Offshore Electricity Infrastructure in Europe - European Wind Energy ...

FIGURE 4.33: cOMPARISON OF NET bENEFIT ANd bENEFIT-TO-cAPEX RATIO PER INTERcONNEcTOR cAblE FOR ThE dIREcT ANd SPlIT
OFFShORE GRId dESIGN METhOdOlOGIES (€ bN)
Net bene�t
(€bn)
2,5
2,0
1,5
1,0
0,5
0,0
Base case
Direct Design
Split Design
The increase of the interconnector capacity with
each step and for each methodology is shown in
Figure 4.30. In step 1 and step 2 the additional capacity
is larger for the Direct Design compared to the Split
Design. This is because split wind farm connections
were dimensioned with slightly lower capacity to be
most beneficial. Furthermore only one beneficial hubto-hub
connection was identified in the Split Design
in step 2. In step 3 the optimal mesh is dimensioned
slightly larger for the Split Design and therefore the
interconnector capacity increase is larger as well.
The additional grid interconnector capacity that is added
to the existing European interconnector capacity
to develop the OffshoreGrid overall designs is 27 GW
(20 GW excluding the TYNDP interconnectors) for
the Direct Design Scenario and 24 GW (16 GW when
excluding the TYNDP interconnectors) for the Split
Design Scenario.
37 For the infrastructure costs in Figure 4.30, the Split Design is more expensive for three cases. This is either because the distances
are too short to cover for the additional equipment (GB-FR), or because a higher capacity is used (second SE-DK, Mesh).
38 For the reduction in yearly system costs in Figure 4.31, the Split Design reduces the system cost more than the Direct Design in
four cases. This is either because no wind farm connection is split and the direct interconnector is still used with higher price differences
because of the constraints in the previous cases (FI-EE, SE-LV), or because the capacity is higher ánd the price differences
are higher (second SE-DK, Mesh).
Note that this is a result of the chosen method to replace the direct interconnectors from the Direct Design. If an offshore grid
would be independently built on split wind connections, the number of possibilities would be higher.
OffshoreGrid – Final Report
SE-DE
FI-EE
SE-PL
SE-DK
SE-LV
GB-FR
SE-DE
GB-BE
GB-FR
Split Design Direct Design
SE-PL
SE-DK
IE-FR
IE-GB
GB-BE
NO-NL
SE-DK
Bene�t-to-CAPEX
ratio
Direct interconnections Split interconnections Hub-to-hub and Tee-in Mesh
Omitted as not bene�cial
Case-by-case: relative comparison
Figure 4.31 and Figure 4.32 show a case-by-case
comparison between the Direct and Split offshore grid
design methodologies, for the reduction in total yearly
system costs respectively for the CAPEX spend. They
clearly show that the infrastructure costs are generally
lower for the Split methodology. Accordingly, the
reduction in system costs is also lower in the Split
Design as lower additional interconnections capacity
is installed (also compare Figure 4.30) 37 .
It is obvious from Figure 4.31 that splitting wind
farm connections (marked with red boxes) is indeed
cheaper than building direct interconnectors. In the
Split Design, 6 direct interconnectors are replaced
compared to the Direct Design 38 . The average reduction
of the CAPEX by choosing a split connection over
a direct interconnector is more than 65% (ranging
from 40%-84%). At the same time for these split wind
NL-GB
GB-DE
Mesh
Direct Design Bene�t CAPEX ratio
Split Design Bene�t CAPEX Ratio
1,600%
1,400%
1,200%
1,000%
800%
600%
400%
200%
0%
71