The most relevant problem right now is not to produce (clean) energy, but to store energy. Hydrogen could be produced in areas which could not be used otherwis

The most relevant problem right now is not to produce (clean) energy, but to store energy. Hydrogen could be produced in areas which could not be used otherwise, as long as water exists - making the worse energy conversion efficiency a bit moot. Large-scale hydrogen production could both desalinate water, making it useful to surrounding areas, as well as produce hydrogen by solar power in areas currently uninhabitable. Hydrogen has to be kept at around 20K to be liquid. It could be transferred though in gaseous form in existing pipelines (see e.g. https://www.energy.gov/eere/fuelcells/hydrogen-pipelines https://www.energy.gov/eere/fuelcells/hydrogen-pipelines), cooled down only at the receiving ends. It could make use of tanker ships, equipped with insulating tanks. In aircraft, hydrogen based fuel needs to be stored as a liquid, requiring expensive (both in terms of weight and of actual cost, see https://en.wikipedia.org/wiki/Hydrogen-powered_aircraft https://en.wikipedia.org/wiki/Hydrogen-powered_aircraft for references) insulation, but still it'd be about one order of magnitude more effective in terms of volume/energy than existing batteries. It is hard to achieve similar results with plain energy. It is a bit comparable to this: https://what-if.xkcd.com/31/ https://what-if.xkcd.com/31/ - latency is much lower with energy lines, but volume could be much higher with bulk transports, like container ships.