Why offshore wind energy?

At the beginning of 2010, only 2000 wind megawatts had been installed offshore. Although the first offshore wind farm experiment took place in 1990, most of the facilities built up to now have been pilot projects. Then, offshore wind power can be considered as an incipient market. However, just at this moment, the growth of this technology finally seems to be happening, being several countries at the top of its development (the United Kingdom, Denmark, Holland, Sweden and Germany). This current situation, the raw materials problems and the general commitments to reduce the emissions of greenhouse gases are leading to predict a promising future for this technology. This paper deals with a brief revision of the state of the art of offshore wind power, followed by a critical discussion about the causes of the recently growth that is currently happening. The discussion is based on the comparison of offshore wind energy with other renewable energies (like onshore wind, marine hydrodynamics, hydraulic, solar, etc.) and even with conventional power.