The Offshore Wind Farm is a very helpful tile improvement as it allows you to make use of water tiles that otherwise would have been unable to be improved. As a bonus, it frees up other land tiles that you may have needed to use for Solar Farms or onshore Wind Farms to construct other improvements instead (which can't go into the water), such as Farms (the Food-producing type) and districts.
This improvement is available around the same time as the Seastead, which provides Housing, Production, Food, and Culture. Because of this, you should only build just enough Offshore Wind Farms to supply Power to the city and prioritize Seasteads on other water tiles due to the Seasteads' superiority in terms of yields.
Civilopedia entry Edit
Everybody knows the feeling of a crisp ocean breeze, and today we are able to harness that breeze for more than just a refreshing breath of fresh air. Offshore winds blowing over shallow waters are ideal placement spots for wind farms, although this application is quite new. It wasn't until 1991 that the first offshore wind energy project came to fruition in Denmark, but the technology has since spread throughout the world.
Similar to onshore wind farms, these wind turbines are turned by winds and generate technology. But unlike the wind farms found across rolling hills, offshore farms require foundations that will weather whatever the ocean brings with it - rolling waves, salt water, or even a hurricane. Though engineers continue to work to improve the technology, we are currently limited by the depth of water into which these turbines can be installed. Even so, offshore wind farms are already improving the lives of coastal communities that may have limited access to other forms of power production.