Klima-, Energi- og Forsyningsudvalget 2023-24
KEF Alm.del Bilag 27
Offentligt
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Cost comparison – Wind turbine installa4on onshore and offshore
In 2020, Rystad Energy performed a study which concluded that it is more cost effec<ve to
install 14 MW wind turbines compared to 10 MW wind turbines as part of a 1 GW offshore
windfarm – including all infrastructure. The report is available online.
Considering the plans of the Danish consor<um Green Power Denmark, and the lobbyism of
countless stakeholders at the government of Denmark to build more wind turbine test
centers onshore, it is worth looking at the cost impact, and Government money spending.
The defini<on of a prototype wind turbine is a “series 0”. This es<ma<on is to provide a brief
cost assessment of series 0 turbine installa<on onshore versus offshore.
The Rystad Energy report and cost data provide a solid basis to compare rela<ve installa<on
costs for wind turbines offshore. In 2020 DTU has published a report on the Østerild wind
turbine test center with a cost breakdown (2010) and lessons learned. These two data
sources along with complementarity sources to perform an es<mated cost calcula<on are
u<lized for the present calcula<on.
Offshore (Rystad)
1 GW windfarm
(10 MW wind turbines)
1 GW windfarm
(14 MW wind turbines)
Difference
Onshore test-site (Østerild)
9 x test-site
(for a 14 MW wind turbine)
Total Cost (bn USD)
2.7
1.93
-28.5%
Total Cost (mm USD)
250.11
Cost per wind turbine (mm USD)
27.00
27.16
+0.6%
Cost per wind turbine (mm USD)
27.79
Looking at the cost breakdown above, it is evident that building a new onshore test-site
would cost more per series 0 wind turbine than if the same series 0 wind turbine would be
installed offshore – if it would be part of an exis<ng or to-build development. Looking at the
total cost of a 1 GW commercial offshore wind farm with 100 x 10 MW turbines, the op<on
to install 99 wind turbines and replace one commercial wind turbine with a series 0 wind
turbine would cost 163.000,00 USD, or 2.25% of the cost of the same series 0 wind turbine
installed onshore. If the series 0 wind turbine would be installed in addi<on to 100 x 10 MW,
so the series 0 would be wind turbine number 101, it would cost 630.000,00 USD less than
building it onshore as part of a test-site.
For correct reasons, the general public and many poli<cians are informed by experts and
specialist advisory bureaus that an offshore wind farm development is more expensive than
an onshore windfarm. The la`er is true for commercial developments only.
However, one needs to compare apples with apples - a commercial wind farm development
is not the same as a wind turbine test-center, neither offshore nor onshore.
 KEF, Alm.del - 2023-24 - Bilag 27: Henvendelse af 22/10-2023 fra Hanne og Niels Refslund, En kreds af borgere på Ballum-egnen, Sønderjylland, om at beskytte vadehavsområdet mod gigant-vindmøller
It looks to be a misleading claim by experts and specialist advisory bureaus that that building
series 0 wind turbines offshore is the most expensive op<on - as per the cost data above,
this is not necessarily true.
The government (and Ørsted as being a majority government owned energy company) need
to take the opportunity to more efficiently u<lize the already established wind farms
offshore and those that are tendered for as new developments. Aeer all, the already
established offshore wind farms and those in development include the en<re package
needed, also for series 0 wind turbines to be build and tested for a rela<vely low cost.
Former and la`er development packages include but are not limited to; permit applica<ons,
engineering, fabrica<on of the substa<on(s) and turbines, installa<on, electricity grid
connec<on, opera<on, monitoring, maintenance and eventually decommissioning. All costs
associated with the en<re life cycle of a wind farm are es<mated prior to tendering for
permits at the government.
Regula<ons for installa<on of series 0 wind turbines should therefore be included by the
government in offshore tender processes. In other words; each new commercial offshore
windfarm development should include (a numer of) dedicated founda<ons on which series 0
wind turbines can be installed and be a part of the infrastructure of said commercial wind
farm. Flexibility could be included such that future series 0 wind turbines could be installed
on those same founda<ons.
The present calcula<on only looks at the cost comparison of test wind turbine installa<on
onshore and offshore. Any other costs that may be associated with installa<on,
compensa<on costs for instance, are not included.
Sources:
Rystad Energy: Less is More If Using 14 MW Turbines
Guidetoanoffshorewindfarm: h`ps://www.thecrownestate.co.uk/media/2860/guide-to-
offshore-wind-farm-2019.pdf
DTU: Østerild Test Center: Lessons Learned in Seing up a Wind Test Center for Offshore
Wind Energy
 KEF, Alm.del - 2023-24 - Bilag 27: Henvendelse af 22/10-2023 fra Hanne og Niels Refslund, En kreds af borgere på Ballum-egnen, Sønderjylland, om at beskytte vadehavsområdet mod gigant-vindmøller
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Sources: Rystad, Guidetoanoffshorewindfarm, Energistyrelsen
Turbines
MW
Turbine
Foundation
Installation foundation
million USD million USD
million USD
10
8
4
1,5
12
10,1
4
1,5
14
12,3
4
1,5
USD
Total cost % per
Installation
Total cost windfarm per Total cost windfarm per Turbine
Total cost 1 GW
Cost Offshore Windfarm windturbine on
Turbine
Total cost turbine Cost for Turbines in Billion USD # turbines turbine
billion USD
windfarm
per windturbine
total windfarm
million USD million USD
for 1 GW windfarm
needed
million USD
(at 2.7 million USD per MW)
billion USD
million USD
cost
1
14,5
1,45
100
27
2,7
2,7
27,000
1,00%
1
16,6
1,38
83
32,4
2,7
2,25
27,1
1,20%
1
18,8
1,34
71
37,8
2,7
1,93
27,163
1,41%
0,60%
higher cost for a 14 MW windturbine compared to a 10 MW windturbine
162,000 extra cost to install 1x 14 MW test windturbine in a windfarm with 100x 10 MW turbines
Windfarm costs excluding
windturbines
(infrastructure/substation
etc) billion USD
1,25
0,87
0,59
Test Site Østerild
Cost per test site 2010
million USD
27,79
Rent per test Tests by DTU
9 test sites site
6 per year
million USD million USD
million USD
3,5
31,5
1
Installation cost
Cost of 1
per windturbine
windturbine onshore
million USD million USD
0,85
18,8
3,64
Total cost for windturbine
testsite
onshore with 14 MW
windturbine installed
million USD
Conclusion
2,23%
million USD
Cost of installation of 1x 14 MW windturbine onshore
Cost of installation of 1x 14 MW windturbine offshore
27,8
27,2
NB: If a test windturbine of 14 MW is installed as part of a planned 1 GW development offshore with 10 MW windturbines, the cost of 1x 14 MW test windturbine would be USD 162.000 more than a 10 MW windturbine
This would mean the 14 MW test windturbine installed offshore would only cost 2.23% of the total cost of the test windturbine being installed onshore