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existing HVDC converters at each hub. Thus, the hub-tohub
investment costs are relatively low.
Along with these infrastructure investments the electricity
generation costs (in Figure 4.24, red curve) in
the European power system decrease. The annual
generation cost curve shows - similar to the cumulative
investment curve - linear reductions for the direct
interconnections, a flattening of the curve for the hub
to hub cases and a further sharp reduction when the
mesh is introduced. The entire Direct Design reduces
the system costs by €1.3 bn per annum (=€20.5 bn
over 25 years) for a total investment cost of €7.4 bn.
How large the benefit per investment is, is best shown
in Figure 4.25. Here the net benefits (red bar) and the
benefit-to-CAPEX ratio (blue marker) of each project are
given for a life time of 25 years. In particular the meshed
network exhibits a large benefit-to-CAPEX ratio. As all investments
are beneficial and produce net benefits, the
benefit-to-CAPEX ratio is always bigger than 100%. Some
investments produce benefits of up to 7 times the initial
investment (benefit-to-CAPEX ratio of 700%).
The final step of the meshed grid design creating a
meshed network between Norway and Great Britain,
Germany, the Netherlands and Belgium generates
significant net benefits over 25 years (€2.3 bn) for a
FIGURE 4.25: GRId dESIGN: NET bENEFIT (REd, lEFT) ANd bENEFIT-TO-cAPEX RATIO (blUE, RIGhT)
[€bN]. (PlEASE NOTE ThE dIFFERENcE bETWEEN NET bENEFIT ANd bENEFIT.)
Net bene�t
(red) (€bn)
25
20
15
10
5
0
Base case
SE-DE
FI-EE
SE-PL
SE-DK
SE-LV
Direct interconnections
GB-FR
SE-DE
Net bene�ts (across lifetime)
GB-BE
GB-FR
SE-PL
relatively modest investment cost (€670 m) reaching
a benefit-to-CAPEX ratio of almost 400%. Again, this
is because the additional investment is only in extra
cabling, as the existing hub converters are utilised.
4.5.3 The split design methodology
The case independent model (section 4.4) clearly
identified that splitting the connection of wind farms
(or hubs) to two separate shores can be a very cost
effective and beneficial solution: the wind farm is connected
to shore and at the same time a relatively cheap
interconnector can be built. It was further identified that
the splitting solution is most beneficial for large wind
farms or hubs which are far from the onshore connection
point but are relatively close to another country,
and when the price difference (see Annex D.III. for price
level differences) between the two countries is high
enough to make up for the additional infrastructure
costs. As these findings presented a very promising
grid design solution, the split wind farm concept was
taken into account for the second methodology. Similar
to the Direct Design methodology, the starting point is
the Hub Base Case scenario 2030 with hub-connected
wind farms and again the three-step methodology
was applied. However, this time also split wind farm
connections were considered in the first step. Even
though the second and third steps for the Split Design
Bene�t-to-CAPEX
ratio (blue) %
64 OffshoreGrid – Final Report
SE-DK
IE-FR
Hub-to-hub Mesh
Omitted as not bene�cial. Shown to compare with direct design
IE-GB
GB-BE
NO-NL
SE-DK
Bene�t CAPEX ratio (across lifetime)
NL-GB
GB-DE
Mesh
800
700
600
500
400
300
200
100
0