Development of a framework for co2 capture, utilization, and sequestration supply chain network optimization

Nguyen Development of a framework for CO2 capture, utilization, and sequestration supply chain network optimization ISBN: The research described in this thesis was carried out at the: La

TUAN B.H NGUYEN

Tuan B.H Nguyen

Development of a framework for CO2 capture, utilization, and sequestration supply chain network optimization

ISBN:

The research described in this thesis was carried out at the:

Laboratory of Process Systems Engineering, Center for Environmental Research and Sustainable Technology (UFT), Department of Production Engineering, Universität Bremen, Bremen, Germany

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D EVELOPMENT OF A F RAMEWORK FOR C O 2

Vom Fachbereich Produktionstechnik

der UNIVERSITÄT BREMEN

zur Erlangung des Grades Doktor-Ingenieur genehmigte

Dissertation

von

M Sc Tuan B.H Nguyen

Gutachter:

Prof Dr Ir Edwin Zondervan

Prof Dr.-Ing Jorg Thöming

Tag der mündlichen Prüfung: 06.09.2019

Dedicated to my family, and my beloved

“Learn from yesterday, live for today, hope for tomorrow The important thing is not to stop

questioning.”

This thesis was successfully completed not only due to my dedication but also with the extended support of many people and organizations I am proud to appreciate all who support me to let this work done

First and foremost, I sincerely appreciate Professor Edwin Zondervan, my supervisor, and promoter for providing invaluable knowledge, creative comments, untouchable experience in the classroom, giving me the best opportunity of working at Process Systems Engineering laboratory (PSE) in the University of Bremen, and kind support throughout this research work

I would like to thank Professor Jorg Thöming for being a second external evaluator of my thesis His suggestions and comments are very beneficial for me and this work

I would like to acknowledge Ms Grazia Leonzio for the excellent supporting regarding AIMMS with patience and total availability to help

I presented my gratitude to all faculty members, research staff and other staff of PSE laboratory and the University of Bremen, for the support and guidance given for better completion of the work The gratitude, in particular, applies to Leonardo, Christos, Anton, and Poland as my co-workers in PSE

I wish to thank my family for their endless love and support of my graduate education, especially for their ability to bring balance to my life at this challenging time Their encouragement and support from beginning to the end makes this thesis possible

I am obliged to all the people I met and took part in my journey, in Germany, Vietnam, Thailand, and Denmark I will keep them in my mind, and try to give them back at least as much as they gave me

Last but not least, heartfelt thanks are due to my beloved Truc, always, for her love, patience, support, understanding during the past years, and for reminding me the beauty of life every day Tuan B.H Nguyen

May 2019

Environmental concerns have provoked a considerable focus on strategies of cutting down emissions from energy production, transportation, and manufacturing A key element is finding routes to minimize carbon dioxide (CO2) discharged into the air Recently, Carbon capture and storage (CCS) and CO2 utilization are considered as two essential tools to drastically reduce

CO2 emissions However, with the implementation of carbon capture, utilization, and storage techniques several hurdles need to be taken as a result of dispersed, bulky, and different flow rates and compositions of flue gases from various sources These obstacles have led to the difficulties in selecting a suitable cost-efficient capture technology It should be noted that CO2

is a highly stable molecule, which makes it highly challenging when converting it into useful products To tackle these challenges the integration of different capture, utilization, and storage stages along with the interaction among equipment, processes, and the complete supply chain network are needed

This Ph.D project, therefore, aims at the development of a general framework that deals with a broad range of problem types and aid design engineers and decision-makers in quickly assessing different scenarios at the conceptual design stages In this study, the framework consists of two distinct steps in which one step operates at the unit and plant scale while another operates at the site scale At the unit and plant scale, the approach focuses on the potential technologies to capture and utilize CO2 over a wide range of industrial gas mixtures Next, the generated results from the first step are integrated into the site scale

In chapter 2, the absorption of CO2 using Ionic liquid (IL), namely methylimidazolium acetate ([bmim][Ac]), is simulated, optimized, heat integrated, economically and environmentally evaluated over a wide range of flue gas compositions and flow rates In specific, an IL-based process is developed in Aspen Plus for separating at least

1-butyl-3-90 % of CO2 from the feed before pressurizing it to 150 bar and transporting to the storage and/or utilization sites The outcome of this analysis showed that IL-based technology is only cost-effective at high flue gas flow rates and CO2 compositions as compared to the conventional process using Ethanolamine (MEA) The results are then used to compute optimal capital and operating costs, which may assist policymakers in determining investment strategies for CO2

capture

In Chapter 3 three new CO2-based processes including hydrogenation, bi- and tri-reforming for converting CO2 into methanol (MeOH) are designed and simulated in Aspen Plus at three

different capacities (300, 1500, and 3500 ton/day) A detailed cost calculation involving annualized investment and operational costs are also completed for CO2-based technologies as well as environmental evaluation Based on the techno-economic- and environmental analysis,

it is concluded that bi- and tri-reforming achieve the better results by 37 and 39 % lower of the annualized total cost of producing methanol on average, respectively as compared to the hydrogenation route

The topology of the supply chain network including various stationary emission sources, transportation modes, storage sites, and utilization sites with different valuable chemicals including methanol, dimethyl ether (DME), formic acid, acetic acid, urea and polypropylene carbonate (PPC) are developed and examined in Chapter 4 Subsequently, the model has implemented in the Advanced Interactive Multidimensional Modelling (AIMMS) software in order to analyze the effectiveness of a CO2 supply chain network in mitigating emissions for the whole of Germany The results indicate that a carbon-based supply chain in Germany can

be profitable with an annual profit of 162.21 billion euros per year at 40 % of CO2 reduction

Ein gestiegenes Bewusstsein für Umweltbelange hat einen verstärkten Fokus auf Strategien zur Reduzierung von Emissionen im Energie-, Transport und Produktionssektor herbeigeführt Dabei ist die Identifikation von Pfaden zur Minimierung des Ausstoßes von Kohlendioxid (CO2) ein Schlüsselelement In diesem Kontext wird der Abscheidung und Speicherung von Kohlenstoff (CCS) sowie der CO2-Nutzung ein gesteigertes Interesse entgegengebracht Beide Varianten werden als maßgebliche Instrumente zur drastischen Reduzierung der CO2-Emissionen angesehen Bei der Implementierung von Technologien zur Kohlenstoffabscheidung, -verwertung und -speicherung müssen jedoch mehrere Hürden genommen werden, die unter anderem auf deutlich abweichenden Charakteristika von Rauchgasen verschiedener Quellen zurückzuführen sind – zu nennen sind beispielsweise unterschiedliche Durchflussraten und Zusammensetzungen Aufgrund dieser Hürden hat sich die Identifikation geeigneter und kostengünstiger Abscheidungstechnologien bis dato schwierig gestaltet Dabei sollte beachtet werden, dass CO2 ein hochstabiles Molekül ist, was die Umwandlung in nützliche Produkte anspruchsvoll gestaltet Um den angeführten Herausforderungen zu begegnen, ist eine Betrachtung verschiedener Optionen zur Abscheidung, Nutzung und Speicherung sowie eine Analyse des Zusammenspiels zwischen Ausrüstungen, Prozessen und der kompletten Supply-Chain erforderlich

Dieses Promotionsprojekt zielt daher auf die Entwicklung eines allgemeinen Bewertungsrahmens ab, der sich mit einer Vielzahl von Problemtypen befasst und Anlageningenieuren sowie Entscheidungsträgern helfen soll, verschiedene Szenarien in der Konzeptionsphase schnell zu bewerten Der Bewertungsrahmen, der in dieser Studie beschrieben wird, unterteilt sich in zwei unterschiedliche Aggregationsebenen Während die erste Ebene den Ausrüstungs- und Anlagenmaßstab betrachtet, widmet sich die zweite Ebene dem Standortmaßstab Dabei liegt der Fokus bei der Ausrüstungs- und Anlagenebene auf der Evaluation von potenziell geeigneten Technologien zur Abscheidung und Nutzung von CO2 für ein breites Spektrum von Industriegasgemischen Im Folgeschritt werden die generierten Ergebnisse in die Standortbetrachtung integriert

In Kapitel 2 wird die Absorption von CO2 unter Verwendung einer ionischen Flüssigkeit (IL), namentlich 1-Butyl-3-methylimidazoliumacetat ([bmim] [Ac]), für ein breites Spektrum von Rauchgaszusammensetzungen und -flussraten simuliert und optimiert sowie hinsichtlich Wirtschaftlichkeit und Umweltverträglichkeit bewertet Dazu wurde in Aspen Plus ein IL-basiertes Verfahren entwickelt, mit dem mindestens 90% des CO2 aus einem Feed-Strom

abgetrennt werden, bevor es auf einen Druck von 150 bar verdichtet und zu den Lager- und/oder Verarbeitungsorten transportiert wird Das Ergebnis dieser Analyse zeigt, dass die IL-basierte Technologie im Vergleich zum konventionellen Verfahren mit Ethanolamin (MEA) lediglich bei hohen Rauchgasströmen und CO2-Konzentrationen einen wirtschaftlichen Vorteil bietet

Um diese Aussage treffen zu können, werden die optimalen Kapital- und Betriebskosten berechnet Diese können ferner politische Entscheidungsträger bei der Ausarbeitung von Investitionsstrategien für Anlagen zur CO2-Abscheidung unterstützen

In Kapitel 3 werden in Aspen Plus drei innovative CO2-basierte Prozesse zur Umwandlung von

CO2 in Methanol (MeOH) entworfen und simuliert Die Betrachtung von Hydrierung, Bi- und Trireformierung erfolgt jeweils für drei verschiedene Anlagenkapazitäten (300, 1500 und 3500 Tonnen pro Tag) Neben der Prozesssimulation wird eine detaillierte Kostenberechnung, inklusive der Ausweisung annualisierter Investitions- und Betriebskosten, sowie eine ökologische Bewertung ausgeführt Die techno-ökonomische und ökologische Analyse zeigen, dass Bi- und Trireformierung vielversprechender sind als die Hydrierung zu Methanol So sind die annualisierten Produktionskosten durchschnittlich um 37 respektive 39% geringer

Die Topologie der Supply-Chain, einschließlich verschiedener stationärer Emissionsquellen, Transportarten, Lager- und Verarbeitungsorte, wird in Kapitel 4 untersucht Dabei werden unterschiedliche Chemikalien berücksichtigt, die Methanol, Dimethylether (DME), Ameisensäure, Essigsäure, Harnstoff und Polypropylencarbonat (PPC) umfassen Das entwickelte Modell wurde in die Software Advanced Interactive Multidimensional Modeling (AIMMS) implementiert, um für Deutschland die Effektivität einer CO2 Supply-Chain zur Emissionsminderung zu analysieren Die Ergebnisse zeigen, dass eine auf Kohlenstoff basierende Supply-Chain in Deutschland mit einem Jahresgewinn von 162,21 Milliarden Euro pro Jahr bei einer CO2-Emissionsreduktion um 40% rentabel sein kann

Table of Contents

Acknowledgments i

Abstract ii

Zusammenfassung iv

1 Introduction 1

1.1 Background 1

1.2 Some Figures on Emissions in Germany 4

1.3 Carbon Dioxide Introduction 7

1.4 Challenges for Control of CO2 Emissions 9

1.5 Carbon Capture and Storage (CCS) 11

1.6 Carbon Capture and Utilization (CCU) 11

1.7 CO2 Capture, Utilization, and Sequestration (CCUS) 12

1.8 Scope and Objectives 12

1.9 Thesis Outline 13

2 CO 2 Capture from Different Sources using IL and MEA 21

2.1 Introduction 22

2.2 Process Parameters 25

2.3 Process Description and Modelling Framework 26

2.3.1 MEA-based CO2 Capture Process 26

2.3.1.1 Process Overview 26

2.3.1.2 Modeling Framework 27

2.3.1.3 Thermodynamic Model 27

2.3.1.4 Reaction Kinetics Model 27

2.3.1.5 Transport Property Models 28

2.3.1.6 Design of Absorption and Regeneration Columns 29

2.3.2 IL-based CO2 Capture Process 29

2.3.2.1 Process Overview 30

2.3.2.2 Modeling Framework 30

2.3.2.3 Scalar properties 30

2.3.2.4 Thermodynamic Model 31

2.3.2.5 Design of Absorption Columns 32

2.4 Process Economic Evaluation and Optimization 32

2.5 Energy Network Optimization 34

2.6 Results and Discussion 35

2.7 Conclusions 39

3 CO 2 to Methanol using Hydrogenation and Reforming Technologies 45

3.1 Introduction 46

3.2 Process Parameters 48

3.3 Process Description and Modeling Framework 50

3.3.1 Hydrogenation-based Methanol Process 50

3.3.1.1 Process Overview 50

3.3.1.2 Modeling Framework 50

3.3.2 Bi-reforming-based Methanol Process 51

3.3.2.1 Process Overview 51

3.3.2.2 Modeling Framework 52

3.3.3 Tri-reforming-based Methanol Process 54

3.3.3.1 Process Overview 54

3.3.3.2 Modeling Framework 55

3.4 Process Economic Evaluation and Optimization 56

3.5 Energy Network Optimization 57

3.6 Waste heat recovery and electricity generation 57

3.7 Environmental analysis 58

3.8 Results and Discussion 58

3.8.1 Process Performance Results 58

3.8.2 Economic evaluation 59

3.8.3 Environmental Impact Evaluation 64

3.9 Conclusions 67

4 CO 2 Supply Chain Network in Germany 73

4.1 Introduction 74

4.2 Model Development 76

4.2.1 Problem Statement 76

4.2.2 CCUS Supply Chain Network Model 78

4.2.2.1 Sets 78

4.2.2.2 Parameters 79

4.2.2.3 Variables 79

4.2.2.4 Constraints 79

4.2.2.5 Cost Equations 80

4.2.2.6 Objective Function 83

4.2.3 Case Study 83

4.3 Results and Discussion 88

4.4 Conclusions 97

5 Conclusions and Outlook 103

5.1 Outlook 104

Appendix I 107

Appendix A.3 Kinetic equations and parameters for hydrogenation-based processes 107

Appendix B.3 Kinetic equations and parameters for bi-reforming-based processes 108

Appendix C.3 Kinetic equations and parameters for tri-reforming-based processes 110

Appendix II 123

Chapter 1

The chapter is devoted to give an overview of the role that CO2 has in climate change and to introduce the basic principles for CO2 control The overview leads to the definition of the objective of this thesis, which is the development of a generic and systematic model-based framework for the design of a CO2 network system Finally, the outline of this thesis is given

1.1 Background

Climate is defined as long-term averages and variations in weather conditions measured over several decades [1] Many pieces of evidence for climate changes are observed in the planet’s weather, oceans and ecosystems In addition, climate change can be measured by several indicators over many decades as presented in Figure 1.1 From these indicators, scientists and engineers from around the world agree with an unambiguous story: Earth is becoming increasingly hotter

Huber and Knutti [2] demonstrated that natural activities could not account for unwanted warming, but natural factors alone would result in a slight cooling through their climate model when separating human factors (as seen in Figure 1.2) Therefore, a large part of warming during five decades on the planet can only be accounted for by the consequences of human impacts, especially the emissions of greenhouse gases (GHGs) from burning fossil fuel and deforestation

The reason why GHGs affect Earth’s temperature is because of its heat-trapping properties In principle, Earth’s temperature relies on the balance between energy entering and leaving the planet’s system The earth receives most energy from the Sun via sunlight When sunlight arrives at the Earth’s surface, it can either be sent back into space directly or absorbed by Earth The Earth also emits some of the absorbed energy into the air as heat GHGs such as carbon dioxide (CO2), methane, and nitrous oxide, and particles such as black carbon (soot) absorb much energy discharged from the Earth's surface, slowing or hindering it from instantly escaping from the planet’s system In this manner, GHGs behave like a blanket, warming the Earth

Chapter 1: Introduction

Figure 1.1 Ten indicators of a warming world [3]

Figure 1.2 Observed and model simulations with and without human factors data for global average changes [2]

Continued emissions of GHGs will give rise to further climate changes It is anticipated that the average global temperature will increase within a range of 0.28 °C to 4.78 °C by 2100 [4] The global temperature is contributing to a sea level rise because of thermal expansion of the sea and reduction of ice and snow cover, as well as permafrost In addition, global warming is affecting the patterns and quantities of precipitation (rain and snowfall) Changes in temperature and precipitation patterns strengthen the frequency, duration, and intensity of extreme weather events, such as floods, droughts, heat waves, and tornadoes [4] Global warming also leads to higher wildlife extinction rates, unstable agricultural yields, less fresh water, the spread of severe diseases such as malaria, and higher death rates In fact, the number of Americans killed

by extreme heat each year is much more than those by hurricanes, tornadoes, floods, and lightning combined [5]

There are four main types of greenhouse gases: carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and fluorinated gases CO2 is the main product of burning fossil fuels (coal, natural gas and oil), solid waste, trees and wood products, and also a byproduct from some manufacturing and industrial processes CO2 is not the most severe GHG, but it is the highest emitted which makes it the most unavoidable anthropogenic GHG [6] Figure 1.3 shows the global amount of CO2 emitted among other GHGs from 1990 to 2010 While there are both natural and human sources of CH4, human activities account for the more significant part of total emissions Activities such as the production of fossil fuels, livestock and other agricultural practices as well as organic waste in landfills are the central sources of the higher CH4

concentration in the air [7] CH4 emissions hold second place in amounts worldwide during the past decade Nitrous oxide is also produced from both natural and human activities, constituting the third largest source of emission from 1990 While N2O is released from soils under natural vegetation and ocean, agriculture, combustion of fossil fuels and industrial activities are the prime sources of N2O emitted by humans [4] In contrast to other GHGs, fluorinated gases including hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride, and nitrogen trifluoride are almost solely produced by human activities Although they only represent a minority of emissions, they are synthetic, potent greenhouse gases which are linked to a range of industrial processes Those gases are anticipated to extend their emissions faster than those from other greenhouse gases [8]

Chapter 1: Introduction

Figure 1.3 World greenhouse gas emissions from 1990 to 2010 [9]

1.2 Some Figures on Emissions in Germany

Greenhouse gas emissions in Germany were 953 Mt in 2013, a decline of 23.8 % as compared

to the 1990 levels of 1250 Mt (See Figure 1.4.) Although the energy sector still emits most of the carbon dioxide in Germany in 2014 accounting for 39 % of the total emissions, a reduction

of 24 % as compared to 1990 is observed This can be explained by a decrease of lignite use as

a result of higher efficiencies in energy production as well as more significant usage of renewable energies The second largest contributor was the industry sector with near 21 % of the discharges Similar to the energy sector, a remarkable drop of one-third between 1990 and

2014 was observed for the industry The changes in the German industrial landscape and the reduction in industrial production are two key factors contributing to this decrease Also, emissions from transportation contributed a lot to the overall carbon dioxide emissions making

up near 20 % of the total Specifically, nearly 95 % of transport-created emissions in 2013 came from road transport, which uses petroleum products as fuel Although there was an increase of

11 % of emissions during first 10 years from 1990 caused by higher transport activities and the use of powerful and heavier vehicles, a decline of 13 % was seen in the next years thanks to the development of more fuel-efficient engines and the introduction of environmental tax Private households’ emissions diminished by 33 % between 1990 and 2014, which is fluctuates because

of weather conditions, economic and social factors Agriculture is the primary source of methane and nitrous oxide emissions from cattle and fertilization, which also experienced a cut

of 21 % of emissions from 1990 The discharges from commerce, trade and services have been halved from 1990 as a consequence of technological improvements such as automation and optimization of processes The most considerable reduction of 70 % of GHG emissions since

1990 was recognized in the waste management sector which only constituted 1.2 % of the releases in 2014 Recycling of recyclable materials such as paper, glass, packaging, and organic wastes allowed to significantly lower energy use and decrease landfill emissions

Figure 1.4 Greenhouse gas emissions in Germany since 1990 [10]

traps radiation 25 times more efficiently than CO2 The majority of CH4 emissions stems from livestock, making up 54 % However, methane emissions have decreased in recent years In fact, a significant saving of CH4 emissions was observed in the waste disposal sector Also, a sharp decline of the extraction and distribution of fuels, especially coal production was contributing to emission reductions

N2O has also achieved a significant reduction with 28 Mt lower than in 1990, standing at 38 Mt emitted in 2014 Similar to CH4, N2O is 298 times as more climate-potent than CO2 Agriculture and chemical industry are the dominant contributors of N2O emissions While emissions from the chemical industry underwent a sharp reduction of 95 % by 2014 as compared to the 1990 level, the proportion of agriculture-created emissions significantly increased from 51 % in 1990

to 77 % in 2014 By contrast, the percentage of “F gases” including fully and partly fluorinated hydrocarbons (PFCs, HFCs), and sulfur hexafluoride (SF6) slightly rose with about 0.6 % between 1990 and 2014, attaining 14.8 Mt in 2014 in terms of CO2 equivalents

1.3 Carbon Dioxide Introduction

Carbon dioxide (CO2) is a colorless and odorless gas A molecule of CO2 is formed of two double bonds with one carbon and two oxygen atoms Although there are requirements to prevent the more considerable amount of CO2 being emitted to the environment by combustion

of carbon-containing substances, the existence of a proper CO2 amount in the atmosphere is absolutely vital because it assists photosynthesis in plants to produce carbohydrates, lipids, and new oxygen to support life on Earth [11] Table 1.1 provides a list of the physical and chemical properties of CO2

Table 1.1 The physical and chemical properties of CO2 [12]

Gibbs free energy of formation at 25 °C, ΔG°gas -394.3 kJ/mol

Viscosity at 25 °C and 1 atm (101.3 kPa) 0.015 cP (mPas)

Liquid density at 25 °C and 1 atm (101.3 kPa) 0.712 vol/vol

Gas density at 0 °C and 1 atm (101.3 kPa) 1.976 g/L

In reality, both natural and human activities are discharging CO2 to the atmosphere Natural sources involve decomposition, ocean release and respiration The source of CO2 emissions from human activities stems from different stationary and mobile energy systems Almost all

of the increase in CO2 in the air is attached to human activities The emitted amount of CO2

Chapter 1: Introduction

from human sources is much smaller than those of nature, but it is disturbing the natural balance

of the carbon-neutral cycle Human activities are modifying the carbon cycle - both by discharging more CO2 to the atmosphere and by influencing natural sinks such as forests, to capture CO2 from the air [13] Table 1.2 suggests the significant sources of CO2 emission into our atmosphere

Table 1.2 Sources of CO2 emissions [12]

Fossil fuel-based electric power

plants

Cars, and sports utility

decay Commercial and residential

Military and government

Applications of CO2 in the industry can be classified into two groups: physical and chemical aspects In terms of physical properties, CO2 is applied in the beverage industry, in enhanced oil recovery, in its supercritical state as a solvent to support reactions, separation, synthesis of nanoparticles or composites, and polymer modification [16] CO2 is also exploited as a protective gas (in steel industries, in food preservations, etc.) and as a fire extinguisher due to its inert and safe properties In addition, CO2 in the solid state is employed to replace the usage

of CFCs in refrigeration, especially in refrigerated railcars and trailers In the other hand, CO2

can be utilized to synthesize some useful chemicals such as urea, salicylic acid, pigments, inorganic and organic carbonates [17]

Figure 1.6 The use of CO2 per year in the industry in megatons in the world [16]

1.4 Challenges for Control of CO 2 Emissions

Figure 1.7 presents significant issues related to greenhouse gas control and utilization The primary problems in GHG control include energy economics, policy regulations, environmental protection, and global climate change Monitoring of CO2 emissions is one of the most critical areas of GHG control [12] A variety of options that could assist in achieving the target for mitigating CO2 are considered worldwide, including energy choices, energy efficiency, CO2

capture, CO2 sequestration, and CO2 utilization Energy choice is the procedure to determine the prime energy input for new energy systems or switch between different kinds of energy for existing installations Typically, there are two broadly defined options of energy: conventional energy and renewable energy

Conventional energy is often referred to as fossil fuels such as natural gas, petroleum, and coal When employing traditional energy, one can decrease the CO2 emissions per million kJ by choosing the less CO2-emitted type of energy, which is generally based on the H/C ratio It is worth to notice that the lower the H/C ratio, the higher the volume of CO2 per million kJ

Chapter 1: Introduction

Renewable energy sources regularly comprise wind, solar energy, biomass, geothermal energy and hydropower, and they can make a significant contribution to the reduction of GHG emissions However, the usage of renewable energies is limited by availability, energy density, energy efficiency, and capital cost Advances in technology for improved energy efficiency is

a required field that significantly contributes to CO2 emission reduction

Figure 1.7 Factors for the control and utilization of greenhouse gas including CO2 [12]

Average efficiency of fossil fuel-based electricity generators is about 35 % while this value is even lower for automobiles, namely below 20 % Developing and implementing new energy systems such as Integrated Gasification Combined Cycle technology (IGCC) for coal-power plants or fuel cell-based hybrid motors could remarkably raise the efficiencies of energy systems by 30 % or more Similarly, the concept can be exerted to the chemical industry, which allows making a process more selective such that CO2 emission is limited at the source In principle, CO2 is a potential carbon source permitting the production of efficient alternative transportation fuels, and useful chemical products In spite of these promises, in recent years study and research experience have shown that visible limitations are linked with CO2 control Those drawbacks encompass: (1) expenses for capturing, separating, purifying and transporting; (2) potential and long-term permanent storages; (3) the safety of CO2 storages; (4) energy need for converting CO2; (5) restrictions in market size; (6) little interest from

manufacturers in recycling and utilizing CO2; (7) the deficiency of socio-economical driving forces [12]

1.5 Carbon Capture and Storage (CCS)

Carbon capture and storage (CCS) is the most common method to capture CO2 in bulk from emission sources and isolate it through its transport and storage in geological formations [18]

In theory, CCS can provide cost-effective emission reductions and also allow lastingly using fossil resources while remaining an acceptable amount of CO2 in air As specified by the International Energy Agency, CCS will provide about 19 % of prime technologies for mitigating

CO2 emissions, and if without CCS, the cost of CO2 reduction will rise by 70 % by 2050 [19] CCS typically involves capture, storage, transport, and sequestration technologies CO2 capture

is the heart of a CCS chain and separates CO2 from a range of stack emissions and intermediate chemical process streams While storage technology keeps liquefied CO2 in large steel tanks or stores it into the ship, transportation technology conveys separated CO2 to sequestration sites Sequestration technology accumulates captured CO2 in non-atmospheric reservoirs (e.g., depleted oil and gas reservoirs, deep saline formations, etc.) for long periods Often the significant obstacle attached to CCS is the high investment and operating costs (changing from

40 to 100 $ per ton, depending on types of CO2 sources [20]) However, studies of recent years have shown that the optimum supply chain network developed by choosing the proper sources, capture techniques, transportation connections, and storage sites could be the solution to minimize the cost of CO2 capture and sequestration [21,22] In addition, CCS technologies must solve problems of potential and long-term permanent storage (due to insufficient storage capacity or storage offshore) as well as public concerns relating to the safety of CO2 storages

1.6 Carbon Capture and Utilization (CCU)

Along with the introduction of CCS technologies, carbon capture and utilization (CCU) is targeted at employing CO2 as a carbon source to support (chemical) industry, and bring about value from a readily available feedstock [23] Utilizing a specific volume of the CO2 as a raw material for the manufacturing of commodity chemicals or direct use in soft drinks, welding, foaming, propellants, drying-cleaning, separation, water treatment, and packaging can divert some CO2 from CCS operations [14] One or more targets for CO2 conversion and utilization can be combined, including: (1) Apply CO2 to friendly environmental physical/chemical processes that adds value to the process, (2) Make use of CO2 to synthesize industrially

Chapter 1: Introduction

profitable chemicals and materials that increase products’ worth, (3) Employ CO2 as a helpful fluid or as a medium for energy recovery, contaminant removal, and emission reduction, (4) Utilize CO2 recycling including renewable sources of energy to preserve carbon resources for sustainable development In principle, CCU can be more attractive than storing CO2 if at all possible [12] However, CCU alone may not mitigate all CO2 emissions due to a lack of value-based driving forces including the potential markets for the individual products, energy and economy trade-offs of CO2 chemical conversion, and social-economical driving forces [12]

1.7 CO 2 Capture, Utilization, and Sequestration (CCUS)

Obviously, a combination of two technologies, called carbon capture, utilization, and sequestration (CCUS), will allow putting more CO2-based projects into reality because it will remediate obstacles existing if only each route is selected For large scale CCUS projects, it is crucial to integrate the capture, compression, transportation, utilization, and sequestration steps Although there are several studies related to regional CO2 capture and sequestration [24–26], such researches only exist in isolation of capturing and storing CO2 without considering the possibilities of directly using or converting CO2 into valuable products [27–32] Such standalone studies, therefore, give rise to a complicated and challenging task in the evaluation

of CCS and CCU together In addition, the variety of emission sources excludes a simple strategy for cost-effective CO2 management Specifically, the CCUS cost depends on flue gas composition and flow rate which are mainly a significant challenge in the selection of CO2

capture technologies and materials [33,34] Selecting the right CO2 sources, the right sequestration sites, the proper utilization sites and the right CO2 amounts used is equally important Importantly, the full integration of CCS and CCU will discover whether a nationwide

or regional CCUS network would be economically practical or not

1.8 Scope and Objectives

Germany currently aims to cut greenhouse gas emissions by 40 percent by 2020 and up to 95 percent in 2050 Parallel to the increasingly rising use of renewables, this target is only achieved with alleviating CO2 from emission sources

The objective of this research is to design a large scale CO2-based supply chain network that can be used to meet the various targets for GHG emission reduction as part of a region or a state

of a country (i.e Germany), or even globally, along with considering multiple criteria such as technological, economic and social aspects while still allowing a continuous usage of some of

the fossil fuel infrastructure that has been built to power civilization, etc In addition, the research will aid the development of a suitable decision-making tool in selecting the optimum solution for obtaining the CO2 emission reduction targets in a range of scenarios and conducting sensitivity analysis through a step-by-step procedure The thesis includes (as shown in Figure 1.8):

 Establishment of optimal strategies (including technologies and materials) to capture

CO2 from different CO2 sources;

 Creation of beneficial pathways for using captured CO2 throughout the conversion and non-conversion processes;

 Formulation of CCUS supply chain network models (a combination of CCS and CCU) that result in a variety of selections to mitigate CO2 emissions at reasonable costs in the regional, national or global level

Chapter 3 pays attention to useful routes for converting captured CO2 In detail, three rigorous processes of CO2 conversion into methanol, namely hydrogenation, bi- and tri-reforming processed are presented Each technology is simulated, optimized, and heat integrated at three different capacities (300, 1500, and 3500 ton/day) Lastly, three different routes are compared and evaluated in terms of economy and environment

Chapter 4 examines the supply chain network models of CO2 Specifically, the topology of the supply chain includes different emission sources, a storage site, and utilization sites with various valuable chemicals including methanol, dimethyl ether (DME), formic acid, acetic acid, urea and polypropylene carbonate (PPC) Therefore, a model is developed to analyze the effectiveness of a CO2 supply chain network in mitigating emissions for the whole of Germany

Figure 1.8 Graphic of the thesis outline.

CHAPTER 3: CO2 UTILIZATION CHAPTER 2: CO2 CAPTURE

FUELS e.g methanol, ethanol, diesel,

INTERMEDIATES e.g formic acid, syngas,

POLYMERS e.g poly(carbonate), poly(urethane),

INORGANIC & ORGANIC CARBONATES e.g calcium carbonate, dimethylcarbonate

ENHANCED OIL RECOVE RY ENHANCED GEOTHERMAL ENHANCED COAL BED METHANE

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