Hi JGMC, Looking at your pictures it looks like there is an extensive distribution of mold. You are right, to eliminate mold you have to increase air movement and decrease moisture.
One eco-friendly option would be to install a power free roof ventilator.
Here is a good visual aid of how roof ventilators
work at increasing the air movement in your house.
But these will not be effective for the underground level of the carport as a powered air ventilator will be needed.
A good eco-friendly option is solar powered ventilation.
Assuming you mainly use the carport for storage, temperature control will not be important, but only ventilation.
Additionally, it would be good to install a humidistat so that you can get reliable humidity levels in the room. This way you will be able to adjust the ventilation accordingly, and have an objective way of measuring the effect of the ventilation.