Max:
Your original query is now starting to form some piece-meal basic data. Now we know that you are working on Photosynthesis - as I guessed. However, this is not what you basically asked. There is no process (to my knowledge) that will reduce CO2 down to a gaseous O2 and solid graphite. That is my answer to your query.
Additionally, you now advise you are working out the type of energy required at each stage (how do you know there are different stages?) and also reproducing the chemicals (which, the CO2? the O2 & C?) "synthetically" at each stage. I don't understand what you mean by "reproducing" the chemicals. I've never heard or read of synthetic CO2, O2, or C. Are these the same as the God-given compounds we presently have?
Also, what do you mean by "type" of energy? Do you mean type as in solar, nuclear, heat, work, etc., etc.? Or do you mean quantity of energy? Please explain; maybe someone on the forum can help out.
Art Montemayor
Spring, TX