I need to lookup the details, but...
Back of the napkin, let's say a hydrogen fuel cell car takes 10 kilos per day.
200,000 cars need 2,000,000 kilos per day
7 kilos per second production is about 600,000 kilos per day.
I was just reading an article that suggested 4.4 kilos fuel tank per car.
So either that is less than half of what it takes to feed 200,000 cars or it is right about enough for 200,000 cars (per day).
Current cost estimate is about $5.60 per gas-gallon equivalent energy.
-- Celanese has a Coal to Ethanol chemistry for like $1.20 per gallon
This opens a question about "what kind of fuel, fuel cells" (of the future)
I think we have some billions of tons of nasty dirty coal that we need to dig out of the ground and dispose of properly anyway...