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Delegates are invited to meet and discuss with the poster presenters in this topic directly after the session 'Remote sensing: From toys to tools?' taking place on Wednesday, 12 March 2014 at 14:15-15:45. The meet-the-authors will take place in the poster area.

Erik Holtslag Ecofys, The Netherlands
Co-authors:

(1) Ecofys, Utrecht, The Netherlands

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Presenter's biography

Biographies are supplied directly by presenters at EWEA 2014 and are published here unedited

Erik Holtslag is Team Leader Wind resource Assessment within the Ecofys-wind unit and he is working as Operational Manager for the Test Site Lelystad prototyping & certification field. After obtaining a master’s degree in Meteorology at the Wageningen University, he has worked in wind energy since 2002. His specializations are in wind measurements using met masts and LiDARs and in feasibility studies. Additional expertise is wind farm design and micro-siting, both for onshore and offshore wind farms. Amongst others he was responsible for the full wind resource trajectories of over 1000 MW of projects worldwide.

Abstract

A strong business case for lidar measurements

Introduction

As operators of Test Site Lelystad, Ecofys has examined the industry applications for LiDAR and how we can improve the bankability of the technology. Following a detailed market study, we find that LiDAR is now a mature technology that has been proven to be as accurate as high-quality anemometers. The objective of a wind measurement campaign is to reduce project uncertainty. The trade-off for increased data acquisition costs should be improved financing terms and reduced project risks. So, Ecofys WTTS will present the business case for LiDAR measurements, complete with an industry overview of its acceptance.

Approach

Our study began with a detailed market analysis of LiDAR products currently on the market and of verifications studies that validate their performance.

In order to demonstrate the potential reduction in uncertainty, we compared different campaign strategies for a representative inland site with flat terrain and nearby forests and towns. Further, we compared the cost-benefit of the different measurement campaign strategies. These calculations are based on the Ecofys Cash Flow model, for a standardized 20 MW wind farm in the Netherlands with typical project finance conditions.


Main body of abstract

LiDAR wind measurements have been extensively verified against reliable reference anemometers over many sites – referring primarily to the ZephIR ZP300 and WINDCUBE v2 LiDARs. As a result, there is now industry consensus that LiDAR is a proven technology for wind resource assessments in simple terrain.

In more complex terrain, site-specific validation of the LiDAR is generally recommended. A limitation to LiDAR campaigns is that turbulence intensity cannot be measured in an appropriate way for comparison with type certification of wind turbines.

Several organisations have also prescribed best practice guidelines for LiDAR campaigns. The recommendations are similar:
- An initial verification of the LiDAR against reference instruments
- Inclusion of on-site met mast, if needed
- Proper siting of LiDAR
- Transparent data analysis and estimation of uncertainties

Our case study shows that the uncertainty in wind speed from a traditional met mast campaign can be reduced by 20-30% with a well-designed LiDAR campaign (from 7% to 5%). This results in a reduction of about 25% in the overall uncertainty in terms of energy yield.

This reduction in measurement uncertainty would require an additional investment of €30-90,000 for a one-year LiDAR campaign. However, the return on this investment is substantial. An improved P90/P50 ratio can lead to improved leverage (84% versus 82%), reduced requirement for equity investment (a savings of up to €600,000 for the case study) and better return on equity (14% versus 12%). Our study shows, that although more expensive than masts, usage of LiDAR has better cost-benefit ratio.


Conclusion

Industry acceptance of LiDAR measurements, as well as our experience with the flexibility of LiDAR deployments, leads Ecofys to recommend LiDAR in the following configurations:
1. LiDAR stand-alone on-site. In simple terrain (flat, few obstacles), a LiDAR can entirely replace a met mast for the wind resource assessment.
2. LiDAR next to a relatively short on-site met mast.
3. LiDAR moved around the site, complementing an on-site met mast.

The advantage of a well-designed wind measurement campaign is clear: reduced uncertainty leading to a lower equity investment and improved return.



Learning objectives
A key objective of this presentation is to demonstrate the strong industry consensus that LiDAR is a valuable tool in wind resource assessments.

We will also demonstrate a methodology for determining the optimal wind measurement strategy on a site-by-site basis. The value of a given uncertainty reduction can be quantified in terms of improved leverage and increased rate of return. This added value can be compared to the costs of a measurement campaign.