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

esults
• There are other connections that already take up
the price difference and provide the arbitrage needed
so that no trade is necessary any more.
Where such impacts can be expected, a detailed assessment
should be done to optimise the rating of
the different lines. For example, in the exceptions described
above, a lower cable capacity from the wind
farm to shore can be a better option.
Offshore grid influence on energy mix
Improved grid infrastructure enables more power flow,
and therefore more flexibility in the power production.
This in turn gives reduced system costs, since it allows
a better use of the generation units with lower
marginal costs. Figure 4.39 shows how large the
change in production is for each technology in the energy
mix.
As expected, it is clear that the offshore grid facilitates
a shift from more expensive gas and hard coal to
cheaper generation, in particular “Other RE”. The category
“Other renewables” stands in this case for all
renewable technologies that are neither wind energy
nor hydro, such as bio energy, solar, tidal and wave.
This shift in generation mix can be best understood
when considering the marginal costs for the generation
technologies, which are:
• Other renewables ~ €50.6/MWh
• Lignite coal ~ €58.3/MWh
• Hard coal ~ €62.0/MWh
• Gas ~ €70/MWh
The small increase in wind power is due to reduced
grid constraints because of the offshore grid 42 . The
increase is indeed small compared to the total annual
production of 530 TWh. The change in hydro power
output is due to pumping facilities.
The change of the energy mix is bigger for the Direct
Design since it involves a higher interconnection capacity,
as described above.
4.5.7 Conclusion and discussion
Summary of the techno-economic
conclusions
Two methodologies have been assessed for the development
of an offshore grid in northern Europe. The
first approach, the Direct Design, was based on the
consideration that currently various direct countryto-country
interconnections are being developed. In
order to develop a most realistic approach the most
beneficial direct interconnectors were identified in a
first step. After that, hub-to-hub and tee-in solutions
as well as a mesh were assessed. The second approach,
the Split Design, is based on results of the
case-independent model (see section 4.4). The caseindependent
model showed that it is promising to
create interconnections by splitting the connection of
large wind farms far from shore to two countries. This
way, the wind farm is connected to shore and at the
same time an interconnector is established at relatively
low costs.
A high number of interconnection cases and design
variations have been assessed with the model. They
have been narrowed down from the vast number of
possible designs by considering the results of the
case-independent model. Furthermore the electricity
price levels within the different countries were analysed
to identify the most promising trading corridors.
The results confirmed that it can indeed be beneficial
from a European welfare point of view to tee-in wind
farms, to interconnect countries via wind farm hubs,
and to split the connection of large wind farms in order
to connect it to two shores.
As shown in section 4.5.4, the conclusion of the caseindependent
model on the split wind farm connections
is confirmed, by the relative comparison of the six split
wind farm connections in the Split Design versus the
corresponding direct interconnectors in the Direct
Design. The average reduction in CAPEX from choosing
a split connection over a direct interconnector is
more than 65%, while the reduction in system cost
42 There are fewer constraints so that more wind power can be transmitted. Due to the interconnections, some of the wind generation
that would otherwise be curtailed because of the 90% assumption can now also be transported.
78 OffshoreGrid – Final Report