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Offshore wind power and solar power plants gain momentum

Enormous wind power projects are being set up in the sea, while industrial-scale solar parks are being built on land. What makes them so compelling now, and how will these projects affect the power system of Finland?

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.”

Still little offshore wind power

Wind power is divided into onshore and offshore according to where the power plants are located and where the electricity cables run.

Although the amount of offshore wind power worldwide is soaring, only about five per cent of all wind power plants are offshore. Europe has long pioneered offshore wind power, but China has caught up in recent years.

The only offshore power in Finland so far is the Tahkoluoto wind farm in Pori, where turbine foundations have now been laid on the seabed. Wind turbines have been built on artificial islands in Ajos, off the coast of the Port of Kemi.

From wind to sun

Ilmatar Energy, which focuses on renewable energy, has also invested in industrial-scale solar power plants. The newest solar power plant just came online in Joroinen.

A diverse energy production mix requires the use of renewable energy sources based on different weather phenomena with production profiles that complement each other.

Ilmatar Energy Oy began working on wind power more than a decade ago. The company now also aims to produce solar energy on an industrial scale.
A solar park with a rated output of five megawatts recently began operating in Joroinen. In the future, Ilmatar will be interested in solar power projects
several times larger, and projects have already been announced in Pöytyä and Ähtäri.

“Different forms of energy production and the decentralisation of production will increase the security of the national energy supply and strengthen local economies in the places where power plants are built. Moreover, as a renewable energy superpower, Finland could also attract international industrial
investments,” says Erkka Saario, VP Projects.

Production maxed, costs controlled

Ilmatar follows a coherent strategy in wind and solar power production. The company is responsible for developing its projects from start to finish.
When an investment gets the green light, Ilmatar builds and owns the plant throughout its life cycle.

According to Saario, solar power plants need to be built in places where production can reach the maximum amount and good connectivity to the network keeps costs under control.

“Energy consumption is concentrated in southern Finland, so establishing solar power production there will reduce the strain on the rest of the main grid.”

Saario notes that ensuring the stability of the grid may become a larger technical challenge for wind and solar power production.

“As energy producers, we would like more flexibility in network connections without compromising the stability of the grid and viability of investments.”


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