Biodiesel Production from Mixed Culture Algae Via a Wet Lipid Extraction Procedure

163 Pages·2016·4.27 MB·English

Utah State University
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All Graduate Theses and Dissertations Graduate Studies
12-2012
Biodiesel Production from Mixed Culture Algae
Via a Wet Lipid Extraction Procedure
Ashik Sathish
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BIODIESEL PRODUCTION FROM MIXED CULTURE ALGAE VIA A WET LIPID
EXTRACTION PROCEDURE
by
Ashik Sathish
A thesis submitted in partial fulfillment
of the requirements for the degree
of
MASTER OF SCIENCE
in
Biological Engineering
Approved:

________________________________ ________________________________
Ronald Sims Byard Wood
Major Professor Committee Member

________________________________ _______________________________
Charles Miller Issa Hamud
Committee Member Committee Member

_______________________________
Mark McLellan
Vice President for Research and
Dean of the School of Graduate Studies

UTAH STATE UNIVERSITY
Logan, Utah
2012
ii

Copyright © Ashik Sathish
2012
iii

ABSTRACT

Biodiesel Production from Mixed Culture Algae

Via a Wet Lipid Extraction Procedure

by

Ashik Sathish, Master of Science

Utah State University, 2012

Major Professor: Dr. Ronald C. Sims
Department: Biological Engineering

With world crude oil reserves decreasing and energy prices continually increasing,
interest in developing renewable alternatives to petroleum-based liquid fuels has increased. An
alternative that has received consideration is the growth and harvest of microalgae for the
production of biodiesel via extraction of the microalgal oil or lipids. However, costs related to the
growth, harvesting and dewatering, and processing of algal biomass have limited commercial
scale production of algal biodiesel. Coupling wastewater remediation to microalgal growth can
lower costs associated with large scale growth of microalgae. Microalgae are capable of
assimilating inorganic nitrogen and phosphorous from wastewater into the biomass. By
harvesting the microalgal biomass these nutrients can be removed, thus remediating the
wastewater. Standard methods of oil extraction require drying the harvested biomass, adding
significant energetic cost to processing the algal biomass. Extracting algal lipids from wet
microalgal biomass using traditional methods leads to drastic reductions in extraction efficiency,
driving up processing costs. A wet lipid extraction procedure was developed that was capable of
extracting 79% of the transesterifiable lipids from wet algal biomass (16% solids) without the use
of organic solvents while using relatively mild conditions (90 °C and ambient pressures).
Ultimately 77% of the extracted lipids were collected for biodiesel production. Furthermore, the
iv

procedure was capable of precipitating chlorophyll, allowing for the collection of algal lipids
independently of chlorophyll. The capability of this procedure to extract lipids from wet algal
biomass, to reduce chlorophyll contamination of the algal oil, and to generate feedstock material
for the production of additional bio-products provides the basis for reducing scale-up costs
associated with the production of algal biofuels and bioproducts.

(162)
v

PUBLIC ABSTRACT

Development of renewable sources of energy has received significant interest due to the
rising costs of energy and the environmental impact of using fossil fuels. Biodiesel production
from renewable sources of oil has shown promise of helping to replace or reduce dependence on
petroleum based diesel thereby reducing demand for crude oil. Microalgae have been considered
as a strong candidate for the production of large quantities of renewable oil for biodiesel
production.
Microalgae are single cell photosynthetic organisms that posses the capability to produce
renewable oil at rates much faster than land based plants and crops. In addition, microalgae can
be grown in non-arable land, use low quality water or wastewater, and do not require significant
maintenance making algal biomass simpler to generate and help in avoiding the food versus fuel
debate. However, the current cost of processing algae has prevented commercial production of
algae biodiesel. Several hurdles exist that contribute to the production cost, some of which
include: (1) the need to dry algal biomass prior to lipid extraction when using traditional methods
of oil extraction, (2) large volumes of organic solvents commonly required to extract the algal
oils, and (3) purification costs associated with generating usable biodiesel.
This research focused on developing a method of processing algal biomass to help
directly address these hurdles. The wet lipid extraction procedure developed is capable of
extracting oil from algal biomass with no drying, reduces the demand for organic solvents, and
removes or reduces chlorophyll contamination from the produced biodiesel potentially reducing
purification requirements. Additionally, the developed procedure produces several additional
streams that can be utilized as feedstock material for the production of additional algae based
bioproducts. Such advances in algal processing technology can aid in reducing the cost of
producing renewable microalgae based biofuels and bioproducts.
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ACKNOWLEDGMENTS

I would like to acknowledge support for this research from the United States Department
of Energy, the Utah State University Biological Engineering Department, the Sustainable Waste-
to-Bioproducts Engineering Center, the Utah State University BioEnergy Center, and the Logan
City Environmental Department. I would also like to thank my committee members for their
technical input and guidance, Dr. Ronald Sims, Dr. Charles Miller, Dr. Byard Wood, and Mr. Issa
Hamud. Additional thanks to Brian Smith, Aubree Hansen, and Clayton Bingham for their
assistance with this research.
I would especially like to thank my parents and brother for their constant support and
guidance through the duration of this project. Special thanks to my friends here who gave me a
chance to relax and enjoy my time while working on this project.
Ashik Sathish
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CONTENTS

Page

ABSTRACT .................................................................................................................................... iii

PUBLIC ABSTRACT. .................................................................................................................... v

ACKNOWLEDGEMENTS ............................................................................................................ vi

LIST OF TABLES .......................................................................................................................... ix

LIST OF FIGURES ....................................................................................................................... xii

CHAPTER

1. INTRODUCTION AND NEED FOR STUDY ................................................................. 1

Need for Renewable Energy ................................................................................. 1
Microalgae as a Source of Renewable Oil for Biodiesel Production .................... 2
Logan Lagoons Project ......................................................................................... 4
References ............................................................................................................. 5

2. LARGE SCALE PRODUCTION OF MICROALGAL BIOMASS
AND METHODS FOR THE EXTRACTION AND CONVERSION
OF MICROALGAL OIL TO BIODIESEL.................................................................. 8

Introduction ........................................................................................................... 8
Large-Scale Algae Growth Systems ................................................................... 10
Collection and Dewatering of Algal Biomass .................................................... 12
Methods of Oil Extraction .................................................................................. 16
Biodiesel Production ........................................................................................... 21
Conclusions ......................................................................................................... 34
References ........................................................................................................... 36

3. BIODIESEL FROM MIXED CULTURE ALGAE VIA A WET
LIPID EXTRACTION PROCEDURE ............................................................................ 43

Introduction ......................................................................................................... 43
Materials and Methods ........................................................................................ 44
Results and Discussion ....................................................................................... 49
Conclusions ......................................................................................................... 53
References ........................................................................................................... 53

4. EVALUATION OF ALGAL BIOMASS MOISTURE CONTENT
ON THE IN SITU TRANSESTERIFICATION OF MICROALGAE
FOR BIODIESEL PRODUCTION .................................................................................. 56

Introduction ......................................................................................................... 56
Materials and Methods ........................................................................................ 58
viii

Results and Discussion ....................................................................................... 61
Conclusions ......................................................................................................... 68
References ........................................................................................................... 69

5. SUMMARY ..................................................................................................................... 70

APPENDICES ................................................................................................................. 72

Appendix A: Method of Lipid Extraction Provisional Patent Application ......... 73

Appendix B: Report- Life cycle analysis: Comparison of RABR Growth
System to Raceways and Net Energy Analysis for the
Logan Lagoons Wastewater Treatment Plant ..................................................... 97

Appendix C: Raw Data for Selected Chapters ................................................... 129

Appendix D: Elsevier License and Permission to Reprint
Published Articles .............................................................................................. 144
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LIST OF TABLES

Table Page

1. Comparison of oil productivity of various oil crops for biodiesel production .................... 3
2. Comparison of oil yields from typical energy crops versus microalgae ........................... 10
3. Heat energy required to dewater algal biomass to the specified moisture
content and generate 1 kg biodiesel .................................................................................. 15
4. Comparison of mechanical harvesting methods for algal biomass ................................... 15
5. Effect of varying parameters on the conversion of oil to Methyl Esters
using an acid catalyst ........................................................................................................ 26

6. Comparison of transesterification methods (SCM- Supercritical Methanol) ................... 30
7. Comparison of transesterification methods ...................................................................... 31
8. Comparison of lipids extracted by solvents versus FAMEs generated by in situ
transesterification. TAG refers to triacylglycerol ............................................................. 33

9. FAMEs generated from streams 1 through 4 from the WLEP and from the
positive control ................................................................................................................. 52

10. Comparison of sources of oil for biodiesel production ..................................................... 57

11. Moisture contents of algal biomass as a function of drying temperature and time ........... 62

12. Biodiesel yields for both wet (84 wt% moisture) and lyophilized algal biomass
using in situ transesterification with varying reaction parameters ................................... 67

A1. Data presenting proof of concept for wet lipid extraction procedure ............................... 87

B1. Rate of nutrient uptake by algae growing in suspended form ......................................... 100

B2. Masses of fertilizer required to reach target phosphorous concentrations of 1.5
and 1.0 g/m3 and energies associated with each fertilizer’s production .......................... 102

B3. Rate of nutrient uptake by algae growing in suspended form ......................................... 103
B4. Summary of energy inputs and output from the RABR system for generating algal
biomass for 1 kg of algal biomass ................................................................................... 106

B5. Summary of energy inputs and output from the RABR system for generating algal
biomass for 1 kg of algal biomass. Using a target
phosphorous concentration of 1.5 g/m3........................................................................... 107