WHAT DO RECENT ASSESSMENTS TELL US ABOUT THE POTENTIAL AND CHALLENGES OF LANDFILL MINING

Abstract

Landfill mining has been proposed as a potential strategy to address unwanted impacts of waste deposits while simultaneously recovering deposited materials and energy resources. So far, however, the realization of such projects is rare, and the development of the area suffers from a general deficit in knowledge of how such projects could be executed in a cost-efficient and environmentally sound manner. For such emerging concepts, systems analysis could be useful for dimensioning potentials, assessing feasibility, and guiding knowledge development toward critical factors for implementation. During the recent years, quite a few assessments of landfill mining have been conducted but there is not yet any systematic synthesis of this body of knowledge. Therefore this study involves a review of 12 economic and environmental assessments. With the overall aim to provide guidance on essential future research topics, the chapter targets both the empirical findings and employed methodologies in the studies. Virtually all the economic assessments conclude nonprofitability and only provide superficial knowledge on what actually builds up the landfill mining economy.

The only environmental impact that has been comprehensively studied is global warming and, for this particular impact, the assessments display somewhat opposing results. A common denominator for the studies is that they constitute ex ante assessments in which the outcome of a planned project is forecasted. Such assessments are inherently uncertain but the emerging character of landfill mining adds more challenges, e.g., due to large epistemological deficits. When it comes to such methodological issues, our review reveals several weaknesses—all of them having implications on the validity and usefulness of the results. Lack of clear criteria for the selection of landfills and material processing lines, scopes limited to just one scenario, arbitrary assumptions on the marketability of exhumed resources, use of unconditioned data from adjacent knowledge fields, and neglecting stochastic and epistemological uncertainties are some examples of such reoccurring concerns. We conclude by providing guidance on how the identified epistemological and methodological challenges could be addressed in the future research. Special attention is given to the need for (1) explorative studies using system analysis as a learning tool, (2) applied research targeting the current black boxes of the landfill mining value chain, and (3) broader research scopes accounting for the various environmental and societal consequences of landfill mining.