A1 - Better measurement techniques for forecasting and resource characterisation

A - Resource and Environment Characterisation

Status - published
Last updated on: 21/03/2022

Challenges/Opportunities

Predictions of the environmental conditions often rely on data from a single point, or sparse locations. This causes uncertainty in the potential energy resource, the loading on devices and the weather windows for offshore operations.

Solution

Develop more reliable and rich measurement systems, to quantify the offshore environment, including combinations of wind, wave and current.

Context And Need

Better and more reliable prediction of Offshore Renewable Energy (ORE) performance will improve confidence in project financial projections. This can be improved with better and more reliable measurement of the resource. Existing methods for measuring waves and currents are expensive and can be difficult to achieve continuous measurement record from offshore deployments of measurement instruments. Remote measurement methods may be a good alternative if the cost can be reduced and methods made more reliable. Autonomous systems also offer new possibilities for resource measurement. New methods for measurement of combinations of wind, wave, water level and current and for analysis of extreme combinations will allow better prediction of the available ORE and better design and operation of ORE systems.

Summary

Measurement of MetOcean data, i.e. wind, wave and current data, including velocity, wave elevation, turbulence data, is necessary to understand the offshore energy resource. Techniques are needed to measure all forms of physical environment data and to take into account the influence of land, accessibility, the need to extrapolate to extreme events, resource variations in time and space, bathymetry and other factors. This data is an essential part of resource assessment, farm planning and prediction of performance.

Impact Potential

This challenge will impact on:

CAPEX, as the resource and environmental conditions will be better understood and therefore the design can be more reliable and less conservative.

OPEX as the available weather windows will be better understood leading to better operations planning.

By making designs more reliable, and operations more efficient, the performance of ORE systems will improve, as well as their longevity. There will also be a reduction in human risk associated with offshore operations.

Research Status

Several methods are generally applied for the resource measurement, e.g.,

  • wave measurements: wave gauges, laser altimeters, pressure sensors, wave rider buoys, ADPs, radar system (like HF radar and X-band radar) and satellite-borne remote sensors (like radar altimeter and SAR);
  • Tidal measurements: ADPs, HF radar and SAR;
  • Wind measurement: wind vanes, wind-cup anemometers, SODAR and LIDAR;
  • Bathymetry measurements: autonomous drones.


The following ongoing projects and information are related:

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Active research projects:

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Supergen ORE Hub - Flexible Fund Research

  • Flow measurement for accurate tidal turbine design
    Lead Institution: University of Bath

    A key problem with predicting tidal turbine lifespan is a lack of data on the unsteady flow conditions at tidal sites. This lack of data causes inaccurate calculations of the lifespan of tidal turbines and drives up the cost of tidal power generation. A prototype probe has been designed which can capture small fluctuations in the flow despite the high hydrostatic pressure when the probe is at depth. This project will develop the probe from a laboratory prototype and prove its operation in marine environments paving the way for cheap, detailed site surveys, and better predictions of turbine lifespan.
  • V-SCORES (Validating Surface Currents at Offshore Renewable Energy Sites)
    Lead Institution: University of the Highlands and Islands
    Marine current measurements are vital for tidal resource estimation and resilient design criteria for all Offshore Renewable Energies (ORE). In-situ measurements are costly, and retrieval of seabed mounted equipment is not guaranteed. Moreover, in many potential ORE locations globally, suitable field survey campaigns may not be viable. Until now, most data for model validation and impact assessment have focused on temporal variability from single-point measurements, yet spatial variability is of critical importance. Additionally, most oceanographic current measurements are sub-surface; the near-surface zone is largely unknown due to instrument limitations (e.g., surface interference making the top few “bins” of ADCP data unusable). The development of low-cost and low-risk surface current mapping tools, and translating this knowledge to flow at depth, is therefore a key challenge in ORE development. Surface current maps would provide high-resolution detail needed to measure spatial heterogeneity, understand realworld wakes and the relationship between flow and animal behaviour when combined with ecological surveys. A better understanding of surface currents will also improve resilience of floating ORE and yield of floating tidal turbines. The aim of V-SCORES is comprehensive validation of unmanned aerial vehicle (UAV) techniques for surface current spatial mapping, demonstrated at tidal stream sites. Field campaigns will be conducted at contrasting commercial sites (Pentland Firth, Scotland & Ramsey Sound, Wales) under different environmental conditions (wave exposure, operational turbines installed, etc.).
  • WTIMTS - Wave-Turbulence Interaction and Measurement for Tidal Stream
    Lead Institution: Swansea University

    WTIMTS proposes a novel combined approach to measurement of turbulence and waves at tidal energy sites. If successful, this will allow an unprecedented level of confidence in decoupling these deeply entangled phenomena using only standard instrumentation (i.e., bed-mounted ADCPs and wavebuoys/WaveNet equivalent) – a limitation that is particularly relevant at the highly energetic sites of interest to the tidal stream industry, where more sophisticated instrument arrays are often impracticable. This will also permit the project to characterise, for the first time, the ways in which wave action enhances turbulence at such sites, and how far into the water column its influence extends.
  • Accounting for Current in Wave Buoy Measurements
    Lead Institution - University of Manchester
    This project will develop a novel methodology to accurately quantify and describe the impact of current on wave measurement buoys. This work enables future measurements to more accurately account for the impact of current, provide a framework for estimating the current from wave buoy measurements, and reprocessing existing buoy datasets to provide historical current estimates. This means that offshore wind, tidal and wave energy technologies can be better designed considering the environmental conditions that they will be exposed to. Furthermore, the opportunity to use common, scaled, characterisation technology in the tank and field will aid the understanding of techniques used to translate site data into the laboratory.

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Links to Industry Priorities

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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.

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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.

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