Techno-economic Assessment of Microalgae Biodiesel

Transcription

1 The1 st International Conference on Applied Microbiology entitled Biotechnology and Its Applications in the Field of Sustainable Agricultural Development March 1-3, 2016 Giza, Egypt Techno-economic Assessment of Microalgae Biodiesel Hassan I. El-Shimi Associate Lecturer Chemical Engineering Department, Cairo University, Egypt Phone: Wednesday March 2 nd, 2016

2 Introduction Why make algae a fuel? Research Objectives Experimental Work Results Conclusions Acknowledgement References 2

3 Introduction

4 Ever-increasing of energy incentives the scientists to search and develop renewable energy sources such as biofuels. Liquid biofuel is the unique alternative for transportation fuel, while solar and wind energy is better to utilize in electricity production. Algal biodiesel is a technically attractive alternative and renewable diesel fuel without excessive engine modifications. 4

5 Why make algae a fuel?

6 Microalgae can be cultivated in domestic wastewater (1m 3 of wastewater is required to produce 800 g of dry algae). Microalgae reduce emissions of a major greenhouse gas (1 kg of algal biomass requiring about 1.8 kg of CO 2 ). 6

7 Biodiesel from Algae doesn t conflict with the food crisis. 7

8 Microalgae reproduce themselves every few days. High oil productivity ( gallon/acre/year) Oil yield exceed 10x the yield of the best oilseed crops. 8

9 Research Objectives

10 Biodiesel Production from Algae Extraction of Algal Oil using Mechanical Pressing followed by Chemical Solvent like Hexane. OR Direct Transesterification of Algal Lipids into Fatty acid Methyl Esters (Biodiesel) without Pre-extraction of Algal Oil. Transesterification of Algal Oil into Biodiesel. 10

11 Chemistry of Transesterification Clean Burning Alternative fuel for diesel engines Produced from Domestic Renewable Resources: any fat or oil, like vegetable oil, used greases, animal fat. Meets health effect testing (CAA) Lower emissions, better lubricity High flash point (>170 o C), Safe to store and burn Biodegradable, Essentially non-toxic. Chemically, biodiesel molecules are mono-alkyl esters produced usually from triglyceride esters 11

12 Research Objectives Highest Algal Biomass Productivity and Lipids % Wastewater Direct Transesterification CO 2 Emissions Egypt Desert Algal Biomass Feasibility Study & Algal Biodiesel Commercialization 12

13 Experimental work

14 Materials Spirulina-platensis Microalgae were supplied from Microbiology Department, Agricultural Research Centre, Giza Compounds % Proteins 61.3 Lipids Minerals 6.95 Fibers 4 Moisture 0.5 Carbohydrates 12.8 Nucleic acid 2.5 Chemicals Methanol CH 3 OH (99.9 % purity) Sulphuric acid H 2 SO 4 as a Catalyst (98% purity) Hexane C 6 H 14 for Decantation Distilled H 2 O All chemicals were purchased from El-Nasr Pharmaceutical Chemicals Co. Egypt. 14

15 Equipment 15

16 Microalgae Powder Algal cake Direct Transesterification "Acidic Methanol" Reactor Water Filtration Filtrate solution: Biodiesel + Glycerol + Catalyst + Methanol + Unreacted Oilgae Reaction Time Temperature Hexane Methanol Generation of two layers Obtain water layer: glycerol + catalyst + excess methanol Hydrophobic layer: hexane + biodiesel + unreacted Oilgae Catalyst Concentration Glycerol Evaporation Filtration over sodium sulphate Biodiesel Evaporation Alcohol/Oilgae (wt./wt.) Agitation Mode 16

17 Filtration Biodiesel Crude Glycerol 17

18 Results

19 Algal Oil Algalcake Fatty acid Spirulina Jatropha Component Value Unit Mystic (C14:0) Carbohydrates 12.6 %wt Palmitic (C16:0) Protein 51.5 %wt Palmitoleic (C16:1) Moisture 1.5 %wt Stearic (C18:0) Ash 7.5 %wt Oleic (C18:1) Ca 400 mg/100 g algae 900 Linoleic (C18:2) P 900 mg/100 g algae Linoleuic(C18:3) Fe 70 mg/100 g algae 500 Ecosanoic (C20:0) N mg/100 g algae Eicosenoic (C20:1) K 1475 mg/100 g algae Saturated Valid as a bio-fertilizer Monounsaturated Polyunsaturated Avg. The Mpredominant wt. fatty acid 845 was the palmitic Nil acid C16:0 (49.58% by mole), which makes the oil a promising feedstock for biodiesel fuel synthesis. The acid value and viscosity of Oilgae were too much; 37.4 mg KOH/g and 58 cp, respectively. Therefore the choice of acidic over alkaline catalysis for the direct transesterification process was justified. 19

20 Variables affecting the direct transesterification

21 Algal biofuel conversion (%) 1. Effect of Alcohol/S.platensis mass ratio The H 2 SO 4 load was optimized to be 100% (wt/wt oil); where further increase had not improved the process efficiency y = 2E-07x x x R² = Methyl alcohol/s.platensis mass ratio Temperature: 65 o C Time: 8 hr Catalyst conc. 100% wt. Stirring: 650 rpm The studied range of methanol/feedstock mass ratio was: 267/1 667/1 that equivalent to ml for each 1g algal biomass. No significant increase in algal biodiesel is reported above 533/1. 21

22 2. Effect of Reaction Time and Temperature Time, hr Yield % 27 o C 40 o C 50 o C 65 o C To investigate the influence of reaction time (2, 4, 8 and 10 hr) and temperature (27, 40, 50 and 65C), a methanol volume of 80 ml, 100% by mol. catalyst conc. and continuously stirring the reaction at 650 rpm conditions were used. The fact that the elevated temperatures (and pressures) improved the initial miscibility of the reacting species, leading to a significant reduction in the reaction times. 22

23 Biodiesel Conversion (%) 2. Effect of Reaction Time and Temperature y = x x R² = y = x2 + 21x R² = y = x x R² = y = x x R² = C 40C 50C 65C Reaction Time (hr) 23

24 Yield % 3. Effect of Stirring Process conditions: 15g biomass, 80ml methanol, 100% H 2 SO 4 conc., at 65 C for 4 hrs. No stirring When the in situ transesterification process was conducted without stirring, no reaction will be obtained, and the equilibrium conversion of the microalgae oil content to biodiesel is zero. Stirred intermittently (1 h off, 1 h on) 30 Stirred continuously Because 87% of the equilibrium FAME conversion was achieved after 1 h with continuous stirring under the experimental transesterification conditions. 24

25 Quality Assessment of Algal Biodiesel Property Unit Petroleum diesel Algal biodiesel Biodiesel (EN 14214) Carbon range C8-C16 C12:0-C22:0 C14:0-C20:2 Density at 15 o C g/cm Viscosity at 40 o C cst Acid number mg KOH/g oil <0.5 Pour point o C -15 to Cloud point o C -15 to Flash point o C >101 Aniline point Distillation range o C Auto-ignition point o C Water content ppm <500 C %wt H 2 %wt 13 < O 2 %wt 0 > S %wt 0.13 Nil <0.01 Calorific value MJ/kg Cetane number >51 Paraffins %wt - 79 (avg.) - Olefins %wt - 20 (avg.) - 25

26 Algal Biodiesel Economics

27 Economic assessment of algal biodiesel project Assumptions The feedstock is Nannochloropsis sp. of 44%wt lipid content. The biomass cost is assumed to be $400/ton, and algal biodiesel price is suggested to be $2500/ton. The production capacity of algal biofuel is 0.5 million tons/year. Operating hours based on three shifts (8h) per day and 300 working days per year. The storage capacity is suggested to be only one week for raw materials and products. The catalyst (H 2 SO 4 conc.) will be supplied by Egyptian Armed-Forces Plants ($1250/ton). Glycerin and algalcake are co-products that help to minimize the annual production cost. Algalcake price is suggested to be $300/ton, whatever its utilization purpose as bio-fertilizer or solid biofuel 80% of methanol is assumed to be recovered. Depreciation estimated using straight line method for 15 years life span and the scrap value is estimated to be 10 % of equipment cost (EC). Electricity cost is $0.1/kWh, and the electricity consumption is assumed to be 70kWh/ton algal biodiesel. Working capital investment (WCI) is represent 20% of fixed capital investment (FCI); as the products are not require marketing heads 10% of gross earnings is accounted for taxes expenses. 27

28 Raw materials and revenues cost Quantity (ton/yr) Unit cost ($/ton) Cost ($/yr) Raw materials Algal biomass Methyl alcohol H 2 SO 4 catalyst Revenues Biodiesel Glycerin Algalcake

29 Equipment cost (EC) Equipment Unit No. Total cost ($) Algae storage tanks (300 m 3 ) Belt conveyor Methanol storage tanks (200 m 3 ) H 2 SO 4 storage tanks (200 m 3 ) Mixing vessels (100 m 3 ) Transesterification reactors (Jacketed & Agitated 100 m 3 ) Mixers (Propeller, 10 hp) Decanters/Centrifuges (bottom driven 3m diameter) Pumps (progressive cavity type, 30gallon/min) Extraction/Distillation columns ( 2m Diameter,20m Height) Algal biodiesel storage tanks (200 m 3 ) Glycerin storage tanks (100 m 3 ) Filters (Hydrocyclone, 1m diameter, m 3 /h) EC

30 Capital investment (CI) Capital investment category Cost ($) Equipment cost (EC) Equipment delivery cost Installation cost Piping Buildings Utilities Instrumentation & Control Site Development Auxiliary buildings Design and Eng Contractor' fee Contingency Legal expenses FCI WCI TCI 276,228,480 30

31 Algal biofuel cost (ABC) Unit cost (US$) Cost ($/yr) Direct Production Cost (DPC) Raw Materials Miscellaneous materials 10% M&O Electricity $0.1/kWh Maintenance and operational cost (M&O) 10%EC Operating labor $13500/employee/year Depreciation Striaght-line depreciation Plant overheads 50% of labor and M &O Interest 2% EC Property insurance cost 5% EC Indirect Production Cost (IPC) Research and Development 5% of DPC General expenses 25% of labor and M&O Contingency 10% of labor, M&O and plant overheads costs ABC ABC/ton biodiesel

32 ROR (%) Pay-back period (years) Techno-economic indicators for algal biofuel production based on the appreciated assumptions Selection of microalgae strain Item Value Raw materials ($/yr) 1,337,519,230 Revenues ($/yr) 1,539,990,072 Algae lipid productivity and fatty Total capital investment ($) 276,228,480 acid profiles that matching the Total production cost ($/yr) 1,437,777,202 biofuel requirements are generally Net profit ($/yr) 91,991,583 used to select the appropriate ROR (%) 33.3 strain, however lipid content is of Pay-back time (yr) 2.4 great importance criteria for algal biodiesel business For profitable algal biofuel 40 5 business, lipids content cannot less 20 than 37.3%; to get US$ net profit and 3.8 years a payback 0 time Microalgae lipid (%) ROR Pay-back period Algae specie Oil %wt Nitzschia sp Neochloris oleoabundans Nannochloropsis sp Botryococcus braunii Schizochytrium sp

33 Conclusions

34 Algal biofuel is interested in recent years; due to the unique benefits of microalgae Oilgae extraction is one of the most costly processes which can determine the sustainability of microalgae-based biodiesel. However, it is necessary to evaluate Oilgae properties and determine the appropriate method for biofuel production. The existence of C16:0-C18:3 in algal oil making it a promising feedstock for green fuel production, but the high viscosity (58cp) and excessive FFA (~18%) resists its direct use as a fuel Direct transesterification (or in-situ) process integrates oil extraction and its conversion into biodiesel in a single step; hence it minimizes the total manufacturing cost. Results reported that methanol/spirulina platensis mass ratio of 533/1 is recommended to be ideal; to yield 84.7% of algal biofuel at 65 o C, 100% catalyst concentration and 8h with experimental error of ±3.5%. Biochemical analysis of algalcake proved its utilization as a bio-fertilizer, animal fodder, solid biofuel, or a feedstock for bioethanol production according to economics view point. Quality assessment of algal biodiesel confirm EN standards. Preliminary economic analysis of algal biodiesel project show that TCI is US$ , annual ABC is US$ , annual net profit is US$ , ROR is 33.3% and payback time is 2.4 yr for production capacity of 0.5Million tons based on algae lipid content of 44% (Nannochloropsis), feedstock cost of US$400/ton and algal biofuel selling price of US$2500/ton. To obtain a profit, the algae oil content cannot be less than 37.3%. 34

35 Acknowledgements The author would like to express his appreciation to the Faculty of Engineering, Cairo University, Egypt for the technical and financial support.

36 References Are available in the conference proceedings.

37 37