NOVELTY - Preparing a gaseous fuel comprises: (a) providing a wet alcohol; (b) adding a fuel constituent to the wet alcohol to form a liquid fuel; and (c) converting the liquid fuel to form a gaseous fuel, where the gaseous fuel has a lower fuel density than the liquid fuel.    USE - The method is useful for preparing gaseous fuel and gaseous fuel substance (all claimed) for a fuel cell and/or a heat engine of piston-powered vehicles.    ADVANTAGE - The gaseous fuel has: higher chemical energy potential and/or a higher pressure energy potential than the liquid fuel; lower availability to be ingested by animals or plants than the alcohol; shorter half-life as a contaminant than the liquid fuel; and shorter time of dispersion upon leakage than the liquid fuel; and improves fuel storage safety for a variety of systems and the overall volumetric efficiency of the engine.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) providing a gaseous fuel to a combustion chamber, comprising the step (a)-(c) as above per se, and delivering the gaseous fuel to a combustion chamber;    (2) providing gaseous components to a combustion chamber, comprising providing a liquid fuel comprising an alcohol and water, passing the liquid fuel through a countercurrent heat exchanger in a first direction to form a heated liquid fuel, passing the heated liquid fuel through an endothermic reactor and/or a heat exchanger to form pressurized gaseous components, passing the pressurized gaseous components through the countercurrent heat exchanger in a second direction opposite from the first direction to form cooled pressurized gaseous components, and introducing the cooled pressurized gaseous components into the combustion chamber, where the cooled pressurized gaseous components have a lower fuel density than the liquid fuel and/or the heated liquid fuel; and    (3) producing a gaseous fuel substance, forming a liquid fuel comprising formic acid, adding a fuel constituent to the liquid fuel to form a mixture, and applying heat and/or electrical energy to the mixture to form the gaseous fuel substance.