Sugar or sugar syrup extracted from sugar beet is highly suitable for the production of bioethanol.
Unlike cereals, however, sugar beet cannot be stored for the whole year. The extraction of sugar is carried out in the autumn in a campaign which lasts about 100 days. So-called thick juice - an intermediate product in the manufacture of sugar - can be stored for the whole year and is available in the sugar factory for the production of white sugar or as a raw material for the production of bioethanol.
In Europe, man was restricted to the use of honey, fruit sweetness or sugar from sugar cane for sweetening food and drink for many centuries. In 1747, the chemist Andreas Markgraf discovered that the coveted foodstuff and food additive could also be extracted from sugar beet. Markgraf's student Franz Carl Achard then created the foundations for the industrial production of sugar from sugar beet and in 1802 opened the first beet sugar factory in Europe. Since about 1850, sugar has been produced in Europe from sugar beet on a large scale.
Botanically, the sugar beet belongs to the goosefoot family (Chenopodiaceae); its original form is believed to be the sea beet. The sugar beet is very demanding as to earth and climate, and thrives best on deep, nourishing soil with an ample supply of water. The harvest is gathered in late autumn with yields which can vary in Germany from 50 to 90 t/ha (roughly 20 to 36 tons per acre).
Sugar content of the beet lies somewhere between 16 and 20%. The beet foliage is either used as animal feed, or may be left on the field as compost, while the beets are cut into chips in the sugar factory. These are then soaked in water and heated. The raw juice thus produced is purified and concentrated into thick juice. The thick juice, with a sugar content of around 63%, can be used for the production of either sugar or bioethanol. For the production of sugar, in the next stage the thick juice is boiled and separated from the syrup in centrifuges. For the production of bioethanol, yeasts are added to the thick juice, which is then fermented directly.
