Reclamation of cutting oil waste to refuse derived fuel: A life cycle assessment approach for a waste-to-energy system

Reclamation and reuse of spent oil waste are preferable resource management practices that provide energy and environmental benefits. This study aims to have a comprehensive understanding of the environmental benefits and tradeoffs regarding the reclamation of cutting oil waste to refuse-derived fuel (RDF) for steam generation through a life cycle assessment (LCA) approach, with special attention given to pollution characteristics during steam generation. Our results confirmed that majority of the environmental impacts associated with the reclamation process (approximately 78.9%) could be attributed to the electricity consumption involved in the process, which could be offset by the energy savings from the avoided oil waste disposal. Thus, the involvement of RDF in steam generation may enhance the environmental performance of the waste-to-energy system from two aspects, including a reduction in global warming potential (22.2%-99.6%) from decreased fossil fuel consumption and a reduction in toxicity impacts (68.2-71.5%) from minimized pollutant emissions under improved combustion efficiency compared to other tests. The global warming potential for generating 1 ton of steam was found to be the lowest at approximately 0.15 kg CO2 eq using a mixture of RDF and wood dust and the highest at approximately 41.18 kg CO2 eq using a mixture of coal and wood dust. Additionally, pollutant emissions from steam generation were identified as a significant contributor to the overall impacts, in which terrestrial ecotoxicity was found to be the most sensitive impact to the reduction of pollutant emissions in all runs. Future practical efforts for waste oil-to-energy systems are suggested to focus on the implementation of pollution control measures that minimize their associated impacts while maximizing their benefits.