Breaking-down and parameterising wave energy converter costs using the CapEx and similitude methods

Wave energy converters (WECs) can play a significant role in the transition towards a more renewable-based energy mix as stable and unlimited energy resources. Financial analysis of these projects requires WECs cost and WEC capital expenditure (CapEx) information. However, (i) cost information is often limited due to confidentiality and (ii) the wave energy field lacks flexible methods for cost breakdown and parameterisation, whereas they are needed for rapid and optimised WEC configuration and worldwide site pairing. This study takes advantage of the information provided by Wavepiston to compare different costing methods. The work assesses the Froude-Law-similarities-based “Similitude method” for cost-scaling and introduces the more flexible and generic “CapEx method” divided into three steps: (1) distinguishing WEC’s elements from the wave energy farm (WEF)’s; (2) defining the parameters characterising the WECs, WEFs, and site locations; and (3) estimating elements that affect WEC and WEF elements’ cost and translate them into factors using the parameters defined in step (2). After validation from Wavepiston manual estimations, the CapEx method showed that the factors could represent up to 30% of the cost. The Similitude method provided slight cost-overestimations compared to the CapEx method for low WEC up-scaling, increasing exponentially with the scaling

Decision support systems optimising effluent release in sub tropical estuarine environment - An Australian case study

Gold Coast Water is responsible for the management of the water and wastewater assets of the City of the Gold Coast on Australia’s east coast. Treated wastewater is released at the Gold Coast Seaway on an outgoing tide in order for the plume to be dispersed before the tide changes and renters the Broadwater estuary. Rapid population growth over the past decade has placed increasing demands on the receiving waters for the release of the City’s effluent. The Seaway SmartRelease Project is designed to optimise the release of the effluent from the City’s main wastewater treatment plant in order to minimise the impact of the estuarine water quality and maximise the cost efficiency of pumping. In order to do this an optimisation study that involves water quality monitoring, numerical modelling and a web based decision support system was conducted. An intensive monitoring campaign provided information on water levels, currents, winds, waves, nutrients and bacterial levels within the Broadwater. These data were then used to calibrate and verify numerical models using the MIKE by DHI suite of software. The decision support system then collects continually measured data such as water levels, interacts with the WWTP SCADA system, runs the models in forecast mode and provides the optimal time window to release the required amount of effluent from the WWTP. The City’s increasing population means that the length of time available for releasing the water with minimal impact may be exceeded within 5 years. Optimising the release of the treated water through monitoring, modelling and a decision support system has been an effective way of demonstrating the limited environmental impact of the expected short term increase in effluent disposal procedures. (PDF contains 5 pages

Wave overtopping layer thickness on the crest of rubble mound seawalls

During storms, ensuring the protection of people, vehicles and infrastructure on the crest of coastal structures from wave overtopping hazards is crucial. The thickness of the wave overtopping layer is a key variable used for assessing safety and maintaining a secure design. Traditionally, this parameter is associated with the height difference between the fictitious wave run-up level exceeded by 2% of waves and the crest freeboard of coastal structures. This study aims to investigate the wave overtopping layer thickness on the crest of rubble mound seawalls. To achieve this, a series of 125 small-scale 2D physical model tests were conducted on a two-layer rubble mound seawall with an impermeable core and slopes of 1:1.5 and 1:2. The obtained results indicated that the existing empirical formulas, originally developed for dikes, underestimate the overtopping layer thickness on the studied seawall. Therefore, modifications were made to the formulas found in the literature specifically tailored for rubble mound seawalls. The newly proposed formulas for estimating overtopping layer thickness at both the seaward edge and the middle of the crest showed improvements compared to the existing formulas

Numerical modelling and video analysis of intermediate beach state transitions

Proceedings of the Seventh International Conference on Hydroscience and Engineering, Philadelphia, PA, September 2006. http://hdl.handle.net/1860/732Numerical modelling of beach morphodynamics is generally recognized as a valuable tool for scientists and coastal managers. However, the utility of numerical models is constrained by our ability to establish that the theoretical dynamics match reality. The integrated modules for simulating wave propagation, hydrodynamics and sediment transport in Delft3D, developed by Delft Hydraulics, were applied to simulate observed beach state transitions in response to wave-induced forcing. Initial model bathymetry was derived from hydrographic surveys conducted at Narrowneck beach during the pre- and post-construction phases of the Narrowneck artificial reef (Boak, McGrath and Jackson 2000, Hutt, Black and Mead 1998). The present study addresses the validity of morphological modeling of an exposed beach by comparing the evolution of a numerical model with data observed using remote imaging. Narrowneck beach on the Gold Coast is a micro-tidal, exposed coast subject to a highly variable wave climate. This beach is monitored by an ARGUS Coastal Imaging system generating high temporal frequency geo-referenced estimates of wave dissipation that may be used to infer sub-tidal bar morphology (Alexander and Holman 2004, Aarninkhof and Ruessink 2004, Turner, Dronkers, Roman, Aarninkhof and McGrath 2001). The numerical model was broadly validated, in that, when driven by similar conditions, the surf zone morphological development is consistent with that observed via optical sensing

Wave transformation within a coral reef lagoon system, Erakor lagoon, Vanuatu

Coral reefs encircle most of the islands in Vanuatu and provide natural breakwaters for coastal communities by reducing wave energy arriving at the shoreline acting to control both inundation and erosion. Climate Change is projected to both exacerbate coastal hazards and endanger corals. The aim of this paper is to better understand the parameters that govern hydrodynamics on fringing reef systems. The interaction between the depth, waves and currents are studied from measurements conducted in Erakor lagoon, Vanuatu

Water circulation and impact on water quality in the southwest of Efate Island, Vanuatu

In Small Island Developing States (SIDS), water pollution is not monitored or assessed frequently enough to fully understand the processes, impacts of water quality issues and what solutions are available This study investigated flushing time in Erakor lagoon and Port Vila Bay, Vanuatu using a numerical model developed in Delft3D. Microbial contamination by Escherichia coli was detected in multiple locations in the lagoon system with counts exceeding thresholds related to human health concerns. Modelling demonstrated a poor flushing time overall with a further decrease as the influence of waves and wind increased, especially in Vila Bay. Sea level rise resulted in an increase in flushing time downstream of the lagoon near the open sea, while with a decrease upstream and in Vila Bay. Based on these results, we recommend long-term continuous monitoring and identification of higher risks areas to prioritise decisions around wastewater management

Opportunistic management of estuaries under climate change: a new adaptive decision-making framework and its practical application

Ongoing coastal development and the prospect of severe climate change impacts present pressing estuary management and governance challenges. Robust approaches must recognise the intertwined social and ecological vulnerabilities of estuaries. Here, a new governance and management framework is proposed that recognises the integrated social-ecological systems of estuaries so as to permit transformative adaptation to climate change within these systems. The framework lists stakeholders and identifies estuarine uses and values. Goals are categorised that are specific to ecosystems, private property, public infrastructure, and human communities. Systematic adaptation management strategies are proposed with conceptual examples and associated governance approaches. Contrasting case studies are used to illustrate the practical application of these ideas. The framework will assist estuary managers worldwide to achieve their goals, minimise maladaptative responses, better identify competing interests, reduce stakeholder conflict and exploit opportunities for appropriate ecosystem restoration and sustainable development

The role of the Connexions service in supporting the transition from school to post-16 education, employment training and work for young people with a history of specific speech and language difficulties or learning difficulties

The transition from school to the world of post-compulsory education is a major landmark in the lives of young people with special educational needs (SEN). In England the Connexions service set up to support young people during transition was planned to provide both a universal service and one that provided special support to vulnerable young people, particularly those at risk of not being in education, employment or training (NEET). The present paper reports the findings of a study of 46 Connexions personal advisers (PAs) who were supporting young people with specific speech and language difficulties (SSLD) or general learning difficulties, as part of a longitudinal study of these young people's development. Interviews were held with the PAs to identify patterns of organisation, the nature of services delivered to these young people and the factors that influenced successful support. The findings highlight the diversity among Connexions services, the limited expertise with young people with SEN and the structural barriers that may limit effectiveness. In addition, the Assessment, Planning, Implementation and Review Framework was not consistently used. The Connexions service has the potential to provide important support to young people with SEN at this key transition point but our study indicates the need for modifications to its operation

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Search of the Orion spur for continuous gravitational waves using a loosely coherent algorithm on data from LIGO interferometers

We report results of a wideband search for periodic gravitational waves from isolated neutron stars within the Orion spur towards both the inner and outer regions of our Galaxy. As gravitational waves interact very weakly with matter, the search is unimpeded by dust and concentrations of stars. One search disk (A) is 6.87° in diameter and centered on 20h10m54.71s+33°33′25.29′′, and the other (B) is 7.45° in diameter and centered on 8h35m20.61s-46°49′25.151′′. We explored the frequency range of 50-1500 Hz and frequency derivative from 0 to -5×10-9 Hz/s. A multistage, loosely coherent search program allowed probing more deeply than before in these two regions, while increasing coherence length with every stage. Rigorous follow-up parameters have winnowed the initial coincidence set to only 70 candidates, to be examined manually. None of those 70 candidates proved to be consistent with an isolated gravitational-wave emitter, and 95% confidence level upper limits were placed on continuous-wave strain amplitudes. Near 169 Hz we achieve our lowest 95% C.L. upper limit on the worst-case linearly polarized strain amplitude h0 of 6.3×10-25, while at the high end of our frequency range we achieve a worst-case upper limit of 3.4×10-24 for all polarizations and sky locations. © 2016 American Physical Society