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

consortium that they will be bringing such components
on the market within the next few years 19 .
Manufacturers have already offered these assets
to commercial projects but no contracts have been
awarded yet. The integrated solutions proposed here
do not rely on the use of fast HVDC breakers, although
these can be added to increase security of supply.
Investigated cases
The cost-benefit analysis of hub-to-hub connections
has been done with reference to the Hub Base Case
2030, in which wind farms are connected to hubs
where beneficial (compare Section 4.2). Infrastructure
costs and system benefits have been calculated in
three case studies for a situation with interconnectors
between offshore hubs (thus becoming integrated
offshore grid nodes). The results were then compared
to a situation where the onshore connection points
of the respective offshore hubs are connected by an
interconnector of the same capacity. The principle is
illustrated in Figure 4.12.
Integrated hubs have been compared to point-to-point
connections for the following cases:
• Great Britain to Continental Europe (Germany) by
interconnecting the Dogger Bank E hub with the
Gaia hub,
• Great Britain to Norway by interconnecting the
Dogger Bank A hub with Idunn,
• Triangular interconnection: Norway – Great Britain
– Germany between the hubs Idunn (NO) -- Dogger
Bank A (UK), Dogger Bank E (UK) -- Gaia Group (DE)
and Horizont Group (DE) – Aegir (NO).
19 OffshoreGrid – 1st Northern European Stakeholder Workshop, 14/09/2009, Stockholm.
OffshoreGrid -- Stakeholder Advisory Board meeting, 21/01/2010, Brussels.
OffshoreGrid -- 2nd Northern European Stakeholder Workshop, 10/06/2010, Brussels.
OffshoreGrid – Final Report
Reduction in infrastructure costs
In all three cases interconnecting countries via the
wind farm hubs leads to a reduction in infrastructure
cost compared to individual connections and a direct
interconnector.
Infrastructure costs for the integrated solution are in all
cases 70 to 80% lower than for the respective solution
with direct lines. The ratio reflects mainly the savings
in numbers of converters and cable costs, due to the
use of the wind farm hubs and the shorter distances
to cover with the integrated solution, respectively. For
the UK-Germany interconnection, the cost reduction is
about €693 m. For the UK-Norway interconnection it
is €600 m, while for the triangular interconnection the
total infrastructure cost reduction compared to direct
interconnections amounts to €1.9 bn.
Reduction in system benefits
The system benefit for the integrated solution is always
lower than for the direct line solution, due to
the constraint on international power exchange. As
can be seen from Figure 4.13, the interconnector
between the hubs can be regarded as equally constrained
as a direct interconnector would be. The
trade is only constrained more than in the BAU case
because of the wind farm connection in the country
with the highest prices (red line in Figure 4.13). If the
cable capacities are the same for both countries, this
is of course identical when the price in Country A is
higher than in Country B.
In relative values comparing to the system benefits
in the direct line solution, the system benefits of a
FIGURE 4.13: SchEMATIc EXPlANATION OF ThE REdUcTION OF SYSTEM bENEFITS WITh hUb-TO-hUb INTERcONNEcTORS, FOR TRAdE
FROM cOUNTRY A TO b. ThE REd lINE ShOWS WhERE ThE SYSTEM cONSTRAINTS ARE INcREASEd
Prices Country A < Country B Prices Country A < Country B
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