3 ms·

For others that may be having similar thoughts, I’ve looked into this before and met this roadblock haha. It’s a great thought experiment for just how much en

For others that may be having similar thoughts, I’ve looked into this before and met this roadblock haha. It’s a great thought experiment for just how much energy a human uses and how much area we need for growing food in the world. > Our body’s demand for glucose is higher than photosynthesis can accommodate. Associate professor Lindsay Turnbull of the University of Oxford determined that if the surface area of an adult woman contained chlorophyll like a leaf, it would produce only 1% of the daily energy requirements for the person to survive. To live by photosynthesis alone, the woman would need a green body with the surface the size of a tennis court.

drewm1980 4y ago
So basically, she would have to be a tree.
edgyquant 4y ago
Makes sense actually. Animals have had half a billion years: if photosynthesis could power them some of them would be using it.
- russdill 4y ago
  The sloth actually supplements their diet with photosynthetic algae that live on their fur. But their metabolism is very very slow.
  - pvaldes 4y ago
    That would be equivalent to us carrying a lattice pot around and then eating the lattice. Not a real example of photosynthetic animals.
    - krageon 4y ago
      The solutions you describe are functionally identical, so I do not see why it wouldn't be a "real example".
- winReInstall 4y ago
  There are undersea slugs who store devoured algeas chlorophyl in transparent pockets under the skin.
runsWphotons 4y ago
in the future women will be even more wrinkled
russdill 4y ago
It's also worth noting that biological photosynthesis is very inefficient. A human consumes on average about 150 watts. The earth gets about 1400 watts of sunlight per square meter. It's not completely impossible to one day have bio-engineered solar powered animals.
- winReInstall 4y ago
  https://www.sciencedirect.com/science/article/pii/S2590346220300134 https://www.sciencedirect.com/science/article/pii/S259034622...
- Mistletoe 4y ago
  Some napkin math (may be wrong). A man is about two square meters of skin. Assuming they lay down to photosynthesize most efficiently from perpendicular sun rays that would be one square meter, so 1400 watts. You would need an ~11% efficient conversion to meet the needs of a human. Plants currently top out at about 6.4% for highly efficient C4 plants like sugarcane. 11% is the maximum efficiency possible. >The photosynthetic efficiency is dependent on the wavelength of the light absorbed. Photosynthetically active radiation (400–700 nm) constitutes only 45% of the actual daylight. Therefore the maximum theoretical efficiency of the photosynthesis process is approximately 11%. Not only would you have to somehow replicate the extreme efficiency of sugarcane on animal skin (an organ with no support structures for photosynthesis), you’d have to double the efficiency.

drewm1980 4y ago

So basically, she would have to be a tree.

edgyquant 4y ago

Makes sense actually. Animals have had half a billion years: if photosynthesis could power them some of them would be using it.

russdill 4y ago
The sloth actually supplements their diet with photosynthetic algae that live on their fur. But their metabolism is very very slow.
- pvaldes 4y ago
  That would be equivalent to us carrying a lattice pot around and then eating the lattice. Not a real example of photosynthetic animals.
  - krageon 4y ago
    The solutions you describe are functionally identical, so I do not see why it wouldn't be a "real example".
winReInstall 4y ago
There are undersea slugs who store devoured algeas chlorophyl in transparent pockets under the skin.

runsWphotons 4y ago

in the future women will be even more wrinkled

russdill 4y ago

It's also worth noting that biological photosynthesis is very inefficient. A human consumes on average about 150 watts. The earth gets about 1400 watts of sunlight per square meter. It's not completely impossible to one day have bio-engineered solar powered animals.

winReInstall 4y ago
https://www.sciencedirect.com/science/article/pii/S2590346220300134 https://www.sciencedirect.com/science/article/pii/S259034622...
Mistletoe 4y ago
Some napkin math (may be wrong). A man is about two square meters of skin. Assuming they lay down to photosynthesize most efficiently from perpendicular sun rays that would be one square meter, so 1400 watts. You would need an ~11% efficient conversion to meet the needs of a human. Plants currently top out at about 6.4% for highly efficient C4 plants like sugarcane. 11% is the maximum efficiency possible. >The photosynthetic efficiency is dependent on the wavelength of the light absorbed. Photosynthetically active radiation (400–700 nm) constitutes only 45% of the actual daylight. Therefore the maximum theoretical efficiency of the photosynthesis process is approximately 11%. Not only would you have to somehow replicate the extreme efficiency of sugarcane on animal skin (an organ with no support structures for photosynthesis), you’d have to double the efficiency.