Synthetic fuel is the Bergius process. In this process, coal is liquefied by heating in the presence of hydrogen gas (hydrogenation). Dry coal is mixed with heavy oil recycled from the process. Catalysts are typically added to the mixture. The reaction occurs at between to and 20 to 70 MPa hydrogen pressure. The reaction can be summarized as follows: formula_1 After World War I several plants were built in Germany; these plants were extensively used during World War II to supply Germany with fuel and lubricants. The Kohleoel Process, developed in Germany by Ruhrkohle and VEBA, was used in the demonstration plant
Evolutionary history of plants also formed shallow rooting systems during the Famennian. The rhizophores of the lycopods provide a slightly different approach to rooting. They were equivalent to stems, with organs equivalent to leaves performing the role of rootlets. A similar construction is observed in the extant lycopod "Isoetes", and this appears to be evidence that roots evolved independently at least twice, in the lycophytes and other plants, a proposition supported by studies showing that roots are initiated and their growth promoted by different mechanisms in lycophytes and euphyllophytes. A vascular system is indispensable to rooted plants, as non-photosynthesising roots need a supply of