Kinondoni, Tanzania
Kinondoni, Tanzania
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Tavner P.J.,Durham University | Greenwood D.M.,Durham University | Whittle M.W.G.,Durham University | Gindele R.,EGG Energy | And 2 more authors.
Wind Energy | Year: 2013

Understanding the availability of wind turbines (WT) is vital to maximize WT energy production and minimize the capital payback period. Previous work on this subject concentrated on reliability and the location of WT failure modes rather than root causes. This paper concentrates on the influence of weather and WT location on failure rate and downtime, to try to understand root causes and the consequences of failure. The paper goes further than a previous study, which used Windstats data from the whole of Denmark, by considering a limited population of identical WTs at three locations on the German Nordzee, Ostzee and in western Germany, using data from WMEP and local weather stations. This new study focuses more precisely than the previous study by using more reliable data. The data were analysed to find the WT failures and weather conditions and then cross-correlate them. To confirm their representativeness, the reliability characteristics of these smaller WT populations followed the average trends of the overall WMEP survey. However, clear differences were observed in the failure behaviour of the WTs at the three locations. Annual periodicity was seen in the weather data, as expected, but not in individual WT population failure data. However, clear cross-correlations can be seen between WT failures and weather data, in particular wind speed, maximum temperature and humidity. These cross-correlations were more convincing than those found in the earlier, larger Danish study, vindicating the more focused approach. It is also clear from the analysis that Operation & Maintenance also has an impact on WT failure rates. These factors will be important for the operation of offshore WTs with the work indicating how weather conditions may affect offshore WT failure rates. © 2012 John Wiley & Sons, Ltd. © 2012 John Wiley & Sons, Ltd.

Clerc A.,EGG Energy | Anderson M.,EGG Energy | Stuart P.,EGG Energy | Habenicht G.,EGG Energy
Journal of Wind Engineering and Industrial Aerodynamics | Year: 2012

An estimate of energy yield uncertainty is essential information for assessing the financial risk of a potential wind farm. The uncertainty associated with the wind flow model can make up a significant part of the overall energy yield uncertainty. In the present work, a systematic method for estimating wind flow modelling uncertainty is presented. The method is easy to implement with basic energy yield variables and is applicable to industry standard wind flow models such as WAsP and MS3DJH. The equations used are empirical fits to real wind flow model errors obtained by analysing historical data from over 500 mast pairs. © 2012 Elsevier Ltd.

Harris G.,EGG Energy | Heptonstall P.,Imperial College London | Gross R.,Imperial College London | Handley D.,EGG Energy
Energy Policy | Year: 2013

Current UK Government support for nuclear power has in part been informed by cost estimates that suggest that electricity from new nuclear power stations will be competitive with alternative low carbon generation options. The evidence and analysis presented in this paper suggests that the capital cost estimates for nuclear power that are being used to inform these projections rely on costs escalating over the pre-construction and construction phase of the new build programme at a level significantly below those that have been experienced by past US and European programmes. This paper applies observed construction time and cost escalation rates to the published estimates of capital costs for new nuclear plant in the UK and calculates the potential impact on levelised cost per unit of electricity produced. The results suggest that levelised cost may turn out to be significantly higher than expected which in turn has important implications for policy, both in general terms of the potential costs to consumers and more specifically for negotiations around the level of policy support and contractual arrangements offered to individual projects through the proposed contract for difference strike price. © 2013 Elsevier Ltd.

McRobie A.,University of Cambridge | Morgenthal G.,Bauhaus University Weimar | Abrams D.,Northwestern University | Prendergast J.,EGG Energy
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences | Year: 2013

Parallels between the dynamic response of flexible bridges under the action of wind and under the forces induced by crowds allow each field to inform the other. Wind-induced behaviour has been traditionally classified into categories such as flutter, galloping, vortex-induced vibration and buffeting. However, computational advances such as the vortex particle method have led to a more general picture where effects may occur simultaneously and interact, such that the simple semantic demarcations break down. Similarly, the modelling of individual pedestrians has progressed the understanding of human-structure interaction, particularly for large-amplitude lateral oscillations under crowd loading. In this paper, guided by the interaction of flutter and vortex-induced vibration in wind engineering, a framework is presented, which allows various human-structure interaction effects to coexist and interact, thereby providing a possible synthesis of previously disparate experimental and theoretical results. © 2013 The Author(s) Published by the Royal Society. All rights reserved.

Clerc A.,EGG Energy | Stuart P.,EGG Energy | Dudfield P.,University of Cambridge
European Wind Energy Conference and Exhibition, EWEC 2013 | Year: 2013

Ambient turbulence intensity is essential information when determining turbine suitability. Therefore, a method of predicting the characteristics of turbulence at all turbine locations is required when designing a wind farm. To meet this need, a new method has been developed which can accurately predict turbulence across a site using a measured wind climate and speed-ups from an industry standard flow model such as WAsP or MS3DJH. The accuracy of the method described in this work, coupled with its ease of implementation, indicate that it could be greatly beneficial to the prediction of turbulence in wind power development.

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