Methods for industry to measure and improve the energy efficiency of utility systems

Industrial utility systems, such as electricity, steam and condensate systems, cooling systems and compressed air, are often considered only as resources to the core production process and may therefore be overlooked by managers and operators in terms of improvement. However, the optimisation of the utility systems may have great importance to energy efficiency and profitability. Aalto University and VTT Technical Research Centre of Finland have carried out a two-year study where the target has been to test and develop methods for industry to measure and improve the energy efficiency of utility systems. This paper gives a short overview of the most important results of the project. Possibilities of different process integration and optimisation methods to analyse and improve the energy efficiency of process industry have been tested. A simulated mechanical pulp and paper mill has been used as a test environment. The mill contains one thermo mechanical pulp (TMP) line and one paper machine. The methods included primary energy consumption with different process alternatives, the pinch, advanced pinch and exergy pinch methods and entropy analysis. In addition, pinch and advanced pinch methods have been used in a case study of an existing mill which produces paper on three paper machines. The mill has three pulp lines; two TMP lines and one DIP line. In the final phase of the project, two interview studies were carried out. The first study focused on companies in the process industry and the latter on engineering and suppliers of the utility systems. The purpose of these studies was to view drivers for and barriers to energy efficiency in the opinion of the process industry and its most important utility system, technology and service providers. The results are used for focusing future research and development and energy policies.