Ready for 200-metre Met Towers ... of Light?
When Laurent and Alexandre Sauvage decided to create Leosphere in 2004 few people anticipated that lidar (light detection and ranging) remote sensing systems would become so useful to the wind-power industry in such a short time. Leosphere and its scientific partner ONERA (the French Aerospace Agency) felt that by turning these complex laser sensors into lightweight, turnkey instruments they could make this innovative technology much more accessible and relevant to industry. The Sauvage brothers realised that although the atmosphere hosted major hazards for the environment (industrial pollution, greenhouse gases) it also potentially contained a partial solution: wind power. The two brothers believed that a technology that could detect invisible atmospheric parameters a large distance away would not only be a real asset to pollution monitoring but could also be a real help to the rapidly developing wind power industry. Thus, the company decided to allocate 100% of the energies of its atmospheric scientists and opto-electronics engineers to the design of several lidars to address the specific needs of air pollution and meteorology agencies, as well as wind power companies.By Laurent Sauvage, co-founder and scientific director, Leosphere, France
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From WindCube Lidar Anywhere to WindCube Everywhere
Designed from the beginning to be used anywhere (the 50 kilogram box can be set up in 15 minutes), today the WindCube lidar is operated on a daily basis by numerous companies over a range of sites in different environmental and topographical regions. In a variety of challenging environments, the WindCube is always required to answer the same question: what is the direction and the actual horizontal and vertical wind speed from the ground up to upper blade height?
Why does everyone want to know that? Because it enhances confidence in a wind project by reducing data uncertainty and project risk, which eventually drives down the cost of project financing. Some of people’s experiences which have adopted the WindCube lidar technology, are recounted below.
Harsh off shore Conditions
Alpha Wind Energy is a Danish company specialising in the development of wind energy projects. It has operated a WindCube lidar for more than a year in Riff, a remote location in the Norwegian Sea with harsh offshore climate conditions and helicopter-only access during the winter. According to Klavs Andersen, wind resources manager at Alpha Wind Energy: ‘Lidars fulfil our requirements to be able to do accurate wind measurement on remote locations where a conventional mast is not feasible for various reasons. This is only the starting point, however; we want to explore other applications such as turbulence measurements where lidars will be a better sensor for a short period. We chose this WindCube lidar technology because it had gone through comprehensive development and test phases. We witnessed parts of this and found WindCube ready for an actual measurement campaign. The results have not let us down. This is only the beginning of lidar technology and we hope to take it much further’.
Complex Terrain
Acciona Energía focuses its activity on wind energy, a field in which it had installed 5,577MW by 30 September 2008. Acciona was one of the first clients for the WindCube and currently operates three units for two main purposes: with a met tower to confirm the wind shears in the upper heights of the vertical wind profile, or as the sole measurement sensor to map the wind flow on complex and difficult sites where the uncertainty for vertical and horizontal extrapolation is too high.
Heavily Forested Areas
Vattenfall AB is a Swedish electricity supplier that is currently investing heavily in order to expand wind power generation in all regions in which the company operates. It uses the WindCube lidar to determine the wind conditions over a large, heavily forested, area of Sweden. Before entering the decision-making process, the system has been tested and validated at Risø’s Høvsøre test site to make sure that the measurements are not only easy to process but also easily available and absolutely dependable.
Reduce Uncertainty
To compute the return on investment generated by the use of a lidar, several experts have undertaken scientific and financial studies to evaluate the impact of accurate lidar wind measurement at hub height. EDF EN, a major French developer, for instance, has worked with Leosphere since 2007 to reduce the uncertainty of the forecasted energy output for several projects in France, using a combination of lidars and conventional met towers. Results will be presented in Marseille at the EWEC 2009 conference. Meanwhile, 3E, a Brussels-based development and consulting firm, published preliminary results showing that lidar measurements at 98 metres reduced the uncertainty in the energy calculation for a 2MW Enercon E82 turbine by 4.5%. A few per cent over 15 years multiplied by the anticipated energy production of a 100MW wind farm equals … significant savings. Isn’t this exactly the type of information a banker is looking for?
From Site Assessment to Turbine Calibration
Several studies are currently being undertaken in preparation for the next version of the international standard for wind turbine power curve testing (IEC 61400-12). While the current version only considers cup anemometers as a reference sensor, remote sensors such as lidars and sodars should enter the standard soon as a complement to cup anemometry.
Beside the IEC maintenance group, a team of German experts, working under the auspices of the German association Fördergesellschaft Windenergie (FGW), is assessing lidar measurement devices and technology. The LIDAR/RAVE1.2 project is an example of their endeavours. A further proposed study will look at the precise specifications that a lidar should have to comply with to meet the future standard. LIDAR/RAVE project members have chosen the WindCube lidar technology for their programme, assessing that its level of performances constitutes the benchmark.
Meanwhile, the European Union has also recently financed the NORSEWIND R&D programme. The consortium will evaluate commercial lidars both onshore and offshore. The NORSEWIND programme’s aim is to promote and increase acceptance of remote sensing within the wind industry. The experience gathered by participants (e.g. the Wind Energy Division at Risø DTU) with WindCube lidar, and other commercial remote sensors, has been of great help in defining the precise and demanding criteria to be used when selecting remote sensors for the project. In the end it will raise the performances of all remote sensors. The Risø DTU Høvsøre test station in Denmark has become a reference test bed. Several WindCube lidars and other remote sensing devices have been compared to calibrated sensors, and this test site will be used during the first onshore phase of the NORSEWIND project. The results will be included in the IEC maintenance group knowledge base, and will complement the working practices document that covers the classification and calibration/verification of remote sensors currently under study within the Upwind WP6 EC programme.
This major progress has become possible thanks to the strong investment of lidar users and independent evaluators such as Deutsche WindGuard, Windtest Grevenbroich, Garrad Hassan, DEWI, Risø DTU, FORWIND and the University of Stuttgart. They have published leading-edge papers to describe how remote sensors operate and interact with their environment.
Conclusion and Perspectives
The WindCube lidar story illustrates how the wind power industry embraces new innovations and quickly brings them into widespread use. It is a tribute to the wind industry as a whole that, in such a dynamic context, with rapid growth, challenging field constraints, increasing financial pressure and technology-oriented players, it has taken less than four years to turn a need that could have seemed unrealistic into a proven product: a 200-metre ‘virtual’ met tower. The next step is to spread the use of lidars to turbine calibration, optimisation and site assessment.
Biography of the Author
Dr Laurent Sauvage is a co-founder of Leosphere and has been its scientific director since its creation in 2004. Dr Sauvage obtained his PhD in astrophysics from the Ecole Polytechnique (tropospheric measurements using lidar systems), and is an expert of aerosol microphysics and atmosphere dynamics.{/access}
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As the founders of Leosphere said in their initial statement: ‘We did not invent lidars, we just made them easy and accurate for meteorologists and wind farmers.’ Only 5 years after the company’s creation, there is a current wide acceptance of lidars by leading research and industrial institutions, while over 60 units have been deployed in 14 countries, and 35 jobs have been created.From WindCube Lidar Anywhere to WindCube Everywhere
Designed from the beginning to be used anywhere (the 50 kilogram box can be set up in 15 minutes), today the WindCube lidar is operated on a daily basis by numerous companies over a range of sites in different environmental and topographical regions. In a variety of challenging environments, the WindCube is always required to answer the same question: what is the direction and the actual horizontal and vertical wind speed from the ground up to upper blade height?
Why does everyone want to know that? Because it enhances confidence in a wind project by reducing data uncertainty and project risk, which eventually drives down the cost of project financing. Some of people’s experiences which have adopted the WindCube lidar technology, are recounted below.
Harsh off shore Conditions
Alpha Wind Energy is a Danish company specialising in the development of wind energy projects. It has operated a WindCube lidar for more than a year in Riff, a remote location in the Norwegian Sea with harsh offshore climate conditions and helicopter-only access during the winter. According to Klavs Andersen, wind resources manager at Alpha Wind Energy: ‘Lidars fulfil our requirements to be able to do accurate wind measurement on remote locations where a conventional mast is not feasible for various reasons. This is only the starting point, however; we want to explore other applications such as turbulence measurements where lidars will be a better sensor for a short period. We chose this WindCube lidar technology because it had gone through comprehensive development and test phases. We witnessed parts of this and found WindCube ready for an actual measurement campaign. The results have not let us down. This is only the beginning of lidar technology and we hope to take it much further’.
Complex Terrain
Acciona Energía focuses its activity on wind energy, a field in which it had installed 5,577MW by 30 September 2008. Acciona was one of the first clients for the WindCube and currently operates three units for two main purposes: with a met tower to confirm the wind shears in the upper heights of the vertical wind profile, or as the sole measurement sensor to map the wind flow on complex and difficult sites where the uncertainty for vertical and horizontal extrapolation is too high.
Heavily Forested Areas
Vattenfall AB is a Swedish electricity supplier that is currently investing heavily in order to expand wind power generation in all regions in which the company operates. It uses the WindCube lidar to determine the wind conditions over a large, heavily forested, area of Sweden. Before entering the decision-making process, the system has been tested and validated at Risø’s Høvsøre test site to make sure that the measurements are not only easy to process but also easily available and absolutely dependable.
Reduce Uncertainty
To compute the return on investment generated by the use of a lidar, several experts have undertaken scientific and financial studies to evaluate the impact of accurate lidar wind measurement at hub height. EDF EN, a major French developer, for instance, has worked with Leosphere since 2007 to reduce the uncertainty of the forecasted energy output for several projects in France, using a combination of lidars and conventional met towers. Results will be presented in Marseille at the EWEC 2009 conference. Meanwhile, 3E, a Brussels-based development and consulting firm, published preliminary results showing that lidar measurements at 98 metres reduced the uncertainty in the energy calculation for a 2MW Enercon E82 turbine by 4.5%. A few per cent over 15 years multiplied by the anticipated energy production of a 100MW wind farm equals … significant savings. Isn’t this exactly the type of information a banker is looking for?
From Site Assessment to Turbine Calibration
Several studies are currently being undertaken in preparation for the next version of the international standard for wind turbine power curve testing (IEC 61400-12). While the current version only considers cup anemometers as a reference sensor, remote sensors such as lidars and sodars should enter the standard soon as a complement to cup anemometry.
Beside the IEC maintenance group, a team of German experts, working under the auspices of the German association Fördergesellschaft Windenergie (FGW), is assessing lidar measurement devices and technology. The LIDAR/RAVE1.2 project is an example of their endeavours. A further proposed study will look at the precise specifications that a lidar should have to comply with to meet the future standard. LIDAR/RAVE project members have chosen the WindCube lidar technology for their programme, assessing that its level of performances constitutes the benchmark.
Meanwhile, the European Union has also recently financed the NORSEWIND R&D programme. The consortium will evaluate commercial lidars both onshore and offshore. The NORSEWIND programme’s aim is to promote and increase acceptance of remote sensing within the wind industry. The experience gathered by participants (e.g. the Wind Energy Division at Risø DTU) with WindCube lidar, and other commercial remote sensors, has been of great help in defining the precise and demanding criteria to be used when selecting remote sensors for the project. In the end it will raise the performances of all remote sensors. The Risø DTU Høvsøre test station in Denmark has become a reference test bed. Several WindCube lidars and other remote sensing devices have been compared to calibrated sensors, and this test site will be used during the first onshore phase of the NORSEWIND project. The results will be included in the IEC maintenance group knowledge base, and will complement the working practices document that covers the classification and calibration/verification of remote sensors currently under study within the Upwind WP6 EC programme.
This major progress has become possible thanks to the strong investment of lidar users and independent evaluators such as Deutsche WindGuard, Windtest Grevenbroich, Garrad Hassan, DEWI, Risø DTU, FORWIND and the University of Stuttgart. They have published leading-edge papers to describe how remote sensors operate and interact with their environment.
Conclusion and Perspectives
The WindCube lidar story illustrates how the wind power industry embraces new innovations and quickly brings them into widespread use. It is a tribute to the wind industry as a whole that, in such a dynamic context, with rapid growth, challenging field constraints, increasing financial pressure and technology-oriented players, it has taken less than four years to turn a need that could have seemed unrealistic into a proven product: a 200-metre ‘virtual’ met tower. The next step is to spread the use of lidars to turbine calibration, optimisation and site assessment.
Biography of the Author
Dr Laurent Sauvage is a co-founder of Leosphere and has been its scientific director since its creation in 2004. Dr Sauvage obtained his PhD in astrophysics from the Ecole Polytechnique (tropospheric measurements using lidar systems), and is an expert of aerosol microphysics and atmosphere dynamics.{/access}
