Nitrogen fuel cell would definite create Nox, which is harmful

nope - nitrogen virtually unreactive - hence 80% of air we breathe

You mean react nitrogen with oxygen? N2 is a very stale molecule, it's reaction with air is endothermic (requires more energy to break the N to N bond than is obtained in the forming the new bonds) and nitrogen oxides (NOX) are some of the worst pollutants produced by cars. Alcohols or hydrocarbons (like we use now) produced from biomass or reaction of hydrogen with carbon dioxide make more sense to me than hydrogen itself tho as they are liquids at ambient temperatures and pressures and in an ideal system any CO2 released by these vehicles would be getting taken in at the other side making more fuel anyway. Remember when someone thought using hydrogen in passenger airships was a good idea? They thought it was safe! Didn't work out too well!

Not likely. N2 is rather stable which is extremely endothermic (i.e. energy consuming) to break the two atoms apart. It will be more likely as the final product of other potential nitrogenous fuels.

besides, the world is trying to reduce the emission of NO2, which is far worse than CO2

It’s hard request; literally. The silicon is heated, pressed, purified, cooled, and then sliced into wafer thin 0.2mm panels which are very susceptible to breakage...can they be made into flexible materials? Good question...

You could use capasitors which is less toxic in its own way. But they come with a number of new problems.

You are quite correct, however, consider,, many of the devices that are discussed are devices used in ambient light conditions. Humans walking, talking, classroom, office,,, any area that is lit enough to function in, there is enough light for an efficient photovoltaic to generate sufficient for a low power device. My desktop hand calculator here in my office at night, functions (only just) in what might be 1/100th of equivalent daylight. Computer screen in front of me, and a 6 watt table lamp in the room behind me. And the darned thing does work. I would think that is must have a capacitor in the system to even out the current,,, and a capacitor is a type of battery/storage device.

Thanks for that insight

Battery can be replace by huge hydro dam .

Ulrich Hager i have just been watching ty vids about Ethanol and Methanol fuel cells. There’s one big problem with Hydrogen fuel cells( don’t know if Ethanol or Methanol are the same) reguire Platinum, I don’t know if the Platinum needs replacing after a while, or if they last as long as needed. But considering Platinum is so rare wouldn’t it be better to use the Hydrogen, Methanol, Ethanol, and liquid fuels from Algae and Pyrolysis in a ICE instead. At least they would be Vehicles the owners or local mechanics can work on!. While avoiding the waste of hundreds of millions of cars being crushed. Sure the day may come when fuel cell technology can avoid precious metals, but while that research is happening we could be phasing our ICE when they come to the end of their repairable life. Also the first Compressed Air Vehicles ( CAV) TATA’s ‘Airpod’ is due to go into production by 2020 . If that takes off as I expect it to, then shortly after that Fords will release their new ‘Model T’ CAV using a much more efficient CA engine design than in TATA’s ‘Airpod’. I truly believe in 5-10 years time we will have a combination of car fuels including CA, Hydrogen, Methanol, Ethanol, and bio fuels from Algae and Pyrolysis, and EV making up about 1/4 of the market.

Ulrich Hager sorry mate I got into one there, and didn’t answer your Q, the reason is I jus don’t know the answer.

12,999,999 views the British museum did a video about there jade collection,it was very good