Browsing by Author "Fidalgo, Beatriz"
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Item Open Access CFD modelling of particle shrinkage in a fluidized bed for biomass fast pyrolysis with quadrature method of moment(Elsevier, 2017-05-08) Liu, Bo; Papadikis, Konstantinos; Gu, Sai; Fidalgo, Beatriz; Longhurst, Philip J.; Li, Zhongyuan; Kolios, AthanasiosAn Eulerian-Eulerian multi-phase CFD model was set up to simulate a lab-scale fluidized bed reactor for the fast pyrolysis of biomass. Biomass particles and the bed material (sand) were considered to be particulate phases and modelled using the kinetic theory of granular flow. A global, multi-stage chemical kinetic mechanism was integrated into the main framework of the CFD model and employed to account for the process of biomass devolatilization. A 3-parameter shrinkage model was used to describe the variation in particle size due to biomass decomposition. This particle shrinkage model was then used in combination with a quadrature method of moment (QMOM) to solve the particle population balance equation (PBE). The evolution of biomass particle size in the fluidized bed was obtained for several different patterns of particle shrinkage, which were represented by different values of shrinkage factors. In addition, pore formation inside the biomass particle was simulated for these shrinkage patterns, and thus, the density variation of biomass particles is taken into account.Item Open Access CFD modelling of post-combustion carbon capture with amine solutions in structured packing columns(Cranfield University, 2016-06) Sebastia-Saez, J. Daniel; Gu, Sai; Fidalgo, BeatrizThe scope of the present thesis is the development of a Computational Fluid Dynamics model to describe the multiphase flow inside a structured packing absorber for postcombustion carbon capture. The work focuses mainly on two flow characteristics: the interface tracking and the reactive mass transfer between the gas and the liquid. The interface tracking brings the possibility of studying the liquid maldistribution phenomenon, which strongly affects the mass transfer performance. The development of a user-defined function to account for the reactive mass transfer between phases constitutes the second major concept considered in this thesis. Numerical models found in the literature are divided into three scales due to the current computational capacity: small-, meso- and large-scale. Small-scale has usually dealt with interface tracking in 2D computational domains. Meso-scale has usually been considered to assess the dry pressure drop performance of the packing (considering only the gas phase). Large-scale studies the liquid distribution over the whole column assuming that the structured packing behaves as a porous medium. This thesis focuses on small- and meso-scale. The novelty of this work lies in expanding the capabilities of the aforementioned scales. At small-scale, the interfacial tracking is implemented in a 3D domain, instead of 2D. The user-defined function that describes the reactive mass transfer of CO2 into the aqueous MEA solution is also included to assess the influence of the liquid maldistribution on the mass transfer performance. At the meso-scale, the Volume of Fluid method for interface tracking is included (instead of only the gas phase) to describe flow characteristics such as the liquid hold-up, the interfacial area and the mass transfer. At the theoretical level, this model presents the particularity of including both a mass and a momentum source term in the conservation equations. A comprehensive mathematical development shows the influence of the mass source terms on the momentum equation.Item Open Access Conceptual environmental impact assessment of a novel self-sustained sanitation system incorporating a Quantitative Microbial Risk Assessment approach(Elsevier, 2018-05-26) Anastasopoulou, Aikaterini; Kolios, Athanasios; Somorin, Tosin; Sowale, Ayodeji; Jiang, Ying; Fidalgo, Beatriz; Parker, Alison; Williams, Leon; Collins, Matt; McAdam, Ewan; Tyrrel, SeanIn many developing countries, including South Africa, water scarcity has resulted in poor sanitation practices. The majority of the sanitation infrastructures in those regions fail to meet basic hygienic standards. This along with the lack of proper sewage/wastewater infrastructure creates significant environmental and public health concerns. A self-sustained, waterless “Nano Membrane Toilet” (NMT) design was proposed as a result of the “Reinvent the Toilet Challenge” funded by the Bill and Melinda Gates Foundation. A “cradle-to-grave” life cycle assessment (LCA) approach was adopted to study the use of NMT in comparison with conventional pour flush toilet (PFT) and urine-diverting dry toilet (UDDT). All three scenarios were applied in the context of South Africa. In addition, a Quantitative Microbial Risk Assessment (QMRA) was used to reflect the impact of the pathogen risk on human health. LCA study showed that UDDT had the best environmental performance, followed by NMT and PFT systems for all impact categories investigated including human health, resource and ecosystem. This was mainly due to the environmental credits associated with the use of urine and compost as fertilizers. However, with the incorporation of the pathogen impact into the human health impact category, the NMT had a significant better performance than the PFT and UDDT systems, which exhibited an impact category value 4E + 04 and 4E + 03 times higher, respectively. Sensitivity analysis identified that the use of ash as fertilizer, electricity generation and the reduction of NOx emissions were the key areas that influenced significantly the environmental performance of the NMT system.Item Open Access Deoxygenation in anisole decomposition over bimetallic catalysts supported on HZSM-5(Elsevier, 2018-10-29) Zhang, Jiajun; Fidalgo, Beatriz; Wagland, Stuart; Shen, Dekui; Zhang, Xiaolei; Gu, SaiThis work investigated the deoxygenation reaction in anisole decomposition over HZSM-5 (HZ(25)) zeolite supported bimetallic catalysts to produce benzene, toluene and xylene (BTX). Experiments were performed in order to evaluate the synergistic effect between the two active metals with the focus on the effect of temperature, metal type, and metal loading ratio. Experimental results showed that 1%Ni-1%Mo/HZ(25) led to both the highest BTX yield (i.e. 30.0 wt%) and selectivity (i.e. 83.7%). On the contrary, bimetallic catalysts containing Fe were less effective in promoting the BTX production. It was identified that the optimum temperature for BTX production over 1%Ni-1%Mo/HZ(25) catalysts was 500 °C. Characterization of fresh and spent catalysts showed microcrystal particles of bi-metal loadings highly dispersed on the zeolite surface, and some agglomeration of metallic particles were also observed. Large amount of carbonaceous deposit was observed on the spent catalysts mainly in the form of amorphous. Density Functional Theory (DFT) modelling was carried out in order to study the adsorption energy of anisole and phenol molecules onto Ni-Mo, Ni-Fe and Mo-Fe surfaces; and the interactions between phenol molecule and bimetal surfaces were further analysed. All the analysed bimetal surfaces exhibited strong interactions with the adsorbed molecule. Ni-Mo surface declined electrons energy levels mainly around 1.5 eV in the adsorbate molecule and released the highest adsorption energy; while Ni-Fe and Mo-Fe surface led to more electrons exchange with the adsorbate during the adsorption. The modelling results agreed well with experiments by revealing that the strong binding between phenolic compounds (Phs) and the Ni-Mo based catalysts bimetal surface would lead to a higher BTX production in the deoxygenation reaction in the decomposition of anisole.Item Open Access Design and commissioning of a multi-mode prototype for thermochemical conversion of human faeces(Elsevier, 2018-03-23) Jurado Pontes, Nelia; Somorin, Tosin; Kolios, Athanasios J.; Wagland, Stuart; Patchigolla, Kumar; Fidalgo, Beatriz; Parker, Alison; McAdam, Ewan; Williams, Leon; Tyrrel, SeanThis article describes the design and commissioning of a micro-combustor for energy recovery from human faeces, which can operate both in updraft and downdraft modes. Energy recovery from faecal matter via thermochemical conversion has recently been identified as a feasible solution for sanitation problems in low income countries and locations of high income countries where access to sewage infrastructures is difficult or not possible. This technology can be applied to waterless toilets with the additional outcome of generating heat and power that can be used to pre-treat the faeces before their combustion and to ensure that the entire system is self-sustaining. The work presented here is framed within the Nano Membrane Toilet (NMT) project that is being carried out at Cranfield University, as part of the Reinvent the Toilet Challenge of the Bill and Melinda Gates Foundation. For this study, preliminary trials using simulant faeces pellets were first carried out to find out the optimum values for the main operating variables at the scale required by the process, i.e. a fuel flowrate between 0.4 and 1.2 g/min of dry faeces. Parameters such as ignition temperature, residence time, and maximum temperature reached, were determined and used for the final design of the bench-scale combustor prototype. The prototype was successfully commissioned and the first experimental results, using real human faeces, are discussed in the paper.Item Open Access Influence of temperature and particle size on structural characteristics of chars from beechwood pyrolysis(Elsevier, 2018-01-31) Yu, Jie; Sun, Lushi; Berrueco, César; Fidalgo, Beatriz; Paterson, Nigel; Millan, MarcosThis work investigates the effect of temperature and particle size on the product yields and structure of chars obtained from the pyrolysis of Beechwood Chips (BWC), a lignocellulosic biomass. BWC of three different size fractions (0.21–0.50 mm, 0.85–1.70 mm and 2.06–3.15 mm) were pyrolyzed at atmospheric pressure and temperatures ranging from 300 to 900 °C in a fixed bed reactor. Tar and gas yields increased with increasing temperature, while char yield decreased, particularly between 300 and 450 °C. The effect of particle size was mostly observed at temperatures lower than 400 °C as a larger char yield for larger particles due to intraparticle reactions. At higher temperatures the larger surface area in the char fixed bed favoured reactions increasing char and gas yields from the smaller particles. Pyrolysis chars were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Raman spectroscopy. Loss in oxygenated functional groups and aliphatic side chains with increasing temperature was revealed, along with an increase in the concentration of large aromatic systems, leading to a more ordered char structure but no significant graphitization. The changes in char nature at high temperature led to a loss in their combustion reactivity. Raman spectra indicated that the temperature needed to completely decompose the cellulose structure increased with biomass particle size and the enhanced intraparticle reactions in pyrolysis of large particles was likely to give rise to amorphous carbon structures with small fused ring systems.Item Open Access Mechanism of deoxygenation in anisole decomposition over single-metal loaded HZSM-5: Experimental study(Elsevier, 2017-11-20) Zhang, Jiajun; Fidalgo, Beatriz; Kolios, Athanasios; Shen, Dekui; Gu, SaiThis work investigates the deoxygenation reaction during the decomposition of anisole (methoxy-rich model compound of lignin) over bi-functional catalyst. The bi-functional catalyst consisted of a single metal loaded on an acid support; the active metals, i.e. Ni, Co, Mo and Cu, were loaded at various rates, and the acid support was HZSM-5 zeolite with a Si/Al ratio of 25 (HZ(25)). Experiments were conducted in a bench-scale fluidised bed reactor within the temperature range from 400°C to 600°C. Experimental results revealed that the increase in temperature and metal loading promoted the selectivity of BTX fraction. Nevertheless, a simultaneous increase in the yield of carbonaceous deposits was also observed at the expense of liquid fraction, both phenolics compounds (Phs) and aromatic hydrocarbons (AHs). 500°C was the preferred temperature for BTX production. Ni-loaded HZ(25) catalyst could dramatically facilitate the conversion of Phs to monoaromatics and increase the selectivity of BTX fraction by 43.4%; Mo-loaded HZ(25) catalyst exhibited the best catalytic activity towards the total production of AHs and promoted the BTX yield by 27.1%. It was also found that 1 wt.% was the optimum loading ratio for both Ni and Mo on HZ(25) to obtain the highest BTX yield and selectivity. Characterization of fresh bi-functional catalysts showed that micro polycrystalline metal sites, in the range of 4 -10 nm, existed on the fresh catalyst and exhibited strong interaction with the HZ(25) support. For the spent catalysts, large amount of amorphous carbonaceous deposit was observed, ascribed to the polycondensation of aromatic compounds during the reaction. Three reaction pathways were proposed for the catalytic deoxygenation of anisole, with the hydrogen being available in-situ as product of the polycondensation reactionsItem Open Access Mechanism of transmethylation in anisole decompostion over Brønsted acid sites: Density Functional Theory (DFT) study(Royal Society of Chemistry, 2017-08-15) Zhang, Jiajun; Fidalgo, Beatriz; Kolios, Athanasios; Shen, Dekui; Gu, SaiIn this work, the mechanism and intrinsic reaction energy barriers of transmethylation, as the initial stage of the catalytic and non-catalytic anisole decomposition, were investigated by Density Functional Theory (DFT). Molecule analyses indicated that methyl free radical transfer happened in the absence of catalyst, and the catalytic transmethylation over Brønsted acid sites was considered based on the dual electrophilic attack mechanism with protonation and carbocation substitution respectively. Reactions modelling for the formation of methyl-contained compounds in both non-catalytic and catalytic anisole decomposition indicated that the energy barriers were significantly decreased in the presence of catalyst by 60 kcal/mol at the most in the case of o-cresol. The results also revealed that the intrinsic transmethylation orientation preferred the ortho- and para-positions on the acceptor compounds contained oxygen-rich substituents due to its large electronegativity, and the lowest energy barrier was observed in the case of transmethylation towards the para-position of the cresol molecule (54.1 kcal/mol).Item Open Access Non-isothermal drying kinetics of human feces(Taylor & Francis, 2019-10-01) Somorin, Tosin Onabanjo; Fidalgo, Beatriz; Hassan, S.; Sowale, Ayodeji; Kolios, Athanasios; Parker, Alison; McAdam, Ewan; Tyrrel, SeanThe non-isothermal drying behavior and kinetics of human feces (HF) were investigated by means of thermogravimetric analysis to provide data for designing a drying unit operation. The effect of heating rate and blending with woody biomass were also evaluated on drying pattern and kinetics. At low heating rate (1 K/min), there is effective transport of moisture, but a higher heating rate would be necessary at low moisture levels to reduce drying time. Blending with wood biomass improves drying characteristics of HF. The results presented in this study are relevant for designing non-sewered sanitary systems with in-situ thermal treatment.Item Open Access Non-isothermal thermogravimetric kinetic analysis of the thermochemical conversion of human faeces(Elsevier, 2018-08-29) Fidalgo, Beatriz; Chilmeran, M.; Somorin, Tosin Onabanjo; Sowale, Ayodeji; Kolios, Athanasios; Parker, Alison; Williams, Leon; Collins, Matt; McAdam, Ewan J.; Tyrrel, Sean F.The “Reinvent the Toilet Challenge” set by the Bill & Melinda Gates Foundation aims to bring access to adequate sanitary systems to billions of people. In response to this challenge, on-site sanitation systems are proposed and being developed globally. These systems require in-situ thermal treatment, processes that are not well understood for human faeces (HF). Thermogravimetric analysis has been used to investigate the pyrolysis, gasification and combustion of HF. The results are compared to the thermal behaviour of simulant faeces (SF) and woody biomass (WB), along with the blends of HF and WB. Kinetic analysis was conducted using non-isothermal kinetics model-free methods, and the thermogravimetric data obtained for the combustion of HF, SS and WB. The results show that the devolatilisation of HF requires higher temperatures and rates are slower those of WB. Minimum temperatures of 475 K are required for fuel ignition. HF and SF showed similar thermal behaviour under pyrolysis, but not under combustion conditions. The activation energy for HF is 157.4 kJ/mol, relatively higher than SS and WB. Reaction order for HF is lower (n = 0.4) to WB (n = 0.6). In-situ treatment of HF in on-site sanitary systems can be designed for slow progressive burn.Item Open Access Performance assessment of biofuel production via biomass fast pyrolysis and refinery technologies(Cranfield University, 2016-01) Shemfe, Mobolaji B.; Fidalgo, Beatriz; Longhurst, PhilipBiofuels have been identified as one of several GHG emission strategies to reduce the use of fossil fuels in the transport sector. Fast pyrolysis of biomass is one approach to producing second generation biofuels. The bio-oil product of fast pyrolysis can be upgraded into essential gasoline and diesel range products with conventional refinery technologies. Thus, it is important to assess their techno- economic and environmental performance at an early stage prior to commercialisation. This research was conducted with the goal of evaluating and comparing the techno-economic and environmental viability of the production of biofuels from fast pyrolysis of biomass and upgrading of bio-oil via two refinery technologies, viz. hydroprocessing and zeolite cracking. In order to achieve this aim, process models of fast pyrolysis of biomass and bio-oil upgrading via hydroprocessing and zeolite cracking were developed. The fast pyrolysis model was based on multi-step kinetic models. In addition, lumped kinetic models of the hydrodeoxygenation reactions of bio-oil were implemented. The models were verified against experimental measurements with good prediction and formed the foundation for the development of a 72 t/day fast pyrolysis plant model in Aspen Plus®. Several strategies were proposed for the two pathways to enhance energy efficiency and profitability. All in all, the results revealed that the hydroprocessing route is 16% more efficient than the zeolite cracking pathway. Moreover, the hydroprocessing route resulted in a minimum fuel selling price of 15% lower than that from the zeolite cracking pathway. Sensitivity analysis revealed that the techno-economic and environmental performance of the both pathways depends on several process, economic and environmental parameters. In particular, biofuel yield, operating cost and income tax were identified as the most sensitive techno-economic parameters, while changes in nitrogen feed gas to the pyrolysis reactor and fuel yield had the most environmental impact. It was concluded that hydroprocessing is a more suitable upgrading pathway than zeolite cracking in terms of economic viability, energy efficiency, and GHG emissions per energy content of fuel produced.Item Open Access Physico-chemical properties of excavated plastic from landfill mining and current recycling routes(Elsevier, 2018-04-02) Canopoli, Luisa; Fidalgo, Beatriz; Coulon, Frederic; Wagland, Stuart T.In Europe over 5.25 billion tonnes of waste has been landfilled between 1995 and 2015. Among this large amount of waste, plastic represents typically 5–25 wt% which is significant and has the potential to be recycled and reintroduced into the circular economy. To date there is still however little information available of the opportunities and challenges in recovering plastics from landfill sites. In this review, the impacts of landfill chemistry on the degradation and/or contamination of excavated plastic waste are analysed. The feasibility of using excavated plastic waste as feedstock for upcycling to valuable chemicals or liquid fuels through thermochemical conversion is also critically discussed. The limited degradation that is experienced by many plastics in landfills (>20 years) which guarantee that large amount is still available is largely due to thermooxidative degradation and the anaerobic conditions. However, excavated plastic waste cannot be conventionally recycled due to high level of ash, impurities and heavy metals. Recent studies demonstrated that pyrolysis offers a cost effective alternative option to conventional recycling. The produced pyrolysis oil is expected to have similar characteristics to petroleum diesel oil. The production of valuable product from excavated plastic waste will also increase the feasibility of enhanced landfill mining projects. However, further studies are needed to investigate the uncertainties about the contamination level and degradation of excavated plastic waste and address their viability for being processed through pyrolysis.Item Open Access Probabilistic performance assessment of complex energy process systems - The case of a self-sustained sanitation system(Elsevier, 2018-02-22) Kolios, Athanasios; Jiang, Ying; Somorin, Tosin; Sowale, Ayodeji; Anastasopoulou, Aikaterini; Anthony, Edward J.; Fidalgo, Beatriz; Parker, Alison; McAdam, Ewan; Williams, Leon; Collins, Matt; Tyrrel, SeanA probabilistic modelling approach was developed and applied to investigate the energy and environmental performance of an innovative sanitation system, the “Nano-membrane Toilet” (NMT). The system treats human excreta via an advanced energy and water recovery island with the aim of addressing current and future sanitation demands. Due to the complex design and inherent characteristics of the system’s input material, there are a number of stochastic variables which may significantly affect the system’s performance. The non-intrusive probabilistic approach adopted in this study combines a finite number of deterministic thermodynamic process simulations with an artificial neural network (ANN) approximation model and Monte Carlo simulations (MCS) to assess the effect of system uncertainties on the predicted performance of the NMT system. The joint probability distributions of the process performance indicators suggest a Stirling Engine (SE) power output in the range of 61.5–73 W with a high confidence interval (CI) of 95%. In addition, there is high probability (with 95% CI) that the NMT system can achieve positive net power output between 15.8 and 35 W. A sensitivity study reveals the system power performance is mostly affected by SE heater temperature. Investigation into the environmental performance of the NMT design, including water recovery and CO2/NOx emissions, suggests significant environmental benefits compared to conventional systems. Results of the probabilistic analysis can better inform future improvements on the system design and operational strategy and this probabilistic assessment framework can also be applied to similar complex engineering systems.Item Open Access Study of the effect of the ultrasonic pretreatment on the hydrothermal liquefaction of microalgae(Cranfield University, 2016-02) Moure Abelenda, Alejandro; Longhurst, Philip; Fidalgo, BeatrizThe depletion of the reserves of fossil fuel promotes the search for sustainable renewable sources of energy. Due to their similarities with the petroleum products, the biofuels represent a better alternative than other clean energies. The conversion process greatly depends on the biomass composition, which is a topic of debate, especially when it increases the price of the food. Therefore, third generation biofuels, derived from algae, are better accepted by society than using other raw materials. Due to the way of cultivating and the high moisture content of microalgae, hydrothermal liquefaction (HTL) is the transformation technology most suitable for this type of feedstock. Even when the application of HTL to microalgae is quite recent, a lot of research is being done because of the good expectations for biofuel production. In this way, the best operating conditions have already been determined, they are the critical point of water (374 ˚C and 221 bar), and the research is focussing now in the improvement of the quality of the products and the upscaling to a continuous process. The most important product is the biocrude, which has a high content of oxygen and nitrogen. The use of hydrogen for the removal of these heteroatoms is one of the most investigated techniques. Especially important is the presence of nitrogen, as the large production of NOx upon combustion is banned. The use of ultrasound as a pretreatment technology before the HTL of the microalgae slurry is intended to increase the yield of the biocrude while reducing the severity of the operating conditions. Also, milder conditions result in lower nitrogen content of the biocrude. This thesis shows the results of the use of a sonication bath to disrupt the microalgae cells before being liquefied. Three different microalgae species were considered: Nannochloropsis gaditana (N. gad.), Scenedesmus almeriensis (S. alm.), and Tetraselmis suecica (T. suec.). The experiments were carried out in a tubular batch reactor without stirrer and with an electric heater. It was found that the ultrasonic pretreatment does not affect the performance of the HTL of microalgae. The lack of influence of the pretreatment on the quantity and quality of the liquefaction products could be related to the fact that the microalgae samples were already disrupted during the drying process to prepare the powder biomass. Moreover, the poor performance of the sonication bath, in terms of achieving the microalgae cell breakage, is also considered as explanation. Therefore, the analysis of the ultrasonic equipment was done to understand the reason for its poor operation. The characteristics of the sonication equipment (configuration, ultrasonic power output, and energy frequency) were defined for future experiments.Item Open Access Study of the mechanism of thermocatalytic decomposition of anisole for producing aromatic-rich fuel additives.(2017-05) Zhang, Jiajun; Fidalgo, Beatriz; Shen, Dekui; Wagland, StuartIn the context of the bio-based economy, lignin is a major source of aromatic compounds. Fast pyrolysis of lignin with catalytic reforming of the liquid fraction provides an efficient approach for producing aromatic hydrocarbons (AHs) as fuel additives. Methoxy compounds abundantly exist in the primary liquid products from fast pyrolysis of lignin, which further convert into phenolic and aromatic compounds via secondary pyrolysis and the upgrading reactions. This thesis focuses on the decomposition mechanism of the methoxyl group, using anisole as a model compound. Methyl transfer (transmethylation) as the primary reaction of the thermal decomposition of anisole, led to the prominent production of phenolic compounds (Phs). Plausible mechanisms for both non-catalytic and catalytic transmethylation were proposed, based on the analyses of the active sites on anisole and phenol by the means of DFT modelling. The intrinsic transfer orientation preferences onto relevant compounds were then predicted by corresponding reaction energy barriers. Experiments investigated the decomposition of anisole in a fluidized bed reactor over no catalysts and a series of HZSM-5 zeolite catalysts with different Si/Al atomic ratios. Study on transmethylation illustrated how the acid catalysts promoted the preferential formation of Phs. Deoxygenation reaction of the Phs as second stage reaction at higher temperatures produced AHs. Metal loaded acid (Bi-functional) catalysts designed by multiscale modelling were used in the investigation. Novel mechanism of anisole decomposition over bi-functional catalyst was proposed with the illustration of each role for metal and acid site in the catalysis. DFT modelling also predicted the reaction energy barriers of deoxygenation for various Phs to exhibit the metals effect in promoting the reactions. Experiments of anisole decomposition over the designed single and bi-metal based bi-functional catalysts revealed the distinct characteristics of each metal loading and their synergistic effect in promoting the BTX production.Item Open Access Thermodynamic analysis of a gamma type Stirling engine in an energy recovery system(Elsevier, 2018-04-01) Sowale, Ayodeji; Kolios, Athanasios J.; Fidalgo, Beatriz; Somorin, Tosin; Parker, Alison; Williams, Leon; Collins, Matt; McAdam, Ewan; Tyrrel, SeanThe demand for better hygiene has increased the need for developing more effective sanitation systems and facilities for the safe disposal of human urine and faeces. Non-Sewered Sanitary systems are considered to be one of the promising alternative solutions to the existing flush toilet system. An example of these systems is the Nano Membrane Toilet (NMT) system being developed at Cranfield University, which targets the safe disposal of human waste while generating power and recovering water. The NMT will generate energy from the conversion of human waste with the use of a micro-combustor; the heat produced will power a Stirling engine connected to a linear alternator to generate electricity. This study presents a numerical investigation of the thermodynamic analysis and operational characteristics of a quasi steady state model of the gamma type Stirling engine integrated into a combustor in the back end of the NMT system. The effects of the working gas, at different temperatures, on the Stirling engine performance are also presented. The results show that with the heater temperature of 390 °C from the heat supply via conduction at 820 W from the flue gas, the Stirling engine generates a daily power output of 27 Wh/h at a frequency of 23.85 Hz.