The first offshore projects were demonstrations giving extra costs, for example, for foundation design and to allow for pitch changes on the blades to improve performance. Due to the difficulties of access by cranes or other large maintenance equipment, turbines at the offshore wind farms are equipped with built-in hoists (Lely, Bockstigen) or cranes (Vindeby, Tun Knob) for replacement of major components (van de Sande, 1997), (Midkraft, 1995), (Kelter-Wesenberg and Stiesdal, 1997), (Lange et al., 1999). In 1998-2000 the first commercial projects were installed where electricity production is expected to be competitive with wind farms on land or other forms of energy. (DEA/CADDET, 2000) expect production costs of the order 0.05-0.055 /kWh or equivalent to land sites. (Greenpeace, 2000) compared costs for projects at 30, 50 and 70 km from the coast and found breakeven costs with a wind speed at a height of 60 m of 8.5, 8.9 and 9.0 m/s, respectively. Costs of producing offshore energy with the current financing structure in the UK have been estimated at 5-6 p/kWh (approx. 8 cent/kWh) (Border Wind, 1998b). The Opti-OWECs project illustrated that offshore wind energy should be economically viable in most Northern European coastal areas (Cockerill et al., 1998). Energy costs in both studies and actual projects have steadily decreased over the last decade (Kuhn, 2001). Capital costs are around 30 to 70 % higher than onshore which is offset to some degree by higher energy yields of up to around 30% (Hartnell and Milborrow, 2000). However recent studies indicate that large offshore wind farms are competitive with other energy sources (e.g. (Svenson and Olsen, 1999)) and the trend towards large wind farms decreases unit costs.
Future developments include the Dutch Offshore Wind Energy Converter presently under development. The DOWEC has 5 or 6 MW rate power and a rotor diameter of approximately 100 meters with output for 4000 households (ECN, 1999).
Table 5 shows details of current offshore wind farms. There is a major difficulty in comparing costs of energy produced due to:
the differences in project financing (lifetime, interest rates)
costs of operation and maintenance
commercial nature of projects means that this information is not in the public domain.
Hence costs are not compared on an equal basis since it is not possible to locate investment and operation and maintenance costs for each project. (Kuhn et al., 1998) also show the average energy costs for offshore wind energy decreasing over the last ten years and give details of the sites.
Table 6 shows planned wind farms and Table 7 tentative site exploration. It is difficult to make this separation since some apparently promising projects stall or fall (Knight, 1995), (Renewable Energy World, 2000) at the last planning hurdle or due to some change in pricing regulations. In Germany for example a number of projects have been announced but none are yet under construction. In May 2001 a number of very large projects were detailed (Schmidt, 2001) for both the North and East Seas (southern Baltic). These sites are at much larger distances offshore than have previously been considered and so represent an interesting new challenge for offshore wind energy. Similarly the UK announced 13 sites for which different consortia have been granted preliminary licences. These are detailed at www.offshorewindfarms.co.uk.
|
Name |
#, size, make of turbines |
MW |
Year |
cent kWh |
Product-ion MWh/y |
Investment1(/kW) |
Min fetch (km) |
Water depth (m) |
Comments |
References |
|
NogersundSE |
220 kW Wind World |
0.22 |
1990 |
|
0 |
|
0.25 |
6 |
|
(Larssen, 1994) |
|
Vindeby DK |
11 450 kW Bonus |
5 |
1991 |
8.5 |
11200-11730
|
1939-2150 |
1.5 |
2-5 |
Availability > 95% in the first 5 years. Lightning strikes more frequent than on land. Mean wind speed 7.5 m/s. |
(Olsen and Dyre, 1993) , (Kelter-Wesenberg and Stiesdal, 1997), (DEA/CADDET, 2000; Kelter-Wesenberg and Stiesdal, 1997), www.bwea.com, (Wind Developments, 1999), (Hartnell and Milborrow, 2000) |
|
Lely, IJsselmeer NL |
4 NedWind 500 kW |
2 |
1994 |
8.6-13.7 |
3800 |
1700-2600 |
0.8 |
5-10 |
Stall-controlled on single pile foundations. Mean wind speed 7.7 m/s. |
(van Zanten, 1996), (DEA/CADDET, 2000),(Henderson, 2000),(Wind Developments, 1999),(Hartnell and Milborrow, 2000) |
|
Tun Knob, DK |
10 Vestas 500 kW |
5 |
1995 |
6.6-8.17 |
12500-12700 |
2040-2200 |
6 |
3.1-4.7 |
Pitch controlled. A vailability better than expected but slightly lower than for a neighbouring onshore farm. Mean wind speed 7.5 m/s. |
(CADDET, 1996) , (Madsen, 1996)(Pedersen, 1998) (DEA/CADDET, 2000) (Kuhn, 2001) ,(Wind Developments, 1999), (Hartnell and Milborrow, 2000) |
|
Name |
#, size, make of turbines |
MW |
Year |
cent kWh |
Product-ion MWh/y |
Investment1(/kW) |
Min fetch (km) |
Water depth (m) |
Comments |
References |
|
Irene Vorrink, NL |
28 Nordtank 600 kW |
16.8 |
1996 |
|
37000 |
|
0.02 |
5 |
|
(DEA/CADDET, 2000), (Wind Developments, 1999) |
|
Bockstigen, SE* |
5 Wind World 550 kW |
2.75 |
1998 |
|
8000-8500 |
1455 |
4 |
5.5-6.5 |
First to use drilled monopile foundations. Costs ~ 15-20% > land based |
(Kuhn, 2001; Lange et al., 1999), (Hartnell and Milborrow, 2000) |
|
Blyth, UK |
2 Vestas 2 MW |
4 |
2000 |
7-8 |
12000 |
|
1 |
8.5 |
Coast approx. 5p/kWh |
(BWEA, 2000) |
|
Middelgrunden, DK |
20 Bonus 2 MW |
40 |
2000 |
6 |
89000 |
|
2-3 |
3-6 |
Owned equally by a wind energy co-operative with over 3000 members & local electricity utility. 56% cost reduction compared with Vindeby. |
(Jessian and Larsen, 1999),(DEA/CADDET, 2000), (International Energy Agency, 2001), Srensen et al. (2000), Larsen and Srensen (2001). |
|
Utgrunden,SE |
7 Tacke 1.425 MW |
10 |
2000 |
|
38000 |
|
8 |
7.2-10 |
|
(Kuhn, 2001) |
|
Yttre Stengrund, SE |
5 NEG MICON 2 MW |
10 |
2001 |
|
30,000 |
|
|
|
|
(Whittaker T.J.T. et al., ) |
|
Total |
|
80 |
|
|
176500 |
|
|
|
|
|
*production figures estimated if not available. See also: (Goodall, 2001).
1 Note that there is considerable variation in these costs from different sources.
Figure 3-1 : Current offshore wind farm developments in Europe (end of year 2000).
|
Table 6: Planned wind farms (Spring 2001): |
||||||||
|
Name |
Turbines |
Total MW |
Year |
Cost/ kWh |
cent/ kWh |
Production MWh/y |
Comments |
Reference |
|
Klasrden |
21 NEG MICON 2 MW |
42 |
2001? |
|
|
|
Gotland |
(Wizelius, 2000) |
|
Horns Rev, DK |
80 Vestas 2MW |
160 |
2002 |
0.35 DKK |
4.7 |
|
|
(Madsen, 1997), (DEA/CADDET, 2000),(Madsen, 1997) |
|
Rdsand, DK |
72 Bonus 2.1-2.2MW |
151-158 |
2002 |
0.36 DKK |
4.8 |
|
|
(Energistyrelsen, 1997),(Madsen, 1997),(DEA/CADDET, 2000),(Madsen, 1997) |
|
Q7-WP, NL |
|
100 |
2002 |
|
|
|
> 12 miles |
|
|
Breedt, FR |
|
7.5 |
2002? |
|
6.4 |
|
|
|
|
Ls Syd, DK |
|
150 |
2003 |
0.35 DKK |
4.8 |
396,000 |
|
(Madsen, 1997), (DEA/CADDET, 2000), (Hartnell and Milborrow, 2000; Madsen, 1997) |
|
Nearshore, NL |
|
100 |
2003 |
0.16 NLG |
7-8 |
300,000 |
Requires subsidy of NLG 60 m |
(Hartnell and Milborrow, 2000) |
|
Om Stlgrunde, DK |
|
150 |
2004 |
0.37 DKK |
5.0 |
434,000 |
|
(Madsen, 1997), (DEA/CADDET, 2000),(Hartnell and Milborrow, 2000; Madsen, 1997) |
|
Name |
Turbines |
Total MW |
Year |
Cost/ kWh |
cent/ kWh |
Production MWh/y |
Comments |
Reference |
|
Gedser, DK |
|
150 |
2006 |
0.38 DKK |
5.1 |
|
|
(Anonymous, 1998)(Energistyrelsen, 1997)(Madsen, 1997), (DEA/CADDET, 2000),(Madsen, 1997) |
|
Arklow Bank, EI |
|
500 |
|
|
|
|
10 km to coast, licence granted for monitoring Sep. 2000. ~ 27% more investment than onshore |
|
|
Kish Bank, EI |
|
250 |
|
|
|
|
|
|
|
Lillegrund, SE |
48 Enercon 1.5 MW |
72 |
|
|
|
|
resund |
(Wizelius, 2000),(Hartnell and Milborrow, 2000) |
|
Sams |
10 2MW |
20 |
|
|
|
|
Public hearing June 1999. Tenders issued November 2001. |
www.veo.dk |
|
Total |
|
1832 |
|
|
|
|
|
|
* Note 13 sites in the UK, 17 in Germany and at least 4 in Poland are not shown. Information on UK sites www.offshorewindfarms.co.uk on German sites (Schmidt, 2001).
Figure 3-2. Planned offshore developments (2001 onwards). Note that detailed plans for Germany, the UK and Poland announced during spring/summer 2001 are not included.
|
Table 7. Tentative site exploration (Spring 2001). |
||||
|
Name |
Total MW |
Year |
Comments |
Reference |
|
Knokke, BE |
100 |
2002 or later |
12-15 km from coast |
(Greenpeace, 2000) |
|
Wenduine |
100 |
2002 or later |
5-11 km from coast |
(Greenpeace, 2000) |
|
Pori, FI |
|
|
|
|
|
Kish Bank, EI |
220-250 |
|
10 km from coast. Licence granted for monitoring Sep. 2000 |
|
|
Codling Bank, EI |
|
|
Licence granted for monitoring Sep. 2000 |
|
|
Blackwater Bank, EI |
|
|
Licence granted for monitoring Sep. 2000 |
|
|
Nord-Pas de Calais, FR |
|
|
Study for local council or French Energy Agency (ADEME) 1998. 5 to 8 km from shore with water depth of 5 to 20 m. Estimated resource 775 MW giving 2.4 TWh/year. |
|
|
Brittany, FR |
|
|
Study for local council or ADEME 1999-2000. 3 to 10 km from shore in water dpeths 5 to 20 m. Estimated resource 2050 MW or 6.3 TWh/year. |
|
|
Normandy, FR |
|
|
Study for local council or ADEME 2000. Basse Normandie 5 to 10 km from shore in water depths 5 to 20 m. Resource estimated 3500 MW or 10.8 TWh /year. |
|
|
Languedoc-Rousillon, FR |
|
|
3.5 to 10 km from shore in water depths 20 to 30 m. Estimated resource 2800 MW 10.6TWh/year. |
|
|
Cadiz, ES |
|
|
Measurements underway. |
|
|
Bialogra, PL |
|
|
Consents issued for 49-61 2 MW turbines |
|
|
Karwia, PL |
|
|
Consents issued for 50 2 MW turbines |
|
|
Solway Firth, UK |
|
|
Off Maryport, Cumbria 9.5 km from shore, Off Rock Cliffe, Dumfries & Galloway 8.5 km from shore. Preliminary consents for 60 turbines1 |
http://www.offshorewindfarms.co.uk/ |
|
Barrow, UK |
|
|
10 km from shore Off Walney Island, Cumbria. Preliminary consents for 30 turbines1 |
http://www.offshorewindfarms.co.uk/ |
|
Shell Flat, Uk |
|
|
Off Cleveleys, Lancashire, 7 km from shore. Preliminary consents for 90 turbines1 |
http://www.offshorewindfarms.co.uk/ |
|
Southport, UK |
|
|
Off Birkdale Merseyside, 10 km from shore. Preliminary consents for 30 turbines1 |
http://www.offshorewindfarms.co.uk/ |
|
Burbo, UK |
|
|
Off Crsoby, Merseyside 5.2 km from shore. Preliminary consents for 30 turbines1 |
http://www.offshorewindfarms.co.uk/ |
|
North Hoyle/ Rhyl Flats, UK UK |
60-90 for North Hoyle |
|
Off Prestatyn, North Wales, 6km from shore and off Abergele, North Wales, 8 km from shore. Preliminary consents for 60 turbines1. The developers of North Hoyle, National Wind Power, report that the site has good wind resources and relatively low exposure in the predominant wind direction. Water depth is 12 m with a 9m tidal range. Plans are to install turbines of 2-3MW. The Delores of Rhyl Flats are Celtic Offshore Wind Ltd. |
http://www.offshorewindfarms.co.uk/ |
|
Scarweather Sands, UK |
|
2004-2005 |
Off Porthcawl, South Wales, 9.5 km from shore. Preliminary consents for 30 turbines1. Developers are United Utilities . |
http://www.offshorewindfarms.co.uk/ |
|
Kentish Flats, UK |
|
2004-2005 |
Off Whitstable Kent, 8 km from shore. Preliminary consents for 30 turbines1. The developers are Global Renewable Energy Partners UK, a subsidiary of NEG MICON. Turbines of 2-3MW will be installed on monopile foundations. Estimated production is 300 GWh/year. |
http://www.offshorewindfarms.co.uk/ |
|
Gunfleet, UK |
100? |
|
Off SE Clacton-on-Sea, Essex, 7 km from shore. Preliminary consents for 30 turbines1. Developers are Enron Wind Gunfleet Ltd. |
http://www.offshorewindfarms.co.uk/ |
|
Scroby Sands, UK |
76 |
2003? |
Off Caister, Norfolk, 2.3 km from shore. Preliminary consents for 30 turbines1. Developers are Powergen Renewables Offshore Wind Ltd. Plans exist to erect 38 2MW turbines. |
http://www.offshorewindfarms.co.uk/ |
|
Cromer, UK |
|
|
Off Foulness, Norfolk, 6.5 km from shore. Preliminary consents for 30 turbines1 |
http://www.offshorewindfarms.co.uk/ |
|
Lynn/ Inner Dowsing UK |
|
|
Off Skegness /Off Ingoldmells, Lincolnshire, 5.2 km from shore. Preliminary consents for 60 turbines1. Developers of the Lynn Site are AMEC Offshore Wind Power Ltd. Earliest construction date is 2004. Developers of Inner Dowsing are Renewable Energy Systems and British Energy. Turbines are 2-3MW. Construction is anticipated in 2004. |
http://www.offshorewindfarms.co.uk/ |
|
Teeside, UK |
|
|
Off NE Teesmouth, Middelsborough, 1.5 km from shore. Preliminary consents for 30 turbines1 |
http://www.offshorewindfarms.co.uk/ |
1 The UK Crown Estate announced the sites and names of the eighteen wind farm developers who have successfully pre-qualified to obtain a lease of seabed for development of offshore windfarms (April 2000).