Screening LCA for large numbers of products

Abstract

CIBA’s Textile Dyes and Chemicals divisions use screening LCAs for their 1700 sales products to improve portfolio management and ecological process development. Material flow, energy, and waste data for in-house manufacturing processes are extracted from our company databases into our LCA system ECOSYS. For meaningful comparisons of whole life cycles, we must include LCA estimates for over 4000 raw materials from other suppliers. Even crude estimates are preferable to the frequently practiced omission of unknown process steps since they allow worst-case or sensitivity analyses. Sources for mass flows are (decreasing order of reliability): process literature (SRI-PEP Yearbook, Ullmann, Kirk-Othmer, patents), yields of analogous processes, theoretical stoichiometry. Energy demands come from literature, or from a set of standard operation estimates developed by our process engineers. Wastes/emissions, if not published, are derived from yields and elemental balances, estimated emissions of energy carriers (BUWAL-132), and typical end-of-pipe measures in CIBA. These data sets are kept as “added-burden modules” (ABM) in our system, each with a set of “inherent burdens”, which are transformed to step-specific burden estimates by a “propagation” program, before the overall burdens of the whole process tree are cumulated. This program checks every process for actually measured burdens, before applying the attached ABM estimates to fill the gaps. Centralization of estimates as ABM with inherent burdens facilitates maintenance and adaptation. At present, well over 250 important intermediates were estimated and used in our product trees; many more follow rapidly. This article is an example of how industry is using LCA to address environmental issues.