Europe pioneered the installation of offshore wind projects and now has almost 1,500 MW operational. At present, these are the only offshore wind projects in the world. However, several projects have been proposed in the United States and other nations. The United States has over 900,000 MW of potential offshore wind energy, which is almost equivalent to the country's total demand for electricity. 
This information is provided by the Department of Energy Resources.
Massachusetts has an abundant source of offshore wind; state and federal waters offer a renewable resource of over 6,000 MW of technical potential. The advantage of offshore wind is that winds blow stronger and steadier than onshore wind; there are also less space limitations in Massachusetts' coastal waters than on land.
In 2010, the Massachusetts Executive Office of Energy & Environmental Affairs will release the Massachusetts Ocean Plan. This plan will include rules and regulations for offshore wind project development to capitalize on Massachusetts' abundant offshore wind resources.
Learn more about offshore wind:
Massachusetts Supplement to Federal Offshore Wind Development RFI
Offshore Renewable Energy Programs: U.S. Mineral Management Services
Offshore Wind Questions and Resources (AWEA)
U.S. Offshore Wind Collaborative (USOWC)
This information is provided by the Department of Energy Resources.