I would choose the windmills for production of electric power.
The modern day windmills are relatively good producers of electric energy. They are not very expensive, they use renewable energy (the wind), and are of great use for both the economy and the people themselves.
The economic benefit can be seen that they produce energy very cheaply, and they do not require and resources for their functioning. Also, they save a lot of money because they manage to produce electricity that otherwise would have been imported, thus hitting the economy badly.
The benefit for the people is that they provide more electricity, stable one, and prevent the lack of electricity when it is used more, especially in the winter months. Also, this electricity is cheaper.