue;
- the final stage of a FCEV car has a battery, because otherwise the delivery of power would be unacceptably sluggish;
prompting a revision of the chart slightly amending the figures to account for the initial transportation loss:
Summing it up, the two cycles are identical (so there is NOT a true “proton cycle”), and the hydrogen path merely replaces a single AC/DC converter with an elaborate “proton loop” which uses electricity to electrolyse water, compress the resulting hydrogen and re-oxydise it in a fuel cell to get back electricity which is then finally fed to an identical (except for its size) battery for conversion and use in the same electric motor.
The proton loop costs about two-thirds of the input energy vs. the about 5% efficiency tax imposed by the battery charger.
Note: readers asked where the efficiencies come from, and apologize if anybody thought I implied they were my own work. They come in fact from T&E and here is the source.