With the term off-shore it is intended all the wind mill plants installed few miles form the coast of the sea or lakes. These areas are subject to continuous and vigorous ventilations that allow to optimize the performances of mid to high size wind mills.
The optimal location for them is in the open sea where there is a shallow sea bottom. The environmental and landscape impact is highly reduced and to better the performance and take advantage of the continuous and vigorous ventilation, high horizontal axis towers are generally opted.
In the next few years, based on some estimates, off-shore plants in European seas could satisfy more than 20% of the energy needs of the coastal countries.