Marginal technologies are defined as the technologies actually affected by the small changes in demand typically studied in prospective, comparative life cycle assessments. Using data on marginal technologies thus give the best reflection of the actual consequences of a decision. Furthermore, data on marginal technologies are easier to collect, more precise, and more stable in time than data on average technologies. A 5-step procedure is suggested to identify the marginal technologies. The step-wise procedure first clarifies the situation in which the marginal should apply, and then identifies what specific technology is marginal in this situation. The procedure is illustrated in two examples: European electricity production and pulp and paper production.
Rather than describing only the average technology used across a sector, the procedure asks which production technology is actually affected by the change in demand being studied. This distinction matters in prospective comparative LCA, where the aim is to understand the consequences of a decision. The authors propose a five-step procedure for making that identification. The abstract highlights its opening logic: first clarify the situation in which the marginal technology should apply, then identify the specific technology that is marginal in that situation. The technology selected is therefore linked to the question and context of the assessment.
The paper illustrates the procedure with European electricity production and pulp and paper production. These examples show how the method can be applied in different production settings; they are not a universal list of technologies that will be marginal in every study. The article’s main practical message is to make the demand change and the relevant production context explicit before selecting life cycle inventory data. This helps readers understand what decision the inventory represents and why the selected technology is relevant to that decision.
