When is a sunlight or air or seawater not a free good?

Answer 1

Sunlight and air are all free goods in general. However, seawater is not a free good unless you are on the sea. This is because, free goods do not have any opportunity cost. Opportunity cost is something that you sacrifies in order to obtain something. We have to remember here that time is also a cost.

In order to obtain sunlight and air, human beings would not stop doing something alse or would not leave or spend anything. However, to obtain seawater you will have to spend time which means that there is something that you could do during that time period which is already sacrificed. How ever if you are on the sea, you would not have to spend any time or anything else to get seawater. It is right there for you.

Sunlight and air would not be classified an economic goods, there will be only free goods.

Answer 2

Sunlight, air, and seawater are considered free goods when they are abundant and not restricted in access. They may become non-free goods when they are scarce or controlled, such as in cases of air pollution (clean air becomes a commodity), water scarcity (potable water becomes valuable), or private beach ownership (access to seawater may be restricted).