What about the Hydrogen Economy

The Hydrogen Economy is a completely different animal to the Magnesium Economy. Both hydrogen and magnesium can be used to transport and store energy but the advantages and disadvantages are very different, thus:

Cost of productionHigherlower
Storagedifficult and expensiveeasy
Efficiency in usebest fuel cell 60% Needs expensive catalystbetter than 90% Cheap
TransportCan be through pipeShipping or other systems
Economic useJust another commodityGood for global bartering
Weight as transport fuelDominated by weight of storage system.Weight of magnesium and cell
Reaction products
Non polluting water. Can be discharged safely; zero weight at end of journeyAre retained in cell which end up heavier at the end of journey
Hydrogen Vs Magnesium

The potential advantages of hydrogen are the potential distribution by pipelines and, IF a sufficiently low weight storage technology can be developed, for air transport.

The overall cost issues for Hydrogen are copmlicated, See https://insideevs.com/news/332584/efficiency-compared-battery-electric-73-hydrogen-22-ice-13/