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In this work, two simple processes for carbon dioxide (CO2) such as capture and utilization have been combined to form a whole systems approach to carbon capture and utilization (CCU). The first stage utilizes a pressure swing adsorption (PSA) system, which offers many benefits over current amine technologies. It was found that high selectivity can be achieved with rapid adsorption/desorption times while employing a cheap, durable sorbent that exhibits no sorbent losses and is easily regenerated by simple pressure drops. The PSA system is capable of capturing and upgrading the CO2 concentration of a waste gas stream from 12.5% to a range of higher purities. As many CCU end processes have some tolerance toward impurities in the feed, in the form of nitrogen (N2), for example, this is highly advantageous for this PSA system since CO2 purities in excess of 80% can be achieved with only a few steps and minimal energy input. Non-thermal plasma is one such technology that can tolerate, and even benefit from, small N2 impurities in the feed, therefore a 100% pure CO2 stream is not required. The second stage of this process deploys a nanosecond pulsed corona discharge reactor to split the captured CO2 into carbon monoxide (CO), which can then be used as a chemical feedstock for other syntheses. Corona discharge has proven industrial applications for gas cleaning and the benefit of pulsed power reduces the energy consumption of the system. The wire-in-cylinder geometry concentrates the volume of gas treated into the area of high electric field. Previous work has suggested that moderate conversions can be achieved (9%), compared to other non-thermal plasma methods, but with higher energy efficiencies (>60%).

The plasma chemical splitting of carbon dioxide (CO2) to produce carbon monoxide (CO) in a\ud pulsed corona discharge was investigated from both an experimental and a numerical standpoint.\ud High voltage nanosecond pulses were applied to a stream of pure CO2 and its mixture with argon,\ud and the gaseous products were identified using Fourier transform infrared spectroscopy. Due to the\ud shape of pulses, the process of CO2 splitting was found to proceed in two phases. The first phase is\ud dominated by ionization, which generates a high electron density. Then, during the second phase,\ud direct electron impact dissociation of CO2 contributes to a large portion of CO production.\ud Conversion and energy efficiency were calculated for the tested conditions. The conversions\ud achieved are comparable to those obtained using other high pressure non-thermal discharges, such as\ud dielectric barrier discharge. However, the energy efficiencies were considerably higher, which are\ud favorable to industrial applications that require atmospheric conditions and elevated gas flow rates.

A novel single dielectric pellet DBD that is designed to facilitate studying the interaction\ud between plasmas and catalysts is presented. The influence of material dielectric constant on\ud plasma dynamics across a range of applied voltages is determined through the use of electrical\ud characterisation combined with videos of the discharge. Different discharge modes in nitrogen\ud are observed and their behaviour is characterised. A particular focus is given to the phenomenon\ud known as ‘partial discharging’. This is where incomplete plasma formation occurs between the\ud electrodes of the reactor, which may have implications for the fair testing of catalysts in packed\ud bed reactors. Additionally, the occurrence of an ‘almond shaped’ QV plot in the event of pointto-point\ud discharging in PBRs is explained. This work provides easily implemented analytical\ud techniques that can be applied to understand the behaviour of plasmas within packed bed DBD\ud reactors.

Biogas from anaerobic digestion of sewage sludge is a renewable resource with high energy content, which is\ud composed mainly of CH4 (40−75 vol %) and CO2 (15−60 vol %). Other components, such as water (H2O, 5−10 vol %) and\ud trace amounts of hydrogen sulfide and siloxanes, can also be present. A CH4-rich stream can be produced by removing the CO2\ud and other impurities so that the upgraded biomethane can be injected into the natural gas grid or used as a vehicle fuel. The main\ud objective of this paper is to assess the technical and economic performance of biogas upgrading processes using ionic liquids that\ud physically absorb CO2. The simulation methodology is based on the COSMO-SAC model as implemented in Aspen Plus. Three\ud different ionic liquids, namely, 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide, 1-hexyl-3-\ud methylimidazoliumbis[(trifluoromethyl)sulfonyl]imide, and trihexyl(tetradecyl)phosphonium bis[(trifluoromethyl)sulfonyl]-\ud imide, are considered for CO2 capture in a pressure-swing regenerative absorption process. The simulation software Aspen\ud Plus and Aspen Process Economic Analyzer is used to account for mass and energy balances as well as equipment cost. In all\ud cases, the biogas upgrading plant consists of a multistage compressor for biogas compression, a packed absorption column for\ud CO2 absorption, a flash evaporator for solvent regeneration, a centrifugal pump for solvent recirculation, a preabsorber solvent\ud cooler, and a gas turbine for electricity recovery. The evaluated processes are compared in terms of energy efficiency, capital\ud investment, and biomethane production costs. The overall plant efficiency ranges from 71 to 86%, and the biomethane\ud production cost ranges from $9.18−11.32 per GJ (LHV). A sensitivity analysis is also performed to determine how several\ud technical and economic parameters affect the biomethane production costs. The results of this study show that the simulation\ud methodology developed can predict plant efficiencies and production costs of large scale CO2 capture processes using ionic\ud liquids without having to rely on gas solubility experimental data.

Hydrogen demand has already significantly increased due to the industry needs. Mature technologies based on fossil fuels are not satisfactory due to greenhouse gas concerns. In response, a range of advanced processes are being developed throughout the world. Within the ‘International Energy Agency – Hydrogen Implementing Agreement – Task 25’, a multicriteria methodology was developed for the evaluation of high temperature hydrogen production processes. The aim is to guide R&D strategy by highlighting to which extent the processes may appear promising. The method that was developed is based on the elimination and choice translating the reality (ELECTRE). This study has conducted a first pass application to hydrogen production and highlights the importance of significant weightings and discriminating criteria. Decision makers can apply this method to extract their own subset of processes from the alternatives, according to their system of values defined through the selection of criteria and the associated weights.

Decreasing the Reynolds number of microfluidic\ud no-moving-part flow control valves considerably below the usual operating range leads to a distinct “subdynamic” regime of viscosity- dominated flow, usually entered through a clearly defined transition. In this regime, the dynamic effects on which the operation of large-scale no-moving-part fluidic valves is based, cease to be useful, but fluid may be driven through the valve (and any\ud connected load) by an applied pressure difference, maintained by an external pressure regulator. Reynolds number ceases to characterize the valve operation, but the driving pressure effect is usefully characterized by a newly introduced dimensionless number and it is this parameter which determines the valve behavior. This summary paper presents information about the subdynamic regime using data (otherwise difficult to access) obtained for several recently developed flow control valves. The purely subdynamic regime is an extreme. Most present-day microfluidic valves are operated at higher Re, but the paper shows that the laws governing subdynamic flows provide relations useful as an asymptotic reference. \ud