Technical seminar on measurement of wind profile with a buoy mounted LiDAR

Supported by:

- The Hong Kong Institution of Engineers, Environmental Division - Department of Land Surveying & Geo-Informatics, The Hong Kong Polytechnic University - The Hong Kong Society for Remote Sensing

Date: Friday 21 June, 2013 Time: 7:00pm – 7:45pm Venue: Room CF305, The Hong Kong Polytechnic University, Hung Hom Language: English Enquiries: Ir. Ian SOLOMON E-mail: isolomon@fugro.com.hk Tel: 2697 1126 Registration: Not required. 50 seats are available on a first come, first served basis.

Attendance certificates will be issued.

Speaker: Mr. Jan-Petter MATHIESEN, Fugro OCEANOR A/S, Trondheim, Norway Abstract: Traditionally, wind profile measurements for offshore wind farms have been obtained by using cup

anemometers mounted on wind masts, which are typically around 80m high. In the past few years, the

use of LiDAR systems for offshore wind measurements has become more popular, and although project

financers currently still require well-understood cup anemometer data for energy assessment, using a

LiDAR to acquire the wind profile data permits fewer cup anemometers to be installed on a much smaller

mast.

Where there are no externally-imposed requirements for cup anemometers, such as for performance

measurements in an operational wind farm, it is a desirable goal to obtain offshore wind data in a more

cost-effective and flexible manner by eliminating the wind mast structure, and using a buoy mounted

LiDAR. In addition to the wind data, a buoy can also measure waves, current profile and other

oceanographic parameters. The wave measurements can be used to compensate for the effects of

buoy movement on the LiDAR measurements, which previously hindered acceptance of the use of buoy-

mounted wind instrumentation.

In the spring of 2012, a field trial was carried out to demonstrate the practicality of a buoy-mounted

LiDAR system. A commercially available wind-profiling LiDAR system was mounted on a well-proven

oceanographic buoy designed for severe environmental conditions. The trial was performed in the

waters off the town of Titran on the island of Frøya in central Norway.

This was an ideal test site as it is in a very harsh environment, and is also only 2.5km from an existing

onshore test centre for wind measurements with three instrumented wind masts. There was also a

reference LiDAR located at the wind test centre. During the month-long trial, the buoy-mounted LiDAR

recorded 10 minutes average wind profile at 10 heights from 11.5m to 218m in significant wave heights

of 0.5m to 3.6m.

Following the trial, it was established that there was good correlation with the measurements between

the buoy-mounted LiDAR and the reference LiDAR, although there was some scatter thought to be

due to the distance between the two LiDARs, and that the fact that the reference LiDAR is located on

land. We are therefore planning to compare the buoy mounted LiDAR measurements with

measurements taken from offshore wind masts closer to the test site.

About the speaker: Jan-Petter Mathisen is a meteorologist and the manager of the metocean consultancy group at Fugro

OCEANOR A/S in Trondheim, Norway, and was project manager for the development of the

SEAWATCH Wind LiDAR Buoy used in this trial.

Jan-Petter Mathisen has been working at Fugro OCEANOR for 25 years, and has been project manager

for several metocean measurements and data analysis projects for the oil & gas industry.

CF305 is on the 3rd floor – one level up from the podium.