Life cycle inventory of refinery products:: Review and comparison of commercially available databases

Refinery products serve as the source for a significant portion of energy use and industrial chemicals. Assessing the variability and reliability of the life cycle inventory (LCI) data for the refinery process is an important issue for the acceptance of life cycle studies. The purpose of this research is to review and compare the LCI results for refinery products among several available databases, evaluating the level of variability and technical consistency among data sets. Another objective is to highlight the need for greater transparency and standardization in LCI databases. We found important links between the type or media of emissions and the unit processes found in typical refineries. The variability of estimated emissions to the atmosphere is approximately 50-150%, while variability in aqueous discharges is higher, approaching 1000%. Variability for solid emissions is on the order of 30%. This variability is believed to be related to the preparation and summary use of individual practitioner databases and not to the actual primary variations among refineries. Some variations clearly reflect technically incorrect data. Improvement of refinery LCI information can be achieved by the research and user communities devoting effort to produce credible, representative LCI data for this critical manufacturing unit. Greater transparency would significantly improve specific areas of LCI assessment, as many of the current databases are highly nontransparent, thus allowing errors to be undetected. The central role of refinery LCI data in life cycle assessment argues strongly for practitioners to develop more representative and less variable LCI information.