The declining reserves of fossil fuel twined with an increasing concern about the environmental consequences of burning these fuels and rising carbon dioxide levels, means that a more sustainable replacement is required. Lignocellulosic biomass is an attractive candidate that has been shown to be the best sustainable alternative source to produce bioethanol for liquid transportation fuels. It has enormous availability, is renewable and cost-effective. As an agricultural residue, it does not compete with food production. However, lignocellulosic biomass of plant cell walls is composed mainly of cellulose, hemicellulose and lignin, which are extremely resistant to digestion. Converting this biomass to useful products of fermentable sugars for bioethanol production has met with little success as harsh pretreatment and costly enzyme applications are required. An arsenal of enzymes and a synergistic mechanism are required to deconstruct recalcitrant lignocellulosic biomass for an efficient production of lignocellulosic bioethanol. To achieve this goal, this study used transcriptomic and proteomic approaches with the objective of identifying new genes and enzymes involved in lignocellulose degradation. This revealed that the only one AA10 of Cellulomonas fimi was among the highest enzymes identified during the degradation of cellulose. Another other 20 hypothetical proteins co-expressed with CAZymes have been identified including a potentially exclusively new C. fimi β-glucosidase (PKDP1) that contains a PKD-domain and oxidoreductase predicted function of PQQ-domain. A naturally mutagenized C. fimi population also was screened from an adaptive evolution experiment involving exposure to a wheat straw environment. One of the strains in the adaptive population (Strain-6) showed a higher association with wheat straw biomass, which may be an indication of the strategy that being used by the adapted strain to tackle obstinate substrates to sustain growth. These results show many new enzymes would be revealed from the C. fimi repertoire in order to have a better enzymatic cocktails for lignocellulose breakdown. For the future, this encourages a deeper understanding of lignocellulose deconstruction mechanisms by an orchestra of multiple enzymes in a bacterial system.

Small scale biomass burning stoves and boilers are growing in popularity in the UK and abroad, owing in part to renewable heat incentives and policies. However, combustion in domestic scale appliances is often inefficient and uncontrolled in comparison to larger systems, leading to high emissions factors of gaseous pollutants such as CO, NOx and PAH, as well as fine particulate matter (PM). Evidence is presented from 105 source apportionment studies from 31 developed countries showing that the impact of residential solid fuel (RSF) combustion on air quality is more wide spread that previously thought. Wood burning contributes to up to 95% of wintertime ambient PM in some rural communities in New Zealand, which is used as a case study throughout this work. Modelling work has shown that emissions from heating stoves may be underestimated in global climate models (GCMs) and UK residential wood consumption is forecast to increase by a factor of 14 between 1990 and 2030. By 2030, annual emissions of black carbon (BC) from UK wood stoves and fireplaces are predicted to exceed 3000 tonnes which is higher than the traffic sector. BC is the most important component of RSF radiative forcing, accounting for over 77% total warming effect. Model inventory and literature emission factors (EFs) for over 150 pollutants have been compared and contrasted, and compiled into a new RSF emissions inventory. Results are presented from experimental work on the emissions testing of a 6 kWth multi-fuel stove and three high quality cook stoves, burning a range of over 25 conventional and novel fuels including wood, coal, agricultural residues and torrefied wood briquettes. Despite a large resource of agricultural residues being available with lower EFs than open burning, their suitability as a residential solid fuel is uncertain. For example, straw briquettes had a measured density less than half that of wood logs and reed briquettes showed evidence of ash melting in the stove bed due to a high sodium, silica and chlorine content. It was found that PM and CO emissions were correlated to the content and composition of volatile matter within the fuel and NOx is linearly dependent on fuel nitrogen content. Mean whole cycle PM EFs ranged from 2.1 g kg-1 for wood logs to 4.2 g kg-1 for coal and 0.5 g k-1 for smokeless fuel. Torrefaction of wood has the potential to significantly reduce emissions, with PM EFs 49% lower than wood logs. However, emissions from all fuels were highly dependent on the duration of the flaming phase of combustion, during which EFs may be a factor of 5-9 higher than the smouldering phase. Heat treatment such as torrefaction removes 10-15% of volatiles, shortening the flaming phase and removing key species involved in the chemical soot formation pathways, which are discussed in detail. The physical and optical properties of collected particulate samples collected were also examined using electron microscopy and spectroscopy, which are useful for GCMs. Flaming phase particles had a high average EC/TC ratio ( > 0.9), a high carbon:oxygen ratio (93:5.4) and an Ångström Absorption Exponent (AAE) near 1 (0.9-1.2). After emission, it was found that particles undergo a significant increase in branching and oxygenation (C:O 88:10). The morphology of particles was also found to change following the injection of plasma into the flue, which is evaluated as a promising retrofit abatement technology.

Carbon capture and storage (CCS) is expected to play an important role in mitigating the effects of climate change. The focus of this work is to determine how the change of combustion environment in an oxy-fuel CCS plant affects the combustion behaviour of coal, biomass and a torrefied biomass. The industrially relevant fuels selected were analysed to determine their fundamental composition and combusted in air and a range of oxy-fuel environments (5-30% O2/CO2) using a thermogravimetric analyser (TGA). The key temperatures and kinetic parameters of both the devolatilisation and char combustion stages were investigated to determine how the shift to an oxy-fuel combustion environment effects overall combustion behaviour. The changes in devolatilisation behaviour were determined through the derivation of apparent first order kinetics and no noticeable difference between combustion in air and 21% O2/CO2 atmospheres were observed. The increase in oxygen concentration in the oxy-fuel environments resulted in linear increases in kinetic parameters which were then used to develop fuel specific empirical equations that relate the devolatilisation rate to the oxygen concentration. The devolatilisation of the biomass fuels were shown to be more sensitive to the change in combustion atmosphere than the coals. Chars were produced using ballistic heating rates in a TGA (1000 K min-1) and it was found that the coals exhibited similar mass loss behaviour in N2 and CO2 environments during char production. The biomass and torrefied biomass samples showed enhanced devolatilisation in CO2 atmospheres which leads to differences in the char combustion behaviour between the coal and biomass fuels. The char combustion behaviour was determined through the determination of apparent mth order kinetics, from which, fuel specific nth order kinetic models were derived to describe char combustion accurately over the full range of oxy-fuel combustion atmospheres. The kinetic parameters determined highlighted the similarity between the N2 and CO2 produced coal chars and the difference between the biomass chars. The coal chars were found to be more sensitive to the change in combustion atmosphere. The work in this thesis gives a good understanding of the differences between conventional air and oxy-fuel combustion atmospheres using industrially relevant fuels. Several useful kinetic models have been derived for both the devolatilisation and char combustion stages that lend themselves to computational fluid dynamics and process optimisation while the fundamental characterisation lends itself to life cycle analysis of CCS systems.

As modernisation takes place, fossil fuel burning is one of the quickest ways to meet the ever rising energy demand. The increasing emissions of greenhouse gases, particularly carbon dioxide, as a result of excessive fossil fuel burning had been blamed for global climate change. Vegetation-based biomass is a form of bioenergy and a recognised solid renewable fuel with potential to replace coal in combating anthropogenic climate change in the power generation sector. Nevertheless, it is not a straight forward case for biomass to replace coal since biomass is an extremely reactive fuel prone to self-heating leading to self-ignition. Spontaneous biomass ignition leading to disastrous fires during biomass handling and storage could be avoided if the causes of biomass low temperature ignition are well understood. Detailed studies on woody and herbaceous biomass fuels commonly used in UK power stations were examined according to several British Standards. On top of characterising all the biomass samples, BS EN 50281-2-1 and BS EN 15188 were adhered to specifically in investigating low temperature ignition during biomass handling and biomass storage respectively. Many power stations use a mix of different biomass in their fuel inventories which can lead to dusts of biomass mixtures. Thus the low temperature ignition characteristics of biomass blends have been studied. Other factors that may impact on ignition risks are binders (added to give strength to briquettes or pellets) and pretreatments (washing and torrefaction). Washing aims to improve ash properties towards the end of combustion process while torrefaction is used to increase the calorific value of biomass that is naturally lower than fossil fuels. The reaction kinetics of some biomass dust layers deposited on a constant temperature hot surface and corresponding ignition delay time were estimated mathematically. Results from minimum dust layer ignition temperature determination showed that all biomass, regardless of woody or herbaceous, with or without binder, before or after pre-treatments, had critically ignited within a very small temperature range. This was consistent with the results of self-ignition propensity risk ranking that concluded that biomass possess medium-high risk of self-igniting. An exception to this is torrefied biomass which had not sustained a much higher temperature before it critically ignited as compared with the untreated counterpart; unlike many anticipations and therefore, the low temperature ignition characteristics were discussed from many other aspects, mainly on the reduced particle size or dust layer density. For biomass storage, scaling up method and Frank-Kamenetskii method derived from Thermal Explosion Theory had been applied to forecast the critical ignition temperature and ignition delay time for large-scale industrial storage from smaller laboratory scale experiments. Non-negligible error was detected when extrapolating to industrial volume especially for the ignition delay time and appropriate recommendation was made as a possible remedy. Emissions when biomass smouldered and critically ignited that happened at 10˚C apart were examined with a three-stage emission sampling and compared, with the aims of obtaining a suitable biomass self-ignition indicator. Detailed studies were required since only one organic compound was detected to be consistently different between smouldering and critically-igniting biomass dust. Within this small temperature difference, different volatile species with respective intensities had been modelled with FG-BioMass software. Towards the end of this work, conclusions were drawn for each section and suggestion of combining both pre-treatments with binder addition were recommended for further studies. The work in the thesis provides a large data-set which will help inform power plant operators in their dust management risks. The laboratory-scale experiments give a useful risk-ranking for dust layer ignition, but uncertainties in ignition-delay times, especially for large biomass quantities, indicate that improvements are required to BS EN 15188 (biomass storage test) to enable scaling-up with more certainty.

Biodiesel produced by the transesterification of vegetable oils (sunflower oil) with methanol is a promising alternative fuel to diesel because of the limited resources of fossil fuel and environmental concerns. A base or acid catalyst is usually used to improve the reaction rate and yield. In this work, comparative studies on homogeneous (NaOH) and heterogeneous (CaO based) catalysts were undertaken at the same reaction conditions (1% catalyst dosage, oil/methanol mole ratio = 1/9,333K water bath). It was found that the NaOH took a shorter time to achieve 95% oil conversion than CaO based catalysts. However, CaO-based catalysts could replace such conventional homogeneous catalysts, because they are reusable and inexpensive. However, Ca2+ leaching from the catalyst was detected. Carbon was introduced as the CaO catalyst support and this gave a significant reduction in the Ca 2+ ions released to biodiesel. In the methanolysis of sunflower oil with NaOH and CaO-based catalysts, reaction orders and activation energies were also assessed. In addition, a microwave heating method was considered. Results show that microwave heating fails for CaObased catalysts, but does work for the NaOH (which takes <1 min) to give 95% conversion (when 1% catalyst dosage, oil/methanol mole ratio = 1/9). Microemulsions may be considered as alternative fuels that achieve better fuel economy and lower pollutant emissions. Hence, the essential features of water - in - diesel (D)/biodiesel (BD) microemulsions systems have been considered with varying level of surfactant (S), cosurfactant (COS), S/COS ratio, D/(S+COS) ratio and H2O concentration. The physicochemical properties of the various W/D(BD) microemulsion have been examined (i. e. viscosity, conductivity and droplet size). The engine performance and engine emission (CO, NO, HC and particulate matters) characteristics between these prepared fuels (D, DBD blends, W/D and W/D(BD) microemulsions) were measured and compared. Results presented show that the microemulsion fuels give lower levels of emission of NO, HC and particulates that represent an environmental and health hazard, and lower fuel consumption (due to better burning efficiency) but an increased level of CO emissions (because of the"microexplosions"). On the other hand DBD blends produced lower concentrations of the HC, particles and CO in the exhaust than neat diesel. However, the fuel consumptions and NO., emissions of blend fuels performed a little higher than diesel fuel operation. Cerium (Cc) fuel-borne (FBC) and water-borne (WBC) catalyst have been introduced as an alternative way to reduce diesel emission particulates (DEPs). The effect of and mode of action of FBCs and WBCs for DEPs structure have been evaluated by EELS, diffraction, TEM and SEM. The rate of DEP oxidation was studied by DSC and TGA, where results indicated that the oxidation activation energy did not change but the oxidation temperature (the temperature for the reaction of carbon with oxygen) was lowered with Cc dosing

This thesis describes the design, implementation and experimental evaluation of a prototype instrumentation system for the three-dimensional (3-D) visualisation and quantitative characterisation of fossil fuel flames. A review of methodologies and technologies for the 3-D visualisation and characterisatiOII of combustion flames is given, together with a discussion of main difficulties and technical requirements in their applications. A strategy incorporating optical sensing, digital image processing and tomographic reconstruction techniques is proposed. The strategy was directed towards the reconstruction of 3-D models of a flame and the subsequent quantification of its 3-D geometric, luminous and fluid dynamic parameters. Based on this strategy, a flame imaging system employing three identical synchronised RG B cameras has been developed. The three cameras, placed equidistantly and equiangular on a semicircle around the flame, captured six simultaneous images of the flame from six different directions. Dedicated computing algorithms, based on image processing and tomographic reconstruction techniques have been developed to reconstruct the 3-D models of a flame. A set of geometric, luminous and fluid dynamic parameters, including surface area, volume, length, circularity, luminosity and temperature are determined from the 3-D models generated. Systematic design and experimental evaluation of the system on a gas-fired combustion rig are reported. The accuracy, resolution and validation of the system were also evaluated using purpose-designed templates including a high precision laboratory ruler, a colour flat panel and a tungsten lamp. The results obtained from the experimental evaluation are presented and the relationship between the measured parameters and the corresponding operational conditions are quantified. Preliminary investigations were conducted on a coal-fired industry-scale combustion test facility. The multi-camera system was reconfigured to use only one camera due to the restrictions at the site facility. Therefore the property of rotational symmetry of the flame had to be assumed. Under such limited conditions, the imaging system proved to provide a good reconstruction of the internal structures and luminosity variations inside the This thesis describes the design, implementation and experimental evaluation of a prototype instrumentation system for the three-dimensional (3-D) visualisation and quantitative characterisation of fossil fuel flames. A review of methodologies and technologies for the 3-D visualisation and characterisatiOII of combustion flames is given, together with a discussion of main difficulties and technical requirements in their applications. A strategy incorporating optical sensing, digital image processing and tomographic reconstruction techniques is proposed. The strategy was directed towards the reconstruction of 3-D models of a flame and the subsequent quantification of its 3-D geometric, luminous and fluid dynamic parameters. Based on this strategy, a flame imaging system employing three identical synchronised RG B cameras has been developed. The three cameras, placed equidistantly and equiangular on a semicircle around the flame, captured six simultaneous images of the flame from six different directions. Dedicated computing algorithms, based on image processing and tomographic reconstruction techniques have been developed to reconstruct the 3-D models of a flame. A set of geometric, luminous and fluid dynamic parameters, including surface area, volume, length, circularity, luminosity and temperature are determined from the 3-D models generated. Systematic design and experimental evaluation of the system on a gas-fired combustion rig are reported. The accuracy, resolution and validation of the system were also evaluated using purpose-designed templates including a high precision laboratory ruler, a colour flat panel and a tungsten lamp. The results obtained from the experimental evaluation are presented and the relationship between the measured parameters and the corresponding operational conditions are quantified. Preliminary investigations were conducted on a coal-fired industry-scale combustion test facility. The multi-camera system was reconfigured to use only one camera due to the restrictions at the site facility. Therefore the property of rotational symmetry of the flame had to be assumed. Under such limited conditions, the imaging system proved to provide a good reconstruction of the internal structures and luminosity variations inside the This thesis describes the design, implementation and experimental evaluation of a prototype instrumentation system for the three-dimensional (3-D) visualisation and quantitative characterisation of fossil fuel flames. A review of methodologies and technologies for the 3-D visualisation and characterisatiOII of combustion flames is given, together with a discussion of main difficulties and technical requirements in their applications. A strategy incorporating optical sensing, digital image processing and tomographic reconstruction techniques is proposed. The strategy was directed towards the reconstruction of 3-D models of a flame and the subsequent quantification of its 3-D geometric, luminous and fluid dynamic parameters. Based on this strategy, a flame imaging system employing three identical synchronised RG B cameras has been developed. The three cameras, placed equidistantly and equiangular on a semicircle around the flame, captured six simultaneous images of the flame from six different directions. Dedicated computing algorithms, based on image processing and tomographic reconstruction techniques have been developed to reconstruct the 3-D models of a flame. A set of geometric, luminous and fluid dynamic parameters, including surface area, volume, length, circularity, luminosity and temperature are determined from the 3-D models generated. Systematic design and experimental evaluation of the system on a gas-fired combustion rig are reported. The accuracy, resolution and validation of the system were also evaluated using purpose-designed templates including a high precision laboratory ruler, a colour flat panel and a tungsten lamp. The results obtained from the experimental evaluation are presented and the relationship between the measured parameters and the corresponding operational conditions are quantified. Preliminary investigations were conducted on a coal-fired industry-scale combustion test facility. The multi-camera system was reconfigured to use only one camera due to the restrictions at the site facility. Therefore the property of rotational symmetry of the flame had to be assumed. Under such limited conditions, the imaging system proved to provide a good reconstruction of the internal structures and luminosity variations inside the flame. Suggestions for future development of the technology are also reported.

No description available.

In the last decade, there has been a resurgence of interest in tidal power as a renewable, and environmentally friendly source of electricity. Scotland is well placed in this regard, as the currents in the surrounding seas are primarily tidal; that is to say, driven by lunar and solar tides. Investigations into tidal streams as an energy source, their viability in particular locales, the efficient organisation of marine turbine farms, and most importantly, the effect of such farms on the environment, demand the use of computational fluid dynamics for effective modelling. They also require a turbine model sophisticated enough to generate realistic power output and wakes for a variety of flow conditions, yet simple enough to simulate a number of turbines on modest computing resources. What is presented here then, is the justification for such a model, the development and deployment of it during my PhD, and my validation of the model in a variety of environments.

This thesis presents the work done within the PhD research project focusing on the utilisation of plant oils in Common Rail (CR) diesel engines. The work scope included fundamental experimental studies of rapeseed oil (RSO) in comparison to diesel fuel, the feasibility analysis of diesel substitution with various plant oils, the definition and implementation of modifications of a common rail injection system and future work recommendations of possible changes to the injection system. It was recognised that neat plant oils can be considered as an alternative substitute for diesel fuel offering a natural way to balance the CO2 emissions. However, due to the differences between diesel and plant oils, such as density, viscosity and surface tension, the direct application of plant oils in common rail diesel engines could cause degradation of the injection process and in turn adversely affect the diesel engine’s performance. RSO was chosen to perform the spray characterisation studies at various injection pressures and oil temperatures under conditions similar to the operation of the common rail engine. High speed camera, Phase Doppler Anemometry and Malvern laser techniques were used to study spray penetration length and cone angle of RSO in comparison to diesel. To study the internal flow inside the CR injector the acoustic emission technique was applied. It was found that for oil temperatures below 40°C the RSO viscosity, density and surface tension are higher in comparison to diesel, therefore at injection pressures around 37.50 MPa the RSO spray is not fully developed. The spray penetration and cone angle at these spray conditions exhibit significant spray deterioration. In addition to the lab experiments, KIVA code simulated RSO sprays under CR conditions. The KH-RT and RD breakup models were successfully applied to simulate the non-evaporating sprays corresponding to the experimental spray tests and finally to predict i real in-cylinder injection conditions. Numerical results showed acceptable agreement with the experimental data of RSO penetration. Based on experimental and numerical results it was concluded that elevated temperature and injection pressure could be the efficient measures to overcome operational obstacles when using RSO in the CR diesel engine. A series of modifications of low- and highpressure loops was performed and experimentally assessed throughout the engine tests. The results revealed that the modifications allowed to run the engine at the power and emission outputs very close to diesel operation. However, more fundamental changes were suggested as future work to ensure efficient and trouble-free long-term operation. It is believed that these changed should be applied to meet Euro IV and V requirements.

A brief overview of the dissertation given in this abstract is divided into five points showing its topicality, objective, goals, scientific novelty, and practical significance. The topicality is reflected in a need for the replacement of the fossil fuels driven economy with economy oriented towards renewable sources of energy, in which hydrogen is used as an energy carrier. This need is dictated by three reasons: (i) ecological problems mostly induced by the carbon dioxide emission; (ii) limitedness of the reserves of hydrocarbons; (iii) political issues related to the localization of hydrocarbons in few places around the globe. In any implementation of hydrogen economy, which is a possible cure for the mentioned issues, the production and storage of hydrogen are the most challenging tasks to solve. The dissertation is focused on the problem of hydrogen storage. For today, none of the known materials meets all the requirements imposed on practical on-board hydrogen storage media. The main idea proposed and explored in this dissertation is the "hierarchical storage of hydrogen". We envisage materials that would offer various means of reversible hydrogen binding. Each level of hydrogen storage would have different characteristics that become advantageous in different circumstances. A material with hierarchical hydrogen storage could be superior in comparison with conventional materials, in which hydrogen is bound at one level only. In particular, we explore materials in which a fraction of hydrogen is physically bound and the remaining part is chemically bound. The physical binding provides hydrogen that is kinetically easily accessible, whereas the chemical binding assures a high overall hydrogen density. We suggest that hydrogen clathrates of a high hydrogen content material, like ammonia borane, could serve as models of hierarchical hydrogen storage. An objective of the dissertation is thus to validate the possibility of storage of molecular hydrogen in clathrates of ammonia borane using methods of theoretical chemistry and materials science. The goals of the dissertation can be formulated as follows: (i) to identify possible structures of clathrates of ammonia borane; (ii) to estimate hydrogen capacity of the clathrates; (iii) to estimate pressure-temperature regimes required for the stabilization of these clathrates. The scientific novelty of the dissertation includes: (i) formulation of the "hierarchical hydrogen storage" concept; (ii) formulation of construction principles for clathrates of ammonia borane and identification of their possible structures; (iii) estimation of hydrogen capacity of the clathrates; (iv) development of a model of clathrates phase equilibria, which is based on the energy of intermolecular host-guest interactions and the entropy of guest molecules enclosed in clathrate cages; (v) an estimation of the pressure-temperature stability zone for these clathrates. The practical significance of the dissertation is in justification of further experimental works on clathrates of ammonia borane, for which the required stabilization pressure and temperature conditions are determined. The work proposed and thoroughly explored hierarchical method of hydrogen storage and resulted in identification of stable cages and periodic structures of possible clathrates of ammonia borane. The most stable extended system of these clathrates was found to be more stable than molecular crystal of ammonia borane at low temperatures. Hydrogen capacity of this hypothetical clathrate structure was estimated to be 21 wt%. To predict the pressure-temperature stability zone of the material a model of clathrate phase equilibria has been formulated and tested on known hydrates. The model showed that clathrates of ammonia borane could be stabilized at ambient pressure when temperature is lowered to 77 K.