The storage and transportation barriers of hydrogen are cleared by sodium metal “Source of Hydrogen” produced from warm seawater discharged at the nuclear power plant. The warm seawater is electrolyzed to produce sodium hydroxide; which is then subjected to molten-salt electrolysis by surplus power of the plant to produce sodium metal “a hydrogen generator”. The seawater contains salt most after fresh water; which is the raw material of sodium metal and is never drained. The sodium metal is transported to the electric power station in a consumption place, where a large amount of hydrogen is generated immediately by adding water on the sodium metal for power generation. Salt, the raw material of sodium metal, is in the sea over the world, and it is not necessary to worry about the maldistribution and exhaustion.