First Successful Trial of a Floating Lidar Device in Real Offshore Conditions in the North Sea
A full-size prototype of the floating lidar offshore resource assessment system, known as FLIDAR, has been successfully tested 15 kilometres off the Belgian coast. It was located next to a stationary lidar (WINDCUBEv2 lidar from Leosphere) on a fixed communication mast for the month of October 2011 in order to test survivability and validate the accuracy of the wind speed measurements.
By Bruce Douglas, Sales & Marketing Director, 3E, Belgium
{access view=!registered}Only logged in users can view the full text of the article.{/access}{access view=registered}This is the first successful trial of a floating lidar device in real offshore conditions in the North Sea. Designed to withstand significant wave heights of over 6 metres, the FLIDAR system was tested in wind speeds up to 25m/s and proved highly accurate, with an r2 of over 0.99 when compared to reference lidar data. These tests have shown that the FLIDAR system can offer fast, cost-effective and accurate offshore wind resource assessments.
The FLIDAR was developed by global renewable energy consultant 3E, and OWA (Offshore & Wind Assistance NV), a 100% subsidiary of the Belgian geotechnical offshore contractor GeoSea. It is made up of an industry-standard buoy adapted to marine regulations for faster permitting. The Leosphere WINDCUBEv2 offshore lidar device is secured on top of a mechanical stabilisation system while a set of photovoltaic panels, small wind turbines and a battery pack provide independent power supply. Data is retrieved and communicated via satellite to a web-based monitoring and reporting tool.
Context
The profitability of offshore wind farms depends heavily on the ability to predict and deliver maximum power output at competitive costs. Furthermore, as the behaviour of the wind has an impact on nearly all the components of a wind farm, a wrong estimation of some parameters (especially turbulence, gusts, extreme wind speed and wind speed distribution) may have an impact on the performance of the turbines, the component lifetime or even the structural integrity of the turbines. Reaching an optimum first requires an in-depth knowledge of the wind resource. Both short-term and long-term characteristics of the wind and the corresponding predictability are important. Offshore, in particular, accurate wind data is useful throughout project development and construction to ensure better planning and maintenance management and thus maintain the financial stability of a large project.
Until now, building fixed measurement masts at sea equipped with standard anemometers or lidar systems was necessary to ensure successful measurements offshore. The construction of this type of infrastructure requires extensive permitting and can cost € 3 to € 8 million.
The FLIDAR is intended to significantly reduce these prohibitive costs and provide more flexibility for offshore wind power developers and asset managers. In addition, the FLIDAR can provide better, more complete assessments (full vertical profile, horizontal profile, turbulence measurements) and be redeployed quickly and easily for efficient and more flexible measurement campaigns.
Testing Conditions
A first series of tests on the FLIDAR (functional, static and oscillating tests) was conducted in the Zeebrugge harbour during the month of August 2011. A reference WINDCUBEv2 lidar, calibrated at Risø, was used for the data comparisons of the test. This testing phase led to a series of improvements to ready the FLIDAR for a full far-shore deployment.
In September 2011, the FLIDAR was towed offshore for its first real far-shore tests. These tests were conducted about 1 kilometre away from the Oostdijk radar platform in the Belgium North Sea, on which the same reference WINDCUBEv2 lidar was placed.
During the testing campaign, the FLIDAR experienced wind conditions up to 24m/s and waves up to 4 metres.
The wind data (10-minute average) from the reference lidar was retrieved via radio on a daily basis. The wind data (10-minute average) from the FLIDAR was sent via satellite communication on a daily basis. Results were analysed according to the methodology of the NorSeWInD project.
Test Results
The results of the validation campaign are highly promising. First and foremost, the FLIDAR proved its survivability and sustained little damage during the trials, despite harsh wind conditions. In addition, the availability of the FLIDAR data is very similar to that of the fixed lidar on the platform. A slight decrease in availability was shown above 150 metres and should be corrected in future trials with an adjustment in lidar settings. Wind speeds seem to have no effect on data availability. Furthermore, there is no significant loss of accuracy in the FLIDAR data for high wind speeds.
The accuracy of the results is generally very satisfying and corresponds to a correlation between both measurements on a regression line with the following parameters: slope: 0.996, offset: 0.043, r²: 0.996. All in all, the results of the FLIDAR test are numerous enough and almost accurate enough to be certified according to the NorSeWInD methodology. Given the implicit constraints of the test (both horizontal and vertical distance between the FLIDAR and the reference lidar) the results are better than could possibly be expected.
In other words, by applying a standard offshore wind turbine power curve to both sets of data, we obtain power outputs within 0.36% of each other for this testing month. This type of analysis makes it possible to apply more weight to the data most relevant for wind power development (with less importance given to the data below 5m/s, but more given to speeds at which wind turbines can produce power).
Next Steps
The FLIDAR will continue to be improved and tested in real conditions in the coming months. It is expected to be commercialised fully from April 2012.
Biography of the Author
Bruce Douglas has been Sales & Marketing Director at 3E since April 2011. His role is to coordinate global sales, marketing and communications for all the company’s activities, including the development of the FLIDAR, floating lidar buoy. Bruce is a Board member of the European Wind Energy Association (EWEA) and sits on their wind project finance committee. Before joining 3E, Bruce was Chief Operating Officer at EWEA in Brussels. He was responsible for the development and implementation of the company’s strategy and directed the operational and financial development of the organisation. He also had a seat on the Board of the Global Wind Energy Council (GWEC). Bruce has had an important influence on decision making in the international wind energy industry, contributing in Europe to a doubling in wind capacity over the last five years. He started working for EWEA in 2001 and previously held both Project and Marketing Director positions. Bruce started off his career in 1998 as a consultant in a British consultancy company focused on energy and environmental issues. He has a BA in Industrial Design and Technology and a master’s degree in Renewable Energy Systems Technology from Loughborough University of Technology (UK).{/access}
A full-size prototype of the floating lidar offshore resource assessment system, known as FLIDAR, has been successfully tested 15 kilometres off the Belgian coast. It was located next to a stationary lidar (WINDCUBEv2 lidar from Leosphere) on a fixed communication mast for the month of October 2011 in order to test survivability and validate the accuracy of the wind speed measurements.By Bruce Douglas, Sales & Marketing Director, 3E, Belgium
{access view=!registered}Only logged in users can view the full text of the article.{/access}{access view=registered}This is the first successful trial of a floating lidar device in real offshore conditions in the North Sea. Designed to withstand significant wave heights of over 6 metres, the FLIDAR system was tested in wind speeds up to 25m/s and proved highly accurate, with an r2 of over 0.99 when compared to reference lidar data. These tests have shown that the FLIDAR system can offer fast, cost-effective and accurate offshore wind resource assessments.
The FLIDAR was developed by global renewable energy consultant 3E, and OWA (Offshore & Wind Assistance NV), a 100% subsidiary of the Belgian geotechnical offshore contractor GeoSea. It is made up of an industry-standard buoy adapted to marine regulations for faster permitting. The Leosphere WINDCUBEv2 offshore lidar device is secured on top of a mechanical stabilisation system while a set of photovoltaic panels, small wind turbines and a battery pack provide independent power supply. Data is retrieved and communicated via satellite to a web-based monitoring and reporting tool.
Context
The profitability of offshore wind farms depends heavily on the ability to predict and deliver maximum power output at competitive costs. Furthermore, as the behaviour of the wind has an impact on nearly all the components of a wind farm, a wrong estimation of some parameters (especially turbulence, gusts, extreme wind speed and wind speed distribution) may have an impact on the performance of the turbines, the component lifetime or even the structural integrity of the turbines. Reaching an optimum first requires an in-depth knowledge of the wind resource. Both short-term and long-term characteristics of the wind and the corresponding predictability are important. Offshore, in particular, accurate wind data is useful throughout project development and construction to ensure better planning and maintenance management and thus maintain the financial stability of a large project.
Until now, building fixed measurement masts at sea equipped with standard anemometers or lidar systems was necessary to ensure successful measurements offshore. The construction of this type of infrastructure requires extensive permitting and can cost € 3 to € 8 million.
The FLIDAR is intended to significantly reduce these prohibitive costs and provide more flexibility for offshore wind power developers and asset managers. In addition, the FLIDAR can provide better, more complete assessments (full vertical profile, horizontal profile, turbulence measurements) and be redeployed quickly and easily for efficient and more flexible measurement campaigns.
Testing Conditions
A first series of tests on the FLIDAR (functional, static and oscillating tests) was conducted in the Zeebrugge harbour during the month of August 2011. A reference WINDCUBEv2 lidar, calibrated at Risø, was used for the data comparisons of the test. This testing phase led to a series of improvements to ready the FLIDAR for a full far-shore deployment.
In September 2011, the FLIDAR was towed offshore for its first real far-shore tests. These tests were conducted about 1 kilometre away from the Oostdijk radar platform in the Belgium North Sea, on which the same reference WINDCUBEv2 lidar was placed.
During the testing campaign, the FLIDAR experienced wind conditions up to 24m/s and waves up to 4 metres.
The wind data (10-minute average) from the reference lidar was retrieved via radio on a daily basis. The wind data (10-minute average) from the FLIDAR was sent via satellite communication on a daily basis. Results were analysed according to the methodology of the NorSeWInD project.
Test Results
The results of the validation campaign are highly promising. First and foremost, the FLIDAR proved its survivability and sustained little damage during the trials, despite harsh wind conditions. In addition, the availability of the FLIDAR data is very similar to that of the fixed lidar on the platform. A slight decrease in availability was shown above 150 metres and should be corrected in future trials with an adjustment in lidar settings. Wind speeds seem to have no effect on data availability. Furthermore, there is no significant loss of accuracy in the FLIDAR data for high wind speeds.
The accuracy of the results is generally very satisfying and corresponds to a correlation between both measurements on a regression line with the following parameters: slope: 0.996, offset: 0.043, r²: 0.996. All in all, the results of the FLIDAR test are numerous enough and almost accurate enough to be certified according to the NorSeWInD methodology. Given the implicit constraints of the test (both horizontal and vertical distance between the FLIDAR and the reference lidar) the results are better than could possibly be expected.
In other words, by applying a standard offshore wind turbine power curve to both sets of data, we obtain power outputs within 0.36% of each other for this testing month. This type of analysis makes it possible to apply more weight to the data most relevant for wind power development (with less importance given to the data below 5m/s, but more given to speeds at which wind turbines can produce power).
Next Steps
The FLIDAR will continue to be improved and tested in real conditions in the coming months. It is expected to be commercialised fully from April 2012.
Biography of the Author
Bruce Douglas has been Sales & Marketing Director at 3E since April 2011. His role is to coordinate global sales, marketing and communications for all the company’s activities, including the development of the FLIDAR, floating lidar buoy. Bruce is a Board member of the European Wind Energy Association (EWEA) and sits on their wind project finance committee. Before joining 3E, Bruce was Chief Operating Officer at EWEA in Brussels. He was responsible for the development and implementation of the company’s strategy and directed the operational and financial development of the organisation. He also had a seat on the Board of the Global Wind Energy Council (GWEC). Bruce has had an important influence on decision making in the international wind energy industry, contributing in Europe to a doubling in wind capacity over the last five years. He started working for EWEA in 2001 and previously held both Project and Marketing Director positions. Bruce started off his career in 1998 as a consultant in a British consultancy company focused on energy and environmental issues. He has a BA in Industrial Design and Technology and a master’s degree in Renewable Energy Systems Technology from Loughborough University of Technology (UK).{/access}
