Lidar better suited for Wind Resource Assessment in South Africa

Opinion

  • The use of Lidar Technology is becoming standard for Wind Resource Assessment (WRA) reports as wind turbines get higher and the industry seeks more accurate data plus site security beyond the traditional meteorological mast (met mast) method.
  • South Africa has seen some met mast’s valued at around R1.5 million cut down for their meagre metal value (R50000.00).
  • A typical WRA must cover a full year but in South Africa, if you want to sell electricity to the state-owned energy utility Eskom, you need a two-year WRA report.
  • The new requirement is currently being challenged in court. Read more

The accuracy of the WRA is a vital part of project development works as it determines project bankability with funders, investors, and the off-taker alike. With each wind project site having its challenges, accurately quantifying, and predicting wind resources at a given site is critical to determining its financial and practical viability.

Related news: Lidar WRA industry is expected to double by 2028 according to the latest Business Research Insights report. Read more

Lidar measures wind speed and wind direction by illuminating pulsed laser light and measuring the time for the reflected light to return. It does not involve the lengthy construction of a conspicuous 120 or 140-meter high met mast with anemometers, a device that measures wind speed and direction, attached at different heights. It also eliminates the need for an aviation permit.

As the capacity and development of wind energy continue to increase, lidar is quickly gaining in popularity among wind-energy industry stakeholders in South Africa as a more cost-effective and accurate means for measuring wind performance. At the same time, lidar system assessments can be continuously validated and verified by independent third-party consultants to ensure data accuracy and project bankability.

Traditional meteorological mast (metmast). Image credit: VE Lički Medvjed

The tech enables unlimited multiple user-defined heights which decreases uncertainties in the annual energy production (AEP) calculations. The technology can be deployed in challenging remote terrain and climates. A big factor is site security and continuity. If a met mast is cut down by thieves, vandalised, hit by lightning or damaged, one must effectively start measuring from scratch. With lidar, several vertical profilers can be used in a measurement campaign: one as a fixed point of measurement while the others are moved around the site to decrease horizontal measurement uncertainty. This provides flexibility and the opportunity to analyse larger land areas. The systems are compact and portable. They can also quickly be replaced if needed.

An added advantage is that the systems can continue to be used after the construction of the wind farm to validate wind farm performance.

These advantages over met masts help ensure a better account for sitewide spatial variation and uncertainty in complex terrain ensuring accuracy, reliability, and bankability. However, always confirm with your target off-taker and funders which WRA technology they accept before starting your WRA.

Author: Bryan Groenendaal

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