There are some people working on hydrogen fuel cells for multirotors but they have some way to go before we are likely to see a hydrogen powered consumer multirotor.They are flying but they are not compact and look a bit ungainly but the flight times are impressive even though most of the 45 minute plus flights are only hovering.
There are a few videos on youtube showing where the technology is at.
This one looks good but it's huge in comparison with most of the multirotors we play with.
