Riffgat grid-link's €100m bomb bill

Transmission operator TenneT has released pictures of the explosive obstacles it faced in linking Germany’s Riffgat offshore wind farm to the grid – ahead of finally connecting the project tomorrow.

Riffgat was completed on time last July for utility EWE – but will only get its grid connection this week.

TenneT has faced criticism in Germany over delays to the connection of the 108MW Riffgat and other offshore wind farms, but said the scale of the challenge to remove World War 2 munitions was far greater than it had been led to believe, as a total of 30 tonnes of debris had to be cleared.

Clearing hazards such as bombs and  boxes of ammunition from the route to the wind farm 15km northwest of the island of Borkum added months to the project and a total of €100m ($136.6m) to the costs – a higher figure than TenneT previously estimated.

Of that, €57m was for the actual bomb clearing, while another €43m are other costs caused by the delay, such as compensation payments to the operator.

World War 2 explosives have become a familiar problem to the fledgling German offshore wind sector.

Some 1.6 million tonnes of weapons from both world wars are still lying on the bottom of the North and Baltic Seas, estimates Heinrich Hirdes, a company specialising in explosive ordnance disposal services.

Allied bombers often dropped unused bombs on the island of Helgoland or the open water when returning to UK bases, while some additional ammunition ended up in the sea for training purposes after the war.

Below: The TenneT operation to make the Riffgat route safe. Pics: TenneT