Scotland is about to get the world’s largest floating wind farm, with five 6-megawatt turbines bobbing 15 miles offshore in the North Sea.The project—which is being developed by Statoil, a Norwegian energy company—marks a shift in offshore wind technology. Most ocean-based turbines to date have been rooted to the sea floor by concrete and steel foundations, similar to oil and gas rigs. But this design limits the projects to shallower waters. Statoil’s floating turbines, known at Hywind, consist of a steel cylinder filled with ballast water and stones, and are tethered to the sea floor by a series of cables. The company, which was granted a lease to build the wind farm this week , will install the Scotland project in water more than 300 feet deep. The plan is for the wind farm to start generating electricity by the end of 2017.