Mooring line fatigue damage evaluation for floating marine energy converters: Field measurements and prediction

publication-status: Publishedtypes: ArticleThe vision of large-scale commercial arrays of floating marine energy converters (MECs) necessitates the robust, yet cost-effective engineering of devices. Given the continuous environmental loading, fatigue has been iden- tified as one of the key engineering challenges. In particular the mooring sys- tem which warrants the station-keeping of such devices is subject to highly cyclic, non-linear load conditions, mainly induced by the incident waves. To ensure the integrity of the mooring system the lifecycle fatigue spec- trum must be predicted in order to compare the expected fatigue damage against the design limits. The fatigue design of components is commonly as- sessed through numerical modelling of representative load cases. However, for new applications such as floating marine energy converters numerical models are often scantily validated. This paper describes an approach where load measurements from large- scale field trials at the South West Mooring Testing Facility (SWMTF) are used to calculate and predict the fatigue damage. The described procedure employs a Rainflow cycle analysis in conjunction with the Palmgren-Miner rule to estimate the accumulated damage for the deployment periods and individual sea states. This approach allows an accurate fatigue assessment and prediction of mooring lines at a design stage, where field trial load measurements and wave climate information of potential installation sites are available. The mooring design can thus be optimised regarding its fatigue life and costly safety factors can be reduced. The proposed method also assists in monitoring and assessing the fatigue life during deployment periods

Regional imaginaries of governance agencies: practising the region of South West Britain

publication-status: AcceptedHarvey D C, Hawkins H, Thomas N J, 2011. The definitive, peer-reviewed and edited version of this article is published in Environment and Planning A 43(2) 470 – 486 DOI: 10.1068/a43380Copyright © 2011 PionChanges in government and governmentality in the UK have witnessed what has been termed a ‘regional renaissance’ over the last decade. This has led to an increase in the number of offices, institutions and agencies operating with a regional remit that is based upon a notion of fixed territorial containers. One sector that has increasingly been brought into the orbit of the new regional policy framework is that of the creative industries, and research is required in order to understand how creative industry governance agencies imagine and interpret the regional spaces that they administer. Notwithstanding the supposedly agreed upon and bounded nature of the territories over which they have competence, we find that personnel working within these regional bodies negotiate and imagine regional space in a number of ways. Drawing on empirical work with three creative governance agencies in the South West of Britain, we consider a range of dynamic and sometimes contradictory understandings of regional space as practised through their policy development and implementation. The paper traces how the practice of creative industry governance challenges the governmentally determined region and, by implication, any territorial unit as a naturally given container that is internally coherent and a discrete space available for governance. In doing so, the paper has broader lessons for effective policy delivery more generally

Potential impacts of wave-powered marine renewable energy installations on marine birds

One potential approach to combat the impacts of climate change is the expansion of renewable energy installations, leading to an increase in the number of wave-powered marine renewable energy installations (MREIs). The consequences of increased use of these devices for birds are unknown. Here we describe the wave-powered energy-generating devices currently either operational or in development and review the potential threats and benefits of these to marine birds, their habitats and prey. Direct negative effects include risk of collision, disturbance, displacement and redirection during construction, operation and decommissioning. Above-water collision is a particular concern with wind-powered devices, but, because of their low profiles, the collision risk associated with wave-powered devices is likely to be much lower. Conversely, wave devices also pose the novel threat of underwater collision. Wave-energy-generating devices may indirectly impact marine birds by altering oceanographic processes and food availability, with implications for trophic cascades. Through appropriate mitigation, wave-powered MREIs offer the potential to enhance habitats. Direct positive effects may include provision of roosting sites, and indirect positive effects may include prey aggregation due to suitable substrates for sessile organisms or because they act as de facto protected areas. The cumulative effect of these could be the improvement and protection of foraging opportunities for marine birds. Recent studies have been critical of the methods used in the assessment of wind-powered MREI impacts, which lack sufficient sample sizes, controls or pre-development comparisons. Here we suggest solutions for the design of future studies into the effects of MREIs. Wave-powered MREIs are certain to become part of the marine environment, but with appropriate planning, mitigation and monitoring they have the potential to offer benefits to marine birds in the future.</p

Regional spaces, spaces of regionalism: territory, insurgent politics and the English question.

Amid the globalization of economic life and a myriad of powerful challenges to Westphalian traditions of political statehood, it is now routinely contended that regions are 'in resurgence'. Nonetheless, much of the debate on this purported regional renaissance is bedevilled by confusion over what scholars and activists mean by regions and an analogous mystification as to why some regions are 'successful', 'lagging' or 'different'. Our paper aims to instil some coherence to this debate by distinguishing between what we term regional spaces and spaces of regionalism. It then draws on this distinction to explore the institutionalization of England's South West region, highlighting some tensions which prevail over its economic future, its political representation, its territorial shape and cultural vernacular. In undertaking this, we demonstrate how the formation of any given regional map is reflective – and indeed constitutive – of an unevenly developing, often overlapping and superimposing mosaic of economic practices, political mobilizations, cultural performances and institutional accomplishments. This prompts us to question the currently fashionable inclination to fully jettison a scalar and/or territorial approach to the theory and practice of spatiality in favour of relational/topological/non-territorial approaches