Presentations

Abstract

Traditional approachesto wind resource assessment relyheavily on the use of historical data that, while often providingan appropriate baseline, may not necessarilyrepresentthe variability likely to be experienced over the full lifetime of installed assets.Much of the existing climate impact research has been globally or regionally focussed, with limited tailored information available to understand potential changes in wind resource. Met Office has been working on aCarbon Trustcommissioned project exploringthe effect of climate change on offshore wind resource as part of the Offshore Wind Accelerator (OWA) program. This presentation reflects the results of this project with a focus on the use of general circulation models (GCMs) for offshore wind resource applications,the assessment of future resource,and its uncertainty estimations. Themethodologypresented permits the effective use of GCM simulations to characterize past and future offshore wind and wind power resource.By combining model reanalysis, marine observations, and wind atlases, a robust datasetwascreated astheoffshore wind 'truth' andithighlightsthe relevance of decadal-scale variability on the wind resource over the case study region, encompassing the North Sea and some surrounding offshore areas.For example, the strongest trends in annual mean wind speed explain less than a 5% change in the long-term mean per decade, while the decadal range exceeds 10%. This datasetwasused to postprocess and bias correct GCM simulations and derive offshore wind and wind power future projections.Offshore wind resourcewasexploredusinga multi model ensemble,forced under two different emissions scenarios,and for a near- and a far-future period, with the near-future representative of the lifecycle of typical offshore infrastructure.Theuse of the Met Office UK Climate Projections 2018 (UKCP18) for this purpose is novel and allows to build on evidence derived from other ensembles such as CMIP6 and EURO-CORDEX. Future trends in wind and wind power metricsremainlargely uncertainover this region, with some stronger regional and seasonal signals. For example, the areacomprisingthe Celtic Sea, coasts of Brittany and the Bay of Biscay was identified as a hot spot for historical trends and variability, showing an increasing trend in wind speed and wind power capacity factors but also considerable interannual-to-decadal scale variability. Future projections, however, onlyindicateweak increases for the summer season. In the case of the North Sea region, historical trendsindicatea decrease in wind speeds andcapacityfactors for the spring and summer seasons. These decreases are also projected tocontinue into the future.Results for other focus regions will be discussed in the presentation. This work shows itis possible totailora set of robust GCM-based future projections over some regions, capturing changes in the large-scale processes thatinduce variability and trends inthe wind resource,without the need forveryhigh-resolutionmodelling. Importantly, in regions where decadal variability explains more variance than the long-term trends, future projections targeting the life cycle of new offshore developments are inherently more uncertain andcouldbe complementedby the use ofdecadal predictions.