How to Produce Gas From Coal

Abstract

Coal owes its origin almost exclusively to plants that grew on our earth many millions of years ago from the Carboniferous to the Tertiary Period. Vast expanses of forest land slowly subsided so that the forests were covered with water and largely shut off from the oxygen of the air. Various microbiological processes occurring at normal pressures and temperatures turned the dead organic material at first into peat, and later on, as it went further down, into brown coal. After this first coalification stage termed the biochemical phase had been completed, the morphologically and chemically inhomogeneous brown coals were converted to bituminous coals in a second, geochemical stage. This second stage, which took place under the long-term effect of an elevated temperature reaching about 150 °C at a depth around 5 000 m, is also called metamorphosis. The end product of this development is believed to be graphite.