160 m is the new benchmark for met masts in South Africa

Technology in the wind power business is advancing rapidly. Today’s turbines boast hub heights of up to 160 m and more, which was hard to imagine in the early days of wind power. But the higher the distance between met mast and turbine hub height, the higher the uncertainties in the energy yield assessment in the development phase.

Higher uncertainties lead to higher risk, and that is what investors, lenders and banks want to avoid. Thus, these projects are usually financed on the P75 or even P90 value of the energy yield (which is the value of the energy yield which will be matched or exceeded with a 75 % or 90 % probability). A higher uncertainty leads to a lower P75 / P90 level of the energy yield – and in low wind conditions this could be the end of a project, even if the average wind speed (P50) would be sufficient. For two of such projects, far away from the stormy coasts of the Western and Northern Cape, GEO-NET installed the two 160 m masts.

The impressive height of these new met masts is only one part of the story. The other one, even more important, is the thorough design, specification, documentation and management of such a measurement campaign. It is vital to pick a measurement location which best represents the wind conditions of the whole project area, to ensure that sensors, set up, and installation of the met masts strictly comply with the latest standards like IEC 61400-12-1 and MEASNET, and to safeguard the traceability with detailed and accurate documentation.

Wind measurement and energy yield assessment go hand in hand, which GEO-NET embodies due to its expertise and experience – the company holds an international accreditation for wind measurements, wind flow modelling and energy yield assessment to safeguard the compliance with MEASNET and IEC61400-12-1. With more than 25 years of experience and over 4000 measurements and yield assessments conducted worldwide the wind experts contribute to the bankability and to the success of these wind power projects.