Chlorophyll as we know it on earth is estimated to be between 3% and 6% efficient in converting light energy to useable biomass. This support slow growth and no movement of plants like that observed in herbivores or carnivores. Higher up the food chain, animals directly or indirectly depend on plants to convert vast quantities of solar energy into useable biomass. Given that 3% efficiency can't support human level activities, how much more efficiency do we need from photosynthesis to change humans from omnivores into photovores?
- Human surface area: average 1.9m^2 for adult males. 1.6m^2 for adult females. Source.
- Want to keep humanoid shape and movements as much as possible. These photosynthesis based creature needs to be able to move comparably to a human.
- Assume a Sol light spectrum and earth atmosphere absorption spectrum.
How much more efficient would a photosynthesis process based on neo-chlorophyll need to be to support human level activities with the surface area of a human?
I'm interested in how much more efficient photosynthesis would need to be to support human level energy needs. How to achieve that increased efficiency is not expected as part of a good answer (unless you work in organic chemistry and feel frisky).