Reducing cost and uncertainties for offshore wind farm developers: Ecofys WTTS contributes to wind measurement campaign

August 2017 - Ecofys WTTS, subsidiary of Ecofys, a Navigant company, will support the Netherlands Enterprise Agency ( in driving down uncertainties and costs for wind project developers. The wind energy experts will assist in performing a data quality review on the Hollandse Kust (noord) metocean measurement campaign. 

Aiming to increase the Netherlands’ offshore wind capacity to 4,500 MW by 2023, the Dutch Government executes a tender scheme to develop new wind farms in five designated offshore zones. In support of this, buoys have been installed by Fugro in all the Wind Farm Zones including two buoys in the Hollandse Kust (noord) zone, to measure wind, waves and current. Ecofys WTTS will perform an independent data check and verification of monthly reports by Fugro and Deltares with the aim of supporting in their preparations of the next round of Dutch offshore wind tenders. 

The goal of the 12-month assignment is to quantify the data availability and quality of the measured wind, meteorological and sea-state data in order to help assure the highest uptime and quality and support in assuring the datasets can be used in calculation of final wind resource assessments and turbine and foundation loads. This drives down the uncertainties and costs for developers. The work constitutes a continuation of the ongoing support Ecofys WTTS has been giving to over the past years and is a follow-up of the support and thought-leadership performed on the sites of Borssele and Hollandse Kust (zuid).

Find the measured data and assessments at:

Full certification of EWT DW61 wind turbine at Ecofys WTTS Test Site Lelystad

EWT has successfully obtained the IEC-64100 wind turbine class certification for its wind energy generator DW61, with 61 m rotor diameter and 900kW rated power.

In 2015, EWT constructed a prototype of its DW61 wind turbine type with a hub height of 69 m at Test Site Lelystad. The wind turbine testing ground is owned and run by Ecofys WTTS, a subsidiary of Ecofys, A Navigant Company. Supporting EWT at the time, Ecofys WTTS conducted the world’s first IEC-compliant site calibration based completely on LiDAR measurements, and build a tubular met mast of 69 m of height to acquire wind measurements according to the IEC specifications.

The wind turbine performance was tested in collaboration with windtest grevenbroich, which comprised power curve measurements, load measurements and power quality. The results of the performance test were certified by DEWI-OCC in 2016, with the wind turbine obtaining the IEC class IIIA. EWT has since moved on to test the DW61 in other power modes.

With this successful certification, Ecofys WTTS supports the turbine manufacturer EWT and takes a big step forward in the use of LiDAR as primary source for site calibration measurements.

Wind measurement: Ecofys WTTS performs uncertainty assessment to support next round of Dutch offshore tenders

September 2016 - In order to support the Netherlands Enterprise Agency ( to drive down uncertainties and costs for developers, Ecofys WTTS has performed the first ever full uncertainty assessment of a floating LiDAR device. LiDAR, or Light Detection And Ranging, is a laser-based measurement device to determine wind characteristics up to 200 meters above ground level. Ecofys WTTS performed the uncertainty assessment to support in their preparations of the next round of Dutch offshore tenders. Aiming to increase the Netherlands’ offshore wind capacity to 4,500 MW by 2023, the Dutch Government executes a tender scheme to develop new wind farms in five designated offshore zones.

The aim of the study was to quantify the certainty with which the wind data, currently measured at the offshore wind farm zones Hollandse Kust and Borssele, can be used in calculation of final wind resource assessments. Ecofys WTTS took an innovative approach in the study by taking the assessment further and investigating what the accuracy of the device (a Fugro OCEANOR AS Seawatch Wind LiDAR Buoy) would actually mean for a typical (Dutch) offshore wind location. 

The calculated uncertainty tables in the report can be used directly in wind resource assessments, together with the classification uncertainty and site-specific uncertainty components. The uncertainty tables apply specifically to the tested device although the results should be representative for similar devices, provided the International Energy Agency recommended practices are followed for the campaign design.

A clearer understanding of the accuracy of wind measurements improves the energy production forecast of a proposed project and enables developers to drive down costs.

Find the uncertainty assessment available at:

Ecofys WTTS to support development of community owned 300 MW wind project Zeewolde

September 2016 - Through a comprehensive wind measurement campaign, Ecofys WTTS will support the development of the up to 300 MW wind farm Zeewolde. This onshore wind project in the Dutch province Flevoland is the biggest of its kind in the Netherlands and enjoys a unique level of local commitment: residents and businesses of the area have joined forces in the Ontwikkelverening Zeewolde to develop the wind farm.

Ecofys WTTS will provide a 120 m high met mast to gain the necessary wind data for yield calculations and engineering purposes. The mast will be constructed in October. It will be the second mast of this height in the Flevopolder, with the first one being installed at the Ecofys WTTS Test Site Lelystad.

The entire wind measurement campaign is expected to take at least one year. At a later stage, Ecofys WTTS may also conduct LiDAR (Light Detection and Ranging) measurements to complete the wind resource picture.

Wind measurement: Ecofys completes advanced cross-correlation for Wind SoDAR remote sensor

August 2016 - In an assignment for the Vaisala Group, Ecofys WTTS validated the performance of the Triton SODAR against Ecofys WTTS’s own acceptance thresholds for SoDAR wind measurements.

SoDAR, or Sonic Detection And Ranging devices, are used to measure the wind resource in a location in order to design and plan the wind park. Ecofys has applied its own standard criteria to verify the performance of SoDAR devices by taking into account the variability of the wind field and the intrinsic characteristics of a SoDAR measurement.

The study is the first cross-validation completed using the most widely used wind measurement equipment. The cross-validation result provides the industry with a better understanding of the performance of these instruments in hybrid wind resource applications.

Reducing costs for power curve measurements: Site calibration performed with LiDAR

Utrecht/Lelystad, The Netherlands, 10 November 2015 – For the first time ever, LiDARs were used for a site calibration in preparation of IEC-compliant power curve certification measurements for a wind turbine prototype. Stand-alone LiDARs have been used for years to assess the wind resource for project development. The technology has global recognition within the wind energy industry and the adoption of LiDARs for IEC-compliant power curve measurements is scheduled to be included in the new revision of the IEC 61400-12-1. Normally, a site calibration is executed using two identical met masts. The use of two LiDARs opens up opportunities to reduce project time-line, complexity, and costs, whilst ensuring the integrity and quality of the final deliverable.

The project was executed in preparation of the certification measurements for the new DW61-900 kW wind turbine by Emergya Wind Technologies (EWT), a product which builds on EWT’s market leading position in the distributed wind sector. Ecofys WTTS from the Netherlands together with its accredited partner windtest grevenbroich GmbH from Germany, conducted the site calibration using two WindCube-V2 LiDARs. The site calibration showed that the site is suitable for certification measurements by validating an appropriate measurable sector. The measurement campaign and subsequent LiDAR verification were approved by the certification body.

This project underlines that LiDAR technology has further matured and that LiDARs can deliver data according to IEC quality standards. The project also shows that Ecofys WTTS and windtest grevenbroich GmbH bring innovative and smart solutions to leading and innovative clients.

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Ecofys WTTS and Ammonit team up for enhanced wind measurements

120 met mast Lelystad (c) Ecofys

March 2015 - Ecofys WTTS has upgraded its 120m met mast with advanced temperature gradient sensors, bringing LiDAR & SoDAR validation measurements to the next level. Validation measurements provide insight to the atmospheric stability and can greatly increase certainty in remote sensing wind measurement studies and improve the bankability of future wind energy projects.

Please see the joint press release by Ecofys WTTS and Ammonit.

Test Site Lelystad: New combination of remote and mast wind measurement

July 2014 - As of this week, a total of seven wind measurement devices will be active at Test Site Lelystad. Unique for a wind measurement testing facility, six out of those are remote sensing devices of different types and brands, meaning that they measure the wind speed and direction without the need for a traditional tall steel mast. The test site now hosts these Laser based (LiDAR) and Sound based (SoDAR) instruments in addition to the 120 m tall meteorological mast which was installed last year. The devices are present at the Test Site as part of individual validation and verification campaigns. However, the testing of many different types of devices in parallel allows Ecofys to gain unique knowledge of which type of measurement equipment best suits a client's project needs.

The diversity of devices is also reflected in their origins which cover three continents: at the test pad there currently are a SoDAR from Australia, two LiDARs from Israel, and two different LiDAR types from French and English origin.

Lagerwey builds largest turbine of Flevoland on Test Site Lelystad

Lagerwey builds largest turbine of Flevoland on Test Site LelystadLagerwey builds largest turbine of Flevoland on Test Site Lelystad

March 2014 – Over the last months, Lagerwey has been working on the construction of a 135 m high shell tower wind turbine. In the week of 16 March, the final construction has taken place, in which the last segments have been mounted, followed by the nacelle, the 2 MW direct drive generator and the 101 m diameter rotor (hub with blades). Over the following months, the turbine will gradually be commissioned. Find some interesting pictures here below. 

Ecofys WTTS develops new test services for LiDAR and SoDAR Verification

December 2013 - Recently Ecofys WTTS completed a - first of its kind – LiDAR & SoDAR cross verification measurements for Nuon/Vattenfall. Ecofys WTTS designed three tailored-made tests that consist of the investigation of the performance of their wind remote sensing fleet, used to execute wind resource assessments for wind farm developments in all kinds of terrains. The tests are centered on the IEC methodology (currently drafted in the IEC 61400-12-1 ed 2) and MEASNET standards, and are increasingly important for the traceability of the data, gaining terrain as a tool to decrease the uncertainties and gain confidence before and after every commercial wind measurement campaign. The tests consist of deploying remote sensing equipment to acquire wind data under carefully controlled conditions, and verifying its performance by means of comparing its wind speeds and wind directions measurements with the ones measured at an IEC-compliant reference Meteorological Mast. Ecofys WTTS’ Test Site is the largest onshore facility of its kind in Europe and its located in Lelystad, The Netherlands. The 120 meters high Met Mast was carefully designed to serve the needs of these tests and commissioned last June 2013. It includes over a dozen sensors distributed in four measurement levels between 40 and up to 120 meters, and the local winds are characterised by two large open valid sectors, one ranging from the north-west to south-west, and the second one towards the east.

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