When I worked on the National Aero-Space Plane (X-30) project from 1988-1995, we were using liquid H2 as the fuel.
The program had several failures, most notably the inability to get the scramjets working to necessary velocities. But we were very successful with producing, storing, pumping and burning H2 proving its worth as a fuel.
Oh, and they said they discovered that if you ran an electric current through the exhaust it would give you ozone . . . so theoretically we could have put back any of the “missing” ozone layer.
That issue kinda went away.
Went away as soon as they stopped the SST in fact.