Not to mention the fact that it’s relatively low on BTUs, unless burned in pure oxygen.
Your physics teacher failed you and for that they should be ashamed.
https://h2tools.org/hyarc/calculator-tools/lower-and-higher-heating-values-fuels
H2 has one of the highest LHV per kg of mass than virtually any other fuel. LHV is in a standard atmosphere of N2 and O2 btw.
H2 is 119.96MJ/Kg
Conventional petrol is 43.44MJ/Kg