Building wind farms out at sea creates a problem. How do you get the power generated into the land-based power grid?
The answer is to install the world's longest HVDC power cable.
A 200km-long connection between an offshore wind farm in the North Sea and the German power grid is the longest power connection of its type.
It uses 400megawatt high-voltage direct current (HVDC) transmission technology, developed and installed by ABB.
The wind farm, located 130km from the German coast in the North Sea, is expected to save carbon dioxide emissions of 1.5 million tons per year by avoiding the need for additional fossil-fuel generation.
Called the 'BorWin1' project, it is in its test phase.
The longest submarine power cable is the NorNed -
a +/- 450kV DC cable between Norway and the Netherlands.