Numerous investors are planning new offshore wind power and solar power plants in Finland. This is reflected in a barrage of connection enquiries sent to Fingrid.
“So far, we have received more than 100 gigawatts of connection enquiries for offshore wind power and solar power,” says Laura Ihamäki, Offshore Wind Power Expert at Fingrid.
Fingrid estimates that 7 GW of solar power production could operate in Finland by 2030. The first offshore wind power plants will come online at the turn of the 2030s, with the biggest growth in offshore wind power occurring in the 2030s and 2040s.
Catering for the green transition and higher electricity consumption
In addition to onshore wind power, offshore wind power and industrial-scale solar power are accelerating the green transition by responding to the increased electricity consumption due to new consumption investments.
Another advantage is that offshore wind and solar power have different production profiles from onshore wind power. In the best cases, large solar parks are relatively straightforward to build once a suitable area has been identified.
However, building wind turbines in the sea is a different proposition entirely. Nevertheless, the location is attractive because it is possible to build much larger wind turbines at sea than on land. This compensates for the large upfront investment.
“The largest offshore wind turbines in the world today are in the 15-megawatt category, while on land, they can reach about 10 megawatts. Designs for 25-megawatt offshore wind turbines are already on the drawing board,” Ihamäki says.
The annual output of a 20-megawatt offshore wind turbine is 2.5 times as much as a 10-megawatt onshore wind turbine.
The wind is also stronger at sea than on land, and offshore wind power can reach a capacity factor of more than 50 per cent, meaning that they operate at peak output for more than 50 per cent of the time. Consequently, the annual output of a 20-megawatt offshore wind turbine is 2.5 times as much as a 10-megawatt onshore wind turbine.
Main grid, connections and faults to be examined
There are still many uncertainties and matters for Fingrid to resolve related to the construction of offshore wind power.
Most offshore wind power projects are in the Gulf of Bothnia. When they are built, they will add to the already considerable pressure on the main grid on Finland’s west coast.
According to the Windy Seas scenario in Fingrid’s electricity system vision published in spring 2023, Fingrid would need to add up to 1,500 kilometres of new 400-kilovolt transmission lines to the main grid – in addition to the investments already included in the investment plan – to cater for 15 gigawatts of offshore wind power.
“If we can tempt new consumption facilities to connect to the same connection points as off-shore wind power plants, there will be less need to strengthen the grid,” says Ihamäki.
“We also need to start thinking about how to connect customers’s high-voltage direct current transmission links to our power system.”
The enormous size of individual offshore wind power projects – some of which have a production capacity two or three times that of Olkiluoto 3 – is also food for thought.
The dimensioning fault is the largest possible individual fault or disturbance that Fingrid prepares for. No individual fault should affect the operation of the main grid or bring it down.
“Because we do not intend to increase the dimensioning fault of the power system, the largest projects need to be divided into several parts. They would then connect to the national grid via separate connection lines to ensure that no individual fault could lead to the loss of more than 1.3 gigawatts of production.”
Practices at sea taking shape
Finland’s sea areas are divided into regional and economic zones, as well as the territorial waters of Åland.
The territorial water zone is closer to the coast, while the economic zone stretches into the waters of Finland’s neighbouring countries, subject to international treaties.
Finland’s territorial waters are administered by Metsähallitus, which leases sea areas to wind power operators using an auction model.
Finland’s territorial waters are administered by Metsähallitus, which leases sea areas to wind power operators using an auction model. The first project based on this approach is Vattenfall’s offshore wind farm, which will be completed in the 2030s off the coast of Korsnäs.
The practices in other sea areas and the procedure for granting exclusive rights to construction projects are still subject to speculation.
Ihamäki points out that Fingrid’s responsibility for all solar and wind farms is clearly delimited. Customers implement the plants and connection lines as far as Fingrid’s designated connection points. The transmission system operator builds connections from there.
However, some countries are drawing up or experimenting with approaches based on political decisions where the transmission system operator assumes more responsibility for the connection lines to offshore wind power plants. Consolidating connection points have been planned in the sea with radial or looped connection lines.
Operating methods and communications will be developed
As the amount of electricity generated by distributed wind and solar power plants with varying levels of output accounts for a larger share of production in Finland’s grid, cooperation between Fingrid, control centre operators, and an increasing number of energy producers will become more important.
“Electricity production and consumption need to be more closely aligned, requiring an effectively managed flow of information in both directions,” summarises Kimmo Kaappola, Business Development Manager of Caverion Industria Oy’s wind power unit, which operates renewable assets from its 24/7 control centre.
He lists the following questions:
“How can we reconcile the technical and commercial aspects of running an electricity grid? How can we communicate situations such as network outages or the need to limit the output of solar and wind power plants in the event of an overload? How can solar and wind power producers contribute to the balancing power and reserve markets?”
Antti-Juhani Nikkilä, Senior Advisor at Fingrid, says that Fingrid is working with operators in the sector to seek new approaches. One example is exchanging information between ICT systems instead of making phone calls.
“The issue is fundamentally one of maintaining the system security of Finland’s grid. Clear ground rules for compliance with the technical requirements, real-time situational awareness, up-to-date contact details, and contribution to the balancing energy market already facilitate large production hubs.”
