The water footprint of sweeteners and bio-ethanol from sugar cane, sugar beet and maize

Sugar cane and sugar beet are used for sugar for human consumption. In the US, maize is used, amongst others, for the sweetener High Fructose Maize Syrup (HFMS). Sugar cane, sugar beet and maize are also important for bio-ethanol production. The growth of crops requires water, a scarce resource. The aim of this study is to assess the green, blue and grey water footprint (WF) of sugar, HFMS and ethanol in the main producing countries. In addition, an impact assessment is carried out for sugar cane and beet production in three large river basins: the Dnjepr, Indus and Ganges basins. The WF of sweeteners and ethanol depends on crop type, agricultural practice and climate. The WFs of cane sugar for the main producing countries appear to be 1285 m3/ton for Brazil and 1570 m3/ton for India. The weighted global average is 1500 m3/ton (45% green, 49% blue, 6% grey). The WFs of beet sugar for the main producing countries are: 545 m3/ton for France; 580 m3/ton for Germany; 1025 m3/ton for the US; 1430 m3/ton for the Russian Federation; and 1900 m3/ton for the Ukraine. The weighted global average is 935 m3/ton (35% green, 49% blue, 16% grey). The average WF of HFMS 55 produced in the US is 720 m3/ton. The global average WF of HFMS 55 is 1125 m3/ton (50% green, 36% blue, 14% grey). The WF of ethanol from sugar cane in Brazil is 2450 litre/litre, in the US 2775 litre/litre and in India 2995 litre/litre. The weighted global average is 2855 litre/litre. The WFs of ethanol from sugar beet for the main producers are: 790 litre/litre for France; 845 litre/litre for Germany; 1290 litre/litre for the US; 2075 litre/litre for the Russian Federation; and 2780 litre/litre for the Ukraine. The weighted global average WF is 1355 litre/litre. The WF of ethanol from maize in the US is 1220 litre/litre. The weighted global average WF is 1910 litre/litre. The WF of sugar cane contributes to water stress in the Indus and Ganges basins. In the Black Sea area, the main problem is pollution from industry and excessive fertilizer application. In that area sugar beet shows a large grey WF and is one of the contributors to pollution. The results of this study may form the basis for or at least trigger more detailed local impact assessments. The study shows that the water footprint of sweetener or ethanol strongly depends on its source (which crop) and origin (which country, climate and agricultural system). Besides, the relative contributions of the green, blue and grey components differ greatly from place to place. The existing differences may be reason to prioritise from where to best source sweeteners and bio-ethanol. Alternatively, instead of switching to another source or place, one could analyse the potential for reducing the water footprints in those cases where footprints are currently relatively high.