By Ulrike Dauer

Canadian energy firm Northland Power Inc. (NPI.T) will buy an 85% stake in three offshore wind farms in the North Sea from utility RWE AG (RWE.XE)'s renewables energy arm RWE Innogy, the two companies said.

The acquisition consists of the 332-megawatt offshore wind farm Nordsee One, which is expected to start operation in 2017, and two other wind farms --Nordsee Two and Nordsee Three--that are in the early stages of development. Financial details of the transaction weren't disclosed. Project costs for Nordsee One alone are estimated around 1.2 billion euros ($1.6 billion).

The three wind farms are located 40 kilometers north of Germany's Juist island, in a 100-square-kilometer area with shallow water and high wind speeds.

The cooperation between Northland, an independent power producer, and RWE, a large diversified utility, is a new approach to ensuring the effective completion of the Nordsee One project, both companies said.

Financing for the Nordsee One project is expected to be finalized in the first half of 2015, with in-water construction scheduled to begin the following year. Once operational, Nordsee One is expected to generate more than 1,300 gigawatt hours of electricity a year from 54 wind turbines, and will meet the needs of 400,000 German households.

Nordsee Two and Nordsee Three will be developed over the next decade as market conditions evolve and the grid infrastructure becomes available. The two farms combined will provide 670 megawatts of renewable energy.

Offshore wind energy is an important part of Germany's move to renewable power generation following its decision in 2011 to exit nuclear energy by 2022, which it took after the Fukushima nuclear accident in Japan.

Write to Ulrike Dauer at Ulrike.Dauer@wsj.com

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