Sources of energy from which hydrogen can be produced in massive quantity and at low cost are surveyed briefly. A short account of devices to be employed for the production of hydrogen are presented. Primarily the sun, sea and runoff waters are to be harnessed. The methodology and devices to be used to convert the available but diffused energy into hydrogen are helio-hydro-gravity, helio-aero-gravity, salt gradient solar pond, principle of magnetohydrodynamics, etc. The discussion on the inexhaustibility of naturally occurring sources utilized and/or harnessed in this process will lead to the low cost for hydrogen production. This process is imagined to be designed in a model city named 'Hydrogen City' which produces hydrogen and is run on hydrogen in order to meet its energy needs.