Calculating the energy and water use in food processing and assessing the resulting impacts

Abstract

The food processing industry is a major consumer of energy and water, the consumption of which has environmental impacts. This work develops a method to determine process-specific water use and utilizes an existing energy use toolbox to calculate the energy and water required for each step of food processing. A life cycle assessment (LCA) is conducted to determine how much processing contributes to a particular product’s cradle to gate impacts for two impact categories. A method to determine water use at each unit process was developed, and in conjunction with an already developed energy use unit process toolbox, the methods were tested using two case studies. Processing data such as flow rates, operation temperatures, and food losses were used from two Swiss food production facilities. Calculation results were compared to measured facility data such as yearly energy and water use. Results were then used to develop LCAs for a total of seven food products, including five types of juice and two types of potato products. The toolboxes were able to calculate the water use of both facilities within 25%, the thermal energy use within 9%, and electricity use within 24%. Impacts from processing were particularly important for the potato products, particularly potato flakes, due to impacts stemming from thermal energy use. For juices, impacts due to raw material growth dominate the LCA, and impacts due to processing are much less significant. A unit process analysis may not be necessary when there is little variation in the unit processes between the different products. In this case, a simple allocation of measured facility energy and water data may be sufficient for calculating the impacts associated with processing. However, products with largely varying unit processes may have very different impacts. Impacts are sensitive to the type of energy required (thermal or electrical) and the sources of electricity and water. These water and energy toolboxes can improve transparency in processing and identify the most water- and energy-intensive steps; however, in facilities with similar products, such an extensive analysis may not be necessary. Results from these calculations are useful in developing food product LCAs.