You cannot efficiently or effectively harness wind energy without a very large device. Nothing that you can fit on your balcony will harvest any significant amo

You cannot efficiently or effectively harness wind energy without a very large device. Nothing that you can fit on your balcony will harvest any significant amount of energy, not even enough to slowly charge your phone. If your balcony gets sun during the day, you would be better off with a few cheap solar panels. They might at least be able to charge your phone for a few hours a day.