ZephIR 300M – Offshore Wind Lidar

ZephIR is the single most experienced lidar operating offshore with extensive global offshore deployments across a 10 year track record including: the world’s first wind lidar to be used on a fixed platform; the world’s first wind lidar to be used on a floating platform; the first wind lidar to be accepted as DNV GL Stage 3 ‘bankable’ on a fixed platform, and; the world’s first wind lidar to be deployed as standard in dual configuration on a buoy for resource assessment. ZephIR 300M causes no flow distortion as found with large lattice tower structure and removes the need for working at height.

ZephIR has been selected by over 90% of all floating platform installations due to the unique properties this continuous wave lidar technology has to provide including range of measurements (10 – 200 metres from installed height), the fast data rate of 50Hz leading to natural resistance to the motion found offshore completely removing the need for mechanical motion compensation in most environments and its proven reliability offshore.

Building on an already impressive list of offshore experience, ZephIR 300M is designed specifically for use offshore and includes as standard:

• A 3 year warranty and 3 year service life – the most extensive available from a remote sensing device that can be used offshore
• Optimised industrial design including high UV stability housing, highest grade of marine connectors, marine MET station for improved yaw determination
• Upgraded cooling and air movement system offering IP68 protection

And, Zephir Ltd. can now uniquely offer customers a non-exclusive license to the patent-approved application of the technology to operate on an offshore floating platform.

ZephIR 300M provides 10 metre to 200 metre wind measurements ideal for site resource assessment offshore, power curve measurements and bankable Annual Energy Prediction (AEP) campaigns at the lowest cost of finance-grade lidar ownership available with no requirement for annual servicing or calibration within the 3 year service period.

ZephIR was the world’s first wind lidar to be deployed offshore – both on a fixed platform and floating – and carries an unparalleled body of evidence for accuracy and availability.

Marine Survivability

ZephIR 300M offshore wind lidar is specifically designed for marine environments. Careful component and material selection provide maximum protection against saline ingress and corrosion, whilst the enclosure is fully certified to IP67. There are no exposed cables to be concerned with or any on site set-up requirements, so the unit can be deployed in the most challenging sea conditions with minimal effort. The unit can be protected against local wildlife with additional bird spikes that can be easily fixed to any exposed surface.

Fixed Platforms

Offshore, leading Banks Engineers DNV GL and Natural Power generally consider Stage 3 Wind Lidars operated on a stationary platform as being comparable to a benign scenario as noted above provided that enough evidence is given to ensure no significant flow distortion from the platform or its components might affect the measurements.

Given the importance of measurements when considered against the substantial economic investment in offshore wind energy development, validation of the specific device should be made at an appropriate onshore flat terrain test site before and after the offshore wind measurement campaign. Comparison with a met mast provides traceability back to traditional anemometry so the validation should be made against a tall conventional meteorological mast.

Under specific conditions advised and audited upon by DNV GL, it is anticipated that similar accuracy and uncertainty results would be obtained from an energy prediction based on data from ZephIR 300M wind lidar mounted on a stationary platform as from an energy prediction based on data from a conventional offshore mast, replacing the need for such traditional anemometry and delivering substantial economic savings in the area of offshore wind resource assessment.

Further, Natural Power consider that “ZephIR can be recommended as a primary wind measurement system for offshore wind farms. There is a significant and consistent body of evidence to support the use of ZephIR in offshore conditions as the sole data capture system.”

Floating Platforms

Doppler Remote sensors measure the wind by detecting the line-of-sight Doppler shift caused by scattering of laser light from aerosols (or in the case of sodar, audible sound scattered by turbulence). Significant motion of the remote sensor affects the relative line-of-sight velocity and can lead to unreliable wind data.

However, continuous wave (CW) lidars can deliver exceptional sensitivity, achieved by focussing all the energy from the onboard laser at the chosen range, and this permits high data rates by scanning at 50Hz / 50 data points per second / measurements every 20ms. Any motion is frozen over this short integration time, so that in many high motion applications, such as those found on floating platforms or when mounted on the nacelle / in the spinner of wind turbines, high quality wind measurement can be carried out without compensation.

Providers of platform technology have also made independent assessments of all remote sensors available and they are summarised below where available. Interested readers should conduct a thorough review of all options available as some prototype platforms are not yet in the commercial domain; the information shown below is correct at time of publication.

 

Data from ZephIR lidar can be uploaded to the AmmonitOR online platform to be monitored and analysed