PRODUCTION
How rape oil is turned into biodiesel and pharmaceutical grade glycerol
Biodiesel from rape (RME or rapeseed oil methyl ester) is the most widespread biofuel in Germany today. Production capacity for biodiesel will have reached 5 million tonnes by the end of 2007. 1.5 million tonnes of biodiesel admixture to conventional diesel, as regulated by German law, can use this capacity only to a small part. The biodiesel industry therefore demands changes in tax politics from the German Federal Administration in order to not lose the market for pure biodiesel. This would be fatal in terms of climate protection, too, because even today production capacity is big enough to substitute 16% of German diesel demand (energetically). This amount would help save about 12 million tonnes of fossil CO2 on the roads at once. (Source: AGQM)
One hectare of agricultural land can yield around 1,700 litres of biodiesel a year.
Rape oil is pressed in oil mills from seeds harvested in summer. The oil content of rape seeds is 40 % to 50 %. The grist that remains is valuable animal feed.
The entire biodiesel production process is a closed cycle of material. Rape oil is refined and transformed into biodiesel by means of a chemical reaction known as transesterification.
- Methanol and a catalyst (e.g. sodium bicarbonate solution) are added to the rape oil.
- The mixture is heated.
- This causes each of the large rape oil molecules to split into three individual fatty acid methyl ester chains and a free glycerol molecule. Glycerol and methanol have changed places. This process is known as “transesterification”.
- In the subsequent refinement stages, among other things the surplus methanol is removed again by distillation and passed back into the cycle. Now, the biodiesel has the optimal flowing behaviour and has already attained its full quality.
- In addition to the main product biodiesel, this process produces the valuable chemical raw material glycerol which after further processing into pharmaceutical grade glycerol is used in the pharmaceuticals, plastics, food and cosmetics industries, amongst others.
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