Offshore wind turbines are becoming common, but fixed-bottom designs are limited to shallow waters. Developers are now exploring floating turbines, using technology from oil and gas rigs, to access deeper waters where most offshore wind potential lies.

"The shift towards floating is driven more by long-term necessity than by any inherent near-term economic advantage," says Cosimo Ries, an energy analyst with consultancy Trivium China. Even in China, the cheapest location for floating projects, costs are two-to-four times higher than fixed-bottom projects. Challenges include expensive platforms, cabling costs for distant installations, and weather-related delays.

Despite high costs, floating offshore wind could become a major clean power driver once overall costs fall. It offers advantages for coastal cities with limited land and steep shorelines. "Floating offshore wind can also be built further from shore, which helps mitigate viewshed and avian species concerns," adds Abby L Watson, co-founder of the Groundwire Group.

Currently, floating offshore wind accounts for less than 1% of the 91GW global offshore wind capacity, but represents 22% of the future pipeline at nearly 200GW of announced capacity, according to Janna Smith of Global Energy Monitor. China leads in construction, while Europe and the UK lead in operating and prospective development.