Offshore Wind Power

Offshore Wind is currently the most developed marine alternative energy technology available. A number of commercially viable projects have been established along the Northeast with tentative completion dates as soon as 2016. Offshore wind facilities are operable in select countries, but have been slower to be introduced to the U.S.

Offshore Wind is defined as wind turbines that are attached to the seabed or float in coastal waters (including the Great Lakes), and generate power from over-water winds. This resource is currently the most developed marine renewable energy technology.

Offshore wind facilities are operable in select European countries, with 8 gigawatts of energy installed globally at the end of 2014, but they have been slower to be introduced to the U.S. (IRENA 2014). However, more companies are beginning to bid for offshore wind energy lease areas to develop commercially viable offshore wind farm projects—specifically in the Northeast (BOEM). A 2015 report from Oceana boasts “a modest and gradual development of offshore wind on the East coast could generate up to 143 gigawatts of power over the next 20 years, which is enough to power over 115 million households” (Menaquale 2015).

Offshore Wind Cumulative Installed Capacity Worldwide


The wind farms Cape Wind, Block Island, Bovoni 1 and 2, and Phase 1 of Atlantic City all share the same ambitious completion date of 2016 for their projects. Block Island wind farm, off the shores of Rhode Island, are on track to be the first offshore wind generating energy facility in the U.S. with 30 MW of power generation (The Boston Globe, 3/02/2015).

Offshore wind turbines are similar in design to onshore turbines, but are larger in size and have a significantly higher capital cost because they need to endure harsh sea conditions and establish grid connections from out at sea. Offshore’s levelized cost of energy ranges between 12 and 20 cents per kwh of power, compared to onshore wind’s six to nine cent range (IRENA 2014).

However, offshore wind turbines are more efficient and have a higher capacity factor as wind is stronger and more consistent on the ocean surface. With no impediments such as buildings and trees to divert wind flow, average capacity factor ranges from 18% to 54% onshore versus around 36% to 54% offshore (IRENA 2014).

updated 20-May-2015