[DIYbio] is BioGlow being realistic?

Of course, that's for every square meter, and each streetlight illuminates a lot of square meters. At the same time, the tree won't be able to use all of its energy to make light or it would promptly die. Plants seem to have some energy to spare—they carry around a lot of superfluous DNA and grow excessively ornate flowers—but there are limits to how much energy they can spare and still keep growing. For argument's sake, let's say they can spare about five percent of their total energy for producing light. That takes us down to 250 lumens for each square meter of foliage, or about the equivalent of a 40W bulb.

But most of that energy will never get made into light. Remember, even basic chemicals like cysteine don't come for free; they cost energy. So does making the enzymes that convert them into more complicated chemicals, as well as (typically) the reactions they catalyze. Then you have to make the luciferase enzyme, as well as the recycling enzyme, and power those. Absolutely none of these processes are going to be 100 percent efficient.

You'd be extremely lucky if five percent of the energy being dedicated to producing light ever ends up getting used that way. We're now at 12.5 lumens.

Of course, about half that light would be pointed directly at the sky, and it wouldn't do much good as far as illumination goes. A lot of what's emitted downward will end up being directed back at the tree's branches and trunk, which will absorb some of it. Some other fraction will be absorbed by the cells in which it's emitted (some of it probably by the chlorophyll that powered the process in the first place). That leaves us with under 5 lumens of potential light for every square meter of foliage, and likely much less.

All of which places this on the very edge of being useful directly under a tree. If any of the above estimates turn out to be wrong—or you get too far from the tree—then all bets are off. Streetlights probably have a long career ahead of them.

The project won't work as things stand, and it probably won't even do what's being promised in the future. If those were the only problems with this project, they would be significant ones. But the fact is that the project is largely recreating the wheel; various academic labs already have luciferase working in plants, including in the arabidopsis species that the project plans on sending out to its backers. Even if you wanted to start from scratch, there are cheaper ways of going about making the DNA required than ordering up the DNA online, one base at a time. Plenty of researchers would send the DNA for the luciferase for free." - john timmer