TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The hydrogenation catalyst used in the step (b) is a Raney-type catalyst. The hydrogenation catalyst which is used in the step (b) comprises at least one following elements, each in oxidic form and/or in elemental form, comprising: copper (Cu), a combination of Cu, and titanium (Ti), a combination of Cu, and zirconium (Zr), a combination of Cu and manganese (Mn), a combination of Cu and chromium (Cr), a combination of Cu and zinc (Zn), a combination of Cu, Cr, and barium (Ba), a combination of Cu, nickel (Ni), and aluminum (Al), a combination of Cu, Al, and at least one groups comprising lanthanum, tungsten, molybdenum, Mn, Zn, Ti, Zr, tin, and/or Ni, a combination of cobalt (Co), Cu, Zn, and Zr, a combination of Cu, Cr and calcium (Ca), a combination of Cu, Cr, and carbon or a combination of Cu, Al, Mn, and optionally Zr.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: In the step (a), a glycerol-containing stream obtained in the preparation of alkyl esters of higher fatty acids by transesterification of fatty acid triglycerides is provided. In the step (a), the glycerol-containing stream is subjected to working-up by at least one working-up process which is thermal working-up, adsorption, ion exchange, membrane separation, crystallization, extraction or a combination of two or more of the processes. In the step (a), the glycerol-containing stream is subjected to a distillation for reducing the water content and/or for removing components which adversely affect the catalytic hydrogenation. In the step (a), the glycerol-containing stream is subjected to catalytic desulfuration, if appropriate in the presence of hydrogen, for reducing the content of sulfur-containing compounds, preferably sulfur-containing aromatic compounds. The step (a) comprises at least one step comprising: (a1) provision of a biogenic fat- and/or oil-containing starting mixture; (a2) trans esterification of the fatty acid triglycerides present in the starting mixture with at least one 1-9C-monoalcohol and, if appropriate, esterification of the free fatty acids present in the starting mixture with formation of an etherification mixture; (a3) separation of the esterification mixture to obtain at least one fraction enriched with 1-9C-monoalkyl esters and at least one fraction enriched with glycerol liberated in the trans esterification; and (a4) if appropriate, purification of the fraction enriched with glycerol. The pressure in the step (b) is 50-300 bars. Preferred Components: The glycerol-containing stream that is provided in the step (a) comprises up to 20 wt.% of water, in respect of the whole glycerol-containing stream. The organic solvent is 1-8C-hydrocarbons, dialkyl ethers with 2-8C, and/or 1-4C-mono alcohols. EXAMPLE - Crude glycerol (9 wt.% of glycerol, 1 wt.% of water, and 90 wt.% of methanol) was used and distilled using a small laboratory distillation setup with a flask containing the crude glycerol and attached condenser. All experiments were carried out using a continuous laboratory hydrogenation plant consisting of three pats such as pre-heater, reactor and collector for the effluent. The solution of glycerol was pumped with a common HPLC pump from Bischoff from a reservoir, mixed with hydrogen and then passed through an electrically heated spiral coil of 5 m length with an inner diameter of 2 mm. The reaction mixture was then passed over the fixed bed catalyst placed within a double jacketed, oil heated reactor of 32 ml volume with an inner diameter of 15 mm, where the catalyst (3 ml of copper catalyst (64 wt.% of copper oxide, 27 wt.% of alumina, 5 wt.% of lanthanum oxide, and 5 wt.% of copper) crushed tablets, sieved to a fraction of 100-200 mu m) was hold in place with plugs of quartz wool. From then, the effluent passed a small path of unheated pipe, the valve to control the pressure of the system before it entered a metal container at ambient pressure and temperature, the collector. For safety reasons, the product was collected under a blanket of nitrogen, preferably if dimethyl ether was used as solvent. A sample of the liquid collected was then analyzed and worked up to obtain the 1,2-propanediol.