Life cycle inventory analysis for waste oil in Japan

This paper deals with the environmental benefits of re-refining waste oil with respect to energy consumption and CO/sub 2/, NO/sub x/, and SO/sub 2/ emissions, compared with using virgin oil. Comparative life cycle inventories were examined and environmental impacts were assessed for the following two cases: (1) re-refining waste oil and burning the re-refined oil; and (2) extracting crude oil, refining it, and burning the resulting heavy oil. In order to equalize the two cases, we included the process of incinerating the waste oil in the second, non-re-refining case. We also include the process of power generation from fuel extraction in the re-refining case. The results depend on the fuel sources used to generate electricity. The use of virgin oil significantly increases consumption of natural energy resources. Emissions by combustion largely account for the life cycle emissions of virgin oil, because of the very high amount of emission volume per unit when burned as fuel and when the waste oil is incinerated. The comparative system boundaries for recycling that we use in this study show the environmental benefits from reuse, recycling, and waste-to-energy strategies.