If this afternoon it's sunny, we'll go to the park with our dogs.
We are talking about the future. We are thinking about a particular condition or situation in the future, and the result of this condition.
There is a real possibility that this situation will happen.
If + present simple, will/going to/may/might/could + infinitive
If in twenty years most of the villages are self-sufficient, we will not need so much electricity to live.
If in the future we don't need so much electricity, we will not need new power-plants.
If we consume less electricity, there could be less contamination of CO2.
