The BIGGEST problem with clean energy

yikes, hydrogen "can" be... but isn't.  Also isn't water the better storage for hydrogen?  There's a company that heats up sand and stores energy that way, they're effectively using dirt.  Why is this subject in vogue right now, why weren't these things thought of before, is it because of the transition to renewables happening only recently?  There are many different viable technologies and we'll get to see who can scale up.  That growth projection mentioned at the end spells doom for fossil fuel generated energy.