Why bother with an actual engine if we are using hydrogen for whatever reason? It reintroduces NOx emissions for less efficency. Fuel cell conversion is more ef

Why bother with an actual engine if we are using hydrogen for whatever reason? It reintroduces NOx emissions for less efficency. Fuel cell conversion is more efficient than heat engines are. And production is already a big haircut. Hydrogen is already a crazy corrosive lighter than air escape artist. If it wasn't such a problem child, then niche high capacity storage for surplus electric generation could justify worse round trip efficency.