In field trials sweet sorghum variety “Keller” was cultivated to investigate how the chopped biomass can be stored to provide an efficient and quality-conserving low-loss supply of mass and sugar yield for ethanol purposes. For this reason sweet sorghum was harvested with a common self-propelled-forage-chopper and transported by a farm trailer. In pilot plant scale two different particle sizes (length 10 mm and 20 mm) and two different loadings of 0.5 % (FM) and 1.0 % (FM) formic acid were tested to conserve the chopped material under anaerobic conditions in plastic barrels, which is common practice for ensilage studies. After 90, 120 and 150 days the barrels were opened and samples were taken to analyse the remaining soluble sugar content. It was shown that the addition of 1.0 % (FM) formic acid fully preserved the sugars for more than 150 days. With 0.5 % (FM) formic acid the formation of lactic acid could be prevented but not the activity of all microorganisms, which resulted in a slow increase of ethanol with time.
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