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

The overall Split Design reduces the system costs by
€15.8 bn across 25 years for a total investment cost
of €5.4 bn.
4.5.4 Comparison of methodologies
It should be highlighted that both the Direct Design
and the Split Design methodology lead to significant
net benefits. Immediately the question raises which
of the two leads to the most cost-efficient offshore
grid design. Such a comparison would be most sound
on an equal basis: either with equal total cumulative
costs in order to see which design brings the most
reduction in system cost, or with equal total system
cost reduction in order to identify which design has the
lowest CAPEX. In our case where neither equal system
reduction costs nor equal CAPEX are given, comparison
of relative benefits by evaluating the reduction in
system cost per invested euro is most useful.
In the following paragraphs, a comparison is made
based both on relative and absolute terms 36 . However,
first of all it is instructive to shortly analyse the in-
36 Please note that the overall cumulative investment costs and the reduction in system generation costs shown in Figure 4.30 to
Figure 4.34 only consider the investments made for the steps described in paragraphs 4.5.2 and 4.5.3. The total costs of the
overall grid design are further detailed in section 4.5.5.
A number of cases does not follow this general rule.
OffshoreGrid – Final Report
Split Design Methodology -
newly installed in each step
Direct design -
newly installed in each step
terconnector capacities that come along with the two
design approaches.
Interconnection capacity – comparison for
the direct and split design approach
OffshoreGrid starts to develop an overall grid design
based on the Hub Base Case scenario 2030. This
scenario includes all existing grid infrastructure and
adds the connection of all 2030 offshore wind farms
with individual connections and hub connections
where beneficial. The existing infrastructure exhibits
an offshore interconnection transmission capacity
in Northern Europe of about 8 GW. Furthermore the
planned interconnectors of the ENTSO-E TYNDP were
added, which represent further offshore interconnection
capacity of 8 GW.
Thus, the overall grid design development within
OffshoreGrid starts with an offshore interconnection
capacity of 16 GW. Based on this the overall grid design
is developed with the Direct and Split Design
methodologies in three steps as aforementioned.
FIGURE 4.30: cOMPARISON ThE cAPAcITY OF All EUROPEAN INTERcONNEcTORS TOdAY, WITh ThE ENTSO-E TYNdP
INTERcONNEcTORS, WITh ThE ThREE STEPS OF ThE dIREcT ANd SPlIT dESING METhOdOlOGY
Offshore interconnection
capacity (GW)
40,000
35,000
30,000
25,000
20,000
15,000
10,000
5,000
0
Existing
Offshore
Interconnector
Capacity
ENTSO-E
TYNDP
Step 1
Direct or
Split design
Step 2
Hub-to-hub
and Tee-in
Step 3
Mesh
Split Design - cumulative
Direct Design - cumulative
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