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A worldwide shift from fossil fuels to zero carbon energy sources is imperative to limit global warming to 1.5°C. While integrating high penetrations of VRE into the grid may introduce the need for upgrading an aging electrical system, renewable energy represents a new opportunity to decarbonize multiple sectors. Otherwise curtailed solar and wind energy can accelerate deep decarbonization in hard-to-reach sectors - transportation, industrial, residential, and commercial buildings, all of which must be decarbonized to limit global warming. With renewable energy as its input, electrolytic H₂ represents a solution to the supply-demand mismatch created by the proliferation of VREs on a grid designed for on-demand power. Electrolytic H₂ can stabilize the grid since the H2 created can be stored and transferred. Thus, Chapter 1 introduces the opportunity of green H2 in the context of low-cost VREs as a means of deep decarbonization through sector coupling, and an overview of the techno-economics, key technologies, and life cycle assessment versus the incumbent steam methane reformation. The growing imbalances between electricity demand and supply from VREs create increasingly large swings in electricity prices. Capable of operating with variable input power and high current densities without prohibitively large ohmic losses, polymer electrolyte membrane (PEM) electrolyzers are well suited to VREs. In Chapter 2, polymer electrolyte membrane (PEM) electrolyzers are shown to help buffer against these supply demand imbalances, while simultaneously minimizing the levelized cost of hydrogen (LCOH) by ramping up production of H2 through high-current-density operation when low-cost electricity is abundant, and ramping down current density to operate efficiently when electricity prices are high. A techno-economic model is introduced that optimizes current density profiles for dynamically operated electrolyzers, while accounting for the potential of increased degradation rates, to minimize LCOH for any given time-of-use (TOU) electricity pricing. This model is used to predict LCOH from different methods of operating a PEM electrolyzer for historical and projected electricity prices in California and Texas, which were chosen due to their high penetration of VREs. Results reveal that dynamic operation could enable reductions in LCOH ranging from 2% to 63% for historical 2020 pricing and 1% to 53% for projected 2030 pricing. Moreover, high-current-density operation above 2.5 A cm−2 is shown to be increasingly justified at electricity prices below $0.03 kWh−1. These findings suggest an actionable means of lowering LCOH and guide PEM electrolyzer development toward devices that can operate efficiently at a range of current densities. Chapter 3 uses techno-economic modeling to analyze the benefits of producing green (zero carbon) hydrogen through dynamically operated PEM electrolyzers connected to off-grid VREs. Dynamic electrolyzer operation is considered for current densities between 0 to 6 A cm-2 and compared to operating a PEM electrolyzer at a constant current density of 2 A cm-2. The analysis was carried out for different combinations of VRE to electrolysis (VRE:E) capacity ratios and compositions of wind and solar electricity in 4 locations – Ludlow, California, Dalhart, Texas, Calvin, North Dakota, and Maple Falls, Washington. For optimal VRE:E and wind:PV capacity ratios, dynamic operation of the PEM electrolyzer was found to reduce the LCOH by 5% to 9%, while increasing H₂ production by 134% to 173%, and decreasing excess (i.e. curtailed) electrical power by 82% to 95% compared to constant current density operation. Under dynamic electrolyzer operation, the minimum LCOH is achieved at higher VRE:E capacity ratios than constant current density operation and a VRE mix that was more skewed to whichever VRE source with the higher capacity factor at a given location. In addition, dynamically operated electrolyzers are found to achieve LCOH values within 10% of the minimum LCOH over a significantly wider range of VRE:E capacity ratios and VRE mixes than constant electrolyzers. As demonstrated, the techno-economic framework described herein may be used to determine the optimal VRE:E capacity and VRE mix for dynamically-operated green hydrogen systems that minimize cost and maximize the amount of H2 produced. Chapter 4 focuses on the production of high-purity water and H₂ from seawater. Current electrolyzers require deionized water so they need to be coupled with desalination units. This study shows that such coupling is cost-effective in H₂ generation, and offers benefits to thermal desalination, which can utilize waste heat from electrolysis. Furthermore, it is shown that such coupling can be optimized when electrolyzers operate at high current density, using low-cost solar and/or wind electricity, as such operation increases both H₂ production and heat generation. Results of techno-economic modeling of PEM electrolyzers define thresholds of electricity pricing, current density, and operating temperature that make clean electrolytic hydrogen cost-competitive with H₂ from steam methane reforming. By using 2020 hourly electricity pricing in California and Texas, H₂ is shown to be produced from seawater in coupled desalination-electrolyzer systems at prices near $2, reaching cost parity with SMR-produced H₂. Chapter 5 concludes the dissertation with an overview of the challenges and research needs for PEM electrolyzers at scale, including projected iridium needs, iridium thrifting, recycling methods, key degradation mechanisms, a failure modes and effects analysis, and LCOH projections.

As the cost of variable renewable energy resources like wind and solar decline rapidly the major barrier to decarbonization of the electrical grid becomes that of energy storage. Current storage technologies are much too expensive to justify widespread adoption and it is unclear what type of technology is even capable of fulfilling this role. Flow batteries are an often proposed technological solution to this problem but they are plagued by high cost and reliability issues due to the expensive and complex balance of plant included in the system design. In this work a new design for a gravity driven flow battery is explored which is capable of drastically lowering the cost of flow batteries by removing the pumps and membranes and replacing their function with density stratification and flow driven by the density change of the electrode reactions. A design for a zinc-bromine battery which makes use of this free convection during operation is explored. The system is studied through construction of prototype cells, exploration of key design variables, and a techno-economic analysis of the technology is performed showing cost viability. The free convection phenomenon which underlies the battery operation is expanded upon by connecting non-dimensional correlations in heat transfer with electrochemical transport equations in order to create predictive understanding of flow behavior based on system composition. This correlative understanding is used to construct a model of a zinc-bromine gravity driven flow battery. This model shows results which align with experimental data and gives insight into the complex transport dynamics of the system.

The response to climate change must include decisive and collaborative solutions that minimize global CO₂ emissions and enable a shift to low-carbon energy (renewable electricity) and CO₂-derived chemicals and fuels. A major challenge of minimizing fossil fuel use is producing critical chemicals and fuels for heavy industry and transportation in novel ways. These traditionally fossil-derived products can be derived from CO₂ that is captured from point sources or the atmosphere. Reactive CO₂ capture is an emerging area of research that focuses on developing materials and processes for CO₂ capture and in situ conversion to valuable chemicals or fuels. By combining these two steps, costly and energy-intensive steps of conventional integrated capture and conversion schemes are eliminated, including sorbent regeneration, CO₂ purification, pressurization, and transportation. These operations typically drive up the cost of capture and conversion processes, making them less economically attractive. The dual function material (DFM) is an Al₂O₃-supported, nano-dispersed catalyst and sorbent combination that demonstrates both capture and catalytic conversion properties, making reactive capture possible. Feasibility of the 1% Ru, 10% “Na₂O”/Al₂O₃ DFM for CO₂ direct air capture (DAC) and in situ catalytic methanation (DACM) has been demonstrated in previous work. Recent work has prioritized advanced laboratory testing and laboratory aging of this DFM under a variety of simulated ambient capture climates to assess the advantages and limitations of the material. A monolith was used as a structured support for the DFM to minimize reactor pressure drop, a particularly relevant challenge for DAC applications where large volumes of air must be processed to separate the small volume of CO₂ (~ 400 ppm). Findings from DFM monolith studies (1% Ru, 10% “Na₂O”/Al₂O₃//monolith) were shared with an engineering partner to support scale up efforts. Laboratory-simulated DACM cycles consisted of DAC performed at various real-world simulated ambient conditions followed by catalytic methanation, where the DFM was heated to 300°C in 15% H₂/N₂. Simulated DAC included O2 and humidity, and a surprising finding showed significant enhancement of CO₂ adsorption due to humidity in the capture feed. The maximum CO₂ capture capacity of the DFM monolith was measured to be 4.4 wt% (based on the weight of DFM material) at 25°C with 2 mol% H₂O in the DAC feed. Aging studies revealed consistent CO₂ capture and CH₄ production after over 450 hours of cyclic DACM testing that included simulated ambient conditions. No signs of deactivation of either the “Na₂O” sorbent or Ru catalyst were observed. The light-off temperature (indicative of kinetic control) observed for catalytic methanation was constant between fresh and aged cycles. These findings verified the qualifications of the 1% Ru, 10% “Na₂O”/Al₂O₃//monolith for the DACM application and supported further advanced bench and pilot plant testing by our engineering collaborator. Additional parametric studies were conducted to evaluate the effects of varying humidity during DAC and revealed that a higher H₂O concentration in the DAC feed correlates with greater CO₂ captured and converted with no evidence of competitive adsorption between CO₂ and H₂O. Additionally, it was found that temperature changes within ambient range (0 – 40°C) played little role in varying CO₂ captured under dry conditions, whereas moisture was found to be a major driver of capture capacity. Furthermore, stable performance at a reference condition was always achieved after excursions to varying ambient conditions. DACM tests revealed 30 – 40% of captured CO₂ desorbs during the temperature swing step, which was attributed mainly to the slow heating rate and low H₂ content (15%) required for safe laboratory operation. Unreacted CO₂ was eliminated by shortening the DAC step and engaging partial capture capacity of the DFM. This mode of cycling is more representative of that which would be carried out at scale, as shorter adsorption durations capitalize on the fastest adsorption kinetics exhibited by a capture material. Consistent with reported literature, findings suggest that CO₂ is preferentially adsorbed to stronger capture sites at the onset of DAC that are better able to retain CO₂ during heat up. Though the DFM is not fully utilized, these partial capacity cycles demonstrated higher conversions to CH₄ and a more efficient use of the material that will require less downstream purification at scale.

Hydraulic fracture is a well-developed and widely used technology across petroleum upstream operations. The process involves the high-pressure injection of ‘fracking fluid’, mainly water containing proppants and thickening agents, into wells to form underground artificial fractures. The fracking fluid extends forward and supports those fractures to create diversion channels which lead to increased production. Therefore, it is of great significance to improve the permeability of the fractured formation, which leads to increased oil and gas production, and improved efficiency of oil and gas wells. Due to the importance of conductivity in such operations, the quality of s proppants are a critical factor affecting the fracturing efficiency and stimulation. For improvement of proppant, high strength often comes at the cost of increased density. During fracturing stimulation, it demands a higher flow rate, viscosities, and pumping pressure. It also results in the consumption of a significant amount of power, fresh water and produces more greenhouse gas and chemical pollution in the formation and the well site. This study investigated the production of an Ultra-Lightweight Proppant made by Graphene Aerogel (GA) and Epoxy Resin (ER) composite. GA with graphene as the basic structural unit is a low-density solid material with a high specific surface area, abundant nanoporous structure and good mechanical properties. Cured ER has the characteristics of small deformation and shrinkage, good dimensional stability, and high hardness. ER is one of the commonly used substrates in resin matrix composites. The main research contents of this study are as follows: 1. Using graphene oxide solution as a precursor to prepare graphene hydrogels, then make graphene aerogels through supercritical drying or freeze-drying. The graphene aerogel was placed in ER, followed by immersion in a vacuum environment, and then thermally cured to obtain a graphene aerogel-epoxy composite. The prepared GA has a network microstructure; the ER combined with the aerogel, and the composite material have good mechanical properties, strength is about 50 MPa. Specific gravity is 1.2, 55% lighter than silica sand and 63% lighter than ceramic proppant. 2. Spherical GA were produced using a droplet freezing method, which was combined with ER to create spherical fracturing proppants. The graphene aerogel-epoxy resin composite compressive strength is about 30 MPa, which is significantly higher than silica sand. The sphericity is about 0.9, better than silica sand (0.6-0.8) and same as ceramic proppant (0.9). its crushing rate is better than intermediate-density ceramic at 50, 70, and 100 MPa. The conductivity test showed that this new proppant was 30% and 50% higher than traditional silica sand and ceramic. 3. In the Field study, collecting core sampling and fluid analysis results to evaluate the porosity formation, permeability, fluid density and oil viscosity. Analyzation of the fracturing treatment data for the pressure testing data within the current field. Using the test results of the graphene aerogel spherical epoxy proppant (GAS-EP) modelling conducted for fracturing half-length and fracturing width, the result showing the new proppant can improve the fracturing length by 35% and increase oil Estimated ultimate recovery (EUR) volume about 10K bbl. 4. Based on field data and modelling results, horizontal well decline curve were generated for each scenario, using economic indicators, such as NPV value, payback time and others estimated that the break-even price of GAS-EP will be $2800/t. 5. Discuss the environmental benefits, using GAS-EP could reduce chemical additives by 4600L, reduce freshwater consumption 190m³ and reduce CO₂ emission 1.3 tons for a single fracturing stimulation. The study resulted in the production of a novel proppant with improved properties compared to the conventional materials. The results of this study provide a better understanding of the novel proppant properties and concluded that the novel proppant could safely use in the petroleum industry for enhance hydrocarbon recovery and significant environmental and economic benefits.

Reducing carbon emissions is a looming challenge that will be required to limit global warming. One approach is to replace energy from fossil fuels with renewable electricity that has low carbon footprints. The continuous decrease of renewable electricity prices makes electrochemical processes very promising for environmentally friendly production of fuels and chemicals. One of the mature electrochemical processes is hydrogen (H₂) production from water electrolysis. If only excess solar/wind electricity is used to power water electrolyzers to produce green H₂, the intermittency of the electricity supply will require low-cost electrolyzer technologies. Emerging membraneless water electrolyzers offer an attractive approach to lowering the cost of H₂ production by eliminating membranes or diaphragms that are used in conventional water electrolyzers. One aim of this dissertation is to understand the performance limits of membraneless water electrolyzers compared to the conventional designs. Another key electrochemical process to reduce carbon emissions is the conversion of carbon dioxide (CO₂) to value-added fuels and chemicals. CO₂ captured from air or flue gas needs to be extracted from carbon capture solution and pressurized before feeding to a conventional CO₂ electrolyzer. In order to avoid these energy intensive steps to make pressurized CO₂, there is a growing interest in developing membrane-based electrolyzers that can directly utilize the carbon capture solution to conduct electrochemical CO₂ conversion. This dissertation also explores a scalable membrane-free electrolyzer design that can convert carbon capture solution to syngas. In Chapter 2, a parallel plate membraneless electrolyzer is used as a model system to demonstrate a combined experimental and modeling approach to explore its performance limits. This modeling framework quantitatively describes the trade-offs between efficiency, current density, electrode size, and product purity. Central to this work is the use of in situ high-speed videography (HSV) to monitor the width of H₂ bubble plumes produced downstream of parallel plate electrodes as a function of current density, electrode separation distance, and the Reynolds number (Re) associated with flowing 0.5 M H₂SO₄ electrolyte. These measurements reveal that the HSV-derived dimensionless bubble plume width serves as an excellent descriptor for correlating the aforementioned operating conditions with H₂ crossover rates. These empirical relationships, combined with electrochemical engineering design principles, provide a valuable framework for exploring performance limits and guiding the design of optimized membraneless electrolyzers. This framework shows that the efficiencies and current densities of optimized parallel plate membraneless electrolyzers constrained to H₂ crossover rates of 1% can exceed those of conventional alkaline electrolyzers but are lower than the efficiencies and current densities achieved by zero-gap polymer electrolyte membrane (PEM) electrolyzers. Chapter 3 presents a packed bed membraneless electrolyzer (PBME) design for which liquid bicarbonate electrolyte flows sequentially through alternating porous flow-through anodes and cathodes. Within this design, hydrogen oxidation at porous anodes is used to produce protons that trigger in situ CO₂ release immediately upstream of porous cathodes, where electrochemical CO₂ reduction generates the desired product and returns the solution pH back towards its inlet value. By using the sequential flow-cell arrangement, the PBME offers the ability to mitigate large concentration overpotentials and non-uniform current distributions that naturally arise during scale-up of conventional membrane-based devices that rely on lateral flow of catholyte parallel to the surface of the electrodes. This study uses in situ colorimetric imaging to highlight the ability of PBME to rebalance pH across electrodes. In addition, results obtained with a multi-cell PBME “stack” demonstrate the scalability of this concept and reveal the ability to increase CO₂ utilization from 12.9% for a single-cell PBME up to 20.5% for a four-cell PBME operated under baseline conditions. Modeling results indicate that current utilization values >80% are theoretically possible for optimized multi-cell PBMEs operated at ambient pressure. Chapter 4 demonstrates a stacked PBME design and an elevated pressure system. Hydrogen oxidation at the anode and hydrogen evolution at the cathode are conducted in this device at pressures up to 5 atm. The pressure of the system can be held at a constant value by the use of a back pressure regulator, and product gases can be collected with a gas sampling bag that’s directly connected to the back pressure regulator. The stereolithography 3D printing technology is used to fabricate components of the PBME from clear resin, which is suitable for the elevated pressure operation. Post-processing of the components makes surfaces transparent for imaging bubble dynamics in the device. Within this system, HOR current density of 120 mA cm-2 can be achieved at different pressures. Finally, Chapter 5 provides concluding remarks and discusses future opportunities and challenges for membraneless electrolyzers for water electrolysis and electrochemical CO₂ conversion.

This dissertation contains two collections of analyses, both broadly focused on energy system planning, but motivated by different research objectives in distinct geographic settings. Part I – Chapters I-III – evaluates decarbonization strategies in New York. These studies are characteristic of the primary energy-related challenge faced by the Global North: How can states cost-effectively meet time-bound emissions reduction targets? A series of linear programs are developed to answer this question, culminating in the System Electrification and Capacity TRansition (SECTR) model, a high-fidelity representation of the New York State energy system that characterizes statewide emissions and allows for comparative study of various decarbonization pathways. SECTR simulations indicate that prioritizing heating and vehicle electrification alongside an expansion of instate wind and solar generation capacity allows New York to meet recently legislated climate goals more affordably than through approaches that mandate substantial low-carbon electricity targets. Additional work also explores the optimal distribution of energy infrastructure within New York to meet specified decarbonization targets, along with the value of supply-side, demand-side, and bidirectional methods of system flexibility. Part II of this dissertation – Chapters IV-VII – is concerned with the energy system challenges faced by the lowest income countries. Set in the Ethiopian Highlands, this work first aims to locate smallholder irrigated areas, as irrigation has attendant energy requirements that are larger and more likely to generate supplementary sources of revenue compared to residential demands. Here, a novel classification methodology is developed to collect labeled data, train a machine learning-based irrigation detection model, and understand the spatial extent of model applicability. Across isolated plots of land as small as 30m by 30m, the resulting model achieves >95% prediction accuracy. Further studies then explore the system planning implications of simulated electricity demands associated with these irrigated areas.

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 (MBA (Business Management))--University of Stellenbosch, 2009.

Thesis (MBA)--Stellenbosch University, 2012. / Companies produce carbon and GHG emissions in the course of doing business. Climate change issues and the impact of global warming affect business conditions. Companies need to deal with these issues and to introduce procedures for their mitigation. They can also aim to formulate strategies to enable the company to achieve a sustainable future. This study was designed to evaluate the motivation for South African businesses to voluntarily invest in becoming carbon neutral and to assess the payoff when adopting such strategies. This study has defined the concept of carbon neutrality, the opportunities of pursuing such a strategy and the risks of not doing so for the purpose of understanding the motivational drivers. An adapted framework was developed to assess whether or not such strategies are attractive. The empirical study examined four companies in terms of motivation. The exploratory case studies were compared to the descriptions and the frameworks discussed in the literature review. The study should serve to inform other companies of the possible opportunities and risks of lowcarbon initiatives. Exploring the methods leading to carbon neutrality should also serve as a tool for companies willing to participate in such projects.