Conference programme

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Delegates are invited to meet and discuss with the poster presenters during the poster presentation sessions between 10:30-11:30 and 16:00-17:00 on Thursday, 19 November 2015.

Lead Session Chair:
Stephan Barth, ForWind - Center for Wind Energy Research, Germany
Konstantinos Gkarakis HWEA/TEI ATHENS, Greece
Michalis Sioutas (2) F P Demetrios Zigras (3)
(1) ELGA-Meteorological Applications Center, Thessaloniki, Greece (2) Nordex UK Ltd, Manchester, United Kingdom

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Presenter's biography

Biographies are supplied directly by presenters at EWEA 2015 and are published here unedited

Konstantinos Gkarakis graduated from the Technological Educational Institute of Athens (TEI Athens) and has Master Science in Energy from Heriot Watt University in Scotland. His employment experience included the Umweltkontor Hellas, WRE Energy, Acciona Energiaki, Elica (Copelouzos - Samaras Group of Companies), AirEnergy, Intracom Constructions. His special fields of interest include wind resource - energy estimations in wind energy projects and wind energy plants development. Now, he is free-lancer wind engineer and wind energy expert for the control of wind measurement laboratories in Hellenic Accreditation System S.A. Also, he is scientific associate in RES Lab, Energy Technology Department, in TEI Athens.


Poster Download poster (10.85 MB)


Extreme weather phenomena in Greece: Tornadoes and waterspouts. An unknown threat for windfarms


Tornadoes and waterspouts occur in various parts of Greece and the research of recent years has shown that it is not as rare as previously thought. Research and systematic recording began in Greece in 2000 and carried out systematically in the last 15 years.


Based on this data, tornadoes and waterspouts or tornado funnel clouds occur at about 50 days a year, on average. Analysis of the geographical distribution showed that tornadoes appear almost in all areas, but with a greater frequency over the Ionian Islands, the coastal areas of Western Greece, the low elevation areas of Macedonia and Thessaly, and the sea areas of northern Crete and Rhodes islands. Regarding the strong and highly destructive tornadoes ie. those with an F2 intensity or greater of the scale Fujita, they appear on average six days a year in various areas of the country.

Main body of abstract

Wind turbines are classified into three IEC classes depending on the wind potential in the installation location (Class 1: high wind potential class 2: moderate wind potential and class 3 for low wind potential). The standard IEC 61400-1 sets out the factors to be tested for the installation of a windturbine through site compliance study. The study was carried out for the type of windturbine for a given installation area of a wind farm and the particular location based on the design limits of the windturbine. The design of windturbine guarantees that can safely withstand the environmental conditions of the installation area. One of the most important factors of the compliance study for the windturbines is the estimation of extreme wind values (Vref- speed reference class (10min). A windturbine is designed for a class with the reference speed Vref is expected to operate safely in climatic conditions where the extreme value of the ten-minute wind speed at the height of the hub height and recurrence interval of 50 years is less than or equal to Vref. The parameter Vref is stochastic expressed in probabilistic terms and its value is likely but not exact. The cumulative incidence of extreme wind speeds is necessary for the calculation of Vref. The calculation is performed by means of statistical methods POT-N (Method of Independent Storms-MIS) and Gumbel. As is well known statistical methods based on wind measurements a few years cannot give predictions for violent natural phenomena such as tornadoes.


The aim of this paper is to examine the occurrence of tornadoes/waterspouts in Greece during the period of 15 years from 2000 to 2014 (spatial and temporal distribution) and to investigate some climatological characteristics including the likelihood of their occurrence by regional unity. Also, a comparison of the above data with the boundaries of the three IEC classes and the under development windfarm area is undertaken. Useful conclusions about the risks of a windfarm and the consequences because of the tornado/waterspout occurrence, are extracted. They can cause large damages, from damage to the blades of a windturbine up to their destruction. Except structural damages, they can also cause total destruction and fall depending on the class and the tornado intensity level .

Learning objectives
Tornado and waterspout climatologies should be taken into account by the companies that develop wind farms in Greece and the windturbine manufacturers, in order to estimate the probability hit by tornado during their twenty-year operation. Better knowledge of tornado and waterspout climatology for Greece, is extremely useful for the safe and smooth operation of the wind farm installations.