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Proceedings of the 12th International Conference on Environmental Science and Technology
Rhodes, Greece, 8 - 10 September 2011
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OFFSHORE WIND POWER IN EUROPE: PERSPECTIVES OF DEVELOPMENT
IN GREECE
N. KARANIKOLAS, K. KYRIAKOU, E. SOURIANOS and D. VAGIONA1
1 Department of Spatial Planning and Development, Aristotle University of Thessaloniki,
Agia Varvara, Veria, 59100, Greece.
e-mail: dimvag@auth.gr
EXTENDED ABSTRACT
The renewable energy resources are internationally recognized as a way towards
sustainability and independency from fuel oils. European Union has given some
directions about the percentage of demanding energy that must be covered by renewable
energy resources. The exploitation of renewable energy resources is necessary in order
to achieve the energy reduction targets. The primary production from wind energy has
been growing up rapidly last years and has more than tripled between 2000 and 2006 in
Europe. In order to exploit higher wind velocities, there is a trend leading to offshore wind
farms.
Offshore wind farms can help the EU meet its commitment to CO2 reduction and gives a
strong impulse to job creation and regional development. The offshore wind farms give
the possibility to create an enormous farm in space as they do not have to confront land
barriers. Moreover, they allow the use of more rapid turbines in order to exploit the wind
power. The first offshore wind farm (11 turbines) was constructed on 1991 in Denmark.
The systematic improvement started on 1997 and culminated after 2005. In this paper,
the evolution of offshore wind farms in selected European countries is presented and the
opportunities to develop this technology in Greece are investigated.
Although Greece is characterized for its high speed velocities, this technology hasn’t
been developed yet. It is extremely important to focus on the development of offshore
windfarms, as their operation will contribute to achieve the energy and climate targets for
the year 2020, according to “20-20-20 plan” (a 20% reduction in greenhouse gas
emissions, a 20% improvement in energy efficiency, and a 20% share for renewables in
the EU energy mix). All coastal areas and islands of Greece are investigated. In the first
level of analysis, areas which don’t fulfill some criteria, such as appropriate wind velocity
and protected areas, are excluded from further analysis with the use of Geographical
Information Systems (GIS). The Analytical Hierarchy Process is then performed and
pairwise comparisons, including information retrieved from GIS applications, provided the
most appropriate sites to locate offshore wind farms in Greece. The average wind speed,
proximity to protected areas, sea depth and the connecting possibility to existing
electricity network consist some of the selection criteria. Karpathos, Skyros, Corfu and
Alexandroupoli are among the most suitable and outstanding locations. Thematic
cartography offers the portrait of the geographic analysis and stands as the last image of
the space characteristics suitable for wind farms.
Keywords: Analytic Hierarchy Process, GIS, offshore wind farms, renewable energy
resources.
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1. INTRODUCTION
Adoption of renewable energy technologies and promotion of green energy have
internationally been recognized as a way towards independency from fuel oils. Green
energy is provided by the natural environment that does not need to be extracted, and it
mainly includes solar, wind, tidal and hydrogen fuel cell power. The various forms of
renewable energy appear advantages, disadvantages and different impacts on physical
and anthropogenic environment in the whole life cycle. One of the most widely exploited
and rapidly evolved type of renewable energy is the wind energy. Onshore wind energy
has been exploited for power generation for thousand years. Nowadays, there is a
considerable trend to the establishment of offshore wind farms. Comparisons between
offshore and onshore wind farms prove that although offshores’ cost is higher and they
affect marine environment, they cause slight optical and acoustic distribution and they
can be extended spatially, as there is no geographical obstacle. Offshore wind farms
typically mean higher efficiency and electricity production, as they flow at higher speeds,
exploiting the moving air over the oceans (Miller and Spoolman, 2009).
Europe has an abundant supply of energy in its waters that could contribute to the
development of local economy and achievement of energy independence. The first
offshore wind farm was constructed during 1991 in Denmark and include 11 wind
turbines. The systematic improvement of this technology started on 1997 and has rapidly
and widely expanded the last five years. Offshore wind power capacity in Europe by the
end of 2006 had reached approximately 900 MW which could cover the electricity needs
of 250000 homes. Most of these wind farms are sited in shallow waters with depths of
less than 25 meters (Asplund, 2008). Today, worldwide, ten out of 25 largest offshore
wind farms in operation are located in United Kingdom, producing annually 1326 MW,
while six of them are sited in Denmark reaching 705 MW. The rest offshore wind farms
are situated in Belgium, Netherlands, Sweden, Finland, Ireland and Germany. It is
important to point out that twenty three out of 25 largest offshore wind farms are located
in Europe, while the other two are situated in China.
In the short run (end of 2013), four out of seven biggest offshore wind farms will be
located in United Kingdom and will produce 1152 MW. Three will be established in
Germany and one in Italy. At the same time, there are nine huge offshore wind farms at a
planning phase in United Kingdom and one in Ireland. It is estimated that until 2015, 37
GW will be produced in European countries. It is obvious that European countries make
an important endeavor to rapidly develop this technology, recognizing the benefits and
the importance to use clean energy and investing considerable amount of money on the
construction of offshore wind farms (wind turbines and windfarms database).
2. EUROPEAN CASE STUDIES
Some European countries that are characterized by intense development of offshore
wind farms are randomly selected in order to examine and analyse the current situation
and the future development, concerning offshore wind energy production. United
Kingdom, Denmark, German and Sweden present the most remarkable examples. All
statistical data were retrieved by the global offshore wind portal, found at
http://www.4coffshore.com
United Kingdom
In United Kingdom, 14 offshore wind farms in operation exist, while nine more are
planned to be constructed in the near future. Seven out of nine have already been
authorized and the rest have just been submitted. Rapid development will be noticed as
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43 additional offshore wind farms are at the stage of initial design. In the next figure
(Figure 1), total offshore wind farm capacity is presented according to the development
status.
Figure 1: Total offshore wind farm capacity in United Kingdom
The producing energy from offshore wind farms will power annually 800000 homes until
2011. This number will be duplicated the forthcoming years reaching around 2000000
homes per year and even 3500000 homes per year by the end of 2015. This evolution
will have an outstanding impact on the environment reducing notably the emissions of
CO2 and SO2. Nowadays, the reduction of emissions is around 2000000 tons of CO2 and
40000 tons of SO2 per year. A depletion of more than 4000000 tons of CO2 and 100000
tons of SO2 emissions is expected during next years while until 2015 the decrease of
emissions could reach the amount of 7000000 tons of CO2 and 160000 tons of SO2 per
year.
The existing average maximum depth of offshore wind farms in United Kingdom reaches
25 meters. Rapid development in offshore wind farm technology is expected to provide
deeper (more than 30 m) siting opportunities in the next two years.
Denmark
In Denmark, there are 13 farms under operation, none under construction and 3 have just
been approved. Until now the power production is more than 800 MW per year and the
next years this amount will reach the value of 1300 MW (Figure 2).
Figure 2: Total offshore wind farm capacity in Denmark
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The number of homes that can be powered is around 500000 and until 2013 this number
will increase to 720000 homes. The reduction of emissions of CO2 and SO2 is
approximately 1000000 tons and 22000 tons per year respectively. These amounts of
reduction will be further augmented to 1500000 and 35000 tons in the future. The
average maximum sea depth of construction is about 12 meters but within next years
such establishments will be sited at 19 meters.
Germany
In Germany, only four offshore wind farms have been operated until now, while four more
are under construction. However, proposals for 51 wind farms have already been
submitted for approval and 27 farms are at the stage of early planning. In figure 3, the
evolution of offshore wind power generation is presented.
Figure 3: Total offshore wind farm capacity in German
Until 2010, only 40000 homes have been supplied by energy retrieved by offshore wind
farms. In 2011, this amount is expected to reach around 264000. This number will be
further increased by the end of 2020 and will possibly cover the electricity needs of
5000000 residences.
Nowadays the reduction of the emissions of CO2 is around 500000 tons. In 2015 the
reduction will approximate 8500000 and 10000000 tons in 2015 and 2020 respectively.
Similarly, important decrease will be noticed in SO2 emissions. In 2010 the depletion of
SO2 was around 10000 tons. Up to 2015, the reduction will overcome the amount of
200000 tons and the decrease in SO2 is expected to reach 250000 tons in 2020.
The average maximum depth until 2009 was only 5 meters. Evaluating the offshore wind
farms this average is now 30 meters and in near future will increase up to 41 meters.
Sweden
Sweden is a country, which presents a stable evolution of offshore wind farms’
development. Until now, five farms are operating, five waiting for approval, 4 being at the
stage of early planning, while four have already been licensed and five have been
rejected. In figure 4, the evolution of offshore wind power generation in Sweden is
presented.
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Figure 4: Total offshore wind farm capacity in Sweden
The operation of the existing offshore wind farms succeeds in reducing emissions of CO2
and SO2 to 200000 and 4000 tons respectively. These values may even verge the
amounts of 3500000 and 80000 tons in the next five years.
The average maximum depth of offshore wind farms in Sweden is expected to reach 22
meters in the near future (4C Offshore).
3. DEVELOPMENT OPPORTUNITIES IN GREECE
Wind power is driving growth in the renewables sector and represents a huge investment
potential in Greece. The superb wind resources in Greece are among the most attractive
in Europe, with a profile of more than 8 m/sec in many parts of the country.
Although the construction of offshore wind farms has already been expanded in many
European countries, as presented above, this sector is quite underdeveloped in Greece.
Up until now, there isn’t any offshore wind farm under operation, while 37 studies are
waiting for approval, three are in the stage of early planning and five have already been
rejected.
In this paper, a systematic methodology is performed, integrating Geographic Information
Systems (GIS) tools and multi-criteria decision making (MCDM) methods, in order to
investigate the initial areas of offshore wind farms’ siting.
The whole process includes two phases (phase 1: exclusion phase, phase 2: evaluation
phase). All coastal areas and islands are candidates for selection. In the phase 1, three
criteria of exclusion are implemented. Thus, areas that don’t fulfill the minimum wind
velocity (6m/sec), that are characterized as protected areas either by National or
European legislation and that their sea depth exceeds 30 meters, are excluded from the
analysis, using GIS techniques.
In the second phase of the analysis, decision – making process is divided in three part:
goal (proper offshore wind farm selection), criteria (average wind velocity, distance to
protected areas, sea depth and possibility of connection to the existing electricity
network) and alternatives (all areas not excluded in the first phase). Analytical Hierarchy
Process (AHP) is selected for the analysis, as it uses a ratio scale, which, contrary to
methods using interval scales (Kainulainen et al., 2007), requires no units in the
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comparison (Ishizaka and Labib, 2009). At each node of the hierarchy, a matrix collects
the pairwise comparisons, performed according to information generated from the
corresponding maps. Expert Choice, a user - friendly supporting software, which
incorporates intuitive graphical user interfaces, is used for the automatic calculation of
priorities.
4. RESULTS
4.1. Exclusion Phase (Phase 1)
In Figure 5, 6 and 7 the three exclusion criteria are presented and in Figure 8 the
candidate areas for the second phase evoke, after the overlapping of the three maps.
Figure 5: Wind velocity > 6m/sec Figure 6: Protected areas
Figure 7: Sea depth < 30m Figure 8: Candidate zones
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4.2. Evaluation Phase (Phase 2)
Two pairwise comparisons are performed in this stage. The first include pairwise
comparisons among the evaluation criteria (average wind velocity, distance to protected
areas, sea depth and possibility of connection to the existing electricity network), while
the second the comparisons among candidate areas for each selection criteria.
Expert Choice software is used and verbal scale judgments are performed. In the first
level of evaluation, the criteria are weighted according to authors’ opinion concerning
their significance to the overall goal. In Table 1, features of the evaluation criteria are
presented.
Table 1: Metadata of evaluation criteria
Criteria Type Description Unit of
measurement
average wind velocity Quantitative the average speed of
wind m/sec
proximity to protected
areas Quantitative distance from – to
protected areas km
sea depth Quantitative the distance from the
bed to the surface of
the see
m
connection to the
electricity network Qualitative feasibility of connection
to electricity network low
medium
high
In the second level of analysis, input is provided from the corresponding maps. Figure 9
reveals the weighting factors of evaluation criteria as well as the prioritization of candidate
areas.
Figure 9: Prioritization of evaluation criteria and site selection
4.3. Further analysis
Additional data is further investigated and three capacity scenarios (1, 2 and 3) are
formed for each selected site, installing turbine capacity of 1.5, 3 and 3.6 MW
respectively. The selection of the turbines used in the above scenarios is based on the
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design choices of leading manufacturers and are among the “top ten” list, according to
global market share in 2007. Table 2 presents the results for the first ten selected sites
and includes the name of the location, area (km2), min water depth (m), max water depth
(m), distance from shore (km), number of turbines, capacity in (MW) under scenario 1,
scenario 2 and scenario 3.
Table 2: Statistics for selected sites
wind farm
location area
(km2) min–max
water
depth(m)
distance
from
shore(km)
number
of
turbines
scenario
1 scenario
2 scenario
3
Karpathos 32.87 0-30 0.0-3.5 745 451 319
Skiros 174.77 0-30 0.0-6.0 3963 2397 1696
Corfu 14.91 0-30 0.0-12.0 338 205 145
Alexandrou-
poli 0.42 0-5 0.0 10 6 4
Amorgos 75.27 0-30 0.0-8.0 1707 1033 730
Paros 31.43 0-15 0.0-6.19 713 431 305
Anafi 13.65 0-30 0.0 310 187 132
Ios 62.84 0-30 0.0-10.10 1425 862 610
Andros 70.44 0-30 0.0-3.17 1597 966 684
Samothrace 279.81 0-30 0.0-16.41 6345 3838 2716
5. CONCLUSIONS
Greek insular territory and seas have often been referred as places of petrol and oil
reserves. Wind velocities and sea depth provide a great opportunity to exploit renewable
energy resources through offshore wind farms’ development. Through this initial analysis,
the first ten sites in the hierarchy with an appropriate surface of more than 740 km2 can
cover a great number of wind turbines and the energy needs of the area. The distance of
the wind farms, which can be located in these areas, can vary from the offshore (0 km) to
15 km. Also the depth of the sea is not so mentionable and can go up to 30 m but there
are locations, which can have less than 5 meters depth.
Of course, a further and more detailed analysis should be performed in order to decide on
the final and exact location as well as the technical characteristics of every wind farm.
Information about ship routes, data on tourism development, seasonal energy demand
and fluctuations during summer and wintertime should also be considered before any
siting of such activities.
REFERENCES
1. Asplund R. (2008), Profiting from clean energy: a complete guide to trading green in solar,
wind, ethanol, fuel cell, power efficiency, carbon credit industries, and more, Hoboken,
Canada
2. Ishizaka A. and Labib A. (2009), Analytic Hierarchy Process and Expert Choice: Benefits and
Limitations, ORInsight, 22(4), 201–220.
3. Kainulainen T., Leskinen P., Korhonen P., Haara A. and Hujala T. (2007) A statistical
approach to assessing interval scale preferences in discrete choice problems, Journal of the
Operational Research Society, 60(2), 252-258.
4. Miller T. and Spoolman S. (2009), Living in the environment, Cengage Learning, Canada
5. Wind turbines and windfarms database URL: http://www.thewindpower.net
6. 4C Offshore URL: http://www.4coffshore.com/windfarms/