EU research for sustainable milk processing

Within the SUSMILK project, a detailed model for energy and material flows in a dairy was developed. The LCA conducted by ESU-services identifies the relevance of energy and water uses in different process stages in a dairy from an environmental point of view. It also shows the potential of improvement options to reduce the impact of heat, cooling and electricity demand. The LCA results including a description of the goal and scope are published in a public report. For the analysis of improvement options, data from project partners was collected. This life cycle inventory analysis is documented in a confidential deliverable.

The environmental impact of dairy processing from cradle to dairy gate was analysed with 15 environmental impact categories (recommended by European authorities) and with the cumulative exergy demand. In addition, these category indicators were summarized to a single score applying different approaches. All recommendations are based on both result types.

Raw milk production has the highest impact from cradle to dairy gate. Thus, the production systems used for the raw milk have a decisive role for the overall environmental impact of dairy products. Raw milk supply and a reduction of milk losses at the dairy should be given priority in environmental improvement strategies. Other important aspects are the choice of packaging, effluent treatment and raw milk transport. The impact of electricity and steam demand has to be considered as well, whereas the impact of the chemicals used for cleaning-in-place is very small.

Different improvement options that deliver heat, cooling and electricity were compared in this study. The best option is the reduction of the energy demand with a clever process design or the integration of heat exchangers.

The next best step is the replacement of existing technologies. For heating, a motor CHP (combined heat and power) plant driven by natural gas can be clearly recommended as a replacement of a natural gas boiler. If waste heat at high temperatures is available, a gas-engine driven heat pump can be recommended as well. Solar collector systems and a CHP plant driven by wood have higher environmental impacts in some environmental categories and lower in others, so that the recommendation depends on personal value choices. For solar collectors, an installation of solar collectors on flat roof is better than an installation on open ground. The share of heat delivered depends on available roof size and location (Southern Europe preferred) and thus the choice of the additional heat source is crucial. Pellet boilers cannot be recommended since they have higher environmental impacts in many environmental categories than the natural gas heating. Cooling with groundwater can clearly be recommended to replace electric cooling if no local environmental problem is affected (water temperature or scarcity). If waste heat is available, the integration of an absorption chiller can be recommended as well. If a co-generation plant was integrated for heat delivery, an absorption chiller driven by this heat can still be recommended, though the reduction potential is less high compared to the use of waste heat.

The detailed model of dairy processes can also be used to better understand the relevance of sub-processes in the dairy and to allocate environmental impacts of processing to single products.

ESU-services participates in the SUSMILK project where we investigate environmental improvements in dairies. Niels Jungbluth explains the tasks and challenges in this project. For more information: SUSMILK