Vindeby Offshore Wind Farm was the first offshore wind farm in the world, erected in 1991 off the coast of the town of Vindeby on the Danish island of Lolland. It was decommissioned for cost reasons in 2017 after 25 years of useful life.
The wind farm started operation in 1991 and cost an estimated €10 million, built by SEAS and Elkraft. The 11 turbines were erected in 11 days.
In 25 years, Vindeby had produced a total of 243 GWh.
The annual power is equivalent to 2-3,000 Danish households. The turbines were modified for offshore use by sealing the towers and controlling the humidity inside with air conditioning, extending the life of the machinery.
According to en.wikipedia