PROCESS BENEFITS OF USING BIOMASS PELLETS IN A BIOREFINERY A Thesis Submitted to the Graduate Faculty of the North Dakota State University of Agriculture and Applied Science By Ramsharan Pandey In Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE Major Department: Agricultural and Biosystems Engineering April 2019 Fargo, North Dakota North Dakota State University Graduate School Title PROCESS BENEFITS OF USING BIOMASS PELLETS IN A BIOREFINERY By Ramsharan Pandey The Supervisory Committee certifies that this disquisition complies with North Dakota State University’s regulations and meets the accepted standards for the degree of MASTER OF SCIENCE SUPERVISORY COMMITTEE: Dr. Scott W. Pryor Chair Dr. Igathinathane Cannayen Dr. Ghasideh Pourhashem FakharLangeroudi Approved: 04/11/2019 Dr. Kenneth J. Hellevang Date Department Chair ABSTRACT Pelleted biomass can help simplify biomass supply systems and reduce downstream processing costs that are vital for the development of commercial biorefineries. This study is based on comparison of process benefits and economic factors of using loose and pelleted biomass over a range of low to high pretreatment severity and hydrolysis enzyme loadings. Use of pelleted biomass provides flexibility either to reduce pretreatment severity, enzyme loadings, hydrolysis time, or combinations of these. Either enzyme loadings can be reduced by 80% or hydrolysis times reduced by 58% with the use of pelleted biomass. A comparative techno- economic analysis using each form of biomass reveals that using pelleted biomass is economically beneficial. The minimum ethanol selling price for loose biomass was found to be $4.41/gal ethanol and $3.83/gal ethanol for pelleted biomass. The economic study suggests that optimizing conversion processes could lower the final ethanol costs even further. iii ACKNOWLEDGEMENTS I would like the express my sincere gratitude to my major advisor Dr. Scott W Pryor for his support, guidance, and encouragement during my graduate study. He has been a true inspiration and was always open for discussions whenever I had problems. Without his motivation, I would not have got this far. Thanks to my committee members Dr. Igathinathane Cannayen and Dr. Ghasideh Pourhashem for their valuable suggestions. Special thanks to Dr. Ghasideh Pourhashem for guiding me through my second paper. I would also like to thank Dr. Nurun Nahar for her guidance in lab works, results interpretation, and also in writing. Thanks to all my family members and friends for their support and encouragement throughout this process. iv TABLE OF CONTENTS ABSTRACT ................................................................................................................................... iii ACKNOWLEDGEMENTS ........................................................................................................... iv LIST OF TABLES ......................................................................................................................... ix LIST OF FIGURES ........................................................................................................................ x LIST OF APPENDIX TABLES .................................................................................................... xi LIST OF APPENDIX FIGURES.................................................................................................. xii 1. GENERAL INTRODUCTION ................................................................................................... 1 1.1. References ............................................................................................................................ 3 2. LITERATURE REVIEW ........................................................................................................... 4 2.1. Biomass Sources .................................................................................................................. 5 2.1.1. Dedicated energy crops ................................................................................................. 5 2.1.2. Agricultural crops .......................................................................................................... 5 2.1.3. Agriculture crop residues .............................................................................................. 5 2.1.4. Forestry residues ............................................................................................................ 5 2.1.5. Aquatic plants ................................................................................................................ 6 2.1.6. Biomass processing residues ......................................................................................... 6 2.1.7. Municipal waste............................................................................................................. 6 2.1.8. Animal waste ................................................................................................................. 6 2.2. Uses of Biomass ................................................................................................................... 6 2.3. Current Trends ...................................................................................................................... 7 2.3.1. Starch and sugar feedstocks – first generation biofuel .................................................. 7 2.3.2. Cellulosic feedstocks – second generation biofuel ........................................................ 7 2.4. Conversion Processes ........................................................................................................... 8 2.4.1. Combustion.................................................................................................................... 8 v 2.4.2. Gasification and pyrolysis ............................................................................................. 8 2.4.3. Biochemical conversion ................................................................................................ 9 2.5. Biomass Composition .......................................................................................................... 9 2.6. Biomass Densification/Size Reduction .............................................................................. 10 2.6.1. Advantages of size reduction and densification .......................................................... 11 2.6.2. Pelletization ................................................................................................................. 12 2.7. Biomass Pretreatment ......................................................................................................... 13 2.7.1. Methods of pretreatment.............................................................................................. 14 2.7.2. Pretreatment selection ................................................................................................. 17 2.8. SAA Pretreatment .............................................................................................................. 18 2.9. Enzymatic Hydrolysis ........................................................................................................ 19 2.9.1. Principle of hydrolysis ................................................................................................. 20 2.9.2. Factors affecting enzymatic hydrolysis ....................................................................... 21 2.10. Effect of Pelletization and Pretreatment on Enzymatic Hydrolysis ................................. 22 2.11. Techno-economic Analysis of Producing Ethanol ........................................................... 27 2.12. References ........................................................................................................................ 31 3. PROBLEM STATEMENT AND OBJECTIVES ..................................................................... 39 3.1. Problem Statement ............................................................................................................. 39 3.2. Hypotheses ......................................................................................................................... 42 3.3. Objectives ........................................................................................................................... 42 3.4. References .......................................................................................................................... 43 4. QUANTIFYING REDUCTIONS IN SOAKING IN AQUEOUS AMMONIA PRETREATMENT SEVERITY AND ENZYMATIC HYDROLYSIS CONDITIONS FOR CORN STOVER PELLETS ................................................................................................ 45 4.1. Abstract .............................................................................................................................. 45 4.2. Keywords ........................................................................................................................... 45 vi 4.3. Introduction ........................................................................................................................ 46 4.4. Materials and Methods ....................................................................................................... 49 4.4.1. Raw material ................................................................................................................ 49 4.4.2. Biomass moisture content...........................................................................................