The start-up of the turbines is some six months later than originally planned, largely as a result of weather conditions. The turbine park will produce 1,000 gigawatt hours of electricity a year, enough to provide for 600,000 people, C-Power said. Because wind is a clean and renewable energy source, the turbines will represent a savings in CO2 emissions of 450,000 tonnes a year, or the carbon equivalent of a strip of forest 15 kilometres wide running the full length of the coastline.

The turbines themselves, considered an eyesore in other locations, will barely be visible on the horizon. This is despite their being 198 metres tall at the highest point - as high as a 45-storey building and nearly double the height of the Atomium.

The construction was a challenge: first, a four-metre layer had to be scraped from the sandbank 27 metres below the surface. Then, a metre-layer of small stones had to be laid down, followed by a 3,000-tonne hollow concrete construction shaped like a champagne bottle, filled with another 3,000 tonnes of sand. The windmills were built on top of this - in the neck of the bottle, as it were.

The windmills are connected to Ostend by a cable 38 kilometres long and 22 centimetres thick, weighing a total of 3,000 tonnes and buried two metres in the sea floor. Laying the cable was the hardest part, project leader Luc Ponnet said. "We really underestimated what a rubbish-tip the bottom of the sea is off our coast. It's unbelievable what's dumped out there - from concrete blocks to steel constructions."