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

of this electricity would be €421 bn. In this regard the
infrastructure costs only represent about a fifth of the
electricity value that is generated.
Please note that in the calculation of the net investment
for the overall grid design, only the additional
benefits of the OffshoreGrid overall design were taken
into account. As the ENTSO-E TYNDP interconnector
plans were included in the base cases (Radial reference
scenario and Hub Base Case scenario 2030),
their system benefits were not explicitly calculated.
4.5.6 Power system impact of the
offshore grid
The power market model provides a large number of
interesting results. In the following paragraphs, the impact
of the offshore grid and the chosen design on the
power system and the infrastructure is investigated, in
particular for the following issues:
• Utilisation of wind farm grid connection cables: The
offshore grid combines the transmission of wind
energy and the trade of electricity, and thus leads
to an increase in wind farm connection cable utilisation
(full load hours of the cable use).
• Influence on energy mix: As the offshore grid enables
more trade of electricity over large distances,
power can be generated where it is cheapest.
• Flexibility provision: The offshore grid leads to the
spatial smoothing of short term renewable energy
variations, as discussed in section 4.1. As such,
this reduces the balancing needs in the system.
The utilisation of wind farm grid connection cables and
the influence of the offshore grid on the energy mix
are explained below. A more detailed analysis on the
balancing of wind power can be found in Annex D.III.V.
Utilisation of cables for wind farm grid
connection
As discussed above, some wind farm hubs are nodes
within the offshore grid and thus not only transport
wind energy but are also used for trade. Accordingly,
41 For individual wind farm connections, the capacity of the wind farm connection cable is 90% of the wind farm capacity, as described
in Deliverable 5.1, available online [26].
OffshoreGrid – Final Report
the utilisation of the cables connecting these hubs
changes with the development of the offshore grid as
also the power flows change.
Table 4.7 illustrates the increase in utilisation of some
representative wind farm hub connection cables that
connect the hub to shore. Of course only those hubs
were selected that connect to more than one country
as otherwise the utilisation of the cables would be
independent of the offshore grid development and remain
constant. The analysis compares the utilisation
of the cables in the hub base case scenario with the
utilisation after step 2 and step 3 within the Direct
and Split Design (compare sections 4.5.2 and 4.5.3).
For the values marked in the table, the wind farm connection
is just an individual connection to one onshore
connection point within the associated design step 41 .
No electricity is traded via these lines and therefore
these do not exhibit changes in utilisation as long
as no wind power is curtailed due to onshore grid
constraints.
Typically the utilisation of the wind farm cables to
shore will increase when the hub is connected to an
offshore grid or to another shore. This is because the
connections are then also used for electricity trade.
On average, for the connections that are coupled to
another point in the Direct Design (before the mesh),
the utilisation rate is improved with 22%. For the Split
Design the increase is even larger (29.7%). Adding the
mesh in step 3 to the design improves the utilisation
rate with about 3-4% in both cases.
As can be seen from the table, there are some exceptions
which see rather a decrease of the utilisation
rate when adding the mesh (e.g. the connection of
Norfolk B to Great Britain, or the connection of Aegir
to Norway). There are always two possible reasons for
these:
• The mesh connection is mostly used to send the
wind energy to a higher priced area so that the original
individual cable connection is used less,
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