This thesis investigates the application of large scale concentrated solar (CSP) and photovoltaic power plants in Libya. Direct Steam Generation (DSG) offers a cheaper and less risky method of generating electricity using concentrated solar energy than Heat Transfer Fluid (HTF) plant. However, it is argued that the location of a DSG plant can be critical in realising these benefits, and that the South-East part of Libya is ideal in this respect. The models and calculations presented here are the result of an implementation of the 2007 revision of the IAPWS equations in a general application based on Microsoft Excel and VBA. The hypothetical design for 50MW DSG power plant discussed in this thesis is shown to yield an 76% reduction in greenhouse gas emissions compared to an equivalent gas-only plant over the ten-hour daily period of operation. Land requirement is modest at 0.7km2. A new method for improving the distribution of heat within the absorber tube wall was developed. Internal helical fins within the absorber tube have been proposed to provide a regularly pitched and orderly distribution of flow from the ‘hot' to the ‘cold' side of the absorber tube. Note that the irradiance profile on the absorber tube is highly asymmetric. A CFD simulation using FLUENT software was carried out for three types of pipes with different internal helical-fin pitch, and an aluminium pipe without fins. The results show that the thermal gradient between the upper and lower temperature for the pipe without a helical fin is considerably higher compared with the pipes with helical fins. Also, the thermal gradient between the two halves for the aluminium pipe (without a helical fin) is much lower when compared to the result for the traditional steel pipe (without a helical fin). A 50MW PV-grid connected (stationary and tracking) power plant design in Al-Kufra, Libya has been carried out presently. A hetero-junction with intrinsic thin layer (HIT) type PV module has been selected and modelled. The effectiveness of the use of a cooling jacket on the modules has been evaluated. A Microsoft Excel-VBA program has been constructed to compute slope radiation, dew-point, sky temperature, and then cell temperature, maximum power output and module efficiency for this system, with and without water cooling for stationary system and for tracking system without water cooling. The results for energy production show that the total energy output is 114GWh/year without a water cooling system, 119GWh/year with a water cooling system for stationary system and 148GWh/year for tracking system. The average module efficiency with and without a cooling system for the stationary system is 17.2% and 16.6% respectively and 16.2% for the tracking system. The electricity generation capacity factor (CF) and solar capacity factor (SCF) for stationary system were found to be 26% and 62.5% respectively and 34% and 82% for tracking system. The payback time for the proposed LS-PV power plant was found to be 2.75 years for the stationary system and 3.58 years for the tracking system. The modelling that was carried was based on the measurements conducted on the experimental system set in a city in the southern part of Turkey. Those measurements are recorded by a Turkish team at Iskanderun. As well as the current, voltage and cell temperature of the photovoltaic module, the environmental variables such as ambient temperature and solar irradiance were measured. These data were used for validation purposes. The correlation for the conversion of solar irradiation from horizontal to sloped surface indicated that the presently used model is highly successful reflected by the goodness of fit parameters: the coefficient of determination is 0.97, and the mean bias error -2.2W/m2. Similarly, the cell temperature model used in the present thesis is validated by the following correlation parameters R2 = 0.97 oC, while MBE is 0.7 and RMSE = 2.1 oC.

This thesis presents a comprehensive investigation into the underlying coupled processes in coal in response to high pressure gas injection. This is achieved by i) developing a new high pressure gas experimental facility and conducting a series of experimental tests, and ii) developing and applying a theoretical and numerical model. A novel experimental facility was designed, which offers stable and continuous high-pressure injection of gases in fractured rocks, for detailed study of the reactive transport processes. It consists of the gas supply and backpressure control system. Using the newly developed experimental facility, the response of coal subject to subcritical and supercritical gas injection under stable and variable temperature conditions was studied. The experimental investigation consisted of a series of tests: i) sorption capacity and kinetics tests, ii) uniaxial compressive tests, iii) sieve analysis tests, iv) flow and deformation tests. Thirty anthracite coal samples from different depths (i.e. 150 m and 550 m) and locations from the South Wales coalfield were characterised and tested. The capabilities of the theoretical and numerical modelling platform of thermal, hydraulic, chemical and mechanical processes were advanced. A new theoretical approach was adopted which successfully incorporates reactive gas transport coupled with coal deformation. The development of constitutive relationships describing the sorption induced elastic isotropic swelling of coal and changes in permeability was considered in detail. Numerical solutions of the governing flow and deformation equations were achieved by employing the finite element method for spatial discretisation and the finite difference method for temporal discretisation. The new model was verified for its accuracy via a series of benchmark tests and validated using high-resolution experimental data. The results of the experimental study showed that the sorption capacity and kinetics are sample-size dependent, particularly for deeper coal. Higher and faster sorption of CO2 obtained on powdered samples compared to intact samples indicated that sorption processes are governed by fracture interconnectivity and accessibility of pores. Sorption of CO2 was found to significantly reduce the brittleness, uniaxial compressive strength and elastic modulus of anthracite coals. The results of the post-failure sieve analysis showed that CO2 saturated samples disintegrated on smaller particles than non-saturated samples indicating that sorption induced swelling weakens the coal structure by enhancing the existing and inducing new fractures. During CO2 flow through coal under constant stress, samples experienced swelling resulting in initial reduction followed by recovery of measured flow rates. CO2 sorption induced changes were found to be non-reversible. The results of high CO2 flow through coal showed that CO2 reduced the temperature of the system, associated with Joule- Thomson cooling, enhancing the coal swelling and opposite to expected, increasing the flow rates. Overall, the high-resolution data-set obtained is a significant contribution to the scientific community and is able to provide a means of validation for future models. The results of the verification and validation exercises demonstrated the capability of the developed model to simulate coupled processes involved in gas transport in coal. A series of numerical simulations were conducted to investigate the permeability evolution and CO2 breakthrough in coal subject to supercritical CO2 injection using the developed model. Different scenarios were considered, involving a range of values of the elastic modulus and the parameter defining the coal swelling. The results of the advanced numerical simulations showed that the effect of CO2 sorption induced swelling on permeability reduces with a decrease in coal stiffness suggesting that CO2 sorption induced reduction of elastic modulus would have a positive effect on the ability of coal to conduct CO2. In this work, confidence in the feasibility of CO2 storage in anthracite coals was improved by enhancing the knowledge of high pressure gas-coal interactions through both experimental and numerical investigations. Moreover, it is claimed that newly developed model enables predictions of coupled processes involved in carbon sequestration in coal.

This thesis focuses on modelling the degradation of particles in gas-solid fluidised beds. Modelling is performed by using a coupled approach where the gas phase is treated as a continuum and the solid phase is represented by individual discrete particles, using the discrete element method (DEM). This approach makes it possible to access individual particle properties. By implementing new modelling techniques into the DEM framework, the individual particle degradation behaviour can be numerically described with high accuracy. The main interest is to understand more complex gas-solid systems as encountered e.g. in fluidised beds which might contain numerous degrading particles. This work focuses on verifying and validating these sub-models to be able to obtain accurate information for further suggestions in operation and optimisation of dense particulate systems. Particle degradation is studied by means of thermophysical, thermochemical and mechanical aspects. Drying (thermophysical) is an energy intensive process which makes further research inevitable for further optimisation. Large particles during drying develop temperature and species gradients along their radius, affecting the product quality. The DEM has been used to monitor flow, particle and subparticle properties which have been found useful to control, operate and optimise such large particle drying processes. Pyrolytic (thermochemical) conversion of biomass in fluidised beds represents a promising route for the production of biooil. This process has been modelled and studied under consideration of drying, shrinkage, segregation and entrainment. Breakage or mechanical degradation is often encountered in engineering applications and requires a much better process understanding. Therefore, a new discrete fragmentation method (DFM) has been developed to study breakage in dense particle systems such as fluidised beds but also mills or crushers. Much reliable breakage information can be obtained to further optimise such systems.

The majority of investigations on municipal solid waste (MSW) landfills have been undertaken during the post-closure period, and therefore, the changes that occur in the properties of refuse layers placed during the period of infilling are often ignored. The impact of fiirther tipping of refuse loads on the moisture content, hydraulic and geotechnical properties of emplaced refuse lifts, and the daily cover was examined in this study by undertaking field and laboratory tests on the refuse fill at White's Pit landfill, Poole, Dorset. The field tests involved mainly pit tests and cone penetration tests. The porosity and field capacity of the refuse excavated fromthe pits were determined in 210 litre drums. In addition, factors that influence leachate production, which include the moisture stored in the topsoil and the runoff fromthe landfill were measured. The laboratory tests involved the determination of compression, porosity, and hydraulic conductivity of pulverised refuse samples with and without a cover soil, under increasing vertical loading. The data obtained fromthe tests were used in the simulation of moisture in refuse lifts at the site, using the Hydrologic Evaluation of Landfill Performance (HELP) model. The data were also used to formulate characteristic equations used for determining temporal changes in the physical properties of emplaced refuse lifts. The results of the investigation show a reduction in porosity and hydraulic conductivity, and increase in the density of an emplaced refuse layer according to the quantity of further filling of refuse loads. The density of an emplaced refuse is further increased by the ravelling of the daily cover materials, but its permeability decrease as a result. Under an applied vertical load of 6 kPa, the hydraulic conductivity and density of refuse-only samples were 1.4 x 10"^ m/s and 291 kg/m^, while that for refuse with 7.5 % cover soil were 9.4 x lO'^m/s and 353 kg/m^ respectively. The hydraulic conductivity of a refuse lift with a slightly clay/silt sand cover, however, appeared greater than its calculated value (10^ m/s) at low effective stresses. The similarity between the results of refuse tested in experimental cells in present study and Beaven and Powrie's (1995) large-scale compression cell suggests that empirical models can be derived from the data obtained from cell tests to predict the behaviour of refuse with different densities. Furthermore, relatively small cells can be used in preliminary study of the behaviour of refuse if the particle sizes are reduced in proportion to the size of the test cell. Apart from direct infiltration of water during waste placement, the volumetric moisture content and degree of saturation of a refuse lift increase during the fill period due to compression from overlying lifts. The saturation of the refuse fill is further enhanced by channelled water through the macropores in the cover soil system. The simulation technique used in this study may be used in evaluating alternative designs and plans of a MSW landfill. Large-scale testing of refuse with an intermediate cover soil is recommended.

An overview of the production and consumption of Kuwait electrical energy, installed capacity and peak loads is presented in this research. The results show that Kuwait has a serious problem because of insufficient electrical energy installed and load peaking, which is considered unacceptable. The research also identifies and analyses the geographical and temporal variability of solar energy inside Kuwait. The fundamental solar models are modified to estimate and identify daily and hourly global (direct-beam) and total solar radiation (SR) on horizontal surfaces on the basis of the more readily available meteorological data such as latitude angle, longitude angle, clearness index, solar time and corresponding hour angle. The presented results demonstrate that Kuwait has an abundance of solar energy capability in terms of almost cloudless atmosphere for nine months and twelve hours solar time a day throughout the year. The daily global and monthly averaged solar intensity have been computed. This research shows that the knowledge of SR data is essential for design and sizing of the photovoltaic (PV) systems. A specific type of PV module has been modelled and its characteristics such as I-V and P-V curves for each month of the year have been calculated and analysed using MATLAB/Simulink to determine the amount of DC current, voltage and power. These results form the basis of the grid-connected PV system (GCPV) design from array construction to the reliability of electrical supply. A technical sizing procedure based on sizing algorithm using iterative manual approach (SAIMA) for meeting specific amount of GWh output required by a potential PV system sponsor in Kuwait is presented. SAIMA has been implemented to determine the configuration of the PV array, inverter-to-PV array sizing factor and efficiency of the system according to previous PV module and inverter database. A novel methodology for approximating Pareto front multi-criteria cost-efficiency optimization problem for a proposed GCPV system has been constructed using system planning constraints. The proposed algorithm is based on bi-objective weighted-sum (BoWS) method to maximize the system efficiency and minimize the system cost. A main objective function of both GCPV system cost and efficiency has been stated as function of PV output power and inverter rated power. The proposed function is performed with the Sequential Quadratic Programing (SQP). The results presented in this research have been acquired through simulation of the proposed GCPV to a specific section of Alsabyia generation station part of Kuwait national grid with efficient maximum power point tracking (MPPT) algorithm incorporated into a DC-DC boost converter. The simulations were performed using Power Simulation Software (PSIM). The analytical model of the PV module has been combined with a ‘perturb and observe’ (P&O) method so that MPP is achieved with the external temperature and SR also considered. An inverter is used to track the output voltage of the converter and interface the PV array with the grid. The results show that the model not only achieves the MPP function but also improves the output of the inverter by reducing the ripples in the sine waveforms. Moreover, this research involved using the software package ERACS to analyze the impact of penetrating approximately 100 MW of the proposed PV generation to a part of the generation unit at Alsybia electrical station in Kuwait. The one-line diagram of the network was modeled in ERACS and it’s used to conduct power flow and fault studies. Four network locations were chosen as potential sites to connect the PV system. Power flow studies were conducted on the network for every hour that the PV array contributed power to the network and for 35 different network configurations for each daylight hour. Computer programs were created to conduct all of these power flow studies and to help analyze the data. Fault studies were then carried out on the network, with the PV array connected at all of the potential locations. There were a few faults that caused a fault level greater than 40 kA to flow through the 13.8 kV busbars.

There has been a great deal written about the difficulties faced by small and medium-sized enterprises (SMEs) compared to larger businesses. SMEs face difficulties complying with environmental legislation, particularly because of the amount of complex law. This can result in the ‘environment’ being treated as less of a priority even though SMEs collectively have a significant environmental impact. Over the past few years, the UK has been focused towards achieving ‘better regulation’. In particular, Hampton highlighted the need for more strategic thinking when it comes to developing regulation. Hampton suggested that regulators should use a risk-based model similar to that used by the England and Wales Environment Agency (EA). This view is shared by Local Authorities and other environmental regulators; however, there has been criticism from some commentators who suggest that certain legislation is not successfully enforced. The increased use of risk assessment by the EA has reduced the number of inspections resulting in more ‘pressure’ being put on remaining inspections as well as there being less opportunity to identify non-compliance. In addition, those businesses not included under direct regulatory regimes are unlikely to be audited for compliance against any environmental legislation; consequently a significant portion of all businesses go un-inspected and uncontrolled. Because of the number of SMEs, there needs to be an effective system of regulation that controls activities and targets those businesses that pose a risk to the environment, without unnecessarily over-burdening SMEs. It is clear from the coalition Government’s planned austerity measures in 2011 that management of the environment will have to be done with less resource than before. This thesis draws together findings from research conducted between 2005-2011. Previous research on compliance with legislation has often been conducted in isolation with little research comparing compliance across a range of legislation, and certainly not using triangulation methods to assess SMEs’ overall legal performance. This study aimed to investigate the legal performance of UK SMEs with a range of environmental legislation. This study identifies: • the level of compliance (‘spirit’ and ‘letter’ of the law) with environmental legislation; • the impact and effectiveness of environmental legislation; and • ways of improving the environmental compliance control systems for SMEs. The study incorporated a wide range of environmental legislation, including that covering:waste management/ transfer, environmental permitting (including waste exemptions), site waste management plans, WEEE, RoHS, packaging, oil storage as well as identifying other potential environmental offences. Detailed compliance audits were conducted with 44 SMEs from 5 different sectors from the north-west of England. Interviews with SME management, site staff, regulators, Government policy officials and support organisations; in total 99 individuals were interviewed. The study indicates: • Low levels of compliance with the ‘letter’ and ‘spirit’ of the law. • Knowledge and understanding of environmental legislation was poor; no single SME, regulator or support organisation appreciated ‘environmental compliance’ as a whole. • Enforcement activity and surveillance of the SMEs audited was very low; this reflected nation enforcement figures. • The impact of environmental legislation on SMEs is overstated. The impact increased commensurate with ‘effort to comply’ and ‘enforcement action’. • There was evidence of direct and indirect environmental harm as a result of noncompliance. • Regulation can only be effective if it is complied with; measuring the link between the legislation and environmental protection must be accompanied by a clear understanding of compliance levels. This study produces an initial assessment methodology for SMEs, compliance performance indicators and recommendations to improve SME compliance controls.

Municipal solid waste is an issue every community in the world has to be concerned with. Without any management, municipal solid waste poses environmental and health risks to the community such as from water and air pollution. In selecting methods to deal with the waste, environmental impacts considerations are important to reduce these risks. Environmentally sustainable waste management processes should also decrease greenhouse gases contributing to global warming and climate change. Waste to energy (WtE) processes lessens and replaces the use of fossil fuels reducing greenhouse gases. The research aims to assess the environmental impacts and energy recovery of WtE processes, specifically incineration or energy recovery facilities (ERF) and anaerobic digestion (AD) to select suitable options or any combinations thereof as part of an integrated waste management system for different locations and conditions by using life cycle assessment (LCA) methods. WRATE (Waste and Resources Assessment Tool for the Environment) an LCA model is used to assess scenarios designed systematically with different combinations of incineration/ERF and AD. The study also varies other factors such as different recycling schemes and recycling rate, household waste composition and population density to determine the suitable combinations for different local conditions. Results for both UK and Thailand confirm the need to reduce disposal of waste into landfills. The scenario with Incineration/ERF for heat recovery and a post collection recycling scheme and the combination scenario with Incineration/ERF for heat recovery and Anaerobic Digestion for vehicle fuel a post collection recycling scheme lead the ranking for most energy recovery and less environmental impacts. The parameter exerting the greatest influence on LCIA of these set of scenarios is WtE technology. Second is recycling scheme with recycling rate as a subset. Third is energy recovery type. Population density also affects the outcome slightly by the magnitude of the values.

Mechanical biological treatment (MBT) is the generic name for a group of processes which have been used to reduce the biodegradable content of municipal solid waste (MSW) in order to aid compliance with the Landfill Directive. As a result of mechanical biological treatment, MSW is converted to a material which has different properties to its parent material, including changes to its mechanical properties. The aims of this research were to identify: • The shear strength characteristics of aerobically treated MBT, processed at New Earth Solutions (NES) in the UK • Changes to the properties of the reinforcing elements due to the MBT process and its impact to the shear strength NES produced two fractions of MBT residue (0-10 mm and 0-20 mm) which were tested using direct shear equipment in order to identify the shear strength characteristic of the MBT residues. It was thought MBT might be a weak material compared to MSW due to the significant reduction of the reinforcing particles size and content, the results confirmed that MBT is a strong material (mobilizes its strength rapidly with displacement) compared to MSW. MBT processes lead to changes in both the content of reinforcing particles and their properties. The reinforcing effect and its impact on the shear strength of MBT waste was tested using direct shear. To an unreinforced basic matrix of either MBT or compost were added reinforcing elements in a controlled way to investigate the impact on shear strength from each identified reinforcement property.

Sugar-lignin bio-refineries using renewable lignocellulosic carbon as an input material could be used in the future to produce a variety of value added products including fuels and specialty chemicals. The bio-refinery aims to replace a proportion of goods currently produced using fossil fuels. Lignocellulosic material has a significant sugar potential in the form of cellulose and hemicellulose and this can be accessed using enzymatic hydrolysis. The lignocellulosic feedstock used in this research was paper pulp derived from municipal solid waste (MSW) and the aim of the work was to maximise the efficiency of producing a concentrated sugar solution from the cellulose (or glucan) component of MSW using commercial enzyme preparations. Analysis of the pulp by acid hydrolysis showed a ratio of 56: 12: 27: 5 of Glucan: Hemicellulosic sugar chains other than glucan: Lignin & pseudo lignin: Ash on total solids (TS). The hydrolysis behaviour of this pulp was similar to that of other lignocellulosic substrates even though the matrix of this material is perhaps more complex. Glucan conversion could be increased by 6% if the pulp was extracted with acetone to remove solvent soluble compounds. Using the additive PEG 6000 increased conversion by 15 % over 48 hours, and allowed a 40 % reduction in the enzyme requirement. PEG also increased the centrifugal dewaterability of the substrate by up to 13%. These results were obtained in single stage batch experiments. It was found, however, that both the glucose concentration in solution and the overall glucan conversion in the substrate could be improved by using a two-stage hydrolysis strategy. Using 50 mg enzyme g-1 pulp at high total solids content >18.5% TS singlestage enzyme hydrolysis gave a maximum glucan conversion of 68%. It was found that two-stage hydrolysis could give higher conversion if sugar inhibition was removed by an intermediate fermentation step between hydrolysis stages. This, however, was not as effective as direct removal of the sugar products, including xylose, by washing of the residual pulp at pH 5. This improved the water availability and allowed reactivation of the pulp-bound enzymes. Inhibition of enzyme activity could further be alleviated by replenishment of β-glucosidase which was shown to be removed during the wash step. The two-stage hydrolysis process developed could give an overall glucan conversion of 88%, with an average glucose concentration of 7.5 wt% in 4 days after combining the hydrolysates of the first and second stage of hydrolysis. The residual washwater from the two-stage hydrolysis with intermediate wash step process contained a dilute amount of sugar. It was found that this washwater could be used as dilution water for a new batch of hydrolysis without any detriment to conversion efficiency. Thus, to further the work above a washwater recycle strategy was applied to the two-stage hydrolysis process. Washwater at various pHs and with or without the addition of PEG 6000 was used as dilution water for a subsequent round of hydrolysis, where up to 6 rounds of 48-hour hydrolysis were completed to reach a steady stage configuration. In these strategies the enzyme dose was reduced to 30 mg C-Tec3 g-1 pulp. Use of a pH 5 or pH 9 wash resulted in an increase in conversion of up to 5% in the first-stage hydrolysis rounds, indicating that enzyme carryover was occurring. The sugar augmentation and enzyme carryover consistently resulted in glucose yields above 7.0 wt% in the first stage hydrolysate when using this lower enzyme dose. The best result achieved in this strategy was obtained when using 0.25 wt% PEG 6000 in the reaction medium and washwater. By reducing the amount of liquid in the second-stage of hydrolysis, it was found that an overall average glucan conversion of 81% could be achieved over the two hydrolysis stages with an average glucose concentration of over 8 wt% in a 4 or 5 day reaction period. This result is significant, as it meets the downstream processing requirements for bioethanol, a major bio-refinery product, and does this with a low enzyme loading. Furthermore, the waste discharge is minimised due to the high glucan conversion.

Gas hydrates are clathrate hydrates, which are solid, ice-like compounds. Gas hydrates exist where there is an ample supply of gas and water combined with high pressure and/or low temperature conditions. In nature these are found in sediments where permafrost is present, and in deep-marine sediments. The morphology of gas hydrate within a sediment has a large impact on the strength and stiffness properties of hydrate bearing sediments. Gas hydrates are metastable and they dissociate if the temperature and/or pressure conditions are sufficiently altered. The dissociation of gas hydrate and its potential as a submarine geohazard have become of increasing importance as oil and gas exploration activities extend into significant water depths on continental margins and seas where gas hydrates are known to exist. Such activities may lead to dissociation of hydrate, possibly increasing pore pressure, and altering the stiffness and strength of the sediment. Due to difficulty in performing field testing and obtaining undisturbed in-situ samples for testing, at present, hydrate dissociation in the natural environment and its effects are hypothesised on the basis of remote observations. Therefore, a series of well-controlled laboratory tests were conducted on laboratory-prepared methane hydrate bearing sand sediments. The tests were undertaken with hydrate saturation ranging from 7% to 27% in the Gas Hydrate Resonant Column Apparatus (GHRC). Factors such as effective stress were also assessed with regard to specimen stiffness. Resonant column testing during hydrate formation and dissociation processes carried out for the first time, such that not only final change in specimen properties to be determined as a function of total hydrate saturation but also the change in specimen properties as function of the percentage of hydrate formation and dissociation. Test results showed that a rapid reduction in stiffness occurred for a minor change in hydrate saturation of sand specimens where dissociation was induced by temperature increase, but for specimens that were dissociated using the pressure reduction method a slower reduction occurred. In contrast, during hydrate formation stiffness increased more gradually. In addition, test results showed that the hydrate formation using the excess gas method led to higher increases in the shear stiffness compared to the flexural stiffness of specimens, and the linear stiffness threshold limit of hydrate bearing specimens were lower than the non-hydrate bearing sands. In addition to laboratory tests, an analytical model was built to predict the increase in pore pressure under undrained conditions within hydrate bearing sediment during dissociation. The results obtained from the laboratory tests were used to compare the predicted results from the model. Analytical model showed that the rise in pore pressure within a sediment was dependent on a number of factors: major factors were initial pore pressure, amount of hydrate dissociation, cage occupancy of gas within hydrate, stiffness of the sediment, and degree of water saturation; Minor factors were methane gas solubility in water, and methane hydrate density.