Watts of  wind power per sq Metre of surface area

If ocean areas with high winds were tapped for wind energy, they could potentially harvest up to 500 to 800 watts of wind power per square meter of blade swept area.  The average solar power at Earth's mid-latitudes under clear-sky conditions is about 300 watts per sq m. Wind power can be converted to electricity more efficiently than solar power and at a lower cost per watt of electricity produced.  NASA

Offshore wind farms

The ocean has a few advantages for wind energy.

• There is more wind.
• Fewer people to complain.
• Noisier more efficient turbines can be used.

The Middlegrunden wind farm built in 2000 in Denmark was the first offshore wind farm to be owned by a community-based co-operative.

The farm delivers about 4% of the power for Copenhagen. Wiki

Floating wind turbines

If the water is deeper than 60 M, then it is more economic to install a floating vertical axis turbine than the taller horizontal wind turbine.

One of the advantages of offshore wind is that longer blades can be used to reduce costs of power. Blade Dynamics

Aerogenerator X

Windpower Ltd is developing a vertical axis wind turbine.

The design is similar in principal to the world's fastest sailing boat the Vestas Sailrocket (65 Knots!). The angled sail lifts the outrigger out of the water to reduce drag.