As devices move from full-scale prototype to commercial installations, it is important that developers have detailed knowledge of the tidal energy resource. Therefore, the spatial distribution of the tidal currents over the northwest European shelf seas has been examined to improve understanding of the tidal-stream energy resource. Using a three-dimensional hydrodynamic model (ROMS) at ∼1 km spatial resolution, and applying device characteristics of the Seagen-S turbine, we show that the ratio of the amplitudes of the M2 and S2 tidal currents can lead to significant variability in annual practical power generation – variability that is not accounted for when considering only the mean peak spring tidal velocities, as is generally the case in resource feasibility studies. In addition, we show that diurnal inequalities (governed by K1 and O1 tidal constituents) and tidal asymmetries (governed by the relationship between M2 and its compound tide M4) over the northwest European shelf seas can further affect power generation at potential high-energy sites. Based on these variabilities, the spatial distribution of the tidal-stream ‘capacity factor’ has been calculated. We find that mean peak spring tidal velocities can under-estimate the resource by up to 25%, and that annual practical power generation can vary by ∼15% for regions experiencing similar mean peak spring tidal velocities, due to the influence of other tidal constituents. Therefore, even preliminary resource assessments should be based on annual average power density, rather than peak spring tidal velocity.
Coastal and Offshore Energy
This contribution investigates the impact of the deployment of tidal stream turbine arrays on sediment dynamics and seabed morphology in the Pentland Firth, Scotland. The Pentland Firth is arguably the premier tidal stream site in the world and engineering developments are progressing rapidly. Therefore understanding and minimising impacts is vital to ensure the successful development of this nascent industry. Here a 3 dimensional coupled hydrodynamic and sediment transport numerical model is used to investigate the impact on sediment transport and morphodynamics of tidal stream arrays. The aim of the work presented here is twofold: firstly to provide prediction of the changes caused by multiple tidal stream turbine array developments to some of the unique sandy seabed environments in the Pentland Firth and secondly as a case study to determine the relationship between impacts of individual tidal stream farms and cumulative impacts of multiple farms. Due to connectivity in tidal flow it has been hypothesized that the cumulative impact of multiple arrays on sediment dynamics might be non-linear. This work suggests that, for the Pentland Firth, this is not the case: the cumulative impact of the 4 currently proposed arrays in the area is equal to the sum of the impacts of the individual arrays. Additionally, array implementation only has minimal effect on the baseline morphodynamics of the large sandbanks in the region, smaller more local sandbanks were not considered. These two results are extremely positive for tidal stream developers in the region since it removes the burden of assessing cumulative impact from individual developers and suggests that impacts to sub-sea morphodynamics is insignificant and hence is unlikely to be an impediment to development in the Pentland Firth with the currently proposed levels of extraction.
The concept of co-location of marine areas receives an increased significance in the light of sustainable development in the already heavily used offshore marine realm. Within this study, different spatial co-location scenarios for the coupling of offshore aquacultures and wind farms are evaluated in order to support efficient and sustainable marine spatial management strategies. A Geographic Information System (GIS) and multi-criteria evaluation (MCE) techniques were combined to index suitable co-sites in the German exclusive economic zone of the North Sea. The MCE was based on criteria such as temperature, salinity or oxygen. In total, 13 possible aquaculture candidates (seaweed, bivalves, fish and crustaceans) were selected for the scenario configuration. The GIS modelling framework proved to be powerful in defining potential co-location sites. The aquaculture candidate oarweed (Laminaria digitata) revealed the highest suitability scores at 10–20 m depth from April to June, followed by haddock (Melanogrammus aeglefinus) at 20–30 m depth and dulse (Palmaria palmata) and Sea belt (Saccharina latissima) at 0–10 m depth between April and June. In summary, results showed several wind farms were de facto suitable sites for aquaculture since they exhibited high suitability scores for Integrated Multi-Trophic Aquaculture (IMTA) systems combining fish species, bivalves and seaweeds. The present results illustrate how synergies may be realised between competing needs of both offshore wind energy and offshore IMTA in the German EEZ of the North Sea. This might offer guidance to stakeholders and assist decision-makers in determining the most suitable sites for pilot projects using IMTA techniques.
Stakeholder participation is an important concept in marine environmental management; thus, their acceptance and opinions might influence policy decision making and effectiveness. This paper explores the factors that affect stakeholders' (traditional ocean users, including fishers and aquaculture farmers) acceptance and conducts an empirical analysis to determine the relationship among stakeholders' perceptions and acceptance. A total of 238 respondents completed a survey that was conducted in six coastal counties in western Taiwan. We used principle component analysis and two logistic regression models for the analysis: one model does not consider perception factors, while the other model estimates perception factors. The empirical results reveal that three perception factors related to the benefits of offshore wind farms significantly affect stakeholders' acceptance. Furthermore, the explanatory power, goodness-of-fit, and the predicted probability are greater when perception factors are considered in the logistic model. As a result, stakeholders' perceptions are important factors that influence their acceptance of OWFs along the western coast of Taiwan. According to our findings, recommendations are offered to resolve the user conflicts regarding OWF turbine construction and operation, including (1) communicating effectively and integrating stakeholder participation and (2) offering benefits to ocean users and local communities.
The multi criteria decision making (MCDM) has been applied in Integrated Energy Planning (IEP) and Integrated Coastal Management (ICM) frameworks. In this paper, a novel hybrid MCDM approach based on the fuzzy analytic network process (ANP), fuzzy decision making trail and evaluation laboratory (DEMATEL) and fuzzy elimination and choice expressing the reality (ELECTRE) methodologies is applied to assist in the site selection of offshore wind farm (OWF) as the renewable energy in the IEP and the ICM frameworks. The aim of this study is to find the best site selection of offshore wind farm for four sites (alternatives) in Bandar Deylam on the Persian Gulf in southwest of Iran. Six criteria (depths and heights, environmental issues, proximity to facilities, economic aspects, resource technical levels and culture) and the related sub-criteria are considered to select proper sites for power station of OWF. The fuzzy ANP method is employed for standpoints of the site selection (goal) subject to the criteria and is performed the criteria subject to the sub-criteria. In addition, due to considering the influences of the criterion to another criterion, the fuzzy DEMATEL is employed in criteria and sub-criteria sections. Moreover, the fuzzy ELECTRE is applied to calculate the decision making matrices of sub-criteria to alternatives. The results show that the alternative A3 is the best site of OWF for Bandar Deylam. Then A2, A4 are the best alternatives and finally alternative A1 is the worst site. Also, a sensitivity analysis is performed to investigate the robustness of the outcomes of decision making by changing the priorities of the criteria. The results indicate the robustness of this method when the experts’ opinions subject to the criteria change. The evaluation criteria and this methodology could be applied to other coastal cities for promoting the progress of ICM towards the goal of sustainability.
As part of a large impact study in a wind farm (OWEZ) in the Dutch coastal zone, the effects of exclusion of bottom trawling on the benthic community were studied by comparison with nearby reference areas which were regularly fished. In addition to a standard boxcorer for common macrofauna, a Triple-D dredge was used to collect longer-lived, more sparsely distributed infauna and epifauna. Multivariate analysis did not reveal any difference between the assemblages in and outside OWEZ with respect to abundance, biomass, and production after a 5-year closure. The Shannon–Wiener diversity index pointed to a significantly higher diversity in OWEZ compared with some of the reference areas. A minority of the bivalve species assumed to be sensitive to trawling showed higher abundances (Spisula solida) or larger sizes (Tellina fabula, Ensis directus) in OWEZ than in some of the reference areas. In general, samples collected with the Triple-D showed more differences between areas than boxcore samples. No evidence was also found that the species composition in OWEZ relative to the reference areas had changed in the period between 1 (2007) and 5 (2011) years after closure. The change observed in all areas between 2007 and 2011 was mainly due to relatively small variations in species abundances. In conclusion, 5 years after the closure of OWEZ to fisheries, only subtle changes were measured in the local benthic community, i.e. a higher species diversity and an increased abundance and lengths of some bivalves. Depleted adult stocks, faunal patchiness, and a limited time for recovery (5 years) might explain that a significant recovery could not be found. The current study shows that designation of large-scale marine protected areas as planned for the North Sea will not automatically imply that restoration of benthic assemblages can be expected within a relatively short period of years.
This paper provides a comprehensive review of the current state of the art of the economics and socio-economics of ocean renewable energy (ORE); the many ways in which the viability and impacts of an ORE project are assessed, and an analysis of the current weaknesses, issues or inappropriateness of the metrics and methodologies used in their definition and presentation. The outcomes of this paper are anticipated to benefit the ORE and wider renewable sector as a whole. The review revealed that, for the most part, the current study of economics and socio-economics of ORE remain separate and discrete areas of research. The economic methods utilised appear to be comprehensive but are limited to project (or private investor) level. The methods identified for socioeconomic assessment fall between traditional, and now routine, environmental assessment approaches and more novel holistic approaches such as ecosystem services and life cycle assessment. The novel section of the paper explored the connectivity between the economics and socio-economics of ORE in relation to project developments and policy/planning. A visualisation method was created of concentric rings intersected by related axis of economic, socio-economic and environment, and enabled the examination of the benefits arising from the connectivity between the two spheres. The concept of sustainable development process and the integration of environmental assessment for ORE was also explored and how it responds to differing stakeholder aspirations and interpretations. The analysis revealed that there was a divergence between public and private economic and socioeconomic assessments for ORE: environmental assessment is primarily a public responsibility but with significant inputs from the private developer involved while economic assessments are conducted primarily by the developer and/or investor at their own behest. However, the two spheres of economic and socio-economic for ORE are highly connected and synergistic and must be examined in a holistic manner.
One of the challenges of offshore wind energy farms lies in their reduced availability relative to onshore facilities. In effect, with wave heights over 1.5 m impeding workboats access, sea conditions often cause delays to operation & maintenance tasks, and thereby impact on the availability for power production of the farm. The most immediate consequence is larger non-operational periods, which could translate into lower power production and, therefore, a reduction of their economic viability. By deploying wave energy converters along the periphery of the wind farm, wave height within the park can be reduced, and the accessibility for operation & maintenance tasks improved. The aim of this work is to analyse this synergy between wave and wind energy through the comparison of four case studies, and more specifically, to investigate how this synergy can be materialised under different conditions in terms of: (i) location (depth and distance from the coast), (ii) sea climate, and (iii) wind farm layout. It was found that the combination of wave and offshore wind energy results in enhanced accessibility for operation & maintenance tasks in all the cases considered, with accessibility values of up to 82%.
This paper argues for a broad evolutionary political economy understanding of local and regional path creation. We adopt a multi-actor and multi-scalar perspective, focusing on the roles of the state and regional policy interventions in mediating the creation of growth paths. The framework interprets attempts in North East England and Scotland to support path creation in the offshore wind sector through evolutionary inspired contextual policies. We demonstrate that the realisation of the these policies remains crucially conditioned by the dynamic and complex interplay between the national political economy of energy market regulation, industrial policy and inter-regional asymmetries in the governance of economic development.
The seas and oceans are the scene of multiple human actions, all of which cause pressures on the marine environment. Marine spatial planning (MSP) systematizes the evaluations of the spatial impacts of the human actions and take into consideration the cumulative impacts of the actions. A probabilistic model is constructed to estimate the impacts of oil shipping and offshore wind power on 16 species. The quantitative indicators of impacts are the loss of breeding success of 5 birds, the loss of the early development stages of 3 fish species and the change in the probability of presence/absence of 3 benthic species and 5 algae. The thesis model works as an independent application, but can be merged as such into an MSP tool that works with a geoinformatic system (GIS) interface. The impacts of offshore wind power and oil shipping, and especially the possible oil spill, have been studied at other marine areas, but there are only few studies about their impacts in the brackish water conditions of the Baltic Sea. The study area of this thesis is the eastern Gulf of Finland (EGOF).
The model is constructed using Bayesian networks (BNs) which are graphical probabilistic models. The most important human pressures caused by the actions are identified based on literature and placed in the model accordingly. The pressures caused by operational offshore wind power are the disturbance to birds and underwater noise. The pressures caused by oil shipping are underwater noise and the oil exposure of species after a possible oil spill. The attenuation of the pressures as a function of increasing distance from the source of pressure is calculated mathematically, where possible. Expert elicitation is conducted to fill in the gaps in existing data over the subject. Altogether 6 experts were interviewed and another two were consulted informally. The different types of data are integrated in the BN, which allows quantified comparisons between different management options and alternative scenarios.
The model predicts that both human actions have negative impacts on the marine environment of the EGOF. The impacts of an offshore wind mill will realize without uncertainty but they will be negligible. An oil spill, on the other hand, is unlikely to happen, but if it does, the losses will be extensive. The disturbance of the wind mill on birds extends to some hundreds of metres from the mill, depending on the bird species. The losses of the early development stages of fish caused by the underwater noise of a wind mill are nearly certainly below 20% at all distances from the mill for all studied species. With the most likely sound pressure levels of tankers, the losses to the early development stages of the fish also remain below 20% with a high level of certainty at all distances. At these tanker noise levels, the harmless noise class of <90 dB re 1µPa will be reached at some kilometres of the fairway, depending on the original noise level from a tanker. Three alternative oil shipping scenarios for 2020 were compared. The differences among the scenarios are negligible both when it comes to the impacts of underwater noise on fish and to the probability of a species to get exposed to oil.
The model successfully describes the impacts of the human pressures that are known to take place, such as the impacts of offshore wind power, but requires a GIS environment and drift models to be able to predict the probabilities of an oil exposure. The applicability of the model can be increased by taking into consideration additional human actions and a wider selection of human pressures. The thesis model is a part of a MSP tool produced in TOPCONS (Transboundary tools for the spatial planning and conservation of the Gulf of Finland) project, which is a prototype of a tool that can be later applied at marine areas worldwide.