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Abstract: Sustainability evaluation of mariculture is needed for policy decision-making in its development. Zhao et al. (2013) developed the method of emergy ecological footprint to evaluate an offshore small fish farm in the East China Sea. After re-examination of their method, data analysis process and results, three questions are presented (1) what is the nature of this method? (2) How much impact do the recognition and classification of input flows on the results? (3) Do their evaluated results confirm to the real situation of this farm? Further discussions are also made on several main studies about the emergy ecological footprint method. Our results imply: (1) there is a need to improve this method; (2) the input flows should be carefully processed due to their great impacts on the results; (3) the essential data and comparative analysis are needed to support this evaluation. [Copyright &y& Elsevier]

The article discusses a paper which aims to develop an effective methodology for assessing the sustainability of metro systems by using emergy analysis. Information on a proposed composite index called the emergy cost-benefit ratio (EmCBR) for understanding the feasibility of metro systems better is provided. Using the project life cycle to evaluate the total costs or benefits is suggested.

Abstract Sustainability evaluation of land resources could help policy decision-making in land use planning and management in a region. Zhang et al. (2018) presented a study on sustainability of land resources in Dengkou County based on emergy analysis. We commented on their major shortcomings including limitations of the energy system diagram, lacks of the emergy accounting of water resources, soil losses, machinery, environmental pollution and control, and the results of dynamic simulation. It is concluded that the emergy analysis method could serve land sustainability analysis, but it is of vital importance to create normative system diagrams and select proper emergy accounting items and dynamic simulation methods for ensuring the validity of evaluation results. Highlights • We commented on limitations of a land resources emergy analysis by Zhang et al. (2018). • Energy Systems Language should be normatively used. • Selection of emergy accounting items is of vital importance. • Land use change and emergy analysis need proper dynamic simulation methods. [ABSTRACT FROM AUTHOR]