Viability of animal plant? (Energy calculation)

I'm trying to design a humanoid or anthropomorphic organism that would be classified as a plant. The main argument people mention is that it wouldn't be able to produce enough energy to survive. I've done some basic calculations but I want to check it with someone else.

The average amount of sunlight in a square meter is equal to $120W$ or $120$ x $24$ x $60$ x $60=10368000J{m}^{-2}$ in 24h.

To increase photosynthesis, they need more surface area. These creatures would be slightly larger than a person. Average area of an adult human male is $1.9m^2$. Slightly larger with tail and features, lets say it's area is $2.5m^2$. Since only about part of them, lets say 35%, can be in the sun at any given time, photosynthetic area is only ${0.81}^2$. This wouldn't be enough. Instead, if they had grass-like fur the area would increase exponentially. Average $30mm$ length, $2mm$ thick base, $200m{m}^2$ area per blade, $250,000blades/m^2$, photosynthetic area x $50=40.5m^2$ x $120W=4860W$. Photosynthetic efficiency is at least 2% so they would produce $97.2W$, the same as what the average person uses. But ps efficiency can get higher, if it was 5% they would produce $243W$.

Did I make a mistake in my calculations?

Note that if this is not a sufficient energy source, they are mobile and are capable of digestion, meaning that they could get energy from external starch and glucose.

(Edit: I recalculated some things, using the sunlight duration by WMO and lowering the amount of sun exposure to 35% not 50%.)

posted over 6 years ago

ZoneWolf‭

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