ETP TWEET Development

“A partnership between QED Naval, Edinburgh University and Scottish Government to develop state of the art tidal energy forecasting design tools to improve confidence within commercial modelling.” 

Results from TWEET to show: a) The tidal model inlet velocity against power produced by the tidal turbine b) Total power available in the flow against power extracted c) Commercial value of power to the grid.

Turbulent Flow Analysis for TWEET Development

This project will develop a new method of assessing turbulent tidal streams and interface to introduce the impacts of turbulence on tidal turbine performance and hence revenue models. The tools developed through this knowledge exchange project will provide QED Naval and their clients with the ability to assess the technical and commercial feasibility of any project at any location in the world from their desktop.

By the end of the project, QED Naval will have the necessary information in order to validate their Tidal and Wave Energy Evaluation Tool (TWEET); the outputs will enable them to improve the design of their Subhub: a self-installing support platform for seabed mounted wave and tidal devices, for more turbulent tidal sites. The University of Edinburgh (UoE)/ SAMS will benefit by having a case study to help them build on previous work. Ultimately, QED Naval will complete site measurement surveys and back filter the results to validate the UoE tidal modelling capability, providing clear insight into the accuracy of the prediction method.

Project Description

University of Edinburgh (UoE) will develop techniques to analyse data from previous numerical simulations for the Sound of Islay, which is owned by UoE/SAMS. This work, undertaken in conjunction with SAMS, will provide a detailed illustration of a turbulent tidal site based on real measurements. This analysis will then be used to generate:

  • The main tidal harmonic constants for an area within the Sound of Islay
  • Minimum 1 month of tidal data
  • Time intervals of either 5, 10 or 20 mins
  • Elevation
  • Velocities (North and East)
  • Flow Direction
  • Turbulent Kinetic Energy, turbulent dissipation rate and/or specific turbulent dissipation rate

This will provide the information required to advance the development of QED Naval’s Tidal and Wave Energy Evaluation Tool (TWEET) and support the development of their Subhub tidal platform for extreme turbulence sites of which Sound of Islay is a good example.

To date, TWEET has primarily been an internal QED Naval tool for assessing the economic feasibility of tidal projects at specific sites using specific technology thus enabling rapid project optimisation. TWEET consists of modules to simulate tidal harmonics and turbine performance; it also calculates energy capture and hydrodynamic loads on the turbines and tidal platform. The analysis supplied by UoE/SAMS will help to validate this innovative tool and further develop the interface between the existing modules; this will open up a commercial opportunity for QED Naval to support other marine energy developers by offering the TWEET application as a service.

The development of these tools by QED Naval, facilitated by the analysis from UoE and SAMS, will provide an assessment of the loads on both the turbines and QED Naval’s novel platform: Subhub.  The results generated from TWEET in relation to the  Sound of Islay site will enable QED Naval to redesign the Subhub for device stability in extreme conditions and create energy output statistics and capacity factors for the site.

TWEET outputs to show, depth averaged, site tidal stream resource as: a) Percentage of time at a particular flow rate b) Most commonly occurring flow rate. 

Outputs from TWEET to show: a) Percentage of time at a particular power rating b) The tidal turbines power curve c) Total energy collected at a particular flow speed d) The highest occurring inlet flow speed at the inlet to the turbine taking into consideration Subhub’s acceleration factors.

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