A Spatiotemporal Methodology for Deep Offshore Resource Assessment

Abstract

Reliable wind measurement campaigns needed to address deep offshore wind energy deployment are constrained by their prohibitive installation and maintenance costs. Floating LIDAR systems are a viable alternative to bottom fixed met masts, although have survivability problems during storm seasons. This chapter presents a methodology, based on already well-established standards, able to reduce the offshore measurement campaigns duration by relating them with reliable and low-cost coastal measurements. A two-step calibration procedure, spatiotemporal, is presented to obtain an accurate characterization of the wind resource in deep offshore regions taking into account the time shift between the two measurement points associated with the different atmospheric phenomena propagation. The methodology is applied in two experimental case studies: The first one deals with measurements taken by a LIDAR installed on an islet (10 km away from the coast), while in the second case study a LIDAR system is mounted on a buoy in a deep offshore region. Results show that the added temporal calibration step is gradually more important as the distance between the measurements points increases. Precision enhancements on the order of 4-5 % were observed in the expected annual energy production for a given offshore site. The proposed calibration procedures presented can be applied in many phases of the offshore development: Resource assessment, power performance evaluation and even for completion of missing data in a measurement campaign.