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Conversion of Waste Cooking Oil to Biodiesel: Life Cycle Assessment Zhang Zhe and Rajasekhar Balasubramanian Division of Environmental Science & Engineering National University of Singapore • To compare the life cycle emission of carbon dioxide and particulate matter (PM) from biodiesel (generated from waste cooking oil) and diesel • To gain insights into biodiesel’s life cycle impacts on the environment What is Life Cycle Analysis? • It is an investigation and evaluation of the environmental impacts of a given product caused by its existence. • It measures the whole life cycle of the product Raw Material Production Process End of Life Use Phase Importance of Life Cycle Analysis • The environmental impact generated from all the processes is analyzed, not only the manufacture or end use process • Gain overall understanding about a product’s entire environmental impact Life Cycle of Petroleum Diesel Shipping with Ocean Tanker Emissions Life Cycle of Waste Cooking Oil Biodiesel Emissions • Process • Transesterification Material (Adapted from the laboratory experiment) Original waste cooking oil 1.0638 L Methanol used 0.2128 L KOH used 8.511 g Biodiesel Generated 1L To represent the industrial practice, the following data obtained from a research done by U.S. National Biodiesel Board were used for the analysis. Energy Use Electricity 0.0502 kWh Natural Gas 0.02581 m3 Applications developed for the life cycle analysis • Entire life cycle is broken down into different life stages of the product. • Each life stage is further broken down to sub-processes. • The environmental impact from each sub-process is analyzed. • The integration of all the environmental impact is the life cycle impact. Life Cycle Emission = ∑ E ×e i j i • i: different life stages • Ei: the amount of sub-process used in that life stage (Unit: L, kWh, etc.) • ej: emission factors associated with each sub-process (Unit: kg/L, kg/kWh) Taking diesel as example, analysis model was used: • Stages: o Crude Oil Drilling in Middle East o Transportation to Singapore with Ocean Tankers o Refinery o Transportation to Retail Stations o End Use • Sub-processes: o Diesel, combusted in industrial boiler o Electricity, at grid o Gasoline, combusted in equipment o Natural gas, combusted in industrial boiler o Residual fuel oil, combusted in industrial boiler All the final results are based on the same comparison basis: 1 MJ of energy that can be derived from the fuel CO2 emission comparison (95.27 % reduction) 1. End Use 2. Refinery 3. Transportation to Singapore: 8000 km 4. Drilling 1. Energy Use During Production 2. Methanol and KOH Only consider about production and transportation stages. 58.96% Reduction PM emission comparison (46.95% reduction) 44.60% Reduction Used to measure the life cycle energy input (except end use phase) 40.57 % reduction Biodiesel’s (from waste cooking oil) life cycle emission of carbon dioxide and particulate matter is much lower than that from diesel The life cycle analysis indicates that the use of biodiesel as an alternative (automotive) fuel is acceptable from the environmental point of view. • To simulate industrial production process • To obtain first-hand data of the resource usage Data Source: National Renewable Energy Laboratory (NREL) Database, experiment Other Data Sources • Saudi Arabia Emission Factor: CO2 Emissions from Fuel Combustion. 2009 ed, International Energy Agency • Singapore Emission Factor: Information on Emission Factors 2010. National Energy Efficiency Committee • Emission Factor for KOH: Korea LCI Database Information Network. Korea Environmental Industry & Technology Institute Cost Aspects • Most of waste cooking oil exported • Supply of WCO cannot meet the designed capacity • Currently producing with cost • Can only achieve break-even with an increase of WCO supply by 80% Life Cycle Analysis Objectives System Boundaries Experiment to Produce Biodiesel Analysis Model Results and Discussion Conclusion