By Matthieu Boquet, head of market and offering, wind energy, Vaisala
Government organizations around the globe are increasingly implementing policies and programs aimed at increasing the number of wind turbines and the amount of power generated from wind energy. To meet this demand, there is continued innovations in the design, development, performance testing, operations and ongoing optimization of wind farms to generate electricity from wind energy. Consequently, wind energy is rapidly becoming one of the planet’s fastest-growing renewable energy segments — and an essential element of building a healthier, greener, more innovative future.
Credit: Jacques Vapillon, Akrocean
As more countries expand their wind-generation capacities — both onshore and offshore — it is vital that wind energy decision-makers understand how to accurately define, measure and forecast the world’s wind resources so that projects can take advantage of the increasing size and capacity of wind turbines — especially in offshore environments. By recognizing the critical importance of wind resource assessment (WRA) and evaluating how several recent offshore projects leveraged recent wind energy industry innovations and evolving best practices, the entire sector can help propel renewable energy to new heights.
Why wind resource assessment?
Before the first turbine begins spinning and producing energy, significant amounts of time and effort are invested in wind farm projects. Considered by many to be the most critical step of any wind farm project, WRA establishes the foundation for determining a project’s business case and acquiring financing.
Each wind farm is unique and accordingly presents its distinct challenges. Wind flow patterns and wind speeds vary greatly worldwide and are impacted by bodies of water, vegetation and differences in terrain. Offshore wind farm development is challenging due to strict environmental standards and operating in harsh, salted environments far from maintenance resources, as well as significantly high costs surrounding the support structure, ongoing operations and maintenance (O&M), electrical infrastructure and ever-growing turbines.
As offshore wind farms leveraging larger turbines than ever continue to be built in deeper waters farther from the shore, the ability to quantify the wind resources at a given offshore site is invaluable in determining what kind of equipment is needed at that location as well as a project’s overall financial and practical viability. Today, meteorological (met) masts — the traditional standard of wind measurement — struggle to keep up with wind turbines’ constantly increasing hub heights in offshore environments. Also, most met masts fail to cover the entire operating region of an offshore wind farm, and the significant majority of today’s masts greatly rely on data extrapolation, which can introduce error and uncertainty into the measurement.
In addition to high permitting and construction costs, obtaining siting permits for met masts can take months. Worse yet, met masts cannot be easily moved around an offshore site, and they are susceptible to mechanical failure, lightning strikes and high winds, which creates insurance risks for project developers. Finally, considering the incredibly high level of investment required, met masts can be prohibitively expensive — and potentially dangerous to install, maintain and repair — for offshore projects.
Constructing a sound financial model for investment requires decision-makers to accurately assess and characterize available wind resources. For bank engineers who judge a wind farm project’s viability, lidar has replaced met mast as a primary measurement device for offshore WRA are being used in many applications to ultimately supply clean, renewable power to businesses and homeowners at lower costs.
Leveraging lidar for offshore WRA
With advances in lidar technology, the assessment of an offshore wind farm site can be completed more swiftly and accurately, as the technology’s mobility, ease of deployment and offshore-ready measurement prowess provides a solution for almost any need in offshore development and operations.
Different lidar devices easily measure up to the full height of today’s turbines without mathematical extrapolation; move around the site for additional measurements (or to support another campaign); can be positioned to increase coverage, accuracy and efficiency; can be deployed for greenfield assessment nearly anywhere; and new breakthroughs are even enabling instruments to achieve the lowest measurement uncertainty.
Dual scanning lidar
Today, offshore developers are increasingly turning to dual scanning lidar for a fuller, 3D understanding of the wind environment, especially for near-shore wind farm development. Consider the Green Power Investment’s project as an example.
A Green Power Investment (GPI) project required wind speed measurements covering the area where all future turbines will be located. With each scanning lidar placed in a strategic location, GPI observed an offshore area from two positions and created several “virtual met masts,” reducing uncertainties and increasing bankability.
GPI was able to set up the dual-lidar configuration faster and more cost-effectively than a met mast. The lidars’ beam crossing and high sampling frequency also enabled the collection of turbulence intensity measurement.
“WindCube Dual Lidar is a game-changer: We can get the whole wind picture with scanning lidar. We can create site conditions for wind turbine design load using dual scanning lidar without an offshore met mast or floating lidar system,” said Atsushi Yoshimura, manager at GPI.
By creating “virtual met masts” that collect accurate data at two to three offshore locations and several heights, this solution’s unique configuration provides the precise, reliable wind measurements that GPI needs to reduce measurement uncertainty, meet ClassNK requirements and ultimately create a feasible project and competitive bid for the upcoming wind farm development auction.
Floating lidar systems
Credit: Accurasea, EOLFI
As organizations continue to develop and deploy offshore wind technologies that can capture the abundant, stronger and more consistent than land-based wind resources available off the coasts of countries around the globe, WRA becomes increasingly tricky at sites where there are no available fixed platforms.
Enter Floating Lidar Systems (FLS). Rugged and versatile, lidars are often integrated onto a standalone floating structure, such as a buoy, to collect offshore wind data. With a robust, marinized casing that ensures wave movement does not create data errors, floating lidar instruments deliver reliable insights vital to construct an offshore wind farm.
With the French government eager to accelerate its offshore wind industry, it needed to quickly and accurately conduct preliminary site assessments of large offshore areas. Deploying FLS over a four-year collaboration in South Brittany, France, it began a campaign to help the French Ministry of Energy define the capacity of future wind farms and clarify needs for the public tenders that will go to developers. As a result of assessing these potential offshore sites with two buoy-integrated lidar units, all bidders will now have accurate data sets to provide quality plans.
Lidar enhancements
To increase data accuracy, operational continuity and bankability of wind energy campaigns both on land and offshore, lidar manufacturers are delivering lidar solutions with increased measurement capabilities, premium services and turnkey options.
As lidar technology advances and scientific breakthroughs are achieved, new lidar innovations are seeing increased measurement ranges of up to 300 meters, which enable dozens of simultaneous measurement heights, and unmatched accuracy in meeting wind industry standards. The improved measurement range can cover the wind profile of even the largest wind turbines, enabling even more accurate WRAs and data-driven decision-making. The algorithmic combination of scalar and vector averaging called hybrid wind reconstruction reduces turbulence sensitivity and provides a cup-equivalent 10-minute wind speed measurement. Manufacturers are garnering industry-leading classification and validation to help developers save time and money on third-party, on-site verification and ensure validation continuity.
With offerings and turnkey solutions that increase efficiency and uptime, as well as validation and certification services that save time and increase trust, lidar manufacturers are empowering customers to harness wind energy in new ways.
Lidar is limitless
While remote sensing has fought an uphill battle for acceptance in the wind industry, the wind industry is finally embracing lidar solutions for onshore and offshore applications in both the wind development and operational phases. As the cases assessing the evolving offshore wind frontier in this article illustrate, lidar innovations provide developers, operators and manufacturers with better, bankable data in a more agile and straightforward manner. Offshore wind resources must be properly assessed to ensure reliable and efficient construction of wind energy infrastructure — and lidar has made this process faster, easier and more cost-effective than ever.
Empowered with the necessary guidelines and standards that create global confidence, knowledge sharing and standardization of lidar as an essential and expected part of most standard wind energy processes, the wind energy industry can more easily meet the growing demand for green energy and a more sustainable future.
Matthieu Boquet is Head of Market and Offering – Wind Energy at Vaisala. In this role, he drives Vaisala’s renewable energy offerings to meet the industry’s high-level expectations while helping customers continually generate value from their projects.
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