Posters

Abstract

Floating LIDARs (FLS) have become an established technology and the measurement method of choice for offshore windfarm wind resource assessments. The Carbon Trust provided strong and consistent support for the maturation of the technology, with IEA and now IEC furthering industry guidance. However, a major challenge to effectively using FLS (and ultimately cost of finance) is the determination of a reasonable and representative measurement uncertainty. Historically, the wind industry has been cautious using new wind measurement technologies, arguably rightly so, to maintain investor and lender confidence. This has been implemented in applying conservative uncertainties to the wind measurement data, resulting in apparently low confidence in the wind climate, even when an on-site FLS wind measurement campaign has been undertaken. Following the strong interest that followed Wonjung Chung from Copenhagen Offshore Partners' presentation during the Lyon WindEurope Tech Conference last year, a Joint Industry Project was formed of offshore wind developers, floating lidar manufacturers, lidar manufacturers as well as research and development organisations and members of the floating lidar standards committees to extend the reconciliation approach to include more datasets and geographies while engaging a wider industry group to scrutinize the approach and results. Windfarm reconciliation exercises are now commonly carried out by consultants, validated the estimated energy production against the operational performance with the distribution of the deviations being compared with the state uncertainties of the estimates. A similar approach can be undertaken comparing wind measurements within a region and investigate whether the deviations align with the stated uncertainties of those measurements. The methodology for the assessment is as follows: * review wind resource data and or assessment reports from each campaign * (if needed) apply spatial adjustment from a wind map - repeated for different wind maps to conform robustness of the conclusions. The use of SAR data has also been considered to further reduce uncertainties of wind maps where available. * the deviations represent the total uncertainty of the wind measurement campaign, constituting: 1) wind measurements 2) long term correction 3) spatial adjustment both horizontal and vertical and 4) methodology / analyst's prerogative Next, we calculate and subtract the uncertainties for the later three categories, the remaining uncertainty is due to the wind measurements. At the time of writing this abstract, the initial findings are: * Uncertainty of FLS measurements is much lower than current assumptions * FLS measurement uncertainties are lower than cup anemometry on met masts * The FLS uncertainty is anticipated to be less than 1% (overall measurement uncertainty). Prior to our presentation at the workshop in June, we plan to conduct additional analyses including, * independent review of the approach, by JIP members * repetition of the Lyon exercise to include additional North Sea datasets as well as an extensive set of Korean floating FLS datasets