The water footprint of winter wheat in Sweden

Abstract: This study attempts to calculate the green blue and gray water footprint of the crop production of winter wheat and three derived winter wheat products: liquid fuel ethanol, wheat flour and macaroni. The calculations were done for Sweden for the period 2008-2010, covering an average of 80% of the annual winter wheat production. The south of Sweden was divided into 18 climate zones for which sufficient climatic data was available. The crop water use and requirements were then calculated for each of these zones using the CROPWAT model developed by the UN Food and Agriculture Organization, FAO. Other activities such as transportation, energy use and processing water were included in the study but combined these activities contribute to less than 1% of the water footprint of raw winter wheat production, referred to as the supply chain system. It is completely dominated by the cultivation component and the total water footprint is 875 m3 (59.4% green, 0.8% blue and 39.8% gray) per ton of wheat with a water content of 14%. Out of the supply chain system the cultivation component stands for 871 m3 (59.5% green, 0.6% blue and 39.9% gray) or about 99.5%. The result compares well to an earlier study by Mekkonen & Hoekstra (2010a). In the case studies of refined winter wheat products the total water footprint is still dominated by the supply chain in general and the cultivation component within it specifically. The water footprint of wheat flour from winter wheat at the mill in Malmö is found to be 1.15 m3 (59.1% green 1.2% blue and 39.7% gray) per kg of flour out of which 99% is from the supply chain component. The water footprint of liquid fuel ethanol from the Agroetanol plant in Norrköping is calculated to 1 477 m3 (57.5% green, 4.2% blue and 38.3% gray) per m3 of ethanol, out of which the supply chain component is almost 95%, while the rest is mostly energy use in the form of bio fuel based steam production and electricity. The water footprint of the production of macaroni at the Ceralia factory in Järna is calculated to 1.30 m3 (57.7% green, 3.8% blue and 38.5% gray) per kg of macaroni. About 95% of this is from the supply chain component while the remaining 5% is mostly attributed to the energy used in the processes.