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Abstract A CFD modelling study has been undertaken to examine the co-firing of pulverised coal and biomass with particular regard to the burnout of the larger diameter biomass particles. Computations were based on a research combustion facility that replicates an industrial coal-fired power station. Three percent, by mass, of pinewood was blended with a bituminous UK coal, and the effects of the wood particle size and shape on the burnout of the combined wood and coal char were investigated. The effect of varying the devolatilisation and char combustion rate constants for the biomass component in the blend was also investigated. It was concluded that the combustion of small (200 μm) wood particles was rapid but the rate of combustion of larger particles was dependent on their composition, size, and shape.

The Sulphurdale Geothermal Field is located in Beaver County Utah, within the boundaries of the Cove Fort--Sulphurdale Known Geothermal Resource Area (KGRA). During the past year, three wells drilled in Section 7, T-26-S, R-6-W, have produced dry steam from a fractured volcanic formation located at a depth of about 1100 feet. Two of these three wells are currently prepared to supply steam to a power plant, and one well has been plugged and abandoned. ThermaSource, Inc. was retained by Mother Earth Industries, the operator of the field, to conduct well tests and render an opinion as to the nature of the geothermal reserves and assess the commercial potential of these reserves. Because of the limited area that has been explored to date, there can be no assurance that the reserves estimate will prove accurate. Project economics are based on parameters believed to be accurate, but there is no assurance that such cash flow projections will be realized.

The Severn Estuary has the world's second largest tide range and a barrage across the estuary, located just seawards of Cardiff in Wales and Weston in the South West England, has been proposed for over half a century, with the objective of extracting large amounts of tidal energy. A Severn Barrage, as previously proposed by the Severn Tidal Power Group (STPG), would be the largest renewable energy project for tidal power generation in the world, if built as proposed, and would generate approximately 5% of the UK's electricity needs. However, concerns have been raised over the environmental impacts of such a barrage, including potential increase in flood risk, loss of intertidal habitats etc. In addressing the challenges of maximizing the energy output and minimizing the environmental impacts of such a barrage, this research study has focused on using a Continental Shelf model, based on the modified Environmental Fluid Dynamics Code (EFDC) with a barrage operation module (EFDC_B), to investigate both the far and near field hydrodynamic impacts of a barrage for different operating scenarios. Three scenarios have been considered to simulate the Severn Barrage, operating via two-way generation and using different combinations of turbines and sluices. The first scenario consisted of 216 turbines and 166 sluices installed along the barrage; the second consisted of 382 turbines with no sluices; and the third consisted of 764 turbines and no sluices. The specification of the sluice gates and turbines are the same for all scenarios. The model results indicate that the third scenario has the best mitigating effects for the far-field and near-field flood risks caused by a barrage and produces the most similar results of minimum water depth and maximum velocity distributions to those obtained from simulating the natural conditions of the estuary, i.e. the current conditions. The results also show that the flow patterns around the barrage are closest to those for the existing natural conditions with minimal slight changes in the estuary. Thus, the results clearly indicate that the environmental impacts of a Severn Barrage can be minimized if the barrage is operated for two-way generation and under the third scenario. Although it appears that the energy output for the third scenario is less than that obtained for the other two scenarios, if very low head (VLH) turbines are used, then the third scenario could generate more energy as more turbines could be cited along the barrage structure. Therefore, the study shows that a Severn Barrage, operating in two-way generation and with 764 turbines (ideally VLH turbines), would be the best option to meet the needs of maximizing the energy output, but having a minimal impact on environmental changes in the estuary and far-field.

Providing access to on-demand energy at the global scale is a grand challenge of our time. The fabrication of solar cells from nanocrystal inks comprising earth abundant elements represents a scalable and sustainable photovoltaic technology with the potential to meet the global demand for electricity. Solar cells with Cu2ZnSn(S,Se)4 (CZTSSe) absorber layers are of particular interest due to the high absorption coefficient of CZTSSe, its band gap in the ideal range for efficient photovoltaic power conversion, and the relative abundance of its constituent elements in the earth’s crust. Despite the promise of this material system, CZTSSe solar cell efficiencies reported throughout literature have failed to exceed 12.6%, principally due to the low open-circuit voltage (VOC) achieved in these devices compared to the absorber band gap. The work presented herein primarily aims to address the low VOC problem. First, the fundamental cause for such low VOC’s is investigated. Interparticle compositional inhomogeneities identified in the synthesized CZTS nanocrystals and their effect on the absorber layer formation and device performance are characterized. Real-time energy-dispersive x-ray diffraction (EDXRD) elucidates the role of these inhomogeneities in the mechanism by which a film of CZTS nanocrystals converts into a dense absorber layer comprising micron-sized CZTSSe grains upon annealing in a selenium atmosphere (selenization). Additionally, a direct correlation between the nanocrystal inhomogeneities and the VOC in completed devices is observed. Detailed characterization of CZTSSe solar cells identifies electrical potential fluctuations in the CZTSSe absorber – due to spatial composition variations not unlike those observed in the nanocrystals – as a primary V OC inhibitor. Additional causes for low VOC’s in CZTSSe solar cells proposed in the literature involve recombination at the interface between the CZTSSe absorber and: (1) the n-type, CdS buffer layer, or (2) the Mo back contact, and work is presented to ...

Biomass plays an important role in the world primary energy supplies, currently providing ∼14% of the world's primary energy needs and being the fourth largest contributor following coal, oil and natural gas. Over the past decade, domestic biomass heating has received more governmental and public supports than ever before in many developed countries, such as the UK. Although biomass combustion releases some combustion pollutants, biomass is renewable and produces little net CO 2 emissions to the atmosphere. Owing to the low sulphur and low nitrogen contents of many biomass materials, substituting biomass for fossil fuels, particularly coal, can reduce SO x and NO x emissions. This study investigated flue gas emissions, particularly carbon monoxide and nitrogen oxides, of a domestic biomass boiler under various operating conditions. The biomass boiler used in this study satisfies the current EU regulation (EN 303-05) on emissions of domestic biomass boilers. Emissions of the boiler had been measured not only under normal combustion conditions, but also under 'idle' combustion conditions when the boiler was not in but was ready for full operation. The experimental results are analysed and presented in this paper. Copyright The Author 2010. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org, Oxford University Press.

Dynamic loading of transformers is the term used when the loading capacity is calculated using an appropriate thermal model while taking into account the load magnitude, load shape, thermal limits and external cooling conditions. For transformer dynamic loading, the aim is to estimate the transformer's maximum dynamic loading capacity without violating the hottest-spot temperature (HST) and top-oil temperature (TOT) thermal limits. These two temperatures are proxy measures of insulation temperature, which can be used to estimate the loss of service life. The accuracy of the TOT and HST predictions is dependent on many things, central to which is the accuracy of the thermal model. This paper introduces metrics that can be used to differentiate between reliable and unreliable transformer thermal models. The two models discussed in this paper for HST and TOT are the non-linear IEEE model and the model developed by the authors using linear regression methods.

Consumer interest in food products, including fresh vegetables, with health promoting properties is rising. In fresh vegetables, these properties include vitamins, minerals, dietary fiber, and secondary compounds, which collectively impart a large portion of the dietary, nutritional or health value associated with vegetable intake. Many, including farmers, aim to increase the health-promoting properties of fresh vegetables on the whole but they face at least three obstacles. First, describing crop composition in terms of its nutrition-based impact on human health is complex and there are few, if any, accepted processes and associated metrics for assessing and managing vegetable composition on-farm, at the origin of supply. Second, data suggest that primary and secondary metabolism can be 'in conflict' when establishing the abundance versus composition of a crop. Third, fresh vegetable farmers are rarely compensated for the phytochemical composition of their product. The development and implementation of a fresh vegetable 'nutritional yield' index could be instrumental in overcoming these obstacles. Nutritional yield is a function of crop biomass and tissue levels of health-related metabolites, including bioavailable antioxidant potential. Data from a multi-factor study of leaf lettuce primary and secondary metabolism and the literature suggest that antioxidant yield is sensitive to genetic and environmental production factors, and that changes in crop production and valuation will be required for fresh vegetable production systems to become more focused and purposeful instruments of public health.

The delivery of precipitation through large and small scale precipitation features plays a key role in the hydrological cycle. Therefore, it is important to understand how the organization of precipitation will change as the earth warms. The organization of precipitation can be characterized into either widespread, mesoscale precipitation features (MPF) or short-lived, isolated precipitation features (IPF). The Weather Research and Forecasting (WRF) model was used to simulate precipitation features at a 3 km resolution during the 17-22 June 2010 period in the Southeast US under present and future climate conditions. In this methodology, the model is first run in present climate mode and then rerun with an adjusted initial state that adds projected temperature anomalies for the 2090s based on Representative Concentration Pathways (RCPs) 4.5 and 8.5 from the Coupled Model Intercomparison Project Phase 5 (CMIP5) in the IPCC Fifth Assessment Report (AR5). In the future climate simulations, small changes in precipitation occurred under RCP4.5 warming, but many significant changes were noted under RCP8.5 warming. Domain-averaged precipitation increased in the future climate simulations, with the largest changes over the ocean relative to the continent. In the future climates, IPF grew larger in length and eventually coalesced into MPF, reducing the total number of IPF and increasing the number of MPF. IPF and MPF also extended deeper into the troposphere and produced more precipitation overall.