mechanically breaking a source substance comprising relatively long carbon chains molecules by application of physical force to said source substance, which force causes the relatively long chain molecules to break into shorter chain molecules so as to produce a product substance comprising shorter chain carbon molecules, wherein breaking the relatively long carbon chain molecules into the shorter chain carbon molecules is carried out at temperatures at or below 0° C., wherein said shorter chain carbon molecules include fuel fractions, and further comprising recovering said fuel fractions from said product substance.