First wind farm on the Gulf of Finland
by S Griinari, Kotka Energy Ltd, Finland

Wind power capacity in Finland has, so far, been situated in the coastal areas of Western Finland and on the fells in Lapland. Now, the first wind farm with commercial-sized wind turbines has been constructed beside the Gulf of Finland. The wind farm is situated close to Kotka city centre, enabling citizens to visit the site.

Construction work at the wind farm


Around Kotka, the best locations for wind turbines are in the open sea and the Kotka archipelago. However, construction costs in these regions are considerably higher than on the mainland and so a wind resource study was undertaken on an area adjacent to an industrial site close to Mussalo deep-water harbour. This area, situated only 5 km from the centre of the city of Kotka, was of interest because construction and maintenance costs for a wind farm sited there would be relatively low, and there is a good electricity network in the area. Based on this analysis, Kotka Energy Ltd, the local energy company, decided to build two wind turbines.

The project

The Kotka Mussalo wind farm comprises two Bonus Energy A/S 1 MW turbines, each with a 60 m tower and a rotor diameter of 54.2 m. Construction work on the site started in February 1999 and the turbines were erected at the end of August - they were connected to the grid within a week. Landscaping of the area started immediately after construction.

Each turbine has: a three-bladed up-wind rotor with stall regulation and constant rotor speed; an asynchronous generator which is coupled directly to the grid; and failsafe safety systems with automatic air brakes and hydraulic disc brakes. The turbines start generating when the wind speed is 3 m/s and reach maximum output at wind speeds of 14–15 m/s, after which the power is limited by stalling the rotor.

The harsh northern conditions in winter were taken into account when designing the project. Wind turbines specifically designed for Arctic conditions have been developed in Finland (see the article in CADDET Renewable Energy Newsletter Issue 3/98, September 1998). In these turbines, special heating elements prevent the blades and mill equipment from freezing.

"Wind's nest". Harmony of wind power and modern art by Annika Tavasti

Energy and environment


Annual energy production is around 2 GWh/turbine, which is about 3% of the total electricity delivered by Kotka Energy Ltd. The wind farm will save about 3,500 tonnes/year of CO2 emissions compared with electricity production by conventional means. The wind farm also provides the Mussalo site itself with environmental benefits. The site already has a harbour, which will be extended, and the Mussalo Power Plant, fuelled by coal and natural gas, is nearby. For these reasons, the wind farm softens the image of the area for visitors, providing Kotka with a more environmentally-friendly appearance. In addition, wind power will contribute to the programme for sustainable development that Kotka is following.


The annual average wind speed in Kotka is about 6.5 m/s, which made the project feasible. The wind farm has a life expectancy of 20–25 years. In total, the project cost about e2.2 million (where e is the euro). Using an electricity price of e43/MWh and an annual maintenance charge estimated at about 2% of the total investment, the payback will be 15–16 years. If interest in wind power among the company’s clients increases and the first phase of the wind farm operates according to expectations, it may be possible to extend it by several turbines using units of the same size, or larger.

For more information contact Kotka Energy Ltd, PO Box 232, FIN-48101, Kotka, Finland. Tel: +358 5 2277 111; Fax: +358 5 2277 250.

The CADDET Renewable Energy Newsletter is a quarterly magazine published by the CADDET Centre for Renewable Energy at ETSU, UK.

The articles published in the Newsletter reflect the opinions of the authors. They do not necessarily reflect the official view of CADDET.

Enquiries concerning the Newsletter should be addressed to Pauline Toole , Editor, CADDET Centre for Renewable Energy, ETSU, Harwell, Oxfordshire OX11 0RA, United Kingdom. Tel: +44 1235 432968, Fax: +44 1235 433595.