Dissertations / Theses on the topic 'Carbon capture engineering (excl. sequestration)'

Thesis (S.M. in Transportation)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2010.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 115-118).
The objective of this report is to determine whether opportunities to use liquefied carbon dioxide carriers as part of a carbon capture and storage system will exist over the next twenty years. Factors that encourage or discourage the use of vessels are discussed. This study concludes that liquefied carbon dioxide carriers can potentially be used in both the near and long term under different sets of circumstances.
by Mary-Irene Alexandrakis and Bret S. Smart.
S.M.in Transportation

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering; and, (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2007.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 83-85).
India is the world's second most populous country with a rapidly growing economy and increasing emissions. With the imminent threat of anthropogenic climate change in the coming decades, helping to control India's emissions will have to be a global priority. Carbon capture and sequestration (CCS) can play a pivotal role in reducing India's emissions in the future, given India's reliance on coal power and the large coal reserves. The motivation for this dissertation is the need to ascertain the current situation and conditions relevant to carbon capture in India so as to help guide the processes to prepare for large scale adoption if desired in the future. For carbon capture to be undertaken at a significant scale, various pieces will have to fall in to place in sync with each other. The technological capability would have to be complemented by adequate geological capacity under the umbrella of the right policies. Adoption of carbon capture would need a tailored approach for each country and for a diverse country the size of India, these approaches may need to be customized even locally to each region.
(cont.) The objective of this thesis is to increase the understanding of the opportunities, issues and challenges amongst the stakeholders regarding CCS in India regarding the capacity, political structures and policies. To address the objective, this dissertation analyzes the current power and coal sector situations, geological capacity for sequestration in India, the political decision making structures and the current views of the relevant civil servants in this field. At the end, there are some recommendations for the government of India and the international climate and CCS community to make conditions conducive for CCS in India.
by Mudit Narain.
S.M.

Thesis (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2010.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 100-106).
Climate change is a threat that could be mitigated by introducing new energy technologies into the electricity market that emit fewer greenhouse gas (GHG) emissions. We face many uncertainties that would affect the demand for each of these technologies in the future. The costs of these technologies decrease due to learning-by-doing as their capacity is built out. Given that we face uncertainties over future energy demands for particular technologies, and that costs reduce with experience, an important question that arises is whether policy makers should encourage early investments in technologies before they are economically competitive, so that they could be available in the future at lower cost should they be needed. If society benefits from early investments when future demands are uncertain, then there is an option value to investing today. This question of whether option values exist is investigated by focusing on Coal-fired Power Plants with Carbon Capture and Storage (CCS) as a case study of a new high-cost energy technology that has not yet been deployed at commercial scale. A decision analytic framework is applied to the MIT Emissions Prediction Policy Analysis (EPPA) model, a computable general equilibrium model that captures the feedback effects across different sectors of the economy, and measures the costs of meeting emissions targets. Three uncertainties are considered in constructing a decision framework: the future stringency of the US GHG emissions policy, the size of the US gas resource, and the cost of electricity from Coal with CCS. The decision modeled is whether to begin an annual investment schedule in Coal with CCS technology for 35 years. Each scenario in the decision framework is modeled in EPPA, and the output measure of welfare is used to compare the welfare loss to society of meeting the emissions target for each case. The decision framework is used to find which choice today, whether to invest in CCS or not, gives the smallest welfare cost and is therefore optimal for society. Sensitivity analysis on the probabilities of the three uncertainties is carried out to determine the conditions under which CCS investment is beneficial, and when it is not. The study finds that there are conditions, specified by ranges in probabilities for the uncertainties, where early investment in CCS does benefit society. The results of the decision analysis demonstrate that the benefits of CCS investment are realized in the latter part of the century, and so the resulting optimal decision depends on the choice of discount rate. The higher the rate, the smaller the benefit from investment until a threshold is reached where choosing to invest becomes the more costly decision. The decision of whether to invest is more sensitive to some uncertainties investigated than others. Specifically, the size of the US gas resource has the least impact, whereas the stringency of the future US GHG emissions policy has the greatest impact. This thesis presents a new framework for considering investments in energy technologies before they are economically competitive. If we can make educated assumptions as to the real probabilities we face, then extending this framework to technologies beyond CCS and expanding the decision analysis, would allow policymakers to induce investment in energy technologies that would enable us to meet our emissions targets at the lowest cost possible to society.
by Eleanor Charlotte Ereira.
S.M.in Technology and Policy

Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 217-222).
The world's growing energy demand coupled with the problem of global warming have led us to investigate new energy sources that can be utilized in a way to reduce carbon dioxide emissions than traditional fossil fuel power plants. One of these unconventional fuels is sour gas. Sour gas consists of mainly methane, containing large concentrations of hydrogen sulfide and carbon dioxide. Over 30% of the world's natural gas reserves are considered sour. However this unusual fuel poses many challenges due to the toxic and corrosive nature of the combustion products. One of the most promising technologies for carbon capture and sequestration is oxy-fuel combustion. This involves separating the nitrogen from air prior to the combustion itself. Then, after combustion, we separate the water and other substances and can use the resulting carbon dioxide stream for enhanced oil recovery representing an added economic benefit of this system. Firing temperatures for pure oxygen combustion can reach values up to 2500° C, which is well above what the combustor can handle. Therefore a diluent has to be added to reduce the temperature back to appropriate levels, but the key question is how this impacts the efficiency and performance of the entire cycle. Hence, if feasible, the use of sour gas in an oxy-fuel power plant could potentially allow us to harness the economic and environmental potential of this unconventional fuel. Depending on the cycle configuration, water or carbon dioxide can be used as diluents to control the flame temperature in the combustion process. All of these cycle types were modeled and the cycles' performances and emissions were studied. When the working fluid condenses in the cycle, sulfuric acid is formed due the presence of SO, compounds, which causes corrosion and can damage power plant components. Therefore, either expensive acid resistant materials should be used, or a redesign of the cycle is required to overcome this challenge. Different options were explored for each of the cycle types mentioned to help in the visualization and performance prediction of possible sour gas oxy-fuel power cycle configurations. A cost analysis of the proposed systems was also conducted in order to provide preliminary levelized cost of electricity estimates.
by Nadim Walid Chakroun.
S.M.

Thesis (MScEng)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: Carbon dioxide (CO2) is seen as one of the main contributors to global warming. The use of fossil fuels for power production leads to large quantities of carbon dioxide being released into the atmosphere. The released CO2 can, however, be captured by retrofitting capture units downstream from the power plant called Post Combustion Carbon Dioxide Capturing. Post combustion CO2 capture can involve the reactive absorption of CO2 from the power plant flue gas steam. Reactive solvents, such as monoethanolamine (MEA), are used for capturing the CO2 and the solvent is regenerated in a desorber unit where the addition of heat drives the reverse reaction, releasing the captured CO2. However, the large energy requirement for solvent regeneration reduces the viability of employing CO2 capture on an industrial scale. This study focused on establishing a facility for CO2 capture studies – the main aim being the construction and validation of the results produced by the pilot plant facility. A secondary aim of this study was developing an Aspen Plus® Simulation method that would simplify simulating the complex CO2 capture process. Results from the simulation were to be compared to that of the pilot plant experiments. A pilot plant facility with a closed gas system, allowing gas recycling from both the absorber and the stripping columns, was set up. The absorber column (internal diameter = 0.2 m) was set up to allow one to obtain information regarding gas- and liquid temperatures and compositions at various column heights. Online gas analysers are used for analysing the gas composition at various locations in the absorber column. The pilot plant was initially commissioned with 20 weight % MEA in aqueous solution; however the main validation experiments were conducted with 30 weight % MEA in aqueous solution. 30 weight % MEA (aq) is generally used as the reference solvent for pilot plant studies. Pilot plant results with regards to the carbon dioxide concentration profiles for the absorber column as well as the regeneration energy requirement and capture rates compared well to literature data. The Aspen Plus® simulation was also set up and validated using published pilot plant data. The comparison of the pilot plant results from this study, to the results from the Aspen Plus® Simulation, showed good agreement between the two. The Aspen Plus® Simulation could further be used to validate pilot plant data that has been gathered outside the range of reported CO2 capture efficiencies. The Aspen Plus®model was evaluated at liquid-to-gas ratios of 1.7 and regeneration energies matching the pilot plant results. It was found that the model under predicts the capture efficiency of CO2 with an average of 4.0%. The model was corrected for this error at liquid-to-gas ratios of 2 and the fit of the model to pilot plant results improved considerably (R2-value = 0.965). Pilot plant repeatability was investigated with both 20 weight %- and 30 weight % MEA in aqueous solution. Temperature- and gas concentration profiles from the absorber column showed good repeatability. The maximum deviation of the regeneration energy and the capture efficiency from the calculation means were ±0.72% and ±1.40% respectively. The aims of this study have been met by establishing, and validating the results of a pilot plant facility for carbon dioxide capture studies. It has been shown that the pilot plant produces repeatable results. Results from the Aspen Plus® Simulation were validated and also match results from the established pilot plant setup. The simulation may prove to provide valuable information regarding the optimal operating conditions for the pilot plant and may aid in performing a full parametric study on the CO2 capture process.
AFRIKAANSE OPSOMMING: Koolstofdioksied (CO2) word geklassifiseer as een van die bekendste kweekhuisgasse wat ʼn groot bydra lewer tot aardverwarming. Die gebruik van fossielbrandstowwe om na die energiebehoeftes van die mens om te sien lei daartoe dat groot hoeveelhede koolstofdioksied, hoofsaaklik vanaf kragstasies, vrygestel word in die atmosfeer. Daar is verskeie maniere hoe die CO2 uit die uitlaatgas van kragstasies verwyder kan word – die vernaamste hiervan is bekend as die Na-verbranding opvangs metode. Die opvangs van CO2 na verbranding van fossielbrandstowwe vir kragproduksie kan vermag word deur van reaktiewe absorpsie tegnieke gebruik te maak. Mono-etanol-amien (MEA) kan vir hierdie doeleindes aangewend word deur dit, in ʼn absorpsiekolom, in kontak te bring met die CO2. Die gereageerde oplosmiddel word geregenereer deur die oplosmiddel te verhit in ʼn stropingskolom. ʼn Bykans suiwer CO2 stroom word vrygestel. Die implementering van hierdie opvangtegniek op industriële skaal lei egter tot groot energieverliese vir die kragstasies. Die hoofrede hiervoor is die hoeveelheid energie wat benodig word om die oplosmiddel te regenereer vir hergebruik. Die hoofdoel van hierdie studie was gemik op die oprigting en inwerkstelling van 'n navorsingsfasiliteit vir studies aangaande die na-verbranding opvangs van CO2. Dit het behels die ontwerp, konstruksie en stawing van gelewerde resultate met resultate in die literatuur. 'n Sekondêre doel van hierdie studie was die metode-ontwikkeling vir die opstel van 'n Aspen Plus® Model wat die simulasie van die CO2 opvangsproses met ʼn reaktiewe oplosmiddel, MEA, vereenvoudig. Gesimuleerde resultate is vergelyk met resultate uit die literatuur. Die toetsaanleg, met 'n geslote gas stelsel, maak voorsiening vir die hersirkulering van gas wat vir eksperimentele doeleindes gebruik word. Die absorpsie kolom (interne diameter van 0,2 m) is opgestel sodat informasie aangaande die gas- en vloeistof temperature, sowel as gas- en vloeistof komposisies vanaf verskillende kolomhoogtes, bekom kan word. ʼn Aanlyn CO2 analiseerder word gebruik om vir CO2 in die prosesgas te analiseer. Die toetsaanleg is aanvanklik in bedryf gestel met ʼn 20 massa % MEA in waterige oplossing; die hoof eksperimente is egter uitgevoer deur van 30 massa % MEA in waterige oplossing gebruik te maak. Die laasgenoemde oplosmiddel word algemeen gebruik in die CO2 opvangs verwante navorsingsveld. Die resultate van die toetsaanleg, vergelyk goed met resultate in die literatuur. Die gesimuleerde Aspen Plus® resultate is ook vergelyk met resultate in die literatuur en die gevolgtrekking is gemaak dat die simulasie gebruik kan word om redelike akkurate voorspellings van die werklike prosesresultate te gee. Die simulasie is verder ook gebruik om resultate, verkry vanaf die opgerigte toetsaanleg, te verifieer en ʼn goeie ooreenstemming tussen die gesimuleerde en die eksperimentele resultate is waargeneem. ʼn Verder gevolgtrekking aangaan die Aspen Plus® simulasie metode was dat dit in die toekoms ʼn groot doel kan dien in die optimeringsproses van toetsaanlegte waar navorsing aangaande die na-verbranding opvang van CO2 gedoen word. Die Aspen Plus® model is geëvalueer by ‘n vloeistof-tot-gas-verhouding van 1,7 en ooreenstemmende toetsaanleg resultate, aangaande die hoeveelheid energie wat ingesit is vir die regenerasie van die oplosmiddel. Die onakkuraathede in die model, met betrekking tot die voorspelling van die hoeveelheid CO2 wat vasgevang sal word, is hierdeur bepaal en die model is daarvoor aangepas. Resultate van die verbeterde model vergelyk baie goed met die toetsaanleg resultate – ʼn R2-waarde van 0.965. Die herhaalbaarheid van die toetsaanleg resultate is ondersoek en ʼn goeie herhaalbaarheid van die temperatuur- en CO2 konsentrasieprofiele is verkry. Die toetsaanleg dui ook goeie herhaalbaarheid met betrekking tot die effektiwiteit waarmee die CO2 uit ʼn gasstroom verwyder word (± 1,40%), sowel as die hoeveelheid energie wat benodig word vir regenerering van die oplosmiddel (± 0,72%). Die doelwitte van hierdie studie is bereik deur die oprigting en verifiëring van resultate gelewer deur 'n toetsaanleg vir studies aangaande die na-verbrandingsopvang van CO2. Die herhaalbaarheid van toetaanleg resultate is bewys. Resultate van die Aspen Plus® simulasie stem ooreen met resultate in die literatuur sowel as resultate van die toetsaanleg wat opgerig is in hierdie studie.

Thesis (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, 2010.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 138-140).
Carbon capture and sequestration (CCS) technology has the potential to be a key CO2 emissions mitigation technology for the United States. Several CCS technology options are ready for immediate commercial-scale demonstration, but three obstacles to commercial deployment remain: the lack of a clear legal and regulatory framework for sequestration, the lack of a demonstration phase, and most importantly, the lack of a market for CCS. A successful demonstration phase will achieve the goal of technology readiness. The demonstration phase should be organized so as to share costs and risks between public and private actors. Project selection responsibility should be assigned to a dedicated private board and project management responsibility to private companies. This analysis recommends a combination of the Boucher Bill proposal for a CCS demonstration phase, as incorporated in the American Clean Energy and Security Act (ACES Act) of 2009, and a continuation of the DOE Clean Coal Power Initiative program. This combined approach can provide productive competition between public and private demonstration programs. Achieving technology readiness will not on its own lead to commercial deployment of CCS. Two additional policy objectives for the commercial deployment phase are considered: market penetration and cost reduction. Market penetration can be ensured through strong market pull policies, but this may be a very expensive policy approach in the long run. A more prudent goal is long-term cost reduction of CCS. Unlike the market penetration goal, the cost reduction goal will not guarantee that CCS will become a major contributor to carbon emissions mitigation, but it will provide a more cost-effective path. Achieving the cost reduction goal will require strong market pull policies for the short and medium term, together with a focus on technology push policies over the entire period. In the long term, market pull policies for CCS should be eliminated; if CCS is not economically competitive with alternative technologies, it should not be deployed on a significant scale. The ACES Act provides a good policy framework to achieve technology readiness through a demonstration phase and to pursue the long-term goal of cost reduction for commercial deployment of CCS technology. This approach will provide a cost-effective strategy for ensuring that CCS, a major scalable option for carbon emissions mitigation, is given the best chance of success in the long term.
by Michael Roberts Hamilton.
S.M.in Technology and Policy

Thesis (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division; and, (M.C.P.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 2010.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student submitted PDF version of thesis.
Includes bibliographical references (p. 91-94).
Carbon capture and sequestration (CCS) is a technology that can significantly reduce power sector greenhouse gas (GHG) emissions from coal-fired power plants. CCS technology is currently in development and requires higher construction and operating costs than is currently competitive in the private market. A question that policymakers and investors have is whether a CCS plant will operate economically and be able to sell their power output once built. One way of measuring this utilization rate is to calculate capacity factors of possible CCS power plants. To investigate the economics of CCS generation, a marginal cost dispatch model was developed to simulate the power grid in the Western Interconnection. Hypothetical generic advanced coal power plants with CCS were inserted into the power grid and annual capacity factor values were calculated for a variety of scenarios, including a carbon emission pricing policy. I demonstrate that CCS power plants, despite higher marginal costs due to the operating costs of the additional capture equipment, are competitive on a marginal cost basis with other generation on the power grid at modest carbon emissions prices. CCS power plants were able to achieve baseload level capacity factors with $10 to $30 per ton-CO2 prices. However, for investment in CCS power plants to be economically competitive requires that the higher capital costs be recovered over the plant lifetime, which only occurs at much higher carbon prices. To cover the capital costs of first-of-the-kind CCS power plants in the Western Interconnection, carbon emissions prices have been calculated to be much higher, in the range of $130 to $145 per ton-CO2 for most sites in the initial scenario. Two sites require carbon prices of $65 per ton-CO2 or less to cover capital costs. Capacity factors and the impact of carbon prices vary considerably by plant location because of differences in spare transmission capacity and local generation mix.
by Gary Shu.
M.C.P.
S.M.in Technology and Policy

In order to reduce the rate of climate change, particularly global warming, it is imperative that industries reduce their carbon dioxide (CO2) emissions. A promising solution of CO2 emission reduction is Carbon dioxide Capture and Storage (CCS) by sequestration, which involves isolating and extracting CO2 from the flue gases of various industrial processes, and thereafter burying the CO2 underground. The capture of CO2 proved to be the most challenging aspect of CCS. Thus, the objective of this research was to identify the most promising solution to capture CO2 from industrial processes. The study focussed on capturing CO2 emitted by coal power plants, coal-to-liquids (CTL) and gas-to-liquids (GTL) industries, which are common CO2 emitters in South Africa. This thesis consists firstly of an extensive literature review detailing the above mentioned processes, the modes of CO2 capture, and the various CO2 capture methods that are currently being investigated around the world, together with their benefits and drawbacks in terms of energy penalty, CO2 loading, absorption rate, capture efficiency, investment costs, and operating costs. Modelling, simulation, and pilot plant efforts are also described. The study reviewed many CO2 capture techniques including solvent absorption, sorbent capture, membrane usage, hydrate formation, and newly emerging capture techniques such as enzyme based systems, ionic liquids, low temperature cryogenics, CO2 anti-sublimation, artificial photosynthesis, integrated gasification steam cycle (IGSC), and chemical looping combustion The technique of solvent absorption was found to be the most promising for South African industries. Vapour-liquid-equilibrium (VLE) measurements of solvent absorption using amine blends were undertaken, using blends of methyl-diethanol amine (MDEA), diethanol amine (DEA) and water (H2O) with composition ratios of 25: 25: 50 wt% and 30: 20: 50 wt% respectively, and with CO2 and N2 gases at CO2 partial pressures of 0.5 to 10.5 bar. Experiments were conducted under system pressures of 5 to 15 bar and temperatures of 363.15 and 413.15 K, using a static analytic apparatus. CO2 liquid loading results were analysed and discussed. The experimental data were regressed in Matlab (R2009b) using the Posey-Tapperson-Rochelle model and the Deshmukh-Mather model. The Matlab programmes are presented along with the regressed binary interaction and model parameters. The accuracy of model predictions are discussed. Thereafter an Electrolyte-NRTL model regression and simulation of the absorption process was conducted using Aspen Plus V 7.1. for flue gas compositions, solvent compositions, temperature, and pressure conditions similar to that of process operating conditions. CO2 loading, design factors, CO2 recovery, and CO2 purity results were analysed and compared where appropriate, with experimental results. Finally a general preliminary energy efficiency and cost analysis was conducted based on the simulation results. The main conclusions reached are that the amine solvent blend containing 25:25:50 wt% of MDEA:DEA:H2O, produced higher CO2 loadings for its respective system conditions than other solvents studied and those found in literature. However, absorption of CO2 was found to be highly dependent on system temperature and pressure. The Deshmukh-Mather model provided higher accuracy than the Posey-Tapperson-Rochelle model, producing CO2 loading predictions with a relative error not exceeding 0.04%, in 1.5 to 3 minutes using a dual core processor. Aspen absorption simulations provided significantly lower CO2 loading results than those experimentally obtained, due to the low contact time achieved and higher temperature dependence in the proposed absorption process. Process improvements were highlighted and implemented to increase CO2 recovery and purity. Energy penalty values were found to be higher than those found in literature, but room for process and design improvement was identified and recommendations were given. Investment cost estimates were found to be justifiable and within reason. Limitations of the simulation were also identified and discussed.
Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2010.

In order to address the global challenges of climate change caused by the increasing concentration of carbon dioxide (CO2), Carbon Capture, Utilization and Storage (CCUS) has been proposed as a promising strategy in carbon management. In parallel with the target of zero emission in fossil-fired power plants, negative emission has also drawn a great deal of attention in other chemical sectors, including cement making and steel production industries. Thanks to the recent reduction in the cost of renewable energy sources, such as wind and solar, a paradigm shifting concept has emerged to directly convert the captured carbon into chemicals and fuels. In this way, decarbonization in various chemical sectors can be achieved with a reduced carbon footprint. A variety of carbon dioxide conversion pathways have been investigated, including thermochemical, biological, photochemical, electrochemical and inorganic carbonation methods. Electrochemical conversion of carbon dioxide has been thoroughly investigated with great progress in electrocatalysts and reaction mechanisms. However, fewer studies have been taken to tackle the constraint of the low solubility of CO2 in conventional aqueous electrolytes. In an effort to improve the solubility of CO2, various novel electrolytes have been designed with a higher uptake of CO2 and a compatibility with electrochemical conversion, including Nanoparticle Organic Hybrid Materials (NOHMs)-based fluids. NOHMs are a unique liquid-like nanoscale hybrid material, comprising of polymers grafted onto nanoparticles (e.g., silica). NOHMs have demonstrated an excellent thermal stability and a high chemical tunability. Two types of NOHMs with ionic bonding (I) between the polymers and nanoparticles were selected in this study: NOHM-I-PEI incorporating polyethylenimine polymer (PEI) and NOHM-I-HPE consisting of polyetheramine polymer (HPE), illustrative of two modes of carbon capture (e.g., chemisorption and physisorption). The NOHMs-based fluids were synthesized with different secondary fluids and salt to tune the viscosity and conductivity. As the first liquid hybrid solvent system for combined carbon capture and conversion, the physical, chemical and electrochemical properties of NOHMs-based fluids were systematically investigated. It was found that NOHMs-based aqueous fluids have exhibited a lower specific heat capacity than that of the 30 wt.% monoethanolamine (MEA) solvents. In addition, upon CO2 loading, the increase in specific heat capacity and the reduction of the viscosity of the NOHM-I-PEI based aqueous fluids can be attributed to the formation of intra-molecular hydrogen bonds. The different chemistries of the two NOHMs can be reflected by the viscosity-based mixing behavior. The smaller critical concentration and the higher intrinsic viscosity of NOHM-I-HPE based aqueous fluids implied a more significant contribution of viscosity to the system by the addition of NOHM-I-HPE. The viscosity of NOHM-I-HPE (30 wt.%) in water was measured to be 395 cP, an order of magnitude higher than that of NOHM-I-PEI (30 wt.%) in water, which was determined to be 22.6 cP. It was also discovered that the addition of N-methyl-2-pyrrolidone (NMP) has resulted in a dramatic increase of the viscosity of NOHM-I-PEI based aqueous fluids, hypothesized to be due to a possible formation of a complex between NMP and NOHM-I-PEI. On the other hand, the presence of 0.1 M potassium bicarbonate (KHCO3) salt greatly reduced the viscosity of NOHM-I-HPE based aqueous fluids. The electrochemical properties of NOHMs-based fluids were also characterized and an excellent electrochemical stability has been demonstrated. The conductivities of NOHMs-based fluids witnessed an unexpected enhancement from the corresponding untethered polymer-based solutions. At 50 wt.% loading, the conductivity was 15 mS/cm for NOHM-I-PEI based aqueous fluids doped by 1 M bis(trifluoromethylsulfonyl)amine lithium salt (LiTFSI), while it was 0.91 mS/cm for PEI based aqueous solutions. Even after the viscosities of the two solutions were converted to the same value, there was still a large gap between the conductivities of the NOHMs-based fluids and polymer-based fluids. The relative tortuosity of ion transport in NOHMs-based fluids compared to untethered polymer-based solutions was less than 1. This result was indicative of a shorter pathway of ion transport in NOHMs-based fluids than in polymer-based fluids. Thus, it is suggested that in addition to a viscosity effect, unique multi-scale structures were also formed, enabling an enhanced ion transport in the NOHMs-based fluids. With this hypothesis, ultra-small-angle X-ray scattering (USAXS) technique was utilized to construct the structures of NOHMs morphology in secondary fluids, from agglomerates at large scale to aggregates at mid-scale, and to the interparticle distance at small scale. The sizes of the aggregates and the interparticle distance were highly tunable by varying the concentrations of NOHMs, and the types of NOHMs and secondary fluids. For example, the aggregate size was (32.30 ± 0.3) nm and (153.9 ± 1.5) nm for 50 wt.% loading of NOHM-I-PEI and NOHM-I-HPE in mPEG, respectively. This hierarchical structure was hypothesized to give ions unique channels and pathways to migrate, resulting in the surprising conductivity enhancement. Cryogenic electron microscopy (CryoEM) was also employed to image such multi-scale fractal structures. The diffusion behavior under this hierarchical structure was studied subsequently. To our surprise, in certain NOHMs-based fluids, such as 10 wt.% NOHM-I-HPE in water at 25℃, the diffusion coefficient of water was 3.43×(10)^(-9) m2/s, higher than that of deionized water, 2.99×(10)^(-9) m2/s. This is evident of the channels created by NOHMs in the secondary fluids to allow faster local diffusion of water and ions. Meanwhile, the diffusion coefficient of NOHM-I-HPE was higher with the presence of 0.1 M KHCO3 salt compared to the salt-free case in water. Though counter-intuitive, this was because salt would interact with the ionic bonding sites of NOHMs, facilitating the dynamic hopping of polymers on the nanoparticle surface, and thus improving the fluidity of the NOHM-I-HPE based aqueous fluids. This investigation of multi-scale structures and diffusion behavior of NOHMs-based fluids was insightful in understanding how the ions move in the system, and in explaining the enhanced conductivity of NOHMs-based fluids compared to the corresponding untethered polymer-based solutions. It is believed that ions move in two regions of the NOHMs-based fluids, the NOHMs-rich region and secondary fluids-rich region, in the mechanisms of translational movement, and coupled and decoupled ion migration with structural relaxation of NOHMs and secondary fluids. With the understanding of the fundamental properties and the construction of hierarchical structures, the carbon capture performance was evaluated for NOHMs-based fluids. The carbon capture behavior can be tuned by the concentration of NOHMs, and the presence of salt and physical solvents. The carbon capture kinetics was determined by both the amount of the capture material and the viscosity of the fluids. It was determined that 30 wt.% NOHM-I-PEI based aqueous fluids exhibited an optimal balance between capture capacity and sorption kinetics. As the concentration of NOHMs further increased, the elevated viscosity of the system limited the mass transfer of carbon capture. It was also found that salt induced a minimal impact on carbon capture in the initial 100 min for 5 wt.% NOHMs loading, but would negatively impact the capture capacity and kinetics at higher NOHMs loadings. Meanwhile, the addition of physical solvent (NMP) reduced carbon capture capacity and kinetics. Various existing forms of CO2 have been identified in NOHMs-based fluids, including carbamate, bicarbonate, and physisorbed CO2. Carbamate came from the reaction between CO2 and the amine functional groups on NOHM-I-PEI. Physisorbed CO2 was identified as the electroactive species for electrochemical conversion of CO2. In the combined carbon capture and conversion experiments using 5 wt.% NOHM-I-HPE based aqueous electrolyte, carbon monoxide (CO) production was enhanced on polycrystalline silver by 60%, and selectivity was changed on a pyridinic-N doped carbon-based electrode, in comparison with conventional 0.1 M KHCO3 electrolyte. The roles of NOHMs in carbon capture and conversion were also explored. The addition of NOHMs was able to improve the solubility of CO2 with a tunable pH change. It is hypothesized that NOHMs can complex with the electrochemical reaction species,CO2 (CO2^-), and this complex formation can be tunable by the concentration and types of NOHMs. In the end, an alternative approach of utilizing NOHMs-based fluids has also been proposed through encapsulation. The encapsulation of NOHMs-based fluids has enabled a higher specific surface area for CO2 uptake, and an enhancement in capture kinetics has been observed compared to the non-encapsulated NOHMs-based fluids. In summary, a novel nanoscale hybrid solvent system has been developed for combined carbon capture and conversion. The insight into the chemistry of this hybrid solvent system is not beneficial to the advancement in carbon capture and conversion, but it is also enlightening for the interdisciplinary development of various areas involving nanoscale hybrid materials.

With the atmospheric concentration of carbon dioxide steadily increasing and little sign of a reduction in fossil fuel demand worldwide, there is a well-established need for an alternative strategy for dealing with carbon emissions from energy production. One possible solution is the accelerated weathering of ultramafic rocks. Accelerated weathering is an environmentally benign route to a thermodynamically and kinetically stable form of carbon. The chemistry is based on naturally occurring reactions and the raw materials are abundant across the earth's surface. However, the reactions are relatively slow, and achieving reaction rates sufficient to match the carbon dioxide production rate at an energy conversion facility is challenging. This work addresses a number of the challenges facing the integration of accelerated weathering with energy conversion, and presents one view of how the integration could be achieved. This work begins by developing a suite of tools necessary for investigating the dissolution and precipitation of minerals. Chapter 2 starts with a description of the minerals that will be evaluated, and then goes on to develop the techniques that will be used. The first is a differential bed reactor, which is used for measuring the dissolution rates of minerals under tightly controlled conditions. Next a bubble column reactor is developed for the investigating the adsorption of carbon dioxide and the precipitation of mineral carbonates in a single vessel. These techniques, together with a batch reactor for studying direct carbonation reactions, constitute a comprehensive set of tools for the investigation of accelerated mineral weathering. With the necessary techniques developed and proven, Chapter 3 addresses the first challenge faced by accelerated mineral weathering; the dissolution rate of magnesium from a silicate mineral. While the dissolution of this mineral is thermodynamically favorable, the kinetics are prohibitively slow. It is thought that this is because silica from the mineral tends to accumulate on the particle surface creating a passivation layer, which limits the reaction rate of the mineral. In this work, the effects of a combination of chemical chelating agents, catechol and oxalate, are evaluated for their ability to circumvent this passivation layer. The results indicate that catechol and oxalate modify the passivation layer as it forms, both accelerating the dissolution rate of the mineral and maintaining pore volume, leading to greater dissolution rates. This pore modification process is proposed as the primary mechanism by which catechol affects the passivation layer. The combination of catechol and oxalate under acidic conditions is also shown be effective when the ambient solution approaches the saturation point of silica. Finally, the chelating does not impede the precipitation of carbonate products, a critical hurdle for a carbon storage process. The chelating agent work is extended in Chapter 4, with a sensitivity study that evaluates the response of the dissolution rate to changes in both pH and the concentration of the chelating agents. Oxalate and pH are found to exhibit a strong influence on the mineral dissolution rate, while the effect of catechol is more apparent after significant dissolution has taken place. These observations are in agreement with the model of passivation layer modification proposed. In addition, some alternatives to the chelating agent catechol are evaluated. It is found that when used in combination with oxalate, these alternatives appeared equivalent to catechol, but alone they had only a minor effect. Catechol was also noted to have a significant effect on the dissolution rate of iron from the silicate mineral, and a mechanism for this effect was proposed. The direct adsorption of carbon dioxide and precipitation of solid carbonates in a single reaction step presents another challenge for accelerated mineral carbonation. In general, the magnesium carbonates formed at ambient pressure and moderate temperatures tend to be hydrated, and at times contain unused hydroxides, leading to inefficiencies in both transport and storage. It is shown in Chapter 5 that by seeding reaction vessels with the anhydrous form of magnesium carbonate, it is possible to grow this desired phase with minimal formation of the metastable hydrated phases. The formation of this phase is primarily limited by the precipitation rate, but in some situations, carbon dioxide hydration kinetics and magnesium hydroxide precipitation kinetics also play a role. In Chapter 6, these developments in both magnesium silicate dissolution and carbonate precipitation are combined into a proposed technology for the direct capture and storage of carbon dioxide. This application of accelerated mineral weathering is shown to significantly reduce the carbon emissions of an energy conversion technology through life cycle assessment. This novel approach to the mitigation of carbon emissions presents a compelling argument for the continued development of accelerated mineral weathering as a combined carbon capture and storage technology.

The demand for energy continues to grow but concerns over climate change means that conventional fossil fuels will eventually need to be replaced. The solution to the energy crisis will require a combination of both conventional energy sources with CO2 capture and renewable technologies. While many renewable technologies exist, it is not common that CO2 capture is incorporated into the process. Biomass is an ideal feed-stock for bio-energy production as it is CO2 neutral. Many thermochemical conversion technologies exist, but the Alkaline Thermal Treatment (ATT) reaction is particularly interesting because it combines conventional thermochemical conversion with CO2 capture in order to create a process that is potentially CO2 negative. By reacting biomass with a metal hydroxide, high purity H2 can be produced while simultaneously locking the carbon as a stable carbonate, which is a form of Bio-energy with Carbon Capture & Storage (BECCS). The H2 can then be used for applications ranging from Fischer-Tropsch synthesis to PEM fuel cells. Group I & II hydroxides were investigated for their ability to react with cellulose (a biomass model compound) in the ATT reaction scheme. Comparison between both groups indicated that NaOH and Ca(OH)2 were the best hydroxides from groups I & II respectively. However, the amount of H2 produced during the ATT of cellulose with Ca(OH)2 is considerably lower than with NaOH. A 10% Ni/ZrO2 catalyst was then added to increase the yield of H2 from the reaction between cellulose and Ca(OH)2. It was found that at 20% catalyst loading, the amount of H2 produced and the suppressed level of CO2 was similar to the ATT with NaOH. Several other catalytic metals were also investigated and found to have the following H2 production activity: Ni > Pt≈Pd > Co > Fe, Cu. Since Ni was the most active and has a considerably lower cost than noble metals it was chosen for additional studies. The ATT reaction in the presence of Ni has two distinct steps in the formation of H2 from cellulose. The presence of Ca(OH)2 enhances the formation of linear oxygenates from cellulose. These oxygenates are then reformed over the Ni-based catalyst to H2 and CO2, the latter of which is captured by Ca(OH)2 to form CaCO3. If either Ca(OH)2 or Ni was removed from the reaction, the yield H2 fell significantly. Although the reactants and the catalyst are all solid materials, they do not need to be physically mixed. The Ni-based catalyst produced H2 primarily through the reforming of gaseous species and therefore could be placed ex-situ of the cellulose and Ca(OH)2 mixture. However, placing the catalyst away from Ca(OH)2 prevented CO2 capture. In order to remedy this Ca(OH)2 was mixed with the Ni-based catalyst and mixture was placed ex-situ of pure cellulose. This created a process whereby cellulose could be decomposed thermally followed by a single gas-phase Alkaline Thermal Treatment (GATT) reforming step of the pyrolysis vapors to H2 with suppressed CO2.

abstract: Carbon capture and sequestration (CCS) is one of the important mitigation options for climate change. Numerous technologies to capture carbon dioxide (CO2) are in development but currently, capture using amines is the predominant technology. When the flue gas reacts with amines (Monoethanaloamine) the CO2 is absorbed into the solution and forms an intermediate product which then releases CO2 at higher temperature. The high temperature necessary to strip CO2 is provided by steam extracted from the powerplant thus reducing the net output of the powerplant by 25% to 35%. The reduction in electricity output for the same input of coal increases the emissions factor of Nitrogen Oxides, Mercury, Particulate matter, Ammonia, Volatile organic compounds for the same unit of electricity produced. The thesis questions if this tradeoff between CO2 and other emissions is beneficial or not. Three different methodologies, Life Cycle Assessment, Valuation models and cost benefit analysis are used to identify if there is a net benefit to the society on implementation of CCS to a Pulverized coal powerplant. These methodologies include the benefits due to reduction of CO2 and the disbenefits due to the increase of other emissions. The life cycle assessment using ecoindicator'99 methodology shows the CCS is not beneficial under Hierarchical and Egalitarian perspective. The valuation model shows that the inclusion of the other emissions reduces the benefit associated with CCS. For a lower CO2 price the valuation model shows that CCS is detrimental to the environment. The cost benefit analysis shows that a CO2 price of at least $80/tCO2 is required for the cost benefit ratio to be 1. The methodology integrates Montecarlo simulation to characterize the uncertainties associated with the valuation models.
Dissertation/Thesis
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M.S. Civil and Environmental Engineering 2012

Optimal operation of plants is becoming more important due to increasing competition and small and changing profit margins for many products. One major reason has been the realization by industry that potentially large savings can be achieved by improving processes. Growth rates and profitability are much lower now, and international competition has increased greatly. The industry is faced with a need to manufacture quality products, while minimizing production costs and complying with a variety of safety and environmental regulations. As industry is confronted with the challenge of moving toward a clearer and more sustainable path of production, new technologies are needed to achieve industrial requirements. In this research, a new methodology is proposed to integrate so-called new technologies into existing processes. Research shows that the new technologies must be carefully selected and adopted to match the complex requirements of an existing process. The new proposed methodology is based on four major steps. If the improvement in the process is not sufficient to meet business needs, new technologies can be considered. Application of a new technology is always perceived as a potential threat; therefore, financial risk assessment and reliability risk analysis help alleviate risk of investment. An industrial case study from the literature was selected to implement and validate the new methodology. The case study is a planning problem to plan the layout or design of a fleet of generating stations owned and operated by the electric utility company, Ontario Power Generation (OPG). The impact of new technology integration on the performance of a power grid consisting of a variety of power generation plants was evaluated. The reduction in carbon emissions is projected to be accomplished through a combination of fuel switching, fuel balancing and switching to new technologies: carbon capture and sequestration. The fuel-balancing technique is used to decrease carbon emissions by adjusting the operation of the fleet of existing electricity-generating stations; the technique of fuel-switching involves switching from carbon-intensive fuels to less carbon-intensive fuels, for instance, switching from coal to natural gas; carbon capture and sequestration are applied to meet carbon emission reduction requirements. Existing power plants with existing technologies consist of fossil fuel stations, nuclear stations, hydroelectric stations, wind power stations, pulverized coal stations and a natural gas combined cycle, while hypothesized power plants with new technologies include solar stations, wind power stations, pulverized coal stations, a natural gas combined cycle and an integrated gasification combined cycle with and without capture and sequestration. The proposed methodology includes financial risk management in the framework of a two stage stochastic programme for energy planning under uncertainty: demands and fuel price. A deterministic mixed integer linear programming formulation is extended to a two-stage stochastic programming model in order to take into account random parameters, which have discrete and finite probabilistic distributions. Thus, the expected value of the total costs of power generation is minimized, while the objective of carbon emission reduction is achieved. Furthermore, conditional value at risk (CVaR), a most preferable risk measure in the financial risk management, is incorporated within the framework of two-stage mixed integer programming. The mathematical formulation, which is called mean-risk model, is applied for the purpose of minimizing expected value. The process is formulated as a mixed integer linear programming model, implemented in GAMS (General Algebraic Modeling System) and solved using the CPLEX algorithm, a commercial solver embedded in GAMS. The computational results demonstrate the effectiveness of the proposed new methodology. The optimization model is applied to an existing Ontario Power Generation (OPG) fleet. Four planning scenarios are considered: a base load demand, a 1.0% growth rate in demand, a 5.0% growth rate in demand, a 10% growth rate in demand and a 20% growth rate in demand. A sensitivity analysis study is accomplished in order to investigate the effect of parameter uncertainties, such as uncertain factors on coal price and natural gas price. The optimization results demonstrate how to achieve the carbon emission mitigation goal with and without new technologies, while minimizing costs affects the configuration of the OPG fleet in terms of generation mix, capacity mix and optimal configuration. The selected new technologies are assessed in order to determine the risks of investment. Electricity costs with new technologies are lower than with the existing technologies. 60% CO2 reduction can be achieved at 20% growth in base load demand with new technologies. The total cost of electricity increases as we increase CO2 reduction or increase electricity demand. However, there is no significant change in CO2 reduction cost when CO2 reduction increases with new technologies. Total cost of electricity increases when fuel price increases. The total cost of electricity increases with financial risk management in order to lower the risk. Therefore, more electricity is produced for the industry to be on the safe side.