The industrial sector is one of the largest emitters of CO2 and a great potential for retrofitting with carbon capture systems. In this work the performance of a palladium-based membrane reactor at 400°C and operating pressures between 100-400 kPa have been studied in terms of methane conversion, hydrogen recovery, hydrogen purity, and CO2 emission. It is found that the MR has the potential to produce high purity hydrogen while the methane conversion values could be as high as 40% at very moderate operating conditions and without using any sweep gases. The H2 permeation and separation properties of two Pd-based composite membranes were evaluated and compared at 400 °C and at a pressure range of 150 kPa to 600 kPa. One membrane was characterized by an approximately 8 μm-thick palladium (Pd)-gold (Au) layer deposited on an asymmetric microporous Al2O3 substrate; the other membrane consisted of an approximately 11 μm-thick pure palladium layer deposited on a yttria-stabilized zirconia (YSZ) support. At 400 °C and with a trans-membrane pressure of 50 kPa, the membranes showed a H2 permeance of 8.42 × 10−4 mol/m2·s·Pa0.5 and 2.54 × 10−5 mol/m2·s·Pa0.7 for Pd-Au and Pd membranes, respectively. Pd-Au membrane showed infinite ideal selectivity to H2 with respect to He and Ar at 400 °C and a trans-membrane pressure of 50 kPa, while the ideal selectivities for the Pd membrane under the same operating conditions were much lower. Furthermore, the permeation tests for ternary and quaternary mixtures of H2, CO, CO2, CH4, and H2O were conducted on the Pd/YSZ membrane. The H2 permeating flux decreased at the conclusion of the permeation tests for all mixtures. This decline however, was not permanent, i.e., H2 permeation was restored to its initial value after treating the membrane with H2 for a maximum of 7 h. The effects of gas hourly space velocity (GHSV) and the steam-to-carbon (S/C) ratio on H2 permeation were also investigated using simulated steam methane reforming mixtures. It was found that H2 permeation is highest at the greatest GHSV, due to a decline in the concentration polarization effect. Variations in S/C ratio however, showed no significant effect on the H2 permeation. The permeation characteristics for the Pd/YSZ membrane were also investigated at temperatures ranging from 350 to 400 °C. The pre-exponential factor and apparent activation energy were found to be 5.66 × 10−4 mol/m2·s·Pa0.7 and 12.8 kJ/mol, respectively. Scanning Electron Microscope (SEM) and X-ray diffraction (XRD) analyses were performed on both pristine and used membranes, and no strong evidence of the formation of Pd-O or any other undesirable phases was observed. The permeation tests with pure hydrogen and inert gases indicate that the MR is highly selective toward hydrogen and the produced hydrogen is an ultrahigh purity grade. The carbon capture experiments in the work consists of dehydrating the retentate stream and redirecting it to a 13X packed bed before analyzing the stream via mass spectrometry. The carbon capture studies reveal that approximately 5.96 mmole CO2 (or 262.25 mg of CO2)can be captured per g of 13X. In this study, SEM-EDS, and XRD technics have been used to characterize the crystallography and morphology of the membrane surface. These material characterization techniques reveal that the surface of the membrane has gone through significant oxidation during the steam methane reforming reaction, although this oxidation is only limited to the few nanometers of depth through the surface of the palladium membrane.

In this study a roof-top PVT/absorption chiller system is modeled for a hotel building in Antalya, Turkey to cover the cooling demand of the hotel, to produce electricity and domestic hot water. PVT modules, an absorption chiller, a hot storage tank and a natural gas fired auxiliary heater are the main components of the system. Elecetrical power produced by the system is 94.2 MWh, the cooling power is 185.5 MWh and the amount of domestic hot water produced in the system is 65135 m3 at 45 0C annually.  Even though the systems is capable of meeting the demands of the hotel building, because of the high investment costs of PVT modules and high interest rates in Turkey, it is not economically favorable. Using cheaper solar collectors, integrating a cold storage unit in the system or having an improved conrol strategy are the options to increase the system efficiency and to make the system economically competitive.

Every day 493 tonnes of waste containing 67% of organic material is generated in the city of El Alto in Bolivia. The majority of the waste is disposed to a landfill that is expected to reach its maximum capacity by 2015. Therefore, new waste treatment methods need to be explored. The high content of organic material in waste makes biogas technologies a potential solution for waste treatment in El Alto. These technologies can generate a renewable energy source and organic fertilizer that can provide several benefits to the city. The objective of this study is to investigate the techno-economic feasibility of a small-scale biogas plant for treating organic market waste in the city of El Alto. To this end, a multi-criteria analysis was performed to identify a suitable technology. The garage-shaped digester was selected as the most appropriate technology for the conditions of El Alto. By implementing this technology, 1.8 GWh of electricity and 2,340 tonnes of organic fertilizer can be produced annually. Furthermore, an economic analysis of two scenarios was conducted. The Net Present Value (NPV), Internal Rate of Return, Payback time, Levelized Cost of Electricity (LCOE) and sensitivity analysis were evaluated. The biogas plant resulted economically viable in both cases. However, the LCOE estimated (0.17-0.26 USD/kWh) were very high in comparison to the LCOE from natural gas in Bolivia (0.026 USD/kWh). Regarding the sensitivity analysis, several parameters were evaluated from which the compost price was the most influential on changing the NPV. The study also included the estimation of the emission savings. A total of 900 tonnes of CO2/year could be avoided for producing electricity from biogas. Moreover, social benefits could also be generated such as new job opportunities. The use of a small-scale biogas plant for treating organic market waste in the city of El Alto is a cost-effective option. Though, it is fundamental that the government support the waste-to-biogas technologies by introducing economic mechanisms and promoting awareness to ensure the markets for both, biogas and organic fertilizer.

The development of high capacity factor solar power plants is an interesting topic, especially when considering the climate and economic conditions of a location such as the Chilean Atacama Desert. The hybridisation of solar photovoltaic (PV) and concentrating solar power (CSP) technologies for such an application is a promising collaboration. The low cost of PV and dispatchability of CSP, integrated with thermal energy storage (TES), has the promise of delivering baseload electricity at a lower cost than what could be achieved with CSP alone. Therefore, the objective of this work was to evaluate whether or not a hybrid PV-CSP plant is more economically viable, than CSP alone or hybrid PV-diesel, for baseload generation. To analyse this hypothesis, a techno-economic optimisation study of a PV-CSP hybrid plant with battery storage and fossil fuel backup was performed. In doing so, a methodology for the identification of optimum solar hybrid plant configurations, given current technology and costs, to best satisfy specific location weather and economic conditions was developed. Building on existing models, for the PV and CSP components, and developing models for further hybridisation, a complete PV-CSP model was created that could satisfy a baseload demand. Multi-objective optimisations were performed to identify optimal trade-offs between conflicting technical, economic and environmental performance indicators. For the given economic and technical assumptions, CSP hybridised with fossil fuel backup was shown to provide electricity at the lowest cost and have the lowest project capital expenditure. This configuration showed a 42% and 52% reduction in the levelised cost of electricity in comparison to CSP alone and hybrid PV-diesel, respectively. It also provides a 45% reduction in CAPEX in comparison to CSP alone. PV-CSP integration increases capital costs and the cost of electricity, but reduced the use of fossil fuel backup and thereby reduced emissions, when compared to CSP with fossil fuel backup. However PV-CSP showed a 97% reduction in CO2 emissions when compared to hybrid PV-diesel. Furthermore, it showed a 35% and 46% reduction in LCOE in comparison to CSP alone and hybrid PV-diesel.

Healthcare in developing countries is confronted with a shortage of skilled healthcare workforce, medical errors, inequity and inefficient healthcare service delivery. Innovative ways of solving healthcare problems through Information and communication technology (ICT) can improve the efficiency, effectiveness, access and quality of the healthcare system. Despite highly anticipated benefits of eHealth system to improve the efficiency of healthcare delivery, the healthcare had barely begun to take advantage of ICT mainly in a resource-constrained environment. The implementation of eHealth systems in developing countries could not proceed beyond the pilot phase to demonstrate sustainability in a large-scale rollout. The general research problem in this thesis focuses on how factors of eHealth implementation interplay to influence technology and information use to ensure the long-term sustainability of eHealth in resource-constrained settings. Systems thinking and system dynamics modelling method were used to handle complexity in the implementation of eHealth. Moreover, sustainability theory, technology acceptance model (TAM) and IS success models were used to develop a system dynamics model of sustainable eHealth implementation. The socio-technical, techno-organizational and techno-economic factors of sustainable eHealth systems are discussed to address the research objectives. The system dynamics simulation model of sustainable eHealth implementation is developed, verified, validated and tested. This applied research study focused on addressing the problems of sustainable eHealth systems implementation in resource-constrained environments. The model-based theory-building research study followed in this thesis aimed at enhancing the understanding of sustainable eHealth implementation in a resource-constrained environment to maximize the acceptance of eHealth by the end-users. Both the ontological and epistemological assumptions of this research study supported the position of the constructivist research paradigm. Methodologically, this study mainly applies qualitative research methodology which is common in the interpretive approach. Structured and semi-structured questionnaires were used to elicit information from purposefully sampled eHMIS and SmartCare health facilities in Ethiopia. Field notes, document review, interview and focus group discussion data were analysed using ATLAS.ti software. Vensim DSS Version 6.3D was used to model and simulate the system dynamics model. Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) approach was followed in the systematic literature review of techno-economic factors. The simulation results confirmed that the ‘effectiveness of training’ was a dominant factor to improve the ‘acceptance rate’ of eHMIS and SmartCare in the socio-technical dimension of sustainable eHealth implementation. The adequacy of ICT and healthcare workforce within eHealth implementing facility and end-users’ familiarity with digital technology showed a stronger influence on the ‘acceptance rate’ of both eHMIS and SmartCare systems in the techno-organizational dimension. An economic incentive, funding duration, funding amount, funding source and economic benefit are identified as techno-economic factors that influence the long-term sustainability of eHealth projects. / Thesis (PhD)--University of Pretoria, 2019. / Graduate School of Technology Management (GSTM) / PhD / Unrestricted

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To decrease global warming, bioenergy with carbon capture and storage (Bio-CCS) has been proposed as an effective and necessary tool. Combusting biomass and capturing carbon dioxide (CO2) from the same process results in net negative emissions, hence, reducing the concentration of CO2 in the atmosphere. The infrastructure around heat and power generation in Sweden has transformed to make use of biomass and waste. Bio-CCS has the potential to be a key factor in making the heat sector carbon negative and the Swedish energy system more sustainable. This study has assessed how Bio-CCS can practically be implemented in the Uppsala heat and power plant. In the assessment, three chemical absorption post-combustion carbon capture (CC) technologies were evaluated based on energy requirement, potential to reduce emissions and economics. They are the amine process, the chilled ammonia process (CAP) and the hot potassium carbonate process (HPC). The process of each technology was modelled by performing mass and energy balance calculations when implementing CC on the flue gas streams of the production units using biomass-based fuel at the plant. The modelling enabled finding specific heating, cooling and electricity requirements of the technologies. With this data it was possible to assess the potential emission reduction and CC cost for the different configurations assessed. A solution was proposed in how a CC technology can be integrated into the system of the Uppsala plant regarding land footprint, available heat supply to the process and possibilities for waste heat recovery. If heat recovery is not utilized the results show that the amine process is the most cost-effective technology when implemented on the flue gas stream of the waste blocks. When utilizing heat recovery to use waste heat to heat the district heating water, CAP becomes more cost-effective than the amine process. Further improvements can be achieved by combining flue gas streams of the waste blocks to increase the number of hours per year CC can be performed. The plant in Uppsala can then capture 200 000 tonne CO2 annually. The total cost of Bio-CCS will be approximately 900 SEK per tonne CO2 captured. / För att minska den globala uppvärmningen har infångning och lagring av koldioxid från förbränning av biomassa (Bio-CCS) föreslagits som ett effektivt och nödvändigt verktyg. Förbränning av biomassa och infångande av koldioxid från samma process leder till negativa nettoutsläpp, vilket minskar koncentrationen av koldioxid (CO2) i atmosfären. Infrastrukturen kring värme- och kraftproduktion i Sverige har omvandlats till att använda biomassa och avfall. Bio-CCS har potential att vara en nyckelfaktor för att göra värmesektorn koldioxidnegativ och det svenska energisystemet mer hållbart. Denna studie har analyserat hur Bio-CCS praktiskt kan implementeras i Uppsalas kraftvärmeverk. I analysen utvärderades tre infångningstekniker av typen kemisk absorption baserat på energibehov, potential att minska utsläpp och ekonomi. Teknikerna är aminprocessen, chilled ammonia process (CAP) och hot potassium carbonate process (HPC). Processen för varje teknik modellerades genom att utföra mass- och energibalansberäkningar vid infångning av CO2 från rökgasströmmarna producerade av produktionsenheterna som förbränner biomassa. Modelleringen gjorde det möjligt att hitta specifika värme-, kyl- och elbehov för teknikerna. Med dessa data var det möjligt att bedöma den potentiella utsläppsminskningen och kostnaden för infångning för de olika konfigurationer som har analyserats. En lösning föreslogs i hur en infångningsanläggning kan integreras i kraftvärmeverkets system när det gäller markanvändning, tillgänglig värmeförsörjning till processen och möjligheter till återvinning av spillvärme. Om värmeåtervinning inte utnyttjas visar resultaten att aminprocessen är den mest kostnadseffektiva tekniken när den implementeras på rökgasströmmen från avfallsblocken. När man använder värmeåtervinning för att använda spillvärme för att värma fjärrvärmevattnet blir CAP mer kostnadseffektivt än aminprocessen. Ytterligare förbättringar kan uppnås genom att kombinera rökgasströmmar från avfallsblocken för att öka antalet timmar per år infångning kan utföras. Anläggningen i Uppsala kan då årligen fånga 200 000 ton CO2. Den totala kostnaden för Bio-CCS kommer att vara cirka 900 SEK per ton infångad CO2.

As a promising approach for sustainable development, distributed energy systems have receive increasing attention worldwide and have become a key topic explored by researchers in the areas of building energy systems and smart grid. In line with this research trend, this dissertation presents a techno-economic analysis and optimization of distributed energy systems including combined heat and power (CHP), photovoltaics (PV), battery energy storage (BES), and thermal energy storage (TES) for commercial buildings. First, the techno-economic performance of the CHP system is analyzed and evaluated for four building types including hospital, large office, large hotel, and secondary school, located in different U.S. regions. The energy consumption of each building is obtained by EnergyPlus simulation software. The simulation models of CHP system are established for each building type. From the simulation results, the payback period (PBP) of the CHP system in different locations is calculated. The parameters that have an influence on the PBP of the CHP system are analyzed. Second, PV system and integrated PV and BES (PV-BES) system are investigated for several commercial building types, respectively. The effects of the variation in key parameters, such as PV system capacity, capital cost of PV, sell back ratio, battery capacity, and capital cost of battery, on the performance of PV and/or PV-BES system are explored. Finally, subsystems in previous chapters (CHP, PV, and BES) along with TES system are integrated together based on a proposed control strategy to meet the electric and thermal energy demand of commercial buildings (i.e., hospital and large hotel). A multi-objective particle swarm optimization (PSO) is conducted to determine the optimal size of each subsystem with the objective to minimize the payback period and maximize the reduction of carbon dioxide emissions. The results reveal how the key factors affect the performance of distributed energy system and demonstrate the proposed optimization can be effectively utilized to obtain an optimized design of distributed energy systems that can get a tradeoff between the environmental and economic impacts for different buildings.

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