The Added Value of Integrating Emergy into LCA

Life Cycle Assessment (LCA) has become a standard procedure to investigate the environmental performance of human-dominated products and processes. It is meant to capture the overall impact of a product or service along its lifetime and supply chain, and it is structured in four steps: goal definition and scoping, inventory, impact assessment, and interpretation. Impact assessment is carried out for an open set of impact categories, which may include abiotic resource depletion (evaluating resource scarcity), cumulative energy demand, global warming, acidification, etc. Where LCA fundamentally differs from Emergy Synthesis is in that the former draws the boundary around the life cycle of the system under study, and looks at impacts that happen as direct consequences of it; conversely, Emergy Synthesis always looks at a system as embedded in the larger natural system that underpins it, and includes all direct and indirect inputs that converged to support it over much larger time and space scales, including ‘freely available’ ones which are typically neglected in LCA (e.g. rainfall, soil organic matter, etc.). From the perspective of the LCA practitioner, the first question regarding the potential use of emergy is that of the added value that it may provide. According to its definition, emergy represents the 'memory' of the total exergy that was previously required to make a product or service. Emergy thus offers arguably a unique donor-side perspective, an approximation of the work of the environment that would be needed to replace what is used, and presents a unified measure of the provision of environmental support. We maintain that it may be viewed as a valuable complement, rather than an alternative, to existing life cycle impact assessment metrics.