E5 - Design tools for arrays

E - Survivability, Reliability and Design

Status - published
Last updated on: 21/06/2022

Challenges/Opportunities

There is insufficient confidence in prediction of energy yield from arrays of new technologies to underpin investment Current models cannot efficiently achieve array optimisation of ORE systems.

Solution

Computationally tractable techniques for system or component design accounting for flow-modification by other devices and arrays Models need to be developed for effective analysis and optimisation of ORE arrays.

Context And Need

Reducing the costs in installation, operation, maintenance meanwhile improving the energy yield can improve confidence in project financial projections. This can be achieved by developing single ORE structure into efficient arrays. Numerical models are needed to predict the optimal arrangement of arrays.

Existing models for wind or wave farms need to be integrated meanwhile including the floating motion responses in order to optimise the ORE farms. Better models are needed to adapt the existing onshore/nearshore farms to offshore farms. Better and more efficient methods are needed, considering optimisation's for the array layout, control of individual or blocking devices, mooring/PTO sharing, foundations, electrical network and the lifecycle logistics, etc. These can minimise the cost of electricity. Integration with ecological models and with sediment dynamics models is needed to understand the ORE farm effects on environment.

It is widely accepted that large numbers of devices will need to be installed in relatively close proximity for large-scale power generation. Turbines and devices must be designed for operation within clusters and arrays, taking account of the modification of design conditions due to other devices and arrays. Array configurations and operating strategies must be developed to maximise fatigue life and performance whilst minimising operating risks and costs.

The challenge is to develop sufficient confidence in design tools to underpin investment in commercial-scale arrays of each ORE type / for effective exploitation of the major ORE sites

Summary

Efficient numerical models need to developed for array optimisation or ORE systems, which include: optimal control; understanding device conditions; hydrodynamic interaction; uncertainty quantification, yield optimisation; blocking and efficient arrays in real channels; mooring or power take off sharing. Better understanding of the hydrodynamics of array interaction, layout performance and design, including moorings and anchors is needed through physical wave tank tests and numerical modelling.

Impact Potential

Essential:

  • to predict array performance
  • to establish designs required for array deployments and hence CAPEX
  • to establish the potential market size for alternative ORE types and hence scope for learning
  • to maximise ecological and environmental acceptance of the exploitation of ORE sites.
  • to establish design conditions for systems operating in arrays.

To enable evaluation of novel siting options such as clustering of design types within a site, optimisation of array layout and ORE device control strategies and selection of design parameters for in-array operation to maximise economies of scale production.

Impact on CAPEX as the arrangements of the ORE farms will be optimised and therefore the design can be less conservative. Impact on OPEX as the mooring/PTO will be efficiently shared within the ORE farms and therefore reduce the O&M cost. Impact on all areas as a result of cost savings and more efficient arrangement of the ORE farms.

Whole systems approach

  • System balancing costs / benefits
  • Time-variation of supply; phasing of sites, integration with storage systems
  • Oceanography
  • Hydrodynamics
  • Aerodynamics
  • Optimisation

Research Status

Research includes:


The following ongoing projects are related:

____________________________________________________________________________________________

Supergen ORE Hub Flexible Funding Research

  • SharEd Anchor Multidirectional Load Envelopes with Strength Synthesis (SEAMLESS)
    Lead Institution: Southampton University

    This project addresses cost reduction in mooring/anchoring which is highlighted as an important research priority for floating wave and wind energy. Anchor sharing, by reducing the number of installed anchors, reduces capital expenditure of floating ORE farms that require hundreds of anchorages. The goal of this project is to identify a method for shared anchor geometry optimisation and develop new design guidance to unlock performance gains. This will be achieved by answering two fundamental questions: "What threshold level of upwards cyclic load can be sustained without significant ratcheting?" and "How does the stress history of vertical-lateral load interactions affect the capacity?" To address these questions, and create a framework for design solutions, this project will identify realistic shared-type loading and use a geotechnical centrifuge to apply these to caisson anchors in dense sand, representative of UK and European seabeds. Additional data from pressure sensors and X-ray tomography of the centrifuge samples alongside element level cyclic direct shear tests (CDSS) will be combined to study the fundamental mechanisms underlying the anchor-scale behaviour. A predictive framework for capacity variations and ratcheting quantification will be developed to create V-H failure envelopes combined with cyclic degradation/enhancement diagrams, extending current practice.
  • FASTWATER: Freely-Available mesoScale simulation Tool for Wave, Tides and Eddy Replication
    Lead Institution: University of Edinburgh

    Offshore Renewable Energy (ORE), and multiple other marine technology interventions, are constrained by insufficient understanding, at the right scales and times, of the dynamic interactions of underlying ocean physical and environmental processes. These processes, including waves-current-turbulent atmosphere, are not adequately measured, statistically characterised or modelled to enable efficient design and operation of offshore infrastructure. For tidal energy sites in particular, spatial variability and the presence of waves result in significant uncertainties in device response and performance, with yield prediction errors of 30% reported. These effects are amplified across arrays. Further, recent research indicates that channel-scale three-dimensional (3D) flow features play a dominant role in the error of array yield predictions. Numerical simulation tools must replicate waves, spatial variability and 3D flow features robustly, with complexity built up in a modular way and with holistic and transparent spatial calibration and validation. Model calibration-validation in ORE lags other sectors e.g., climate modelling, epidemiological models of the covid pandemic and petrochemical exploration. Statistical techniques, commonly used in e.g., economics, neurology and seismology, are underused and could be readily adapted to help characterise spatial features of the flow. The project team have identified a large and costly gap between the development of increasingly complex and powerful models in academia and their adoption & exploitation by ORE organisations. FASTWATER is a targeted programme of research which - informed by industry - builds on multiple EPSRC academic and UK and EC industrial-academic projects, to bridge this gap. The primary aim is to reduce the cost of tidal energy arrays by developing powerful simulation tools that can be readily exploited by the sector.

____________________________________________________________________________________________

Links to Industry Priorities:

____________________________________________________________________________________________

We would also like to invite UK researchers and industry stakeholders within ORE to submit links to research projects, both past and present, for inclusion within the landscape.

Therefore, if you have a UK-based research project within an area of ORE that you feel is relevant to a specific research theme or challenge within the Research Landscape, click HERE to submit your research project to the research landscape

____________________________________________________________________________________________

PhD projects in Offshore Renewable Energy

In order to better understand the breadth of ORE research currently being conducted in the UK, the Supergen ORE Hub has collated from its academic network, UK Centres for Doctoral Training and Industrial partners, a list of PhDs currently being undertaken in ORE.

Access a PDF of the list and find out more about including your PhD.

Return to homepage