In recent years, microwave pyrolysis has been the focus of intense research due to the claim that it produced better quality products at a lower power input compared to the electrical furnace pyrolysis system. This study aimed to investigate the influence of both pyrolysis methods on yield and product composition obtained from Malaysian biomass, i.e.: empty fruit bunch and rice husk pellets. They represent lignocellulosic biomass procured as by-products of the milling process. In the first part of the thesis, an initial characterisation of biomass was conducted to determine the chemical composition. It was found that the biomass in this study has moisture and volatiles content at around 5.4 wt.% and 70 wt.%, respectively which makes them ideal for the pyrolysis process. 200g of biomass was loaded into a 15.8kW fixed bed pyrolysis reactor once the reactor had reached the set temperature. Typically, 40g of biomass was pyrolysed in a specially designed 1000W multi mode microwave oven, where microwaves were fed into the oven cavity through a bottom feed waveguide. It was found that microwave pyrolysis gave a higher bio oil and char yield than conventional pyrolysis at a similar reaction temperature. Up to 8.40% increase in bio oil yield was observed when rice husk pellets were pyrolysed under microwave radiation at 800ºC. GC-MS analysis revealed a greater content of mono-aromatics compounds obtained from microwave pyrolysis oils with negligible Polycyclic Aromatic Hydrocarbons (PAH) than conventional pyrolysis oils. Similarly, greater cracking of heavier hydrocarbons at high temperature resulted in up to 44% increase in phenol formation from microwave pyrolysis oils. A maximum surface area of 410m2/g was also recorded during microwave pyrolysis of rice husk pellets at 500ºC, where this value reduces with an increase in pyrolysis temperature. Moreover, microwave pyrolysis resulted in up to 29% increase in syngas (H2+CO) evolution and about 42% lower greenhouse gases (CH4+CO2) than conventional pyrolysis. These differences can be attributed to internal heat generation during microwave processing in contrast to conduction from the surface inwards during conventional heating. Energy yield analysis suggested that microwave pyrolysis can be optimised for the production of high quality char and bio oil. Meanwhile, conventional pyrolysis can be optimised to enhance syngas production. The second part of this thesis looks into the effect of waveguide position and biomass bed height on the electric field and its corresponding temperature distribution. Numerical modelling has shown that higher temperature rise can be generated in a larger load due to greater microwave power deposited. Moreover, an increase in relative permittivity was observed as biomass was converted into char during pyrolysis. This showed that microwave pyrolysis of biomass can be a self-sustaining process, without any addition of microwave absorber. It was concluded that viable industrial application of microwave pyrolysis is very promising.

This study is based on the Bahraini government's interest in the construction of largescale renewable energy projects in Bahrain. This thesis investigates the impact of integrating a high penetration of wind power into Bahrain's power system. It includes wind and site assessment and a study of the correlation between wind power and power demand. The power system is analysed before and after wind integration covering different wind penetration levels. In order to mitigate against the possible impact of high levels of wind power, the operation of reverse osmosis stations is modelled as a means of providing additional grid balancing. The geographical distribution of wind speed (the wind atlas) for the kingdom of Bahrain is presented, based on measured data and on calculations undertaken using WAsp and Matlab. The data used were recorded by the Meteorological Directorate using a weather station at Bahrain International Airport. The data were taken on an hourly basis for a period of ten years. These data indicate an annual mean wind speed of 6.93 m/s at 60 m height and mean Weibull scale and shape parameters C and k of 7.80 m/s and 1.79 respectively. This suggests that the area has a good wind resource. The wind atlas shows that several locations in the less populated central and southern regions of the main island of the archipelago of Bahrain are potentially suitable for wind energy production.

In this research, hydrogen production from conventional slow pyrolysis, flash pyrolysis, steam gasification and catalytic steam gasification of various biomass samples including rice husk, wood pellets, wheat straw and sugarcane bagasse was investigated at ultra-high temperature (~1000 °C). During flash pyrolysis of the waste wood, the gas yield was improved to ~78 wt.% as compared to ~25 wt.% obtained during slow pyrolysis. The addition of steam enhanced the hydrogen concentration from 26.91 vol.% for pyrolysis to 44.13 vol.% for steam gasification. The comparison of pyrolysis, steam gasification and catalytic steam gasification in a down-draft gasification reactor at 950 °C using rice husk, bagasse and wheat straw showed a significant increase in gas yield as well as hydrogen yield. The hydrogen yield was enhanced from ~2 mmoles g-1 for pyrolysis to ~25 mmoles g-1 during steam gasification using a 10 wt.% Ni-dolomite catalyst. The higher hydrogen yield was due to the enhanced steam reforming of hydrocarbons and thermal cracking of tar compounds at higher temperature. When compared with the other catalysts such as 10 wt.% Ni-dolomite, 10 wt.% Ni-MgO, and 10 wt.% Ni-SiO2, the 10 wt.% Ni-Al2O3 catalyst showed the highest hydrogen yield of 29.62 mmoles g-1. The investigation on gasification temperature showed that the hydrogen yield was significantly improved from 21.17 mmoles g-1 at 800 °C to 35.65 mmoles g-1 at 1050 °C. The hydrogen concentration in the product gas mixture was increased from 50.32 vol.% at 800 °C to 67.41 vol.% at 1050 °C. The increase in steam injection rate from 6 to 35 ml hr-1 enhanced the hydrogen yield from 29.93 mmoles g-1 to 44.47 mmoles g-1. The hydrogen concentration increased from 60.73 to 72.92 vol.%. The increase was mainly due to the shift in the equilibrium of the water gas shift reaction as H2:CO ratio increased from 2.97 to 7.78. The other process variables such as catalyst to sample ratio, carrier gas flow rate showed little or no influence on the gas yield and hydrogen yield. The steam gasification of residual biomass char was performed at 950 °C to recover extra hydrogen. The presence of 10 wt.% Ni-Al2O3 in the gasifier improved the hydrogen yield to ~47 mmoles per gram of biomass as compared to the other catalysts such as 10 wt.% Ni-dolomite and 10 wt.% Ni-MgO. The gasification temperature showed a positive influence on hydrogen yield from 750 °C to 950 °C. The increase in steam injection rate from 6 ml hr-1 to 15 ml hr-1 enhanced the hydrogen yield from 46.81 to 52.10 mmoles g-1 of biomass.

The rise of biorefining and application of biotechnology to combat climate change and accomplish energy security is a necessity. There have already been steps to produce sustainable biofuels and products throughout the world. However, not all processes are economically viable due to costs of enzymes, pre-treatments, and scale-ups. In this project Miscanthus sp. was the main source of bacterial isolation due to its bioenergy characteristics as a low-input high-output crop. Specifically, due to the high sugar content of harvested senesced Miscanthus. The aim of this project was to discover novel microbes and enzymes with potential to contribute to the generation of fuels and chemicals from plant biomass. Specifically, we aimed to isolate and characterise enzymes capable of efficiently releasing sugars from pre-treated lignocellulosic biomass, for subsequent fermentation to ethanol and platform chemicals. Aerobic bacteria were cultured from harvested chipped Miscanthus and soil surrounding Miscanthus crops and were characterised morphologically, functionally and taxonomically. Bacteria in our collection included amongst others: Pseudomonas sp., Burkholderia sp., Variovorax paradoxus, Luteibacter sp. and Bacillus sp. The collection was screened for carbon utilisation using cellulose (in the form of carboxymethyl cellulose), xylan (from beechwood) and starch by enzymatic activity, at a range of temperatures and pHs. From the bacterial library, 88.5% of cultures showed cellulase activity, 93.2% xylanase activity, 79.7% starch degradation activity over the temperature or pH range, with 66.2% demonstrating activity over all three assays. Proteins were isolated from bacteria that demonstrate effective starch utilisation for further characterisation. Bacterial isolates that exhibited xylan utilisation at high pH and temperature were characterised by whole genome sequencing to identify interesting enzymes and pathways using bioinformatics software CLC genomics and Seed RAST. Finally, homologous proteins have been modelled using Phyre2 and 3DLigandSite to analyse structure and binding sites. This work was part of the wider BEACON project which aimed to establish Wales as a Biorefining Centre of Excellence. BEACON built integrated 'Green Supply Chains' with a focus on developing new routes to functional, cost competitive products using biomass rather than fossil fuels.

Since the first implantation of a cardiac pacemaker numerous efforts have been made to develop miniature implantable power devices, which would be able to run continuously for long periods of time without the need for replacement. In this context enzymatic biofuel cells (EBFCs) represent an attractive alternative, as they work at body temperature, are light and easy to miniaturise. Additionally, enzymatic biofuel cells can generate energy from the metabolites already present in physiological fluids, and produce waste products that naturally occur in the human body. With a view to improving the biocompatibility of such devices, the use of highly porous gold (hPG) as a non-toxic high surface area alternative to the carbon nanotube based materials currently used was here investigated. The process for directly depositing hPG onto conductive surfaces was further developed to improve the stability of the deposited hPG films. The possibility of depositing these films on a range of different materials was also investigated. In particular it was shown that hPG films could also be deposited on very low cost materials, such as graphite composites. It was also demonstrated that these hPG electrodes exhibited potential for the direct electro-oxidation of aldehyde group containing sugars. The potential use of hPG electrodes as abiotic glucose sensors was consequently investigated and found to give stable amperometric responses between 0 and 50 mM, with a strong glucose dependant response even at the lowest concentration investigated of 0.5 µM. However, since hPG electrodes were found to be susceptible to a large degree of interference and fouling in biological solutions, the use of glucose oxidase (GOx) on hPG electrodes was investigated in order to increase the specificity and stability of such electrodes in biological systems. A rapid and simple technique for the direct and functional deposition of GOx onto hPG was developed without using foreign electron mediators. These hPG-GOx electrodes were found to act as glucose sensors with extremely high sensitivity (22.7 µA mM-1 cm-2), and a linear response to glucose in a range of between 50 μM and10 mM. Finally EBFCs that exhibit continuous flow through were developed using fast prototyping techniques that employ 3D printed moulds. These EBFCs employed hPG-GOx electrodes coupled with hPG and laccase electrodes in order to generate power from glucose. The continuous and stable power production from a flow through EBFC for up to 30 days was subsequently demonstrated for the first time, with a peak power output of approximately 2 µW.

Cellulosic biomass is one of the most abundant industrial waste products and an appealing substrate for biorefining strategies to produce biofuels by fermentation. The metabolic engineering of fermentative bacteria, such as the thermophile Geobacillus thermoglucosidasius, for high bioethanol yield is well characterised. This has been traditionally facilitated by an economically inefficient multistep process referred to as separate hydrolysis and fermentation (SHF), in which the enzymatic hydrolysis of the cellulosic substrate and fermentation of the liberated sugars is performed sequentially. Consolidated bioprocessing (CBP) involves performing these two process steps simultaneously, by either introducing cellulolytic capabilities into naturally fermentative organisms or implementing fermentative capabilities in cellulolytic organisms through metabolic engineering. CBP is believed to be a potentially cost-efficient and commercially viable way to produce cellulosic biofuels since the feedback inhibition of glycosyl hydrolases by monosaccharides as they are released is reduced by their rapid conversion through microbial fermentation. This results in faster rates of production and higher yields than those possible with SHF. Furthermore, CBP offers energy savings by removing the need for a complex multistage process with multiple heating and cooling steps. The aim of the present project is the engineering of CBP capabilities in the ethanologen G. thermoglucosidasius through the heterologous secretion of active glycosyl hydrolases into the extracellular milieu or employing surface-layer homology domains to attach them to the bacterial cell-wall. Iterative optimisation will serve to evaluate the feasibility of CBP as a strategy for production of biofuels from lignocellulose using G. thermoglucosidasius.

For sustainably produced fuels and chemicals to become viable resources they need to be cost comparable with crude oil based products. Microbial fermentation is a promising alternative route to a variety of sustainable fuels and chemicals; however, due to increased production costs, it is not currently as economical as crude oil extraction and refining. The recovery of the dilute fermentation products from the broth can be incredibly energy intensive due to distillation still being the main separation process utilised. For high boiling organics, such as 2,3 butanediol, purification from the fermentation broth can contribute to over half of the cost of production. Therefore, there is a clear need for lower energy technologies for the separation and purification of fermentation products. This thesis presents an investigation into the application of membrane processes for the lower energy recovery of a number of different fermentation products: Nanofiltration (NF) and Reverse Osmosis (RO) membranes have been investigated for the purification and concentration of 2,3 butanediol and acetate within the broth of a gas fermentation process, developed and commercialised by LanzaTech, USA. A number of commercial NF and RO membranes were screened for their separation properties of 2,3 butanediol and acetate with BW30 identified as the highest performing membrane with a rejection of 2,3 butanediol and acetate of 96.1 % and 94.6 % respectively at pH 6.5 within the gas fermentation broth. A membrane series was then developed to purify the broth before concentration to limit the reduction in permeability due to fouling. The membrane series was studied at LanzaTech, USA and consisted of a microfiltration membrane for retention of cells, nanofiltration for the retention of salts and macromolecules and NF / RO for the concentration of 2,3 butanediol and acetate within the broth. 2,3 butanediol and acetate were successfully concentrated to > 5 times that of the fermentation broth. The effect of 2,3 butanediol and acetate on the pervaporative recovery of ethanol from a gas fermentation broth using a MMM of ZIF-8 and PDMS has been investigated. ZIF 8 was shown to increase the uptake of 2,3 butanediol by the MMM. The as-synthesised membranes were also shown to be sensitive to the pH of an acetate solution. Increasing 2,3 butanediol concentration was shown to increase the total flux and decrease the separation factor and has been attributed to the increased uptake. When pervaporation of a fermentation broth was conducted, an increase in total flux with only a small decrease in separation factor was observed. This led to an increased average PSI of 1281 compared to the model solution of 805. This has been attributed to some beneficial effects of components of the fermentation broth. An investigation into MMMs of two analogous MOFs composed of copper, glutarate and a bipyridine was undertaken. The two MOFs exhibit similar pore environments but different crystal morphologies depending on the solvent used in the synthesis and have been related to the overall performance of these novel MMMs. The Cu MOFs of larger plate-like crystals blocked permeation through the membrane. This has been shown to be due to the non-ideal orientation of the 1-dimensional pores of the Cu-MOF within these membranes. However, the smaller crystals exhibited better performance as inorganic filler and exhibited increased performance with a maximum at a 15 wt% loading for pervaporation of acetone from water. A total flux of 0.061 kg m-2 h 1 and separation factor of 10.3 were observed for a 5 wt% acetone solution at 30 ºC. Finally a novel method for the determination of the molecular weight cut-off (MWCO) of organic solvent nanofiltration (OSN) membranes utilising polypropylene glycols has been developed. The method overcomes the limitations of previous methods that utilise polystyrene or polyethylene glycols. Advantages include low cost of polypropylene glycol, high resolution of oligomers (58 g mol 1) and being suitable for use within polar, non-polar and polar aprotic solvents. Overall this thesis presents investigations into a number of different membrane separation processes relevant to the recovery of dilute organics from fermentation broths. Specifically: 1. NF and RO have been identified as suitable for the partial purification and concentration of 2,3 butanediol and acetate within a gas fermentation broth. 2. The effect of 2,3 butanediol and acetate on the pervaporation of ethanol using a ZIF-8-PDMS MMM has been investigated. 3. Two novel MMMs of PDMS and Cu-MOFs have been developed for the removal of acetone from an aqueous feed and the relationship between structure and performance studied. 4. Finally a novel method for characterising the MWCO of OSN membranes has also been developed utilising polypropylene glycols.

Global warming is perhaps the most urgent and critical problem that we face today. A large proportion of anthropogenic global warming is understood to occur due to the combustion of fossil fuels for the purpose of transportation. The contribution of aviation to global warming has, in recent years become increasingly recognised. Due to the significant increase in passenger air travel predicted in the future we must seek to lessen the impact of aircraft emissions through the development of suitable alternative liquid fuels that may be used within current infrastructure. Whilst alternative fuels have been developed such biodiesel from triglycerides and bio-ethanol, these utilise food competitive feedstocks, and also exhibit some undesirable physical properties meaning that whilst they may be used in road transport infrastructure, they remain unsuitable for use in aviation. The production of sustainable alternative fuels that possess suitable physical properties for use in aviation, necessitates design of biomass conversion technologies in order that they may yield products which satisfy the stringent criteria set out in aviation turbine fuel standards. In chapter 2 a biocatalytic route to C10-12 alkane precursors was investigated. A benzaldehyde lyase catalysed conversion of the biomass derived furanic compounds, furfural and 5-hydroxymethylfurfural (5-HMF), was found to carboligate these molecules at room temperature and ambient conditions. The product mixture was found to be tailorable between 10 and 12 carbon chain length precursors. In chapter 3, the suitability of a low temperature thermochemical conversion technology was explored. A previously reported Pd/C catalysed alkylation was used for alkylation of a theoretical permutation of a product mixture available from Acetone Butanol Ethanol (ABE) fermentation. Whilst straight chain products available through the use of ABE, the substitution of the alcohol constituents for isoamyl alcohol and isobutanol was found to enable production of branched chain aviation fuel precursors, with much improved low temperature properties relative to their straight chain analogues. In chapter 4 is presented an investigation into a liquid phase pyrolysis technology, with analysis of its efficacy with regard to conversion of a food industry waste to biofuel using zeolite catalysts. Conversion efficiencies were found to be up to 7 % iii using the bench scale system in this investigation, however oxygen content of the fuels produced were found to be exceptionally low for a biomass derived feedstock, and as such the process warrants further investigation. The fuels from chapter 2 and 3 were taken forward for engine testing. Blends of these potential alternative fuels were made up with Jet A-1, and used to power a AMT, mercury HP micro gas turbine. The test cycle used ranged across 4 throttle settings from 0, 30, 60 and 90 %. It was found that whilst emissions for alternative fuel blends remained largely unchanged for most emissions, a difference in thrust was measured, with hydrocarbon fuels providing higher thrust at lower throttle settings and at 60 % and 90 % throttle, oxygenate fuels providing more thrust.

Microalgae are a promising feedstock for the production of sustainable, 3rd generation biofuels; however, current lipid-based processes are too expensive to effectively compete with existing transportation fuels. A potential solution is to convert the entire algae via hydrothermal liquefaction (HTL) instead, therefore allowing the use of faster-growing, and cheaper microalgae. This project sought to address some of the main challenges with this technology, currently restricting its use for large-scale fuel production. Fuels are low value products and unlikely to pay for the entire fuel production process on their own. Consequently, the possibility of producing additional by-products from the conversion of polymer- containing algae, or combining HTL with a more conventional lipid- extraction process, was explored. In addition, the project studied the conversion of microalgae produced during the bioremediation of domestic wastewater, in order to help to offset the overall biomass production costs. The majority of research into algal HTL has been confined to batch systems, which are not fully representative of the continuous flow processes used for large-scale fuel production. Consequently, an inexpensive laboratory-scale system was designed to study the continuous HTL of algae under a range of operating conditions. Using this system, it was found that, compared to a batch reactor, significantly enhanced oil yields could be obtained from the system, as a result of increased heating rates, together with prolonged reaction times. Finally, the poor quality of the bio-oils produced by the HTL of microalgae is a major challenge. Particularly their high nitrogen content restricts their conversion within conventional petrochemical refineries. Therefore, significant upgrading is required before the oil can be fractionated into fuels. In order to achieve this, a range of zeolite-supported nickel phosphide catalysts were synthesised in this project, and tested for the denitrogenation of the model compound quinoline, before they were applied to the upgrading of bio-oil obtained from the continuous liquefaction of the wastewater-derived algae. Although the synthesised catalysts showed only low activity towards the denitrogenation of the bio- oil, they were more active for the hydrogenation of quinoline, compared to two conventional sulphided transition metal catalysts, and following further optimization, could therefore represent a viable class of oil upgrading catalysts.

The design, modelling and optimisation of biofuel thermochemical processes are mainly based on the knowledge of reliable chemical kinetics. The determination of reaction kinetics of biomass at high heating rate still highly depends on the extrapolation of results from kinetic data determined at a comparatively low heating rate. To provide more comprehensive kinetic data for gas-solid reactions under isothermal conditions, a thermogravimetric fluidized bed reactor (TGFBR) was designed. Using this novel fluidised bed, gravimetric measurements and high heating rate, the thermal conversion of biomass was investigated. Using a thermogravimetric analyser (TGA) as a fixed bed and the TGFBR as a fluidized bed, the pyrolysis kinetics of olive kernels was studied. The pyrolysis in the TGFBR was analysed using the isothermal kinetic approach and it was theorised that the pyrolysis decomposition reaction occurred by two mechansims. Dependent on the temperature, the resultant activation energy was 67.4 kJ/mole at < 500 °C and 60.8 kJ/mole at > 500 °C. For comparsion, the TGA gave a higher activation energy of 74.4 kJ/mole due to external particle diffusion. To study the impact of torrefaction on gasification performance, gasification experiments were performed on “as received olive kernels” (AROK) and “as received torrefied olive kernels” (ARTOK) in the TGFBR. The effect of equivalence ratio (ER) (0.15-0.35) and bed temperature (550-750°C) on gasification performance was investigated. Based on thermogravimetric measurements using a mass balance model, the activation energy of AROK was found to be 84 kJ/mole, whereas ARTOK was found to be 106 kJ/mole. The results suggest that diffusion controls the reaction of AROK, while oxidation controls the reaction of torrefied biomass. The pyrolysis of date palm stones was also studied in the TGFBR, and the kinetic expression was determined using a model fitting method. The most probable reaction mechanism for the thermal decomposition of palm stones was three-dimensional diffusion. The activation energy for experiments between 350°C and 600°C for date palm stones was 27.67 kJ/mole. Furthermore, the gasification of date palm stones was investigated at ER (0.15-0.35) and a temperature range of 600-750°C in 50°C increments. Based on the energy yield (7 MJ/kg), the results suggest that the optimum conditions were at T=750°C and ER=0.2. Overall, the result reveals that the TGFBR, in comparison with TGA, would be a viable reactor that enables kinetic analysis of gas-solid reactions under isothermal conditions, benefiting from its features. The parameters obtained from the kinetic study of TGFBR are essential in the scale-up design of useful conversion technologies such as gasification. Also, the pre-treatment of biomass via torrefaction is a promising route to improve gas production in a bubbling fluidised bed gasifier.