During today’s LW event, I chatted with Ruby and Raemon (seperately) about the comparison between human-made photovoltaic systems (i.e. solar panels), and plant-produced chlorophyll. I mentioned that in many ways chlorophyll is inferior to solar panels—consumer grade solar panels operate in the 10% to 20% efficiency range (i.e. for every 100 joules of light energy, 10 − 20 joules are converted into usable energy), while chlorophyll is around 9% efficient, and modern cutting edge solar panels can go even as high as nearly 50% efficiency. Furthermore, every fall the leaves turn red and fall down to the ground only for new leaves – that is plant-based solar panels – to be generated again in the spring. One sees green plants where there very well could be solar panels capturing light, and naïvely we would expect solar panels to do a better job, but we plant plants instead, and let them gather energy for us.
One of them (I think Ruby) didn’t seem convinced that it was fair to compare solar panels with chlorophyll – is it really an apples to apples comparison? I think it is a fair comparison. It is true that plants do a lot of work beyond simply capturing light, and electricity goes to different things than what plants do, but ultimately what both plant-based farms and photovoltaic cells do is they capture energy from sunlight coming to the earth from the sun, and convert them to human usable energy. One could imagine genetically engineered plants doing much of what we use electricity for these days, or industrial processes being hooked up to solar panels that do the things plants do, and in this way we can make a meaningful comparison of how much energy plants allow us to use for human desired goals and compare that to how much energy photovoltaic cells can redirect to human-desired uses.
Huh, somehow while chatting with you I got the impression that it was the opposite (chlorophyll more effective than solar panels). Might have just misheard.
The big advantage chlorophyll has is that it is much cheaper than photovoltaics, which is why I was saying (in our conversation) we should take inspiration from plants
There’s plenty of land area for solar. I did a rough calculation once, and my estimate was that it’d take roughly twice the land area of the Benelux to build a solar farm that produced as much energy per annum as the entirety of humanity uses each year (The sun outputs an insane amount of power, and if one steps back to think about it, almost every single joule of energy we’ve used came indirectly through the sun—often through quite inefficient routes). I didn’t take into account day/night cycles, or losses of efficiency due to transmission, but if we assume 4x loss due to nighttime (probably a pessimistic estimate) and 5x loss due to transmission (again, being pessimistic), it still comes out to substantially less than the land we have available to us (About 1⁄3 the size of the Sahara desert)
During today’s LW event, I chatted with Ruby and Raemon (seperately) about the comparison between human-made photovoltaic systems (i.e. solar panels), and plant-produced chlorophyll. I mentioned that in many ways chlorophyll is inferior to solar panels—consumer grade solar panels operate in the 10% to 20% efficiency range (i.e. for every 100 joules of light energy, 10 − 20 joules are converted into usable energy), while chlorophyll is around 9% efficient, and modern cutting edge solar panels can go even as high as nearly 50% efficiency. Furthermore, every fall the leaves turn red and fall down to the ground only for new leaves – that is plant-based solar panels – to be generated again in the spring. One sees green plants where there very well could be solar panels capturing light, and naïvely we would expect solar panels to do a better job, but we plant plants instead, and let them gather energy for us.
One of them (I think Ruby) didn’t seem convinced that it was fair to compare solar panels with chlorophyll – is it really an apples to apples comparison? I think it is a fair comparison. It is true that plants do a lot of work beyond simply capturing light, and electricity goes to different things than what plants do, but ultimately what both plant-based farms and photovoltaic cells do is they capture energy from sunlight coming to the earth from the sun, and convert them to human usable energy. One could imagine genetically engineered plants doing much of what we use electricity for these days, or industrial processes being hooked up to solar panels that do the things plants do, and in this way we can make a meaningful comparison of how much energy plants allow us to use for human desired goals and compare that to how much energy photovoltaic cells can redirect to human-desired uses.
Huh, somehow while chatting with you I got the impression that it was the opposite (chlorophyll more effective than solar panels). Might have just misheard.
The big advantage chlorophyll has is that it is much cheaper than photovoltaics, which is why I was saying (in our conversation) we should take inspiration from plants
Gotcha. What’s the metric that it’s cheaper on?
Well, money, for one?
It would be interesting to see the efficiency of solar + direct air capture compared to plants. If it wins I will have another thing to yell at hippies (before yelling about there not being enough land area even for solar)
There’s plenty of land area for solar. I did a rough calculation once, and my estimate was that it’d take roughly twice the land area of the Benelux to build a solar farm that produced as much energy per annum as the entirety of humanity uses each year (The sun outputs an insane amount of power, and if one steps back to think about it, almost every single joule of energy we’ve used came indirectly through the sun—often through quite inefficient routes). I didn’t take into account day/night cycles, or losses of efficiency due to transmission, but if we assume 4x loss due to nighttime (probably a pessimistic estimate) and 5x loss due to transmission (again, being pessimistic), it still comes out to substantially less than the land we have available to us (About 1⁄3 the size of the Sahara desert)