PARENT SESSION

(04-02) Economic input-output models for allocation in LCA.

Suh, Sangwon^*,1, Huppes, Gjalt¹, ¹ CML, PO Box 9518, Leiden, Netherlands

ABSTRACT- The allocation problem has been a critical subject not only in the LCA community but also with input-output economists, for a long time. In this paper implications of such economic models for allocation in LCA are presented using numerical examples. The options for allocation in IOA models can be applied in LCA inventory, both in full process modelling LCA, in hybrid analysis when combining process analysis and IOA, and when using IOA separately. Three models, and combinations of these, are applicable for the allocation problem in LCA. The industry-technology model assumes that each industry has its own technology that cannot really be separated into sub-technologies for each of its multiple products. So the direct requirements of an industry are distributed over multiple products proportional to the economic value of each output. The commodity-technology model assumes that each commodity has its own characteristics in input requirements in producing them wherever they are produced. The characteristics are given by referring to the specific process that produces one of the multiple products separately, as primary (= main) products. The by-product technology model assumes that production of a non-primary product is fully dependant upon the production of primary product, and demand for the non-primary product does not affect the operation schedule of the industry that produces the non-primary product. Finally a mixed technology model utilises the above described three models all together by disaggregating a system into several subsystems and applying the most preferred model to each subsystem. The framework so far discussed covers the whole issue of allocation using a consistent problem formulation, and provides a solution using the supply and use framework. The industry-technology model explains the economic basis of the partitioning method using economic allocation or also mass or energy content-based allocation. The commodity-technology model and the by-product technology model show two approaches of substitution method. Based on these economic models a general calculus for allocation in LCA has been developed, and advantages and limitations of these models are discussed.

Key words: IOA, hybrid analysis, allocation, substitution