Fats, Oils and Greases to Biodiesel: Technology Development and Sustainability Assessment A dissertation submitted to Department of Biomedical, Chemical and Environmental Engineering Division of Graduate Studies University of Cincinnati In partial fulfillment of the requirement for the degree of DOCTORATE OF PHILOSOPHY 2015 By Qingshi Tu B.E. in Environmental Engineering, University of Shanghai for Science and Technology, 2008 M.S. in Environmental Engineering, University of Cincinnati, 2012 Committee: Mingming Lu, PhD (Chair) Tim Keener, PhD Ting Lu, PhD Drew C. McAvoy, PhD Raymond Smith, PhD Abstract Fats, oils and greases (FOG) in the wastewater stream have long been a nuisance to the environment because they clog sewer pipes, causing overflows and damages. FOG can be classified as trap grease if obtained directly from food services, or sewer grease if mixed with FOG in the sewer system. This dissertation evaluated the technical feasibility and several sustainability parameters of converting trap/sewer grease into biodiesel. This waste-to-energy practice can provide the dual benefit of waste reduction and biofuel production. Monte Carlo simulations were conducted to model the energy consumption and GHG emissions from trap grease-to-biodiesel production life cycle at a wastewater treatment plant. Results were highly dependent on both the trap grease properties (e.g., FOG concentration, free fatty acid (FFA) concentration, etc.) and the utilization of non-lipid fraction of the FOG. Trap grease can provide lower energy consumption and lower GHG emissions for biodiesel production when compared to other feedstocks. This is particularly true for the trap grease with high FOG concentrations, low FFA concentrations, and a high performance anaerobic digestor (AD). As compared to other feedstocks, the probabilities that energy consumption of trap-grease biodiesel production life cycle would be lower were 46% (vs oil crops), 65% (vs waste cooking oil and animal fats) and 88% (vs algae). The probabilities were 89%, 67%, and 93%, respectively, when GHG emissions were compared. Of all the cases that energy consumption of trap-grease biodiesel was lower, the average reductions were 24% (vs oil crops), 36% (vs waste cooking oil and animal fats) and 73% (vs algae). When GHG emissions were compared, the average reductions were 76%, 54%, and 84%, respectively. i Both sewer and trap grease have FFA levels higher than the acceptable level (15-20%) of the current biodiesel industry. Due to emulsion, the lipid fraction of the sewer grease cannot be directly obtained by heating. Two innovative technologies, glyceroloysis and in-situ transesterification, were tested to make biodiesel from these FOGs. The goal is to short circuit the solvent extraction process, which is impractical for the biodiesel industry. For trap grease, the results of glycerolysis showed that crude glycerin was effective in reducing the FFA% to < 1 wt% with an optimum condition of 230 °C for 150 min and 1:1 molar ratio between glycerin and FFA. The study on the time series of the mono-, di-, tri-glycerides (MAG, DAG, TAG), FFA and glycerin was conducted to better understand the reaction mechanisms, and the FFA reduction kinetics were estimated (as it fits the first order approximation). The advantages and disadvantages of this process were compared against the two-step process, an industry standard among biodiesel producers. For sewer grease, a direct transesterification process (in-situ conversion) was developed to extract the lipid and make biodiesel in one step. The optimum condition was determined as 20% (of dry sewer grease) H2SO4, 65 °C and 7hr, under which a 85.43% extraction rate (biodiesel+unreacted FOG vs. total FOG) and a 76% FOG-to-biodiesel conversion rate (biodiesel vs. total FOG) were achieved. ii [ This page is intentionally left blank ] iii Acknowledgement Sincere gratitude is extended to my adviser, Dr. Mingming Lu, for her guidance throughout my entire period of graduate study. Thanks are given to the other committee members, Dr. Tim Keener, Dr. Ting Lu, Dr. Drew C. McAvoy, and Dr. Raymond Smith, for their advice and suggestions for this dissertation. Special thanks are given to Dr. Ming Chai (Greenleaf Biofuels) and Dr. Gerhard Knothe (Bio- oils unit, USDA-ARS) for their suggestions and help with the analytical work. I would also like to say thank you to my colleagues, Yang Liu, Tongyan Li, Thiansathit Worrarat, and Junsong Zhang for their help during my graduate study. Many thanks also go to the US EPA People, Prosperity and the Planet (P3) Phase I (SU836038) and Phase II grant (SU835291) for providing financial support for part of the study. Last but not least, I would like to thank my wife, Lijuan Sang, my parents, and the rest of my family for their love and support in helping me to accomplish the degree. iv Disclaimer The U.S. Environmental Protection Agency, through its Office of Research and Development, funded and managed, or partially funded and collaborated in, the research described herein. It has been subjected to the Agency administrative review and has been approved for external publication. Any opinions expressed in this paper are those of the author(s) and do not necessarily reflect the views of the Agency, therefore, no official endorsement should be inferred. Any mention of trade names or commercial products does not constitute endorsement or recommendation for use. v Table of Contents Abstract ...................................................................................................................................................... i Acknowledgement ..................................................................................................................................... iv Disclaimer .................................................................................................................................................. v List of Figures ........................................................................................................................................... ix List of Tables ............................................................................................................................................. xi Chapter 1. Overview of the Dissertation ................................................................................................. 1 1.1 Introduction........................................................................................................................................... 1 1.2 Goal Statement ...................................................................................................................................... 2 1.3 References ............................................................................................................................................ 5 Chapter 2. Evaluation of Life Cycle Energy Consumption and Greenhouse Gas (GHG) Emissions for Biodiesel Production from Trap Grease ........................................................................................... 6 2.1 Introduction........................................................................................................................................... 6 2.2 Goal and Scope Definition .................................................................................................................... 8 2.3 Functional Unit and Assumptions ....................................................................................................... 10 2.4 Methodology ....................................................................................................................................... 10 2.4.1 Data sources ................................................................................................................................. 10 2.4.2 Unit processes .............................................................................................................................. 11 2.4.3 Randomization and Monte Carlo simulation ................................................................................ 15 2.5 Results ................................................................................................................................................ 16 2.5.1 Baseline case (sample calculation) ............................................................................................... 16 2.5.1.1 Life cycle energy consumption ............................................................................................. 17 2.5.1.2 Life cycle GHG emission ...................................................................................................... 18 2.5.2 Monte Carlo simulation................................................................................................................ 19 2.5.2.1 Life cycle energy consumption ............................................................................................. 19 2.5.2.2 Life cycle GHG emission ...................................................................................................... 20 2.5.3 Sensitivity analysis ....................................................................................................................... 21 2.5.3.1 Life cycle energy consumption ............................................................................................. 21 2.5.3.2 Life cycle GHG emission ...................................................................................................... 22 2.6 Discussion ..........................................................................................................................................