Using solid methane, oxygen, etc as a rocket propellent?

[Starstruck69]

The conversion i presume would be done on earth so although yes there would be a cost (Thermodynamics wise) it could be spent at home and not space. The conversion back to a liquid/gas could be a bye product from the heat generated through combustion. You could use the heat from that. Would it be hot enough i have no idea? It would be relatively easy to calculate though. 

On an other point Hydrogen is a pain to work with due to instability and unpredictability. They did a lot of testing in the 60's and it was binned for the above reason if i remember correctly.

Ultimately the problem is the more equipment you take for conversion or to accomodate alternative fuel, you add mass to your craft....