Solar Process Heat in the Food Industry – Methodological Analysis and Design of a Sustainable Process Heat Supply System in a Brewery and a Dairy

The food industry is a large consumer of industrial energy. A very large portion of this energy is needed in the form of thermal energy at medium to low temperatures. Fossil fuels remain the dominant sources of this energy. This combination provides various possibilities to reduce energy consumption and CO2 emissions with heat recovery, but also with the integration of solar process heat. Energy efficiency must provide the context, or background, of such considerations, and is therefore a very important aspect of them. It is a complex task to design an efficient heat supply with a variety of energy sources. An analysis of standards for energy audits, guides for energy efficiency and guides for solar process heat integration confirms that complexity. However, no available methodology considers all the necessary steps. These must range from analysis of the existing heat supply to the redesign of an efficient heat supply system. The focus must be on heat sources with waste heat and on solar process heat that might be used to complement the conventional sources. The design of a process heat system is mainly the task of design engineers in engineering offices. Specific tools and measures are needed to support these experts. However, the companies of the food industry sector employ their own energy engineers for energy issues. These people are actually the decision makers responsible for the configuration of the company energy supply systems, who also possess knowledge of the processes in their industry subsector. The expertise of the energy engineers varies within a broad range and is also connected to their area of responsibility. Therefore, it is important to consider these energy engineers when developing a methodology. The development of the methodology proposed herein consists first of the configuration of the tools and measures, which were assigned to four elements and functions. Second, the methodology so developed was applied at two companies in cooperation with their energy engineers, in detailed case studies. The feedback from the energy engineers is therefore a main objective and provides a background for evaluation of the usability of the methodology. It demonstrates the expertise required of the energy engineers, for the application of the tools and measures provided. Moreover, the development and application of the methodology involving real companies demonstrates the necessity of getting feedback from energy engineers. That finding is very important, and has been insufficiently considered in previous guides or methodologies. It is proposed that further work be aimed at providing additional case studies to extend the use of this methodology to other parts of the food industry