New insights on ecological footprinting as environmental indicator for production processes

Abstract

The ecological footprint (EF) has reached worldwide popularity in the last decade as an interesting environmental indicator, and its applications have been extended to different fields. However, shortcomings of the methodology behind the EF calculations have been reported and the need for further improvements has been remarked, especially when this indicator is applied to measure the sustainability of production processes. This paper deals with three controversial aspects of the EF. First, the influence on estimates of using regional or global factors was explored; thus, a specific CO₂ absorption rate was assessed for Galicia (NW Spain) using two different methodologies. These were applied to assess the EF of a ceramic industry (manufacture of bricks in baked clay) typical from Galicia, and the results were compared to the case when a global rate was employed. Another aim of the paper was to assess the effect of incorporating acidifying emissions, which are generally excluded from EF appraisals (as well as any other emissions apart from CO₂). With this purpose, the critical load concept was applied to the same case study in order to analyze the impact of acidifying emissions derived from the burning of fuel oil or natural gas for the drying and firing stages of a ceramic production process, as well as their influence in the EF figure. Finally, a methodology that models a closed cycle for wastes – including hazardous ones – through a plasma process was presented and analyzed, assessing the influence of carbon content and observing the likely contribution that considering waste production can have on the EF calculation.