Dear Planelover, sorry, that system won't work on planes. The system would be way too heavy.
What they think of in cars is also quite heavy stuff, which will generate only some 5 or 10 horsepower continuously.
That would be OK in a small town car. The fuel cell would constantly feed electric power corresponding to 5-10 HP into a battery, very likely an ordinary, but large lead-acid battery. You would pull maybe up to 50 HP from that battery when starting at green light or climbing a steep hill, but the fuel cell would deliver its 5-10 HP to the battery also at "idle" at red light and when driving downhill. You might even use the electric motor as a brake delivering energy back to the battery.
Flying, however, requires constant high energy. A large and heavy wide body plane requires something comparable to 100,000 to 200,000 HP to get in the air and for initial climb. And much less for level cruise of course - 25,000 to 50,000 HP. Fuel cells with that sort of capacity would be way too heavy if we don't dream up a technology break-through which nobody can imagine today. It is not a question about making it 50 or 75% lighter. We are talking about an entirely different scale.
Also imagining four electric motors driving the fans on a B747 at 200,000 HP, they would be prohibitively heavy. Have a look at a 2,000 HP electric motor in a train locomotive. And multiply by 100.
But hydrogen is a perfect turbine fuel. Only the storage is a huge problem. And of course producing it.
Regards, Preben Norholm
Always keep your number of landings equal to your number of take-offs