4 ms·

At the moment it's comparable to glow-in-the-dark paint, imagine those stars many people had on their ceiling as kids. we are working on improving the luminosit

At the moment it's comparable to glow-in-the-dark paint, imagine those stars many people had on their ceiling as kids. we are working on improving the luminosity however, we are improving it about 10-25% per week using a process known as directed evolution.

aetherson 12y ago
Aren't there some pretty fundamental physical limits here? This wikipedia article: http://en.wikipedia.org/wiki/Incandescent_light_bulb http://en.wikipedia.org/wiki/Incandescent_light_bulb claims that the luminous efficiency of a low-wattage incandescent bulb is maybe in the neighborhood of 1%. So that suggests that to get as much light as a 25 watt incandescent bulb, assuming that your plant is perfectly converting input energy to light output, you'd need to be continuously burning 0.25 watts. Can a plant possibly metabolize or store that much energy for long?
- technotony 12y ago
  Bioluminescense is known as cold-light because it's so efficient - basically zero energy is wasted as heat. There will be fundamental limits (currently unknown), most likely from toxicity or waste products hurting the cells, but we are far from pushing those boundaries yet.
  - dekhn 12y ago
    Right, but a good first order estimate woudl be to take the brighest bioluminenscent molecule, pack it in a sphere with volume = your plant, and compute lux at 3 meters. Or something like that. Without growing lensing structures or other ways to focus/point light, the r3 falloff is gonna kill you.
    - adwn 12y ago
      Shouldn't the falloff be proportional to 1/r^2, instead of 1/r^3?
      - jarman 12y ago
        1/r^3 = 1/r^2 (falloff in vacuum) * 1/r (light absorption by air)
        deleted 12y ago
        [deleted]
      - dekhn 12y ago
        point sphere radiating a point at distance r. I'm not doing the calculation the way a physicist would, or rather, I'm calculating the amount of EMF falling on a point, not the energy of the full surface. The reason being, a person standing and looking at something cares how much illumination falls on the destination point, not the total illumination of the scene.
        dekhn 12y ago
        Ah, duh. Had to go back and look up some basic geometry. So, surface of sphere is proportional to r2. At distance r, with 1/r absorption, the illumination of a spot on a sphere at distance r would fall off as 1/r3. But I wasn't including absorption, so my original claim of 1/r3 due to spherical emission was wrong.
- Retric 12y ago
  Typical crop plants are ~1-2% efficient at gathering sunlight. You get ~100 watts of solar energy per square foot for ~8 hours a day. So that's 8-16 watt hours per day our .33 to .66 watts per hour so it's at least in the right ballpark. Note: Sugarcane peaks at around 7-8% efficient so with the right plant .25w seems doable. http://en.wikipedia.org/wiki/Photosynthetic_efficiency http://en.wikipedia.org/wiki/Photosynthetic_efficiency

aetherson 12y ago

Aren't there some pretty fundamental physical limits here? This wikipedia article: http://en.wikipedia.org/wiki/Incandescent_light_bulb http://en.wikipedia.org/wiki/Incandescent_light_bulb claims that the luminous efficiency of a low-wattage incandescent bulb is maybe in the neighborhood of 1%. So that suggests that to get as much light as a 25 watt incandescent bulb, assuming that your plant is perfectly converting input energy to light output, you'd need to be continuously burning 0.25 watts. Can a plant possibly metabolize or store that much energy for long?

technotony 12y ago
Bioluminescense is known as cold-light because it's so efficient - basically zero energy is wasted as heat. There will be fundamental limits (currently unknown), most likely from toxicity or waste products hurting the cells, but we are far from pushing those boundaries yet.
- dekhn 12y ago
  Right, but a good first order estimate woudl be to take the brighest bioluminenscent molecule, pack it in a sphere with volume = your plant, and compute lux at 3 meters. Or something like that. Without growing lensing structures or other ways to focus/point light, the r3 falloff is gonna kill you.
  - adwn 12y ago
    Shouldn't the falloff be proportional to 1/r^2, instead of 1/r^3?
    - jarman 12y ago
      1/r^3 = 1/r^2 (falloff in vacuum) * 1/r (light absorption by air)
      - deleted 12y ago
        [deleted]
    - dekhn 12y ago
      point sphere radiating a point at distance r. I'm not doing the calculation the way a physicist would, or rather, I'm calculating the amount of EMF falling on a point, not the energy of the full surface. The reason being, a person standing and looking at something cares how much illumination falls on the destination point, not the total illumination of the scene.
      - dekhn 12y ago
        Ah, duh. Had to go back and look up some basic geometry. So, surface of sphere is proportional to r2. At distance r, with 1/r absorption, the illumination of a spot on a sphere at distance r would fall off as 1/r3. But I wasn't including absorption, so my original claim of 1/r3 due to spherical emission was wrong.
Retric 12y ago
Typical crop plants are ~1-2% efficient at gathering sunlight. You get ~100 watts of solar energy per square foot for ~8 hours a day. So that's 8-16 watt hours per day our .33 to .66 watts per hour so it's at least in the right ballpark. Note: Sugarcane peaks at around 7-8% efficient so with the right plant .25w seems doable. http://en.wikipedia.org/wiki/Photosynthetic_efficiency http://en.wikipedia.org/wiki/Photosynthetic_efficiency