202 research outputs found

    Energy policy in transition: evidence from energy supply and demand in the UK

    Get PDF
    Whilst much of Europe is turning to supplier obligations in order to compel energy companies to deliver energy efficiency improvements, the UK, after 18 years of using such schemes, will from 2013 have a financing scheme as the central delivery mechanism, relying fully on the market rather than government intervention. The remaining supplier obligation will focus on the areas that financing is not expected to fully support: more expensive insulation and help for those with no access to finance. In addition, the publicly funded fuel poverty policy is to be terminated: for the first time since 1978, there will be no taxpayer funded energy efficiency programme for the most vulnerable. These changes represent the biggest shift in the history of energy efficiency policy in the UK since the first and second oil crisis. Yet, despite appeals from many stakeholders, no period of transition will exist between the end of the current and the start of the new policies. The impact is likely to be stark: the expectation is for a dramatic reduction in the delivery of cost-effective energy efficiency measures leading to a big fall in employment and carbon reduction.Plans for the supply-side are equally profound. In order to create a market with greater capacity and to encourage nuclear investment, the Government has unveiled plans for electricity market reform (EMR). For renewable generators, EMR will mark a change in policy support, from a quantity-based green certificate mechanism (the Renewables Obligation) to a price-based feed-in-tariff approach. In contrast to the approach on the demand-side, Government is allowing a three year transition between these schemes. The paper outlines the reasons for the different approaches to policy continuity across the demand and supply side. It highlights what we see as key considerations for policy makers when planning a transition from a supplier obligation to a finance mechanism. We assess the implications of this shift in terms of carbon reduction effort, the industry and fuel poverty

    Optimization of a CFD – Heap leach model and sensitivity analysis of process operation

    Get PDF
    A comprehensive heap leach model, developed within a computational fluid dynamics software framework, provides a modeling tool to capture reactive dissolution in low grade ores of oxide and sulfide minerals. These systems involve suites of very complex reactions, which are closely coupled with thermal conditions and key microbial populations. One of the key challenges when modeling heap leach scenarios is characterization of the ores and parameterization of the model in order to utilize the model as an investigative tool. The calibration of the model can be a lengthy process requiring many simulation runs. An optimization tool has been incorporated into the model to allow automated searching for multiple ‘best fit’ parameter values and to determine sensitivity. Once the model has been parameterized, large-scale forecasts can be simulated or a sensitivity analysis can be performed to investigate a range of process variables, such as irrigation rate, lift, air injection, acidity, head grade and dripper emitter spacing, amongst others. One such example is explored here for the Zaldivar ore body

    Development management and localism: Zeitgeist or lasting change?

    Get PDF
    The spatial planning approach has become accepted as the progressive theoretical and professional currency in England following the 2004 Planning and Compulsory Purchase Act. The reforms which followed sought considerable change in the remit of planning and the approach to community engagement. However, an often overlooked component of the spatial planning approach is development management; and yet it is potentially of most relevance to the challenges of neighbourhood planning and community resilience. Development management focuses upon outcomes (i.e. meeting needs) rather than outputs (the implications of permitting/refusing development - normatively related to the regulatory ‘DC’ function). The methodological approach is based around a more varied and multi-faceted concept than in the reactive past. A key part of this relates to the way in which community participation occurs and decision making takes place. This artcile discusses the concept that empowering communities through early engagement, support for community led initiatives/plans, Local Development Orders, and enhanced delegated decision making at the Parish level are examples of localism before Localism, and highlight the contemporary relevance of the development management approach. It is suggested, therefore, that rather than requiring a planning revolution, the current changes represent an opportunity to firstly recognise and secondly utilise existing tools to support community planning. Implementing further significant change in the planning system may not be in anyone’s best interest, least of all for the resilience of those communities it seeks to empower.This article explores the evolution of the development management approach and its significance in the context of the proposed neighbourhood planning systems, including Neighbourhood Plans and Development Orders, the Community Right to Build, and community engagement and participation methods

    Fit for purpose? Fitting ontological security studies 'into' the discipline of International Relations : towards a vernacular turn

    Get PDF
    The performance of International Relations (IR) scholarship – as in all scholarship – acts to close and police the boundaries of the discipline in ways that reflect power–knowledge relations. This has led to the development of two strands of work in ontological security studies in IR, which divide on questions of ontological choice and the nature of the deployment of the concept of dread. Neither strand is intellectually superior to the other and both are internally heterogeneous. That there are two strands, however, is the product of the performance of IR scholarship, and the two strands themselves perform distinct roles. One allows ontological security studies to engage with the ‘mainstream’ in IR; the other allows ‘international’ elements of ontological security to engage with the social sciences more generally. Ironically, both can be read as symptoms of the discipline’s issues with its own ontological (in)security. We reflect on these intellectual dynamics and their implications and prompt a new departure by connecting ontological security studies in IR with the emerging interdisciplinary fields of the ‘vernacular’ and ‘everyday’ via the mutual interest in biographical narratives of the self and the work that they do politically

    Finite element microstructural homogenization techniques and intergranular, intragranular microstructural effects on effective diffusion coefficient of heterogeneous polycrystalline composite media

    Get PDF
    Microstructural intergranular and intragranular effects play a vitally important role in mass transport within heterogeneous polycrystalline composite media. Full scale macroscopic specimen or component modelling of heterogeneous polycrystalline composite media is complex, time consuming and computationally expensive. Consequently it is important to develop a homogenous model to predict the effective diffusion coefficient of the heterogeneous polycrystalline composite media. It is also important to investigate the effect of intergranular and intragranular microstructure on effective diffusivity of heterogeneous polycrystalline composite media. A two dimensional finite element microstructural representative volume element (FEMRVE) model with different intergranular and intragranular microstructures has been developed using the well-known Voronoi tessellation technique. The effective diffusivity predicted by the FEMRVE model with various intergranular and intragranular microstructures of heterogeneous polycrystalline composite media agrees well with the results of various effective medium theories

    Heap Leaching: Modelling and Forecasting Using CFD Technology

    Get PDF
    Heap leach operations typically employ some form of modelling and forecasting tools to predict cash flow margins and project viability. However, these vary from simple spreadsheets to phenomenological models, with more complex models not commonly employed as they require the greatest amount of time and effort. Yet, accurate production modelling and forecasting are essential for managing production and potentially critical for successful operation of a complex heap, time and effort spent in setting up modelling tools initially may increase profitability in the long term. A brief overview of various modelling approaches is presented, but this paper focuses on the capabilities of a computational fluid dynamics (CFD) model. Advances in computational capability allow for complex CFD models, coupled with leach kinetic models, to be applied to complex ore bodies. In this paper a comprehensive hydrodynamic CFD model is described and applied to chalcopyrite dissolution under heap operating conditions. The model is parameterized against experimental data and validated against a range of experimental leach tests under different thermal conditions. A three-dimensional ‘virtual’ heap, under fluctuating meteorological conditions, is simulated. Continuous and intermittent irrigation is investigated, showing copper recovery per unit volume of applied leach solution to be slightly increased for pulse irrigation

    Influence of grain boundary misorientation on hydrogen embrittlement in bi-crystal nickel

    Get PDF
    Computational techniques and tools have been developed to understand hydrogen embrittlement and hydrogen induced intergranular cracking based on grain boundary (GB) engineering with the help of computational materials engineering. This study can help to optimize GB misorientation configurations by identifying the cases that would improve the material properties increasing resistance to hydrogen embrittlement. In order to understand and optimize, it is important to understand the influence of misorientation angle on the atomic clustered hydrogen distribution under the impact of dilatational stress distributions. In this study, a number of bi-crystal models with tilt grain boundary (TGB) misorientation angles (θ) ranging between 0°≤ θ ≤ 90° were developed, with rotation performed about the [001] axis, using numerical microstructural finite element analysis. Subsequently, local stress and strain concentrations generated along the TGB (due to the difference in individual neighbouring crystals elastic anisotropy response as functions of misorientation angles) were evaluated when bi-crystals were subjected to overall uniform applied traction. Finally, the hydrogen distribution and segregations as a function of misorientation angles were studied. In real nickel, as opposed to the numerical model, geometrically necessary dislocations are generated due to GB misorientation. The generated dislocation motion along TGBs in response to dilatational mismatch varies depending on the misorientation angles. These generated dislocation motions affect the stress, strain and hydrogen distribution. Hydrogen segregates along these dislocations acting as traps and since the dislocation distribution varies depending on misorientation angles the hydrogen traps are also influenced by misorientation angles. From the results of numerical modelling it has been observed that the local stress, strain and hydrogen distributions are inhomogeneous, affected by the misorientation angles, orientations of neighbouring crystal and boundary conditions. In real material, as opposed to the numerical model, the clustered atomic hydrogens are segregated in traps near to the TGB due to the influence of dislocations developed under the effects of applied mechanical stress. The numerical model predicts maximum hydrogen concentrations are accumulated on the TGB with misorientation angles ranging between 15°< θ < 45°. This investigation reinforces the importance of GB engineering for designing and optimizing these materials to decrease hydrogen segregation arising from TGB misorientation angles
    • …
    corecore