Graphical abstract

۱٫ Introduction

۲٫ Energy efficiency evaluation methods

۳٫ Discussion

۴٫ Development in the future

۵٫ Conclusion

Declaration of interest statement

Acknowledgement

References

Abstract

As the most effective indicator for energy saving and emission reduction, energy efficiency evaluation is widely used in complex petrochemical industries. It is nowadays common to combine traditional mechanism methods based on momentum transport, energy transport, quality transport (TT) and reaction engineering (RG) (TT-RG), with data-driven artificial intelligence methods. Using the combined method to achieve production optimization and energy saving by analyzing the evaluation indicator of energy efficiency has gradually become an important part in complex petrochemical industries. Therefore, this paper introduced the main methods and the latest research results of energy efficiency evaluation of complex petrochemical industries. These methods are mainly divided into three parts, including the mechanism methods based on TT-RG, the data-driven artificial intelligence methods, and the hybrid methods combining the mechanism and the data-driven. Then, different methods are compared and described in detail. Moreover, the best method for evaluating the energy efficiency can be found to provide theoretical guidance for energy saving and emission reduction of complex petrochemical industries. Finally, the future development direction for energy efficiency evaluation in complex petrochemical industries is given.

Introduction

With the continuous development of economy, China has become the second largest economy nation in the world. As a pillar of modern economy, energy has greatly promoted the economy development. However, problems of environmental pollution and high energy consumption become more and more serious. The comparison of carbon dioxide (CO2) emissions and energy consumption between China and other countries (or regions) in 2018 are shown in Fig. 1 and Fig. 2, respectively, where the data are from the World Energy Statistics Yearbook. It can be seen from Figs. 1 and 2 that improving the energy efficiency and reducing pollutants emission have been in a highly strategic position for the sustainable development of all countries in the world [1]. In the process of energy utilization, the ratio of the working energy to the actual consumed energy is the energy efficiency. How to improve the energy efficiency is the main goal of the energy development. The energy efficiency evaluation can provide the most effective indicator for this goal, which explores ways to improve the energy efficiency by establishing mathematical models of production processes, or to reach the same or more output with less energy input [2]. The complex petrochemical industry in China is a high energy consumption industry with large scales. Therefore, by evaluating the energy efficiency, finding efficient ways of energy utilization, and then reducing pollutants emission such as CO2 are hot research topics for energy saving and emission reduction [3]. At the same time, it has far-reaching significance for the sustainable development of economy and society [4].