How wind energy sensors behave in icing conditions?

Wind energy in cold climates is growing rapidly around the world [1] but measuring the different phases of icing with weather sensors and ice detectors is not an easy task. See a Youtube testing video here.

Sensors and ice detectors are needed to evaluate the risks on wind farm icing in pre-constructions energy assessments and safety as well as to control operational wind turbines during icing events. Some outdoor, full-scale ice detector benchmark tests have been performed in the past two decades but little focus has been put so far on controlled laboratory testing in realistic icing conditions [2] [3] [4]. Thus there is a large need from the industry to develop and test ice detectors for wind power purposes and potentially other industry sectors.

Testing 5 winter seasons in one week

VTT has over 25 years of experience working with icing challenges within wind power sector and today, one high priority topic is revolving around VTT Icing Wind Tunnel (Figure 1) testing. Based on the industry needs and VTT knowhow, VTT has initiated and coordinates an industry consortium project with aim to increase ice detector reliability and substantially reduce time-to-market of new ice detector products. The goal is to shift from current slow ”winter season” outdoor full-scale testing of ice detectors to accelerated, controlled and repeatable laboratory “5 winters in one week” testing at VTT Icing Wind Tunnel. The novelty content of this project is high and the results will benefit both industry and research community.

Project industry partners are Vattenfall AB, Statkraft AS and Labkotec Oy.

Icing Wind Tunnel

Figure 1. Layout of VTT Icing Wind Tunnel, operational since 2008.

So far 6 wind energy sensors have been tested at VTT Icing Wind Tunnel ranging from ice detectors (Labkotec LID) to standard cup anemometers and other “normal” weather sensors used for ice detection today by the wind industry. See some ice cool results in this Youtube video.

See also more information and pictures from WinterWind 2017 presentation “Standardizing ice detector tests in icing wind tunnel”.

As future plans, further analysis of already performed tests will take place. The project continues until end of 2017 and key results and inter-comparisons of sensor behaviour and performance in icing conditions will be presented at WinterWind 2018 conference.

For more information please do not hesitate to contact me.

Ville Lehtomäki VTT

Ville Lehtomäki
Senior Scientist, Wind power
Mobile: +358 50 370 7669
Email: ville.lehtomaki (a)



[2]: B. Tammelin and a. et, “Wind Turbines in Icing Environment: Improvement of Tools for Siting, Certification and Operation – NEW ICETOOLS,” Finnish Meteorological Institute, Helsinki, Finland, 2005.

[3]: S. Fikke, G. Ronsten, A. Heimo, S. Kunz, M. Ostrozlik, P. E. Persson, J. Sabata, B. Wareing, B. Wichura, J. Chum, T. Laakso, K. Säntti and L. Makkonen, “COST 727: Atmospheric Icing on Structures Measurements and data collection on icing:,” MeteoSwiss, Zurich, 2007.

[4]: H. Wickman, “Evaluation of field tests of different ice measurement methods for wind power,” Uppsala Univ (MSc thesis), 2013.

In-cloud icing detection with new prototype short range cw LIDAR

VTT’s Wind Power team has over 25 years of experience in cold climate wind energy applications ranging from icing wind tunnel testing to blade heating development to simulation of aeroelastic effects of icing on turbine lifetime. Senior Scientist Ville Lehtomäki writes about team’s newest results.

Ville Lehtomäki VTT

In order to explore new technical innovations within cold climate wind energy and specifically wind tunnel testing, VTT has teamed up with Danish Technical University (DTU Wind Energy) and Norwegian University of Science and Technology (NTNU) and research organization Sintef in a collaborative research project called LIDARS for wind tunnels (L4WT). The aim of the project is to gain and share knowledge about the possibilities and limitations with LIDAR (LIght Detection And Ranging) instrumentation in wind tunnels and to foster collaboration for alignment of research activities relevant to wind conditions in cold climate.

Wind energy in cold climates (encompassing both low temperatures and icing climates) is expanding rapidly with an amazing 12 GW/year rate [1] equivalent of 4,000 large 3MW wind turbines with hub heights up to 160m and rotor diameters typically around 130m. This large market has some special challenges especially regarding atmospheric icing conditions leading to ice accretion for wind turbines. Ice accretion on turbine blades may cause severe production losses up to 20 % of annual energy production, increase turbine mechanical loading and sound emissions from blades as well as increasing of ice throw hazards.

DTU Wind Energy has developed a new continuous wave short range compact LIDAR telescope (called Lidic) prototype for very small sampling volumes for studying blade section wind inflow conditions as well as wind farm wake dynamics of scaled wind turbines in boundary-layer wind tunnels. This new Lidic prototype was also tested at VTT Icing Wind Tunnel for unique observations of single droplets of typical in-cloud icing conditions seen in nature.

VTT Icing wind tunnelThe lidar telescope mounted on an robot arm in the VTT Icing Wind Tunnel in Finland, Mikko Tiihonen from VTT Wind Power team making final adjustments before measurements

The uniqueness of this project is that once the project ends in 2017, all measurement data will be made available for EERA JP WIND research community to boost new research innovations from the conducted Icing Wind Tunnel experiments. It is foreseen that the conducted experiments will result into novel research articles as well as increasing knowledge of icing wind tunnel testing.

The work described here has received support from IRPWIND, a project that has received funding from the European Union’s Seventh Programme for Research, Technological development and Demonstration.

Ville Lehtomäki, Senior Scientist 

[1] IEA Wind Task 19. (2016, July 29). Emerging from the cold. (WindPower Monthly) Retrieved August 22, 2016, from