Genetically Modified Plants To Produce Natural Lighting

Yeah, my first thought was that it's not going to be very bright. I did a back of the envelope calculation.

According to Wikipedia photosynthesis efficiency is about 3 to 6% of incoming sunlight. Lets call it 4.5%. That's the energy a plant uses to grow and just to keep itself alive - lets assume we can burn about half of that energy for light production without starving the plant itself. In fireflies Lucifer is about 90 to 98 efficient in converting energy into light. Lets say out engineered plant manages 90%. Next let's note that this plant is going to waste energy glowing even during midday sun. That basically cuts in half (or less) the amount of useful energy spend on blowing at night in the dark. Next let's note that the light is going to be generated inside the plant, but only a portion of it will make it out and be visible. The rest will hit internal plant tissue and be absorbed (remember, the very purpose of leaf tissue is to be a good absorber of light). The fraction of light that usefully escapes is hard to estimate, but lets call it 50%.

At this point we're down to about 1/200th.

Peak direct visible sunlight is about 440 watts per square meter. Average from sunrise to sunset will be less than half that. And with the 1/200th factor above we're looking at less than 1 watt of light output per square meter. (Note that we don't need to mess with the leaf surface area, we only need to consider the 2-D cross-section of the plant intercepting the available sunlight.)

The good news is that at this point in our calculation our wattage gets translated into light as if it's 100% efficiency. This means that a modest size BUSH that's 1 meter (or 1 yard) in diameter could, optimistically, glow at night with the equivalent light output of a 20-watt to 40-watt incandescent bulb.

That's probably close to the high end of what's possible, and I doubt their first attempt will be that good, but it is more than I expected. If you have good night vision, and if you sat right up against a bush, it may be just enough to (uncomfortably) read by. If all you have is typical size potted plant you'll only get a tiny fraction of that much light though.... maybe 5% of that.

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Source: http://rss.slashdot.org/~r/Slashdot/slashdotScience/~3/WxwuuJ6JvnM/story01.htm

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