Wind energy resource in Kosovo

Prologue 
In this article I will try to elaborate the viability for building of electricity generating capacities based on wind power in Kosovo.
This is a very actual subject in Kosovo as well, and as such, it deserves a rather serious treatment. Even though a number of studies on wind power energy resources in Kosovo are already available, in our media we quite often see shallow opinions, which may lead to wrong conclusions.
This paper presents in brief basic information derived from certain relevant studies and explains basic principles of physics on derivation of electricity from wind power, always concentrating on the data related to and specificities of Kosovo.
Does the wind blow in Kosovo?
The correct answer to this question is determinant to the fact whether wind powered electricity generators should be built in Kosovo or not. Of course, we are talking about the low cost energy generation which will be feasible for investors, whoever they may be.
The papers below treat certain different aspects of the wind resources worldwide and from these analysis relevant data may be drawn on the winds in Kosovo. At the end, a research undertaken on 8 different geographical points in Kosovo, with relatively accurate measurements is presented, and as such it represents one of the more exact sources of information that exists till now.
As far as the credibility of the sources of information is concerned, I have tried to rely only on maximally credible sources, and I will leave it upon the readers to make their own judgments on this issue.
1. Paper entitled “Evaluation of global wind power” , by Cristina L. Archer, carcher@UDel.Edu and Mark Z. Jacobson jacobson@stanford.edu , University of Stanford ,USA, see the link: http://www.stanford.edu/group/efmh/winds/global_winds.html , published on 2005 at Journal of Geophysical Research – Atmospheres, which is the first of its kind worldwide, treats the potentials for generation of energy by utilization of wind power around the world. According to the maps presented by this paper, one can see that the maps and data for the winds in Kosovo have been presented as well. As this paper discusses global world resources, Kosovo is represented with one single point, and this point is surely Prishtina. At this point, average annual wind, at an altitude of 80 meters, blow with a speed of 5.9 m/s, and according to this measurement, this region (Kosovo) is categorized as Class 1 wind power region, out of 7 classification classes. In Kosovo, as in many other countries around the world, weather stations acquire wind data at only 10 meters altitude, hence this paper has utilized sophisticated mathematical methods to calculate wind speed at altitude of 80 meters.
Another conclusion made by this paper states : “Globally, ~13% of all reporting stations experience annual mean wind speeds ≥ 6.9 m/s at 80 m (i.e., wind power class 3 or greater) and can therefore be considered suitable for low-cost wind power generation. This estimate is believed to be conservative.”

2. On the intensity of winds blowing in Kosovo, we can also learn from the European wind map, available at the following link: http://www.awstruepower.com/wp-content/uploads/2012/07/Wind-Resource-Map-EUROPE-11×17-bleed-FINAL.pdf. At this map, which has a resolution of 200m, we can see that average annual wind speed on the largest part of the territory of Kosovo, at an altitude of 80m, is mainly 3m/s, with the exclusion of some small oasis where maximum wind speed is 6m/s. Data from this map, with the application of sophisticated mathematical methods (smaller squares method) have a higher resolution than the map presented by the paper we discussed at point 1). However, even this data only confirm that winds in Kosovo have a low, Class 1 intensity.
3. According to the USA Wind map, published at the “Wind Powering America” site of the US Energy Department, http://www.windpoweringamerica.gov/wind_maps.asp , one can see that winds are of higher intensity at the central parts of the continent as well as at oceanic coastal areas. For us in Kosovo, this has almost no importance, but this site contains detailed and practical information for all those planning to invest in this field of business. As far as our subject is concerned, the average wind speed, which is the primary and decisive condition on whether wind power generating capacities should be built or not, this site provides the following recommendation:
“Areas with annual average wind speeds around 6.5 meters per second and greater at an 80-m height are generally considered to have a wind resource suitable for wind development.” Of course, this does not mean that one may not undertake the adventure of investing even in regions with lower wind speeds, because, as the Americans say :“it is a free country”.
4. The following study is the most serious and accurate ever undertaken in Kosovo, on wind as an energy source. This study was financed by REPIC and was supported by the Swiss Confederation and certain Swiss state institutions, and was undertaken by the Swiss Consulting Company NEK Umwelttechnik AG. This study can be found at the following link: http://files.repic.ch/files/Schlussbericht_NEK_Kosovo_vf.pdf. The excellent results of this study, published on December 2012, is the exceptionally exact map of the winds in Kosovo, prepared based upon measurements during a whole calendar year ( August 1st 2009 – July 31st 2010 ) on ten different geographic positions, dispersed in relatively uniform locations in the Kosovo territory. Due to thunder bolts and ice blockage of the anemometers during the winter season, two to three measurement points have lacking data recordings, but in general, measurements are quite trustworthy.

From this study, we may conclude that winds in Kosovo, at an altitude of 80 meters, do not exceed the average annual speed of 6m/s, except at the Budakova peak (near Suhareka- 1667 m above the sea level) where the wind speed reaches 7.0 m/s.

Recapitulation on winds in Kosovo

Based on the studies presented by papers analyzed above, I conclude that data on winds in Kosovo, presented by all the sources cited, agree with each other in general. From this we can conclude that winds in Kosovo are not of high intensity and do not present a potential, economically viable resource for generation of electric energy. Data for wind speed are presented for an altitude of 80 meters from the surface, as this altitude is almost standard for the generators of 2MW capacity, with the helix span of 77 meters and which have so far shown to be technically and economically most optimal. Winds in Kosovo, at 80 meters, do not exceed the average annual speed of 5.9 m/s in the largest part of the territory of Kosovo, apart from certain “oasis”, as is the Budakova peak, where average annual speed of 7.0 m/s has been measured.
Currently available published data are not perfect, and there is a possibility for more exact measurements to be undertaken in the future, especially at the higher altitude pints, e.g. Budakova peak, even though the building conditions and connection of these points to the existing energy distribution network will be harder and economically costlier. But, we will leave this to the future.
Based on available data, wind resource in Kosovo falls under the lowest category, Class 1, with the average annual speed below 6.5 m/s at an altitude of 80 meters. All relevant scientific literature, considers that spaces where winds are of Class 1, do not poses the necessary wind resources for generation of low cost wind powered electricity.
A little bit of classical mechanics
According to the principles of classical mechanics, established by the German mathematician and philosopher Gottfried Leibniz and Swiss mathematician Johann Bernoulli, towards the end of the 17th century, energy “E” of a body with a mass “m”, moving in a linear manner with the speed “v” is proportional to the E ∝ mv². This energy is known as kinetic energy, the energy of the motion. It is of a particular importance that kinetic energy of a body is proportional to the square of the speed “v2”. Hence, if you increase the speed of your car on a motorway from 40km/h to 120km/h, kinetic energy of the vehicle will increase 9 fold. It may be that this physics fact does not agree with your intuition, but this is the truth, it’s a law of physics.
But, how much energy can we harness from wind?
However, things become more un-intuitive, or more paradoxical, when we have to deal with wind turbines. According to the science of physics, if the intensity of the wind blowing through a turbine is increased 3 fold, then the energy output provided by that turbine is 3x3x3=27 fold higher. The energy of the turbine is increased by the power of three, the cube of the wind speed “v3”! How is this possible? This has been explained by the German physicist Albert Betz on 1919. According to the law, named in his honor as the Betz law, two fundamental facts are concluded:
1. A theoretically ideal turbine, could harness maximally 59.3 % of the energy of the wind passing through its helices. This theoretical maximum has been increased by 2 % of energetic yield according to the newest studies, only that much. Modern turbines achieve a yield of 40 to 45 %.
2. Energy yielded from wind, is proportional to the wind speed on the power of three!
Modern wind turbines, depending on their size and electrical power, start to rotate when the wind speed reaches at least 2, 5 -5 m/s. Beyond this speed, the turbine power increases according to the Betz law and for most of the turbines, nominal power (the maximal power output it was designed to achieve) is reached at wind speeds of 11-15 m/s. For more information on types and functioning of the wind turbines, see link below: http://www.uni-hildesheim.de/~irwin/inside_wind_turbines.html

Let us compare, how much energy contain winds in Kosovo and how much in United Kingdom?
The fact number 2, above, is very meaningful, as a turbine placed let’s say at the coastal spot in United Kingdom, where on a large space, average annual wind speed is above 9.4 m/s, (Class 7 ), compared to an exactly same turbine but this time placed in Kosovo, where the average annual wind speed is of Class 1, less than 5.9 m/s, would yield (9.4×9.4×9.4)/(5.9×5.9×5.9) = 831/205=4 times more energy within a same time period, let’s say a year. Very disappointing, isn’t it! The same turbine, manufactured by the same producer, of the same power and dimensions, would yield four times less energy during a year only because it has been placed in Kosovo and not in United Kingdom. I do not know why does this remind me of football? I wander how would an imaginative football game between Manchester United and the best Kosovar team result? Maybe 10:0? Well, let’s leave the irony aside, miracles might happen in a football game, but there is no joke with physics and finances.
Is there a benefit in investing in wind power energy generating capacities in Kosovo?
In some places around the world, where there is sufficient wind and other optimal natural and infrastructural conditions exist, government policies encourage building of the wind power generating capacities. Subventions are necessary to stimulate and support the investors for building of such wind generating capacities. The need for subventions in itself shows that costs incurred for building of such capacities are relatively high compared to any other type of energy. But of course, if the money for subventions would be collected from the savings on carbon credit costs, then everything would be fine. This happens as a rule in almost all economically developed countries, where energy production in large extents is based on coal burning, e.g. Germany, United Kingdom, Australia etc.
Energy Regulatory Office in Kosovo has foreseen a feed-in tariff for the purchase of energy produced by wind power of 84 Eur /MWh. I do not know who could persuade Çalik-Limak or KOSTT to purchase electric energy from future wind energy generators with such a tariff, but I have seen that respectable analysis on this issue have been undertaken and I would like to believe that everything is in order.
At the end, please allow me to say that if I personally, would inherit millions of dollars from my American grandmother, who I never knew she existed, and who died suddenly from a heart attack and I was the only inheritor of her wealth, I would never invest my wealth in wind generators in Kosovo. I would rather build 100 new petrol stations, why should I lose sleep on worrying whether the wind is blowing or not in Kosovo.
Before I published this article, I consulted with my fellow engineering colleagues and experts of relevant fields, Mr. Skender Shala, Mr. Naim Hoxha, Mr. Sylë Tahirsylaj, Mr. Avni Bërveniku, and others, whom I would like to thank for their comments and making this paper better than what it was as a first draft.
Agron S. Dida, Project Manager at Komtel Project Engineering, Prishtina, Kosovo
Diplom Ingenieur and Master of Science in electrical engineering

energjia.al, 06.06.2013