This paper gives an overview of the many developments in offshore wind energy in the last two years, since the 12th ISOPE conference in Kitakyushu, Japan in 2002, in terms of the technology of the support structure and wind turbine, the construction of new projects and the development of the legal framework. Notwithstanding some delays and difficulties experienced in construction and operation of wind farms, overall progress has been remarkably rapid and successful, due to positive collaboration between government and industry. All in all, offshore wind energy is bound to fulfill its potential for success.
At the end of 2001 offshore wind energy was just emerging from a pioneering phase, with six pilot projects and three multi-megawatt projects in place. Experience with the first wind farms, and the projected market potential of offshore wind energy, appeared so positive that a special topic conference on offshore wind energy, organized by EWEA in December 2001, attracted over 500 participants, most of whom were new to the field and eager to participate in the expected rapid growth. At that time, plans were presented for the construction of over 800 MW of wind farms by the end of 2003. That only half of this has been realized on time is nonetheless an impressive achievement, increasing the capacity of offshore wind energy by a factor of four in two years (See Fig. 1 and Table 1). By far the largest impact, both in terms of numbers and as a representation of the new era, has been made by the Horns Rev wind farm off the west coast of Denmark, which came into operation at the end of 2002. With 80 Vestas 2 MW turbines at an exposed offshore site, the project has focused the attention of the industry.