At Present,it Will Be Difficult and Perhaps Inappropriate to Develop

At present,it will be difficult and perhaps inappropriate to develop an economy based on burning hydrogen rather than natural gas or gasoline because

A) hydrogen is a dirty fuel.Burning hydrogen produces significantly more pollutants than burning natural gas or gasoline.
B) hydrogen is not an efficient fuel.Per gram,hydrogen has about the lowest heat of combustion of any known substance,much lower than natural gas or gasoline.
C) although hydrogen is abundant,pure hydrogen is not found naturally on earth.Hydrogen is difficult or expensive to isolate and collect.
D) being such a light element,hydrogen will not flow through pipelines the way natural gas or gasoline do.Hydrogen cannot easily be delivered from where it is produced to the places where it is needeD.