Life Cycle Assessment as an engineer’s tool? Anneliese Niederl-Schmidinger, Michael Narodoslawsky * Institute for Resource Efficient and Sustainable Systems, Graz University of Technology, Inffeldgasse 21 B, 8010 Graz, Austria Received 1 January 2004; received in revised form 1 January 2006; accepted 18 August 2006 Available online 13 November 2006 Abstract Life Cycle Assessment (LCA) is an increasingly important evaluation tool for decision making and stakeholder discussion; especially when applied during the planning phase, it can pinpoint process steps with a high environmental impact and thus, provide guidance towards optimising the actual technology implementation. These aspects influencing the engineer’s work are investigated on the basis of an LCA of the production of Biodiesel from Tallow and Used Vegetable Oil. Impact assessments with the Sustainable Process Index (SPI) and with the problem-oriented approach, show largely concordant results. The highly aggregated indicator SPI makes comparison between options possible. It provides ‘‘a bigger picture’’ of the environmental impacts and is helpful in decision making. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Life Cycle Assessment; Sustainable Process Index; SPI; Biodiesel 1. Introduction Processes on the base of renewable resources always have an ‘‘intrinsic’’ perception of being environmentally friendly and sustainable. However, as this property is a major advantage for products generated by these processes, there is a necessity to prove their sustainability credentials in a rigorous manner that can withstand the scrutiny of a competitive market. Product and process evaluations may be based on Life Cycle Assessment in order to account for all environmental impacts incurred by the provision of the good in question. These LCAs in turn adhere to strict standards laid down in ISO standards of the 14,000XX family. However, it must be noted that these standards only guide the procedural side of an evaluation and do not prescribe a fixed evaluation method. On top of this, LCAs of processes and goods on the base of renewable resources are bound to face special methodological challenges. On the one hand, many industrial raw materials are by-products or surplus products from agricultural activities leading to other (more valuable) products. In these cases, the general problem of allocating the pressures of the agricultural sector arises which may considerably influence the outcome of any valuation. In some cases the raw materials are even streams that are considered to be wastes, which makes a pru- dent valuation even more complicated. On the other hand, any evaluation of the sustainability of processes leading to the same sort of goods on the basis of dif- ferent raw materials must account for the different impacts from raw materials generation. Especially, the difference between renewable and depleteable raw material systems must be evaluated. This clearly exceeds the capabilities of nor- mal and descriptive life cycle impact assessments with the problem-oriented approach and leads to the necessity to employ an evaluation method that aggregates impacts in order to make different impacts comparable. The case study presented in this paper describes the LCA of the production of biodiesel from tallow and used vegetable oil. On the one hand, it shows the difficulties that arise with LCA of renewable products with wastes or by-products as raw materials. On the other hand, the application of the sustainable process index (SPI) Krotscheck and Narodoslawsky [1] (see Section 2.3) turns out to be a convenient methodology for as- sessing technological implications of the results in order to * Corresponding author. Tel.: þ43 316 8737468; fax: þ43 316 8737963. E-mail address: narodoslawsky@tugraz.at (M. Narodoslawsky). 0959-6526/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.jclepro.2006.08.024 Journal of Cleaner Production 16 (2008) 245e252 www.elsevier.com/locate/jclepro