Catosynthesis

$CATOS

He is green and he has a sprout, so the claim is that he runs on sunlight. This page takes that seriously. Move the sun.

a green cat with a sprout growing out of his head, sitting
elevation
0.0 deg
on the grass
0 W/m2
into the cat
0 mW

The bar is 1 to 1 with his daily need. That is not a rendering fault.

0.00 kcal collected of the 260 kcal a 4.5 kg cat burns in a day. 0.00% of a cat.

Drag the sun across the sky. The day only goes forward.

model: idle

The arithmetic, in full

  1. 19.4 MJ per square metre. One clear day, 45 degrees north, equinox, peak 1000 W/m2 at noon. That is the sunlight landing on a patch of ground the size of a doormat.
  2. 45% of it is even the right colour. Photosynthesis only works on 400 to 700 nm, the band called PAR. The rest is heat.
  3. 1% of that becomes sugar. C3 plants manage one to two percent in a real field. The theoretical ceiling is 4.6% and nothing alive has ever reached it.
  4. He covers 0.09 m2. That is a sitting cat seen from above, sprout included.
  5. He needs 260 kcal a day. Resting need is 70 x kg^0.75, so 216 kcal for 4.5 kg, times 1.2 for an indoor cat who does nothing.

To live on light alone he needs 12.4 m2 of leaf. He has 0.09. For catosynthesis to work, the cat has to be a rug three and a half metres on each side.

Sources: Zhu, Long and Ort, What is the maximum efficiency with which photosynthesis can convert solar energy into biomass?, Current Opinion in Biotechnology 19(2), 2008 . PAR band and fraction, standard plant physiology . Feline energy requirement, 70 x BW^0.75 resting, 1.2 to 1.4 maintenance.