How does energy pass from the sun to the rice?

It happens by photosynthesis, in which carbon dioxide from the air is separated out into carbon, which is used to make the rice, and oxygen, which is mostly dumped into the atmosphere.

Separating the carbon and the oxygen needs energy to break the chemical bonds between the atoms. That energy is recovered when the carbon is burned with oxygen, but that produces carbon dioxide as well, approximately as much as was absorbed in the first place.