Energy and Value Added Products from Marine

biomass and Wasteland Derived biomass

Ph.D Synopsis

Submitted to

Gujarat Technological University, Ahmedabad

For the degree

of

Doctor of Philosophy

in

Chemical Engineering (Specialization Renewable Energy)

by

Prasanta Das

Enrolment No.: 139997105007

(2017)

Supervisor:

Dr. Subarna Maiti, Sr. Scientist, PDEC,

CSIR-CSMCRI, Bhavnagar, Gujarat

Doctoral Progress Committee Members

Dr. Parimal Paul Chief Scientist,

Head in Analytical

CSIR-CSMCRI

Bhavnagar

Dr. M. Shyam (Retired)

Director in SPRERI,

V.V. Nagar, Anand

Dr.Piyush B. Vanzara

(New)

Associate Professor,

VVP Eng. College

Rajkot

2

Contents

Page no.

1. Abstract 3 – 4

2. Introduction

2.1 General introduction 5

2.2 Review of earlier research works in the relevant field 6 – 7

3. Objective and scope of the work 7

4. Brief description of the present work in the relevant field 7

5. Characterization methods to determine fuel suitability of selected biomass 8 – 9

6. Case studies of harnessing energy from wasteland biomass and seaweed

(macroalgal biomass)

6.1 Utilization of Jatropha curcas shells for energy 9

6.1.1 Brief description of both the gasification and pyrolysis. 9 – 10

6.2 Thermochemical conversion of Kappaphycus alvarezii granules

seaweed for energy.

11

6.2.1 Brief description of both the gasification and pyrolysis. 11 – 13

6.3 Harnessing energy from other seaweeds: Ulva fasciata, Gracilaria

corticata, Sargassum tenerrimum

13 – 14

6.3.1 Brief description of the production of bio-oil through slow

pyrolysis process with Arrheniuous kinetic model

14 – 15

7. Conclusion 15 – 16

8. Publications 17

9. Patent 17

10. References 18 – 19

3

1. Abstract

With increasing energy consumption day to day around the world coupled with ever

increasing global pollution level in the atmosphere with high carbon footprints, several

technologies with low carbon footprints comprising of pyrolysis, gasification, combustion,

liquefaction and steam gasification have emerged. The present study has focussed on three

technologies pyrolysis, gasification, and steam gasification of selected wasteland biomass and

seaweed biomass. Fuel characterization of both genres of biomass predicted the suitability in

thermochemical conversion processes for each type of biomass considered. For experimental

validation, some case studies were investigated. Jatropha curcas shells was considered as an

important wasteland biomass in the view of ongoing Institutional activities on jatropha bio-

diesel and wasteland development. Firstly, the gasification of Jatropha curcas shells was

investigated in a 10 kW downdraft gasifier. For this, a thorough fuel characterization of the

shells was carried out. The gasifier was connected to a 100% producer gas engine and

continuous power generation (~10 kWe) was achieved with overall efficiency of 24.5%.

Secondly, the pyrolysis of the shells was also demonstrated in a fixed bed reactor to produce

bio-oil at the temperatures of 300, 400, 500, and 600°C. The bio-chars from the experiments

were evaluated and steam gasification of the chars demonstrated a H2 rich ‗syn-gas‘.

Complete thermochemical characterization was also carried out for 10 other wasteland

biomass. For marine macroalgae, a detailed thermochemical study was carried out for

Kappaphycus alvarezii granules. The biomass was investigated in four different kinetic

models (i) multilinear regression technique, (ii) Friedman method, (iii) Flynn-Wall-Ozawa

(FWO) (iv) Kissinger–Akahira–Sunose (KAS) methods and the kinetic parameters at

different heating rates were evaluated. The results were compared with terrestrial biomass -

sawdust. Like jatropha shells, Kappaphycus granules were gasified and pyrolyzed separately

and the products characterized. Three other macroalgae, namely Ulva fasciata, Gracilaria

corticata, Sargassum tenerrimum were utilized as a potential source of pyrolytic bio-oil. The

kinetic study was done for optimizing the temperature zone in which the pyrolysis

experiment was to be conducted. The characteristics of bio-oils and bio-chars too were

investigated. The graphical abstract of the present study is shown below:

Non-conventional biomass for energy

Wasteland derived biomass Seaweeds

Jatropha

shells

Cassia

auriculata

Cassia

tora

Jatropha

gossypifolia

Dichanthium

annulatum

Sphaeranthus

indicus

Eclipta

alba

Desmostachya

bipinnata

Solanum

xanthocarpum Sargassum

tenerrimum

Gracilaria

corticata

Ulva

fasciata

Kappaphycus

alvarezii

Butea

monosperm

a

Prosopis

juliflora

Characterization as solid fuel for thermochemical conversion

process including determination of kinetic parameters

Downdraft gasification

of jatropha shells

Slow pyrolysis of

jatropha shells for bio-oil

production

Two stage thermochemical

process for H2 generation from

jatropha shells

Downdraft gasification of

Kappaphycus alvarezii

granules

Slow pyrolysis of

other seaweed species

Thermochemical case

studies

Upgradation of bio-oil Life cycle assessment (LCA) studies

4

2. Introduction

2.1 General introduction

The salient feature of this PhD thesis to explore the vast potential of renewable energy

especially bio-energy because conventional energy sources are limited and the consumption

of energy has increased rapidly leading to exhaustion of availability very soon. The burning

of the fossil fuels can cause several deleterious effects on environment-related issues.

Renewable energy sources such as solar energy, bio-energy, etc. are available to reduce stress

on conventional energy sources. The deployment of these energy sources would produce less

emission than conventional energy sources [1 – 9]. The present work lays ample stress on the

introduction of energy scenario for both world and India.

The chapter one of the thesis describes the general introduction of energy scenario in the

world and India. This general introduction also includes the different thermochemical

technologies such as gasification, pyrolysis, combustion, kinetic study through

thermogravimetic analysis, and steam gasification of char or biomass.

Gasification is defined as the partial oxidation of solid fuel at elevated temperature that

produces syn-gas mainly composed of CO, H2, and CH4. This technology opts for converting

solid fuel to convenient gaseous form which is easy to manage in the downstream process.

For example, this gas can directly be utilized in gas turbine, engine for producing electricity,

etc. The major feedstock in gasifier is solid fuel and the gasifying agents are generally air or

pure oxygen, and some others gasifying agents are CO2, and steam. These gasifying agents

highly influence the product yield quality and quantity of syn-gas and calorific value. For

example, the calorific value is the highest for a gasifier when gasifying agent is pure oxygen

followed by air, while for carbon dioxide and steam gasification; the calorific value of syn-

gas is more for the former.

Pyrolysis is defined as the conversion of solid fuel into liquid, gas, and char or ash in absence

of air or inert atmosphere at elevated temperature. Based on the final product yield, pyrolysis

is classified into slow, medium, fast and flash pyrolysis. In case of slow pyrolysis, the major

products are liquid, gas, and bio-char and heating rate is also very less, while fast pyrolysis

occurs within 1 to 2 s and major product is liquid or bio-oil. Finally, flash pyrolysis occurs in

less than 1 s and the major product is bio-oil with better yield than fast pyrolysis. Combustion

is also another technology which produces carbon dioxide and heat. Steam gasification of

5

6

biomass produces hydrogen rich syn-gas which has more calorific value than conventional

syn-gas.

2.2 Review of earlier research works in the relevant field

The literature review of each relevant field comprising of the thermochemical conversion of

biomass, gasification, pyrolysis, thermogravimetric analysis, and steam gasification of

biomass is done in the present study. First of all, the thermochemical conversion of biomass

is abridged as literature survey one. The thermochemical routes are gasification, pyrolysis,

liquefaction, and combustion. The chemical composition of biomass is extremely important

prior to harnessing energy by thermochemical route. It was found from the literature survey

that terrestrial biomass having high cellulose, hemicellulose, and lignin content is most

suitable for a thermochemical process, while marine algae have no lignin content and has low

cellulose and hemicellulose. So, for this marine biomass hydrothermal liquefaction or

pyrolysis may be a good option for extracting energy and value added chemicals. So based on

the chemical constituents of any biomass, the selection of some thermochemical routes have

been explored in the present work.

The second literature survey is based on gasification technology. This literature survey

extensively deals with the processes comprising of the different types of gasifiers, such as

downdraft, updraft, fluidized bed, bubbling fluidized bed, and entrained bed gasifier. Apart

from the different types of gasifiers, its operating fundamentals are also described with the

outlet gas cleaning systems.

The third literature survey contains pyrolysis of different feedstocks ranging from terrestrial

to marine biomass. The products from pyrolysis comprising of bio-oil, syn-gas, and bio-char

are delineated here. Bio-char utilized in various applications such as soil amendment,

fertilizer, fuel are also elaborated here. Fischer-Tropsch synthesis is mentioned in this

literature survey. The pyrolysis process depends on the heating rate and final temperature and

the physical and chemical properties of biomass. The reaction mechanism is elaborated in the

present study. The probable chemical composition of bio-oil after splitting of individual

chemical species cellulose, hemicellulose, and lignin along with the characterization of bio-

oil is also studied. The literature survey of pyrolysis comprises terrestrial or woody type

biomass, and marine algae.

The fourth literature survey deals with kinetic study of solid biomass for thermochemical

process for evaluating the kinetic parameters under different models. The pyrolysis

7

mechanism of solid biomass is best described by the kinetic study promoted to identify exact

temperature zone for selecting the optimum temperature of pyrolysis. There are different

methods available for analysing solid state kinetic and some of them are model free

isothermal Friedman, and model free non-isothermal Flynn-Wall and Ozawa, and Kissinger–

Akahira–Sunose.

Fifth literature survey illustrates steam gasification of bio-char or biomass. Bio-char derived

from biomass at certain temperature was surveyed and effects of catalysts, steam flow rate,

temperature were studied. The purpose of choosing steam gasification for solid biomass is to

convert biomass to gaseous form having high calorific value and it is the best technology for

clean energy production.

The literature survey mainly highlights the different thermochemical routes of biomass

conversion to find out a suitable technology for extracting energy and value added chemicals.

3. Objective and Scope of the work

The wasteland derived biomass and marine macro algae are a potential source for extracting

energy and valuable chemicals as these kinds of biomass can be exploited for

thermochemical routes or biochemical routes instead of burning directly in situ. Direct

burning is an uncontrolled way of incineration which has negative impact on soil,

environment and culminates in soot particles in the atmosphere [10 – 12]. So, efficient and

technical methods should be designed to convert the biomass into energy. For this appropriate

method such as gasification, pyrolysis, and steam gasification technology are of principal

importance.

4. Brief description of the present work in the relevant field

To harness energy from wasteland products and marine biomass from various feedstocks by

suitable thermochemical conversion routes, the selected biomasses were characterized by

different methods as shown in Figure 1. Jatropha shells were gasified for energy in a typical

downdraft gasifier and power generated by a 10 kW engine using 100% producer gas engine.

The production of bio-oil from the same biomass was investigated and the oil was later

upgraded by an organic reaction. Jatropha shell chars were also steam gasified for H2 rich

syn-gas generation. Several other wasteland biomasses were also characterized. For marine

biomass, after obtaining sap from the red alga Kappaphycus alvarezii, it was dried and

8

crushed into Kappaphycus alvarezii granules (KAG) and then utilized for energy application

in gasifier for syn-gas production to run an engine for electricity generation. Pyrolysis for

bio-oil production and the kinetic studies were done. Three other macroalgae named Ulva

fasciata, Gracilaria corticata, and Sargassum tenerrimum were investigated for bio-oil

production by slow pyrolysis process and Arrhenius approach was used for kinetic studies.

5. The characterization methods to determine fuel suitability of selected biomass

This chapter highlights the detailed characterization procedure of selected biomass as a solid

fuel in thermochemical process. The introduction part elucidates about the different class of

wasteland derived biomass and its productivity throughout the year and location from where

these biomasses have been cultivated. The biomass samples were collected from these

locations for further processing such as drying, sizing into small pieces, grinding to powder

form. For characterization of this biomass as a solid fuel, several analyses are briefly

described here. Proximate and ultimate analyses are the most important parameters for any

solid fuel. The, calorific value has been determined for each biomass.

Biomass/bio-char

Pre-processing such as drying,

sizing, grinding of solid biomass

Proximate analysis

Ultimate analysis

Ash fusion test

Fibre estimation

ICP analysis for

determination of

ash composition

Calorific value

(CV) analysis

FT-IR

analysis

DSC

analysis

TGA

analysis

CHNS

analysis

XRD

analysis

The obtained bio-oil

from pyrolysis process

FT-IR, GC-MS,

CHNS, CV

For determination of syn-gas

from gasification or pyrolysis

Online producer

analyzer/portable

gas analyzer

pH ,Viscosity, Density, Refractive

index, moisture

9

FIGURE 1: Schematic diagram of different analysis being carried out in different

instrument.

Figure 1 shows the schematic diagram of different analysis that has been investigated using

different analyzers or instruments. The solid samples such as biomasses were analysed for

fibre estimation, FT-IR, TGA, DSC, CV (calorific value) and CHNS, while bio-chars were

characterized by the above same methods except fibre estimation. The ash composition or ash

of the biomass was analysed by ICP, XRD, and ash fusion test. For bio-oil characterization

pH, FT-IR, GC-MS, CHNS, CV, viscosity, density, refractive index and moisture analysis

was done. The syn-gas composition from gasification, steam gasification, and pyrolysis was

determined by the online producer gas analyzer. Finally, indices such as alkali index, base-to-

acid ratio, and bed agglomeration index were established from earlier literatures based on the

ash composition of biomass which is an important part of this study.

6. Case studies of harnessing energy from wasteland biomass and seaweed (macroalgal

biomass)

6.1 Utilization of Jatropha curcas shells for energy

The jatropha shell is the outer cover of its fruit and it is shrub type plant mainly grown in

marginal lands and hence can be classified under wasteland biomass. The whole fruit

comprises of shell, kernel, and seed. The kernel is a white part that covers the seed. This seed

is most commonly utilized for the production of bio-diesel in commercial application. CSIR-

CSMCRI has developed an integrated bio-diesel demonstration plant and it is a patented

process [13, 14]. In this process, the total electrical energy requirement is 500 kWh, and

furnace oil requirement is 50 kg to avail the following products starting from 6.06 t/day dry

jatropha fruit: 1 t jatropha biodiesel; 0.08 t neat glycerol; 2.54 t oil cake; 0.056 t soap cake;

0.022 t potassium sulphate; 2 t empty shells. The jatropha shells are rich in calorific value and

the power and steam requirement can be met from the shells. The requirement of jatropha

shells would be around 0.85 – 0.90 t as underscored in the present study. So naturally the rest

of jatropha shells ca. 1.1 t can be utilized for the bio-oil production which could meet the

requirement of electrical energy for the fixed bed reactor. Thus the whole process would be

sustainable. This is the core target of this study.

10

6.1.1 Brief description of both the gasification and pyrolysis

The gasification of jatropha shells was demonstrated in a typical downdraft gasifier with feed

rate 15 kg h-1

and it was connected to a 100% producer gas 10 kW engine and the

performances were investigated in this study. The basic feedstock of this present study was

empty shells having calorific value quite good 17.2 MJ kg-1

. The calorific value of producer

gas was found to be 5.2 MJ m-3

measured by a potable gas analyzer. Efficiency of 64.8% was

achieved over 8 h continuous operations. The engine performance was demonstrated in a

100% producer gas engine with overall efficiency of 24.5%. Thus, the captive power could

be obtained and can be utilized to tackle the need for external sources of power for the

operations of deshelling, screw pressing, oil refining, transesterification, glycerol purification,

and soap making in the integrated bio-diesel production process from the whole dry fruits.

The intermediate producer gas has added advantages as it provides thermal energy for the

process.

FIGURE 2: Schematic diagram of the whole process of jatropha curcas shells for

gasification and pyrolysis.

Again, these jatropha shells were utilized for the production of bio-oil by slow pyrolysis

process in a fixed bed reactor. The moisture free bio-oil was subsequently upgraded by a

Jatropha

curcas shells

Characterization as

solid fuel in

thermochemical

conversion process

Pyrolysis in a fixed

bed reactor

Gasification in a 10

kW gasifier adjoined

with 100% producer

gas engine

Overall efficiency

engine performances

evaluated

The sustainability of the

whole process calculated

The obtained bio-oil

moisture freed and

characterized

Upgraded bio-oil

obtained by an organic

reaction

Bio-char

Steam

gasification

11

simple organic reaction. In order to avail of the maximum productivity of the bio-oil, reaction

was carried out at temperatures of 300, 400, 500 and 600°C. The kinetic study indicated the

suitable heating rate was 5°C min-1

. The optimum result was found at 400°C, with yield of

31.14%, and with a holding time of 4 h. From the FT-IR and GC-MS analysis, the bio-oil

containing ca. 40% carbonyl (>C = O) derivatives, was converted into the corresponding

methylene (-CH2-) derivative by an organic reaction with hydrazine hydrate/sodium hydrate.

Thus, the resultant oil, containing mostly ethylbenzene, had a high calorific value of 50 MJ

kg-1

. It might be suitable to replace fossil diesel or gasoline. The obtained bio-chars at the

different temperatures were characterized for their potential use as a solid fuel. The whole

process is shown in Figure 2.

6.2 Thermochemical conversion of Kappaphycus alvarezii granules (KAG) seaweed for

energy

The brief introduction of Kappaphycus alvarezii granules is presented below. The

Kappaphycus alvarezii seaweed belongs to the genre of red alga (Rhodophyta). The

generation of bio-oil from marine seaweeds have been engaging the attention as a third-

generation biofuel, in the recent times. Marine seaweed has immense potential to produce

bio-energy to be utilized in commercial purposes due to it fast growth, high photosynthesis

efficiency, no requirement of cultivable land, and no competition with food crops. Another

excellent characteristic of seaweed is sequestering the CO2 from atmosphere as it is growing

primarily in intertidal coastal water. This marine seaweed can be readily converted into

biofuels through suitable biochemical or thermochemical routes [15, 16]. Kappaphycus

alvarezii is a red alga, which is generally commercially cultivated for the linear sulfated

polysaccharide, κ-carrageenan. CSIR-CSMCRI had pioneered a process to obtain two

products in an integrated way from seaweed [17, 18]. The alga is harvested and then collected

to crush to expel sap (a liquid plant stimulant). The whole solid mass is then centrifuged to

separate ―sap‖ and the solid residue left as seaweed granules. The detailed compositions of

the fresh seaweed sap and granules are already reported [17]. Several field trials of ―sap‖ as a

foliar spray in a variety of crops has indicated enhanced growth and product yields in diverse

geographical locations across India. So taking advantage of extended coastal line, large

multitude of this biomass is thus required to fulfil the ―sap‖ production requirement for the

country. Hence the present study explores most suitable thermochemical pathway which

should be adopted by converting the high volume residual granules to convenient gaseous or

12

bio-oil form to make the ―sap‖ production process standalone and energy efficient. So to

attain this objective, the kinetic study was initiated in the present investigation. For this,

selected models were employed for analysing the solid-state kinetic data obtained from TGA,

and through kinetic study to further to explore the devolatization process.

6.2.1 Brief description of both the pyrolysis through different models and gasification

The present study reports the kinetic behaviour of granules using thermogravimetric analysis

(TGA), at different heating rates 5, 10, 15, and 20 k min-1

in N2 atmosphere and the evolving

gaseous products being analysed by the thermogravimetric-mass spectrometry (TG-MS).

Sawdust was considered for the comparative study as it is a lignocellulogic biomass. The

selected four models (i) multiliear regression technique, (ii) Friedman method, (iii) Flynn-

Wall-Ozawa (FWO) method, and (iv) Kissinger-Akahira-Sunose (KAS) method were utilized

to evaluate the apparent activation energy, the pre-exponential factor, and the overall reaction

order. From the TG-MS study, the maximum SO2 peak was observed at 300°C and 950°C

which indicated that slow pyrolysis at 500°C, with a packed bed lime scrubber at the outlet

during temperature rise, was the best thermochemical pathway for energy harnessing.

Characterization of the seaweed was done in order to determine how the different parameters

affected the degree of ease with which the biomass can be ignited and subsequently used as

an energy source. Sawdust exhibited more VM (volatile matter) and FC (fixed carbon) than

KAG, thus making it a better fuel. The calorific value for KAG and sawdust were 9.19 MJ

kg-1

and 17.76 MJ kg-1

, respectively. The presence of mineral content also affected the

thermochemical behaviour of seaweed. The mineral content was also analysed for both acidic

and basic content in the present study. An attempt was made for the gasification of KAG in a

typical downdraft gasifier that was used previously [19] having feed rate 15 kg h-1

. The

gasifier and 10 kW engine were operated for 2 h at a continuous full load. However, during

entire operation, SOx emissions were noticed. Gasification required high temperature 700 –

900°C and this is most likely to yield substantial sulphur oxide emissions according to TG-

MS result. So in these circumstances, it was advisable to avoid the gasification of KAG

because of the corrosive nature of syn-gas. After 2 h run, the performance of gasifier

deteriorated gradually and sufficient power could not be generated even when fresh charge of

seaweed was provided because of the formation of soft lumps which probably had prevented

further downward flow of KAG. The ash content of the granules along with their fluffy

nature was apparently the contributing factor behind its improper fuel response.

13

FIGURE 3: Schematic diagram of the whole process carried out in this study of KAG.

The SOx emission was minimized by incorporating with lime and seaweed at a ratio of 3.33:

1 and charged in the gasifier, the product gas yielded SOx emissions were minimized. The

slow pyrolysis of KAG was investigated in a stainless steel fixed bed reactor. The rate of

heating was kept at 20 K min-1

. A packed bed lime scrubber at the outlet assisted to minimize

the gaseous sulphur compounds release during experiment when the temperature raised upto

500°C. After some experiments, bio-oil yield was optimized at 500°C with holding time 4 h.

The average yield of bio-oil, bio-char/ash, and syn-gas obatained during pyrolysis were 28.6,

47.28, and 24.12 wt. % respectively. All characterization of bio-oil was done. The moisture

free bio-oil had a calorific value of 18.23 MJ kg-1

burnt with a flame. This obtained bio-oil

was upgraded to 41.10 MJ kg-1

by reduction. Finally, the energy balance on slow pyrolysis

process resulted in 21.8% efficiency as shown in Figure 3.

6.3 Harnessing energy from other seaweeds: Ulva fasciata, Gracilaria corticata,

Sargassum tenerrimum

Bio-oil = 0.0858

kg, EC = 1.56 MJ

Syn-gas = 0.1206

kg, EC = 0.32 MJ

Bio-char = 0.2364

kg, EC = 1.95 MJ

Pyrolysis Kappaphycus

alvarezii

Water wash

& Dry

Efficiency ɳ =

21.8%

Fresh Seaweed =

0.5 kg

Energy content

(EC) = 4.59 MJ

Energy input,

3.15 MJ

Gasification,

feed rate = 15

kg/h

Utilized

different kinetic

models

Profuse SOx

emission found in

syn-gas

Hence pyrolysis at suitable

temperature is the best

pathway for energy

Sap

extraction

14

Evidently, there are about 800 seaweed species of 29 orders belonging to different classes in

India [20 – 22]. The estimated global production seaweed was found around 7.5 to 8 million

tons and such wet seaweeds are being produced along the coastal regions worldwide every

year [23]. There are huge variations of production of seaweed in India due to the influence of

climate on the seaweed species. It was reported by earlier researchers that the estimated

productivity of seaweed was found to be more than 100000 ton wet weight consisting of 6000

ton agar yielding seaweeds, 16000 ton of algin yielding seaweed, 8000 ton of carrageenan

yielding seaweeds and the remaining 70000 ton of edible and green seaweed [24].

The main focus of this present study is the study of some macroalgae for energy application.

India (08.04–37.06 N and 68.07–97.25 E), a tropical South Asian country has a stretch of

about 7500 km coastline, excluding its island territories with 2 million square km Exclusive

Economic Zone (EEZ) and nine maritime states. The seaweed flora of India is highly

diversified and comprises mostly tropical species [25].

6.3.1 Brief description of the production of bio-oil through slow pyrolysis process with

Arrhenius kinetic model

Red seaweed Gracilaria corticata (GC), brown seaweed Sargassum tenirimum (ST) and

green seaweed Ulva fasciata (UF) were collected from Veraval (20.55°N and 70.20°E) west

coast of India. After cleaning the seaweed with water, sap was removed. It was found that the

extracted sap from these species comprised of several valuable macro nutrients such as K,

Na, Ca, and Mg which can be utilized various applications. The pyrolysis process was

described by the kinetic mechanism by Arrhenius approach. It was found that the three

seaweed species have comparatively low calorific value than terrestrial biomass due to the

presence of large amount of inorganic species. From the TGA curves, it was revealed that

there were three degradation temperature zones, (1) 150 – 260°C, 530 – 800°C and 800 –

900°C for UF, (2) 125 – 270°C, 270 – 350°C and 580 - 760°C for GC, (3) 180 – 330°C, 580

– 730°C and 750 – 950°C for ST for degradation. The weight loss pattern and kinetic

parameters were evaluated based on these temperature zones for respective seaweed species.

It was evident from the TGA curves that the best pyrolytic temperature was 500°C as most of

the volatiles were removed in this temperature. The product yield of these seaweeds was

evaluated and the obtained bio-oils were characterized for each species. The bio-oils

exhibited quite good calorific value in the range 27 to 34 MJ kg-1

and could be a substituted

15

for furnace oil. From FT-IR and GC-MS analyses, the functional groups were determined for

the bio-oils. The obtained bio-chars from slow pyrolysis were also characterized. The bio-

chars exhibited high fixed carbon and ash content. The ash compositions of the seaweeds

were determined. The major constituents in the ash were Na, K, Ca, and Mg. Ash fusion test

was also done. The whole process is described in Figure 4.

FIGURE 4: Schematic diagram of the whole process for three seaweed species.

7. Conclusions

The final conclusion of this PhD thesis is encapsulated here and the summary of each chapter

and subchapters are briefly described step by step. The current energy scenario for both world

and India is enumerated briefly so that the readers can understand the importance of

renewable energy sector. The literature survey about the different thermochemical conversion

processes such as gasification, pyrolysis associated with different kinetic models, and steam

gasification are elucidated and covered in the chapter two. The aim and the scope of the work

Seaweed

species

Ulva

fasciata

Gracilaria

corticata

Sargassum

tenerrimum

Characterization as a solid

fuel for the thermochemical

process

Pyrolysis at 500°C with

10°C min-1

heating rate

Kinetic

study by

Arrhenius

Bio-oil extracted

with ethyl acetate

and then

characterized

Bio-chars

characterized as a

fertilizer or solid

fuel

Syn-gas

characterized

SAP

extracted

16

are described in chapter three. Chapter four includes both wasteland derived biomass, and

marine macroalgae characterization as solid fuel. The complete characterization of the

selected biomass species predicts the suitable thermochemical routes and some of them are

experimentally validated and the rest predicted based on fuel characterization while

harnessing the renewable energy. The experimental case studies are described in chapter five.

Jatropha curcas shells were investigated in both gasification and pyrolysis process. The

second case study is about the gasification and pyrolysis of Kappaphycus alvarezii granules

for extracting energy. For the validation of pyrolysis process the different kinetic models are

undertaken for Kappaphycus alvarezii granules and comparison is done with sawdust. The

third case study is of harnessing energy from the three selected seaweed species named Ulva

fasciata, Gracilaria corticata, and Sargassum tenerrimum. The full characterization of the

seaweeds is done as a solid fuel. Kinetic model with Arrhenius approach is considered to

describe the kinetic parameters and from TGA curves suitable pyrolytic temperature is found

out. And finally, the chapter six contains conclusion and future scope of the work.

The biomass data bank especially from the angle of thermochemical conversion, available

today is deficient on the feed stock studied in this PhD thesis. A good contribution is

expected to reach the research fraternity in the aligned field through this work. In addition,

scale up of some of the processes described, through industrial forefront holds promise to

decrease India‘s import of fossil fuel.

17

8. List of Publication related to PhD thesis:

[1] Subarna Maiti, Pratap Bapat, Prasanta Das, Pushpito K. Ghosh. Feasibility study of

jatropha shell gasification for captive power generation in biodiesel production process from

whole dry fruits. Fuel 121 (2014) 126–132.

[2] Prasanta Das, Milan Dinda, Nehal Gosai, and Subarna Maiti. High Energy Density Bio-

oil via Slow Pyrolysis of Jatropha curcas Shells. Energy Fuels 2015, 29, 4311−4320.

[3] Prasanta Das, Dibyendu Mondal, Subarna Maiti. Thermochemical conversion pathways

of Kappaphycus alvarezii granules through study of kinetic models. Bioresource Technology

234 (2017) 233–242.

[4] Prasanta Das, Samir Charola, Milan Dinda, Himanshu Patel, Subarna Maiti. Hydrogen

from empty cotton boll agro-waste via thermochemical route and feasibility study of

operating an IC engine in continuous mode. International journal of hydrogen energy 42

(2017) 14471 – 14484.

[5] Sumit Sahitya, Hasan Baig, Ruchita Jani, Nirav Gadhiya, Prasanta Das,Tapas K. Mallick,

and Subarna Maiti. Hydrogen rich syn-gas from Jatropha curcas shell biomass char in Fresnel

lens solar concentrator assembly. Energy and Fuel, DOI: 10.1021/acs.energyfuels.7b01406.

9. List of Patent

[1] Process for potash recovery from biomethanated spent wash with concomitant

environmental remediation of effluent. Inventors: Pratyush Maiti, Subarna Maiti, Soumya

Halder, Krishna Kanta Ghara, Prasanta Das, S. K. Charola and Neha P. Patel. Patent filed in

CSIR, New Delhi, India. Pub. No. WO/2017/042832, International Application No.

PCT/IN2016/050298.

18

10. Reference:

[1] Onda K, Kasuga Y, Kato K, Fujiwara M, Tanimoto M (1997) Electric discharge removal

of SO2 and NOx from combustion flue gas by pulsed corona discharge. Energy Conversion

and Management 38, 1377–87.

[2] Gnanapragasam N, Reddy B, Rosen M. Reducing CO2 emissions for an IGCC power

generation system: effect of variations in gasifier and system operating conditions (2009)

Energy Conversion Management 50, 1915–23.

[3] Peng Y, Zhao B, Li L (2012) Advance in post-combustion CO2 capture with alkaline

solution: a brief review. Energy Procedia 14, 1515–22.

[4] Fine P, Hadas E (2012) Options to reduce greenhouse gas emissions during wastewater

treatment for agricultural use. Sci Total Environ 416, 289–99.

[5] Burcu Ertit Tastan, Ergin Duygu, Orhan Atakol , Gonul Donmez. SO2 and NO2 tolerance

of microalgae with the help of some growth stimulators (2012) Energy Conversion and

Management 64, 28–34.

[6] Radmann EM, Camerini FV, Santos TD, Costa JAV (2011) Isolation and application of

SOX and NOX resistant microalgae in biofixation of CO2 from thermoelectricity plants.

Energy Conversion and Management 52, 3132–6.

[7] Jacob-Lopes E, Scoparo CHG, Queiroz MI, Franco TT (2010) Biotransformations of

carbon dioxide in photobioreactors. Energy Conversion and Management 51, 894–900.

[8] Murray KE, Shields JA, Garcia ND, Healy FG. Productivity, carbon utilization, and

energy content of mass in scalable microalgae systems (2012) Bioresorce Technology 114,

499–506.

[9] Bilanovic D, Holland M, Armon R. Microalgal CO2 sequestering – modelling microalgae

production costs (2012) Energy Conversion and Management 2058, 104–9.

[10] V. Ramanathan and G. Carmichael, Global and regional climate changes due to black

carbon (2008) Nat. Geosci. 1, 221–227, doi:10.1038/ngeo156.

[11] S. Sahai, C. Sharma, D.P. Singh, C.K. Dixit, N. Singh, P. Sharma, K. Singh, S. Bhatt, S.

Ghude, V. Gupta, R.K. Gupta, M.K. Tiwari, S.C. Garg, A.P. Mitra, P.K. Gupta, A study for

development of emission factors for trace gases and carbonaceous particulate species from in

situ burning of wheat straw in agricultural fields in india (2007) Atmos. Environ. 41, 9173–

9186. doi:10.1016/j.atmosenv.2007.07.054.

[12] A. Awasthi, R. Agarwal, S.K. Mittal, N. Singh, K. Singh, P.K. Gupta, Study of size and

mass distribution of particulate matter due to crop residue burning with seasonal variation in

19

rural area of Punjab, India (2011) J. Environ. Monit. 13, 1073–1081,

doi:10.1039/c1em10019j.

[13] Ghosh PK. et al. Process for the preparation of fatty acid methyl ester from triglyceride

oil by transesterification (2010), US Patent 7666234.

[14] Ghosh PK. et al. WO2011027353 (Filing date 22-09-2011, Publication date 29-03-2012)

– Integrated process for the production of jatropha methyl ester and by products.

[15] Azar, C., Lindgren, K., Andersson, B.A (2003). Global energy scenarios meeting

stringent CO2 constraints—cost-effective fuel choices in the transportation sector. Energy

Policy 31, 961–976.

[16] Bridgwater, A.V., Meier, D., Radlein, D (1999) An overview of fast pyrolysis of

biomass. Org. Geochem. 30, 1479–1493.

[17] Eswaran, K., Ghosh, P.K., Siddhanta, A.K., Periyasamy, P., Mehta, A.S., (2005) U.S.

Patent 6893479, May 17.

[18] Mondal, D., Sharma, M., Maiti, P., Prasad, K., Meena, R., Siddhanta, A.K., Bhatt, P.,

Ijardar, S., Mohandas, V.P., Ghosh, A., Eswaran, K., Shah, B.G., Ghosh, P.K.(2013). Process

for improved seaweed biomass conversion for fuel intermediates, agricultural nutrients and

fresh water. RSC Adv. 3, 17989–17997.

[19] Maiti, S., Bapat, P., Das, P., Ghosh, P (2014). Feasibility study of jatropha shell

gasification for captive power generation in biodiesel production process from whole dry

fruits. Fuel 121, 126–132.

[20] A.B. Ross, J.M. Jones, M.L. Kubacki, T. Bridgeman (2008) Classification of macroalgae

as fuel and its thermochemical behaviour. Bioresource Technology 99, 6494–6504.

[21] Abbott, I.A., (1982) Seaweeds and their uses. Aquatic Botany 12, 389–390.

[22] Oza RM, Zaidi SH (2001) A revised checklist of Indian marine algae. CSMCRI,

Bhavnagar, pp 24–29

[23] McHugh, D. J. (2003) A guide to the seaweed industry. FAO Fisheries Technical Paper,

441, p. 105.

[24] P. Kaladharan and N. Kaliaperumal. Seaweed Industry in India (Jan-Mar 1999) Central

Marine Fisheries Research Institute, Kochi-682014, India.Quarterly (Vol. 22, No.1).

[25] P. V. Subba Rao and Vaibhav A. Mantri. Indian seaweed resources and sustainable

utilization: Scenario at the dawn of a new century. Review article. Marine Algae and Marine

Environment Division, Central Salt and Marine Chemicals Research Institute (CSIR),

Gijubhai Badheka Marg, Bhavnagar 364 002, India.