I believe that you’re thinking of Helium. As @deelowe said, the issues with a Hydrogen are safe and stable storage, and the tendency of Hudrogen to penetrate me

I believe that you’re thinking of Helium. As @deelowe said, the issues with a Hydrogen are safe and stable storage, and the tendency of Hudrogen to penetrate metals and make them brittle. Producing hydrogen is trivial with electrolysis or water, which could be achieved using nuclear and renewable power sources. Of course burning coal to produce Hydrogen is currently cheaper and more common, and an environmental disaster. The problem with Hydrogen is that you want to store it in big, strong metal containers, but it destroys the container and leaks out. So instead you store it in composite fiber containers, but then you have an explosive gas under pressure in a vessel that can be cracked. This is part of the reason that research tends to focus on processes within fuel cells which produce hydrogen JIT, so you obviate the need to produce and store large volumes. The problem with that is the need for more power input than you get out, or the need for expensive catalysts like Platinum. tl;dr With current tech you need nuclear power to efficiently produce large volumes of Hydrogen, but that’s a political minefield. Storing Hydrogen is a nightmare. Hydrogen explodes, and peolle are rightfully wary of carrying and transporting it in large volumes. The kinds of containers which are affordable and practical are made of materials Hydrogen readily attacks.