To produce an alternative fuel like Methanol from scratch, on a miniature scale- the reactants CO2 and H2O are sourced locally. Zero Emission Fuels B.V. (ZEF) does this by collecting carbon dioxide from the air, via carbon capture techniques and compressing it to high pressure of 55bars. As a consequence of humidity inside the captured CO2, condensation is observed which is detrimental to the life of the compressor. To avoid this, a packed-bed drying system is designed as an auxiliary to the rolling piston compressor. This study aims to understand and model these two systems and subsequently integrate them to examine the effects of their dynamic operation. The purpose of this model is to provide a design tool, with the ability to predict the reaction of the system when sized differently, in various environments.

At first, the physics and governing principles of the two subsystems are studied and a layered modelling approach was devised. The systems were modelled individually and then integrated using Simulink- a tool that allows this layering up of the models. To build a dynamic model of such a setup, a characteristic time scale analysis was performed to identify the relevant phenomena inside each subsystem. Significant internal factors to be modelled were variations in relative humidity and temperature caused by the drying system, the changes in thermo-physical properties of the gas due to a change in temperature and the pressure fluctuations caused by the compressor. The external factors to be modelled were the changes in ambient temperature over operation time, caused by a variation in solar irradiation. The main finding was that the compressor's characteristic time scale (300s) was considerably smaller than that of the drying system (4-8hours/day). This meant an almost instantaneous operation of the compressor, rendering it uninteresting in the dynamic model of the integrated system.

A mechanistic dynamic model of the drying system, based on literature, was made with inherent controls to flip it between adsorption and desorption modes. It is responsive to the changes in the ambient and allows optimisation by changing the duty cycles of energy inputs. The model was then validated using experimental data from two working prototypes at ZEF. Some heat and mass transfer properties were then fitted to conform to these setups. A methodology to obtain these parameters while sizing a new design is discussed. The key performance indicators, which are cycle time and cycle capacity are given by the model and are crucial in deciding the energy consumption of the system.

On the other hand, an empirical model is built to replicate the rolling-piston compressor. The compressor is treated like a grey box and is described by a polytropic coefficient. A novel approach to create a compressor map for a positive displacement compressor, that is not mass-produced, is chosen. This compressor map is then used to predict the mass flow and output temperature of the system. Since the compressor map is empirical, the model was also validated using data from the literature.

Finally, the drying system and the compressor were integrated, in the model and experiments, by means of a capillary tube. A model was made for this as well to obtain the `interacting parameters'- which were the mass flow into the compressor, mass flow out of the capillary tube and the temperature and pressure of this re-loop flow. The effects of integration and the consequences to other systems upstream and downstream of this setup were scrutinised.

To conclude, a validated model is built to size new iterations of the setup. Multiple cycle models of a packed bed drying system and compressor maps of positive displacement compressors- that are not found commonly in literature are explored in this study and recommendations to further develop them are given towards the end.

To produce an alternative fuel like Methanol from scratch, on a miniature scale- the reactants CO2 and H2O are sourced locally. Zero Emission Fuels B.V. (ZEF) does this by collecting carbon dioxide from the air, via carbon capture techniques and compressing it to high pressure of 55bars. As a consequence of humidity inside the captured CO2, condensation is observed which is detrimental to the life of the compressor. To avoid this, a packed-bed drying system is designed as an auxiliary to the rolling piston compressor. This study aims to understand and model these two systems and subsequently integrate them to examine the effects of their dynamic operation. The purpose of this model is to provide a design tool, with the ability to predict the reaction of the system when sized differently, in various environments.

At first, the physics and governing principles of the two subsystems are studied and a layered modelling approach was devised. The systems were modelled individually and then integrated using Simulink- a tool that allows this layering up of the models. To build a dynamic model of such a setup, a characteristic time scale analysis was performed to identify the relevant phenomena inside each subsystem. Significant internal factors to be modelled were variations in relative humidity and temperature caused by the drying system, the changes in thermo-physical properties of the gas due to a change in temperature and the pressure fluctuations caused by the compressor. The external factors to be modelled were the changes in ambient temperature over operation time, caused by a variation in solar irradiation. The main finding was that the compressor's characteristic time scale (300s) was considerably smaller than that of the drying system (4-8hours/day). This meant an almost instantaneous operation of the compressor, rendering it uninteresting in the dynamic model of the integrated system.

A mechanistic dynamic model of the drying system, based on literature, was made with inherent controls to flip it between adsorption and desorption modes. It is responsive to the changes in the ambient and allows optimisation by changing the duty cycles of energy inputs. The model was then validated using experimental data from two working prototypes at ZEF. Some heat and mass transfer properties were then fitted to conform to these setups. A methodology to obtain these parameters while sizing a new design is discussed. The key performance indicators, which are cycle time and cycle capacity are given by the model and are crucial in deciding the energy consumption of the system.

On the other hand, an empirical model is built to replicate the rolling-piston compressor. The compressor is treated like a grey box and is described by a polytropic coefficient. A novel approach to create a compressor map for a positive displacement compressor, that is not mass-produced, is chosen. This compressor map is then used to predict the mass flow and output temperature of the system. Since the compressor map is empirical, the model was also validated using data from the literature.

Finally, the drying system and the compressor were integrated, in the model and experiments, by means of a capillary tube. A model was made for this as well to obtain the `interacting parameters'- which were the mass flow into the compressor, mass flow out of the capillary tube and the temperature and pressure of this re-loop flow. The effects of integration and the consequences to other systems upstream and downstream of this setup were scrutinised.

To conclude, a validated model is built to size new iterations of the setup. Multiple cycle models of a packed bed drying system and compressor maps of positive displacement compressors- that are not found commonly in literature are explored in this study and recommendations to further develop them are given towards the end.

In conventional compressor technology, high pressure ratios are often achieved by multiple, successive compression stages. This is done to avoid high temperatures due to the adiabatic nature of most compression processes which deteriorates the working of oil lubrication. The aim of this work is to reduce a conventional four-stage system to only two stages as this may improve the size and expenses of the system. This goal combined with a long desired lifetime, makes that a compressor is developed that operates based on gas bearing technology.

The design is focused on two main subjects. Firstly, the load capacity of the gas bearings is significantly lower than oil lubricated bearings due to the reduced viscosity. To avoid mechanical contact and wear of the components this has been thoroughly analysed using finite element methods. The oscillating nature of the loads in the system enhances the squeeze effect from the Reynolds equation. Secondly, the sealing function of gas bearings opposing internal leakage is evaluated carefully to obtain a desired efficiency. Based on these simulations, the mechanical design of the compressor is optimized to improve the manufacturing of the compressor components.

In conventional compressor technology, high pressure ratios are often achieved by multiple, successive compression stages. This is done to avoid high temperatures due to the adiabatic nature of most compression processes which deteriorates the working of oil lubrication. The aim of this work is to reduce a conventional four-stage system to only two stages as this may improve the size and expenses of the system. This goal combined with a long desired lifetime, makes that a compressor is developed that operates based on gas bearing technology.

The design is focused on two main subjects. Firstly, the load capacity of the gas bearings is significantly lower than oil lubricated bearings due to the reduced viscosity. To avoid mechanical contact and wear of the components this has been thoroughly analysed using finite element methods. The oscillating nature of the loads in the system enhances the squeeze effect from the Reynolds equation. Secondly, the sealing function of gas bearings opposing internal leakage is evaluated carefully to obtain a desired efficiency. Based on these simulations, the mechanical design of the compressor is optimized to improve the manufacturing of the compressor components.

To answer the need for renewable fuels, Zero Emission Fuels is designing a microplant to create methanol from carbon dioxide and water from the ambient air using only renewable energy from solar panels. For this microplant, gaseous carbon dioxide must be compressed from 1 to 50 [bar] with the low mass flow of 336.7 [g/h]. This thesis examines the compression system which uses rolling piston compressors. This thesis also examines a solution to compress the carbon dioxide optimally.

Because of the low mass flows, the compressors are very small and have relatively high friction and leakage losses. Meanwhile, due to the high pressure ratio of the system, the temperature increase due to compression also poses a problem for the lubrication of the system. Therefore, this thesis looks for solutions for these problems while trying to gain a better understanding of what exactly is happening inside the compressors.

For the temperature regulation, different options for active cooling were assessed with a dimensionless analysis. Eventually, the concept of cooling through the compressor housing was chosen. Afterwards, a computational model was made to calculate the inner workings of the compressors and assess whether the concept of active cooling would still work. Then the computational model was verified by doing experimentation.

After that, the results from the model and the experimentation were compared. The model was able to predict the mass flow and the outside heat transfer coefficient accurately. However, the model was still off from the experimental values by quite a margin. After assessing all the data, the system seemed to perform better as a 2-stage system then as a 3-stage system. However, due to the inaccuracies of the model and experimentation, a definite recommendation on the number of stages of the system cannot be formed.

The capture of carbon dioxide before or after it is emitted has been regarded as a crucial mitigation pathway to prevent the rapidly increasing accumulation of CO2 in the atmosphere. The valorisation of the captured CO2 into value added products such as methanol provides an additional economic incentive to continue developing these technologies. The company Zero Emission Fuels B.V. (ZEF) is currently developing a mass-producible miniature methanol plant that houses a Direct Air Capture and CO2-compression unit, an Alkaline Electrolysis Cell, a Methanol Reactor, and a Distillation unit. Potential benefits of this approach are in the economies of scale of production, and autonomous operation in areas of high solar irradiation due to direct integration with PV systems.
To validate the microplant-concept from an environmental perspective, a research project was executed with the goal to establish the environmental profile of the microplant, to identify hotspots for impact mitigation, and to assess the position of the microplant’s environmental profile in relation to results of comparable technologies reported in literature. To do so, multiple technological development pathways were considered that project the current microplant’s performance into a range of future states.

The impact assessment of the future PV-powered air-to-methanol plant, suggests that it is likely that methanol produced using this approach will exhibit a low (negative cradle-to-gate) climate change impact along its production chain, especially compared to conventional methanol produced via the steam reforming of natural gas. Environmental trade-offs are incurred by the additional material demand compared to conventional methanol, instilled both by the electricity generation from PV panels and the added material demand of the thousands of micro-plants that need to be produced for sufficient methanol production volume.
Using polyamine sorbents for the process of capturing CO2 from the atmosphere inevitably leads to sorbent degradation which in turn can cause emissions of various substances. Using rough estimations via a worst/best case approach, it was analysed that emissions from the capture unit are relevant in three impact categories.
Overall, the additional material demand and sorbent-related emissions introduce significant trade-offs in between 5-8 impact categories, depending on the followed technological scenarios. Additional technological improvement may reduce the trade-off effect, leading to a reduction of trade-off categories to a number of four.

The analysis concluded that it is likely that there are benefits to using the microplant-approach to methanol production, though additional research is critical to iron out the large uncertainties that are paired with future-oriented life cycle assessment.

The capture of carbon dioxide before or after it is emitted has been regarded as a crucial mitigation pathway to prevent the rapidly increasing accumulation of CO2 in the atmosphere. The valorisation of the captured CO2 into value added products such as methanol provides an additional economic incentive to continue developing these technologies. The company Zero Emission Fuels B.V. (ZEF) is currently developing a mass-producible miniature methanol plant that houses a Direct Air Capture and CO2-compression unit, an Alkaline Electrolysis Cell, a Methanol Reactor, and a Distillation unit. Potential benefits of this approach are in the economies of scale of production, and autonomous operation in areas of high solar irradiation due to direct integration with PV systems.
To validate the microplant-concept from an environmental perspective, a research project was executed with the goal to establish the environmental profile of the microplant, to identify hotspots for impact mitigation, and to assess the position of the microplant’s environmental profile in relation to results of comparable technologies reported in literature. To do so, multiple technological development pathways were considered that project the current microplant’s performance into a range of future states.

The impact assessment of the future PV-powered air-to-methanol plant, suggests that it is likely that methanol produced using this approach will exhibit a low (negative cradle-to-gate) climate change impact along its production chain, especially compared to conventional methanol produced via the steam reforming of natural gas. Environmental trade-offs are incurred by the additional material demand compared to conventional methanol, instilled both by the electricity generation from PV panels and the added material demand of the thousands of micro-plants that need to be produced for sufficient methanol production volume.
Using polyamine sorbents for the process of capturing CO2 from the atmosphere inevitably leads to sorbent degradation which in turn can cause emissions of various substances. Using rough estimations via a worst/best case approach, it was analysed that emissions from the capture unit are relevant in three impact categories.
Overall, the additional material demand and sorbent-related emissions introduce significant trade-offs in between 5-8 impact categories, depending on the followed technological scenarios. Additional technological improvement may reduce the trade-off effect, leading to a reduction of trade-off categories to a number of four.

The analysis concluded that it is likely that there are benefits to using the microplant-approach to methanol production, though additional research is critical to iron out the large uncertainties that are paired with future-oriented life cycle assessment.

The capture of carbon dioxide before or after it is emitted has been regarded as a crucial mitigation pathway to prevent the rapidly increasing accumulation of CO2 in the atmosphere. The valorisation of the captured CO2 into value added products such as methanol provides an additional economic incentive to continue developing these technologies. The company Zero Emission Fuels B.V. (ZEF) is currently developing a mass-producible miniature methanol plant that houses a Direct Air Capture and CO2-compression unit, an Alkaline Electrolysis Cell, a Methanol Reactor, and a Distillation unit. Potential benefits of this approach are in the economies of scale of production, and autonomous operation in areas of high solar irradiation due to direct integration with PV systems.
To validate the microplant-concept from an environmental perspective, a research project was executed with the goal to establish the environmental profile of the microplant, to identify hotspots for impact mitigation, and to assess the position of the microplant’s environmental profile in relation to results of comparable technologies reported in literature. To do so, multiple technological development pathways were considered that project the current microplant’s performance into a range of future states.

The impact assessment of the future PV-powered air-to-methanol plant, suggests that it is likely that methanol produced using this approach will exhibit a low (negative cradle-to-gate) climate change impact along its production chain, especially compared to conventional methanol produced via the steam reforming of natural gas. Environmental trade-offs are incurred by the additional material demand compared to conventional methanol, instilled both by the electricity generation from PV panels and the added material demand of the thousands of micro-plants that need to be produced for sufficient methanol production volume.
Using polyamine sorbents for the process of capturing CO2 from the atmosphere inevitably leads to sorbent degradation which in turn can cause emissions of various substances. Using rough estimations via a worst/best case approach, it was analysed that emissions from the capture unit are relevant in three impact categories.
Overall, the additional material demand and sorbent-related emissions introduce significant trade-offs in between 5-8 impact categories, depending on the followed technological scenarios. Additional technological improvement may reduce the trade-off effect, leading to a reduction of trade-off categories to a number of four.

The analysis concluded that it is likely that there are benefits to using the microplant-approach to methanol production, though additional research is critical to iron out the large uncertainties that are paired with future-oriented life cycle assessment.

Increase in global energy demand has brought to a massive rise in greenhouse gases emissions. In particular, the continuously increasing atmospheric concentration of carbon dioxide is a major concern among the scientific community. This paved the way for an intense research of CO2 emissions mitigating technologies. Those ones including carbon capture, storage and utilisation are seen as part of the solution for this global problem. In this framework, Zero Emission Fuels (ZEF), a startup company located in Delft (The Netherlands) set the ambitious goal of developing a micro process plant producing methanol from ambient air and sunlight only. Part of the process involves direct capture of carbon dioxide from the atmosphere (direct air capture) with the use of a pure tetraethylenepentamine (TEPA) absorbent. ZEF sets itself aside from the rest of the industry developing an absorber which collects CO2 with no support structure by continuously flowing TEPA inside open channels. Previous research shows how this approach brings limitations connected to slowly diffusing CO2 molecules in the absorbent liquid film in proximity of the gas-liquid interface. In this framework, circulation of TEPA particles from the gas-liquid interface into the bulk of the flowing absorbent is seen as a viable solution to improve the process. This thesis focuses on investigating this hypothesis by inducing mixing on the liquid side. That is done by building two experimental setups investigating both passive and active mixing. Experimental results show that active mixing can be used to improve the rate of CO2 absorption, while passive mixing does not bring significant advantages. Results from the passive mixing experiments are further investigated by modelling the fluid dynamics of the process through a Direct Numerical Simulation of the particular Stokes’ flow in the engineered absorption channel. The process is characterised with the definition of a theoretical framework describing mass transfer in the liquid side. Following an analogy with ice formation on top of a frozen lake, this theory, also known as the ”Ice-Sheet” theory, shines some light on the way this diffusion limitations are happening at a molecular level. In particular, a highly viscous, heavily loaded layer of sorbent on the gas-liquid interface is believed to be the cause for observed CO2 diffusion limitations. This theory is backed-up by defining its mathematical equivalent in the form of a mass transfer model. Comparing the results of the model with experimental results, a very good agreement is observed. That is believed to add credibility to the proposed theory. Moreover, that is also found to be in line with the latest knowledge available in literature about CO2 absorption in TEPA films. Finally, the experimental results and the developed models are used to engineer a new iteration of ZEF’s absorber on a cost reduction basis.

Increase in global energy demand has brought to a massive rise in greenhouse gases emissions. In particular, the continuously increasing atmospheric concentration of carbon dioxide is a major concern among the scientific community. This paved the way for an intense research of CO2 emissions mitigating technologies. Those ones including carbon capture, storage and utilisation are seen as part of the solution for this global problem. In this framework, Zero Emission Fuels (ZEF), a startup company located in Delft (The Netherlands) set the ambitious goal of developing a micro process plant producing methanol from ambient air and sunlight only. Part of the process involves direct capture of carbon dioxide from the atmosphere (direct air capture) with the use of a pure tetraethylenepentamine (TEPA) absorbent. ZEF sets itself aside from the rest of the industry developing an absorber which collects CO2 with no support structure by continuously flowing TEPA inside open channels. Previous research shows how this approach brings limitations connected to slowly diffusing CO2 molecules in the absorbent liquid film in proximity of the gas-liquid interface. In this framework, circulation of TEPA particles from the gas-liquid interface into the bulk of the flowing absorbent is seen as a viable solution to improve the process. This thesis focuses on investigating this hypothesis by inducing mixing on the liquid side. That is done by building two experimental setups investigating both passive and active mixing. Experimental results show that active mixing can be used to improve the rate of CO2 absorption, while passive mixing does not bring significant advantages. Results from the passive mixing experiments are further investigated by modelling the fluid dynamics of the process through a Direct Numerical Simulation of the particular Stokes’ flow in the engineered absorption channel. The process is characterised with the definition of a theoretical framework describing mass transfer in the liquid side. Following an analogy with ice formation on top of a frozen lake, this theory, also known as the ”Ice-Sheet” theory, shines some light on the way this diffusion limitations are happening at a molecular level. In particular, a highly viscous, heavily loaded layer of sorbent on the gas-liquid interface is believed to be the cause for observed CO2 diffusion limitations. This theory is backed-up by defining its mathematical equivalent in the form of a mass transfer model. Comparing the results of the model with experimental results, a very good agreement is observed. That is believed to add credibility to the proposed theory. Moreover, that is also found to be in line with the latest knowledge available in literature about CO2 absorption in TEPA films. Finally, the experimental results and the developed models are used to engineer a new iteration of ZEF’s absorber on a cost reduction basis.

Alkaline water electrolysis will become increasingly important for supplying the world with sufficient renewable energy, and with raw material for the chemical and pharmaceutical industry. Zero Emission Fuels B.V. (ZEF), a technology start-up based in the Netherlands, is developing a small scale alkaline electrolysis cell (AEC), which is integrated in a methanol producing micro-plant. The challenge of this project is to look into the use of polymers for the encapsulation of the ZEF AEC. The conditions of the ZEF AEC are not to be neglected. The system will run in a 30wt% KOH solution at a temperature of 90 °C and a pressure of 50 bar. Not many polymers will be able to withstand these conditions for a desired lifetime of 20 years. Using CES EduPack, a selection of 30 potentially suitable polymers has been made, from which high density polyethylene (HDPE), 40% glass-reinforced polyphenylene sulfide (PPS-40%gf) and polysulfone (PSU) are further investigated. Based on a literature review and a simple KOH ageing test, HDPE is found unsuitable for application in the ZEF AEC. PPS-40%gf and PSU have been subjected to durability testing for a range of different conditions involving a variety of KOH concentrations (15, 30 and 45wt%), and two oxygen partial pressures (O2 at 5 bar and air with pO2=20%) at different temperatures (90, 120 and 170 °C). The purpose of the ageing experiments is to give a better understanding of the effect of these parameters on the structure and integrity of the polymer; and to eventually be able to acquire a lifetime prediction. Extensive characterisation of the exposed samples has been carried out using different techniques, including weight measurement, tensile testing, DMA, creep-recovery testing, DSC, FTIR, XRD and SEM. After 12 weeks of ageing, it is found that glass-filled polymers are unsuitable for application in a strong alkaline solution at elevated temperatures, due to the dissolution of the glass fibres, which leads to a reduction in mechanical and barrier properties. However, the PPS matrix and PSU are found to be resistant to thermo-oxidative and chemical degradation in the tested ageing conditions. Only subtle changes in mechanical, visco-elastic and thermal behaviour are observed, which can be assigned to the effects of physical ageing. Due to the undesirable brittle nature of PPS, it can be concluded that PSU is the most promising candidate for the long-term application in alkaline electrolysis.

Alkaline water electrolysis will become increasingly important for supplying the world with sufficient renewable energy, and with raw material for the chemical and pharmaceutical industry. Zero Emission Fuels B.V. (ZEF), a technology start-up based in the Netherlands, is developing a small scale alkaline electrolysis cell (AEC), which is integrated in a methanol producing micro-plant. The challenge of this project is to look into the use of polymers for the encapsulation of the ZEF AEC. The conditions of the ZEF AEC are not to be neglected. The system will run in a 30wt% KOH solution at a temperature of 90 °C and a pressure of 50 bar. Not many polymers will be able to withstand these conditions for a desired lifetime of 20 years. Using CES EduPack, a selection of 30 potentially suitable polymers has been made, from which high density polyethylene (HDPE), 40% glass-reinforced polyphenylene sulfide (PPS-40%gf) and polysulfone (PSU) are further investigated. Based on a literature review and a simple KOH ageing test, HDPE is found unsuitable for application in the ZEF AEC. PPS-40%gf and PSU have been subjected to durability testing for a range of different conditions involving a variety of KOH concentrations (15, 30 and 45wt%), and two oxygen partial pressures (O2 at 5 bar and air with pO2=20%) at different temperatures (90, 120 and 170 °C). The purpose of the ageing experiments is to give a better understanding of the effect of these parameters on the structure and integrity of the polymer; and to eventually be able to acquire a lifetime prediction. Extensive characterisation of the exposed samples has been carried out using different techniques, including weight measurement, tensile testing, DMA, creep-recovery testing, DSC, FTIR, XRD and SEM. After 12 weeks of ageing, it is found that glass-filled polymers are unsuitable for application in a strong alkaline solution at elevated temperatures, due to the dissolution of the glass fibres, which leads to a reduction in mechanical and barrier properties. However, the PPS matrix and PSU are found to be resistant to thermo-oxidative and chemical degradation in the tested ageing conditions. Only subtle changes in mechanical, visco-elastic and thermal behaviour are observed, which can be assigned to the effects of physical ageing. Due to the undesirable brittle nature of PPS, it can be concluded that PSU is the most promising candidate for the long-term application in alkaline electrolysis.

In recent years, the energy transition has led to increasingly higher installed capacities of intermittent renewable energy sources. This has sparked the interest in power-to-fuel technology to store excess renewable energy in the chemical bonds of synthetic fuels. As a highly reactive, turn-key process, plasma-chemical conversion offers a promising approach to power-to-fuel technology. However, recent studies have shown limitations in either energy efficiency, conversion or flow rate. The novel Spinning Arc Plasma Reactor (SAPR) developed by J. van Kranendonk stabilises the plasma by mechanical rotation with the potential to contain a liquid film for in-situ product removal. The aim of this thesis is to characterise this reactor by studying the effect of rotational confinement on the reactor performance. To this end, the prototype initially built by J. van Kranendonk was further developed. A wealth of recent studies on the plasma-chemical conversion of CO2 as a step in the formation of synthetic fuels serves as a benchmark to compare reactor performance of the SAPR concept against. A series of experiments with argon were performed to establish the relationship between the system variables (pressure, power, flow rate and rotational speed) and the plasma parameters (electron temperature and electron density). Based on this knowledge, a series of experiments with CO2 were performed to establish the relationship between the reactor performance measured by the conversion and energy efficiency and the system variables: pressure, power and flow rate. The maximum conversion of about 30% to 55% was obtained at an energy efficiency of approximately 0.25% and the maximum energy efficiency of about 3% was achieved at a conversion of approximately 8.5% conversion. Similarly to other studies, improvements to either one came at the expense of the other. The performance of the SAPR proved comparable to dielectric barrier and other glow discharges but was outperformed by microwave and gliding arc discharges. Especially energy efficiency was inferior to these configurations. Further analysis of the discharge emission spectra suggested that CO2 dissociation mainly occurred through electron impact excitation. This explains the large difference in energy efficiency as microwave and gliding arc configurations are able to exploit more energy efficient dissociation channels. Nonetheless, this study was able to further develop the concept and has laid the ground work to explore the potential effect of a liquid film and in-situ product removal on the reactor performance.

In recent years, the energy transition has led to increasingly higher installed capacities of intermittent renewable energy sources. This has sparked the interest in power-to-fuel technology to store excess renewable energy in the chemical bonds of synthetic fuels. As a highly reactive, turn-key process, plasma-chemical conversion offers a promising approach to power-to-fuel technology. However, recent studies have shown limitations in either energy efficiency, conversion or flow rate. The novel Spinning Arc Plasma Reactor (SAPR) developed by J. van Kranendonk stabilises the plasma by mechanical rotation with the potential to contain a liquid film for in-situ product removal. The aim of this thesis is to characterise this reactor by studying the effect of rotational confinement on the reactor performance. To this end, the prototype initially built by J. van Kranendonk was further developed. A wealth of recent studies on the plasma-chemical conversion of CO2 as a step in the formation of synthetic fuels serves as a benchmark to compare reactor performance of the SAPR concept against. A series of experiments with argon were performed to establish the relationship between the system variables (pressure, power, flow rate and rotational speed) and the plasma parameters (electron temperature and electron density). Based on this knowledge, a series of experiments with CO2 were performed to establish the relationship between the reactor performance measured by the conversion and energy efficiency and the system variables: pressure, power and flow rate. The maximum conversion of about 30% to 55% was obtained at an energy efficiency of approximately 0.25% and the maximum energy efficiency of about 3% was achieved at a conversion of approximately 8.5% conversion. Similarly to other studies, improvements to either one came at the expense of the other. The performance of the SAPR proved comparable to dielectric barrier and other glow discharges but was outperformed by microwave and gliding arc discharges. Especially energy efficiency was inferior to these configurations. Further analysis of the discharge emission spectra suggested that CO2 dissociation mainly occurred through electron impact excitation. This explains the large difference in energy efficiency as microwave and gliding arc configurations are able to exploit more energy efficient dissociation channels. Nonetheless, this study was able to further develop the concept and has laid the ground work to explore the potential effect of a liquid film and in-situ product removal on the reactor performance.