Browsing by Author "Causon, Paul"

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    Modification of benthic ecosystems by offshore wind farms: implications for natural capital and ecosystem services
    (2019-05) Causon, Paul; Leinster, Paul; Gill, Andrew B.; Brennan, Feargal
    Due to concerns about climate change and energy security there has been considerable growth in the installed capacity of offshore wind energy worldwide over the last two decades. Owing to engineering constraints offshore wind turbines have generally been installed in areas characterised by soft sediments. Offshore wind farms introduce hard substrate and intertidal zones into these areas and have the capacity to alter natural capital, including biodiversity, in benthic ecosystems. Changes in benthic habitats may result in changes to the ecosystem services (goods and benefits people receive from nature) provided by natural functions and processes. Thus, continued expansion in offshore wind energy has the potential to affect natural capital and the associated delivery of ecosystem services. Differences in benthic community composition between manufactured structures, natural rock reefs and soft sediments in the southern North Sea were found to be significant (P <0.05) through permutational analysis of variance (PERMANOVA). However, evidence suggests that ecosystem functioning remained similar between natural substrata and offshore energy structures. Based on a Monte-Carlo analysis there were no significant differences in trait expression between the habitat types for the most dominant taxa. There were significant differences in feeding mode, longevity and larval duration amongst less common taxa (P <0.05), however their effect is likely to be muted. An assessment of natural capital demonstrated that offshore wind farms present risks and benefits to natural capital and the associated ecosystem services. The Thanet offshore wind farm was used as a case study. Overall, the natural capital increased following the installation of the wind farm. Targeted investment to support natural capital within offshore wind farms can produce functional ecosystems that not only produce low carbon energy but also augment ecosystem services; a number of which can have economic benefits. The findings have implications for the design, operation, maintenance and end of life treatment of offshore windfarms.
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    Multi-criteria decision analysis for benchmarking human-free lifting solutions in the offshore wind energy environment
    (MDPI, 2018-05-07) Richmond, Mark; Balaam, Toby; Causon, Paul; Cevasco, Debora; Leimeister, Mareike; Kolios, Athanasios; Brennan, Feargal
    With single components weighing up to hundreds of tonnes and lifted to heights of approximately 100 m, offshore wind turbines can pose risks to personnel, assets, and the environment during installation and maintenance interventions. Guidelines and standards for health and safety in lifting operations exist; however, having people directly beneath the load is still common practice in offshore wind turbine installations. Concepts for human-free offshore lifting operations in the categories of guidance and control, connections, and assembly are studied in this work. This paper documents the process of applying Multi-Criteria Decision Analysis (MCDA), using experts’ opinions for the importance of defined criteria obtained by conducting an industry survey, to benchmark the suitability of the concepts at two stages. Stage one streamlined possible options and stage two ranked the remaining suite of options after further development. The survey results showed that criteria such as ‘reduction of risk’, ‘handling improvement’ and ‘reliability of operation’ were most important. The most viable options, weighted by industry opinion, to remove personnel from areas of high risk are: Boom Lock and tag lines, a camera system with mechanical guidance, and automated bolt installation/fastening for seafastening. The decision analysis framework developed can be applied to similar problems to inform choices subject to multiple criteria.
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    Profiling corrosion rates for offshore wind turbines with depth in the North Sea
    (MDPI, 2020-05-15) Khodabux, Waseem; Causon, Paul; Brennan, Feargal
    Corrosion in the marine environment is a complex and expensive form of damage. It is commonly studied by the deployment of coupons that reflect the marine corrosion a structure will experience, thus allowing design and maintenance prevention strategies to be developed accordingly. This study stems from the lack of information in the literature regarding the profiling of corrosion with respect to marine depth in the North Sea where important wind farm developments have been undertaken. To address such issue a field experiment has been designed and carried out in the vicinity of the Westermost Rough Windfarm in the North Sea. The field experiment consists of deploying steel S355 coupons below the tidal area and capturing the effects of corrosion, the mass loss from which the corrosion rate is derived and the chemical products that makes up the rust with water depth. The study involves proper planning and logistics to ensure that the field experiment survives the rough conditions of the North Sea for a duration of 111 days. A high corrosion rate of 0.83 mm/year has been observed in this experiment. This paper goes into the details of the deployment blueprint employed and the analyses of the coupons to provide a conclusive observation and modelling of corrosion with respect to water depth under free or open sea water corrosion condition