An Exploration of the Use of EMERGY in Sustainability Evaluation

This paper has the goal of exploring the possibility of using EMERGY in sustainability evaluation. A case study that compares the sustainability of two maize irrigation systems (furrow vs. solid set sprinkler, both with electric pumping) is used as the basis of the discussion. The furrow irrigation system presents a lower total EMERGY, yielding a lower transformity. The main reason is the lower electricity needs for pumping. This system also has a lower Investment Ratio and Environmental Loading Ratio, due to both higher renewable resource consumption (lower water efficiency) and less use of market purchased resources (lower electricity use). EMERGY analysis allows the comparison of the use of different resources, which is important for sustainability evaluations, when evaluating technologies in terms of impacts on resources. For example, it accounts for labor and services, which are not commonly considered in other biophysical methods. One major limitation is the absence of threshold values, making the analysis of EMERGY results more complex. Total EMERGY still has some limitations when used to evaluate sustainability but, with further development, it has strong potential.