5 ms·

Once you realize how much more efficient solar panels are (compared to plants) at capturing energy from the sun, the next logical question is: could it make sen

by wcoenen 5mo ago

Once you realize how much more efficient solar panels are (compared to plants) at capturing energy from the sun, the next logical question is: could it make sense to synthesize food with the help of electricity from solar power? There is a company called Solar Foods which is exploring exactly that: they use solar power to produce hydrogen, feed that hydrogen and CO2 to Xanthobacter bacteria, and harvest the produced protein. https://www.sciencedirect.com/science/article/pii/S016777992500321X https://www.sciencedirect.com/science/article/pii/S016777992...

aaron695 5mo ago
[dead]
rubyfan 5mo ago
sounds delicious
IncreasePosts 5mo ago
AIUI plants are actually only responsive to a few wavelengths of light for most of their growth. I've wondered, if solar panels can collect energy over a broader spectrum, if it could actually be more efficient to drive LEDs tuned to just what plants need, driven by broad spectrum solar power. In this way you could, theoretically, power a 3d growing operation based solely on the solar panels on the roof.
- zhivota 5mo ago
  I love this idea and it's one of those ideas I categorize into the bucket of "when all the other lower hanging fruit has been picked", just because it's more complicated. When we've got actually braindead policy like ethanol fuel mandates, the ROI of switching a corn farm to solar is so incredibly high that solutions like this just aren't competitive. I wish some of our billionaire class would turn their attention to these things rather than building yet another rocket company. Maybe that's why Gates is buying up farmland, who knows.
  - tbrownaw 5mo ago
    Maybe present it as proving out technology that could be helpful in building a self-sustaining Mars colony?
- CGMthrowaway 5mo ago
  Back of the envelope math: Solar panel captures energy from an 800nm wide range (300-1100nm) Plant captures energy from a 300nm wide range (400-700nm) The solar panel could reproject and amplify the 300nm range at (800/300=) 2.7X more power than the sun
  - magicalhippo 5mo ago
    But solar panels are only about 30% efficient, so that kinda kills any gains.
    - pinkmuffinere 5mo ago
      Thanks, this is exactly the comment I was looking for. In addition to the 70% loss due to the solar panel efficiency, I think we should also lose some efficiency in the conversion to light via leds (although I expect that’s much more efficient, perhaps at like 80%). I’m curious what is physically possible, if we assume we can achieve the max possible efficiency. I’m guessing there’s behavior like a Carnot engine, and the energy transfer can only be up to ~86% efficient (but please correct me if I’m wrong!!). In that case, conversion from light to energy via solar panels -> conversation back to light via leds should be 0.86*0.86 = 73% efficient in best case. And the full effect should be (800/300)*0.73 = 1.94, about twice as good as growing plants with the sun’s direct light. I’m surprised that seems possible! p.s. My efficiency guesses are probably wrong. Please correct me.
      - magicalhippo 5mo ago
        By using multiple junctions and stacking them, top one converting the most energetic photons, then the second-most etc, one can approach the theoretical limit of about 95% or whatever it is. However in practice it's very expensive and difficult as I understand. AFAIK the current state of the art is about 6 stacked junctions at around 60% efficiency, at great cost. And as you say the LEDs aren't 100% efficient either, though both deep red and bright blue are among the most efficient, about 85% there. So that leaves you with about 50% overall just from those two.
      - 5mo ago
- imtringued 5mo ago
  Every vertical farming company says this in their advertising. That didn't stop them from going bankrupt. Conventional agriculture works much better. You can build acres of greenhouses and make a profit. Vertical farming is such an abject failure that every single vertical farm is biomass constrained, meaning that they have to stretch their biomass with water. This is why vertical farms generally only sell "leafy greens", a marketing term that tries to sweep the inherent technical failure of vertical farming under the rug.
imoverclocked 5mo ago
Efficiency is a funny thing to argue here; Plants do a lot more than just produce food for humans. Also, I'll wager that whatever "produced protein" is manufactured will be only edible/palatable with other additives and processes. It would be cool if we spent more time understanding our soils and all of the things living in them more instead of finding ways to require more artificial energy to sustain our civilization.
- adrianN 5mo ago
  If we reduce land use for food production, it's not like that land will turn into a parking lot. Other plants will grow there, hopefully with richer biodiversity than an agricultural monoculture.
  - bitmasher9 5mo ago
    Also some locations do not have climates great for agriculture, but may have climates suitable for solar panels.
    - imoverclocked 5mo ago
      You are both ignoring the "soils" part of my comment; Even deserts have things growing in their soils. Putting solar panels into these places disturbs the natural soils. Transporting that energy requires infrastructure that also messes with habitats. Using it on-site requires different infrastructure and activity that is also disruptive. Just because the land is "virgin" or "barren" doesn't mean nothing is there biologically. Part of biodiversity is biodiversity in the soil itself. Much of that diversity hasn't been officially studied/documented. ie: We don't even know what we are killing off. Solar panels do have an ecological cost. Expanding to cover the entire planet is the wrong approach (IMO.) We have plenty of urban space and existing infrastructure that we can cover with solar without disturbing farm land or what's left of natural habitats. Beyond all of this, TFA was comparing corn vs solar. That implies we are talking about farmable land.
      - 5mo ago
downboots 5mo ago
Corn cyborgs, the future
anon84873628 5mo ago
Caves of Steel, here we come!
ZeroGravitas 5mo ago
There's also a startup that claims you can turn fossil fuels directly into butter and use less fossil fuels than you would going through the traditional process of farming.
- AngryData 5mo ago
  The first part we know is true, the Germans in WW2 fed some troops up to 800 calories a day of coal butter, which was black margarine synthesized from coal. Using less than needed for fertilizer for farming though seems unlikely, coal butter was born from desperation for immediate calorie source, not because it was cheaper or more efficient.
Someone 5mo ago
Another next logical question is whether we can engineer plants to get better at capturing solar energy. Turns out we (somewhat) can. See for example https://www.science.org/doi/10.1126/science.aai8878 https://www.science.org/doi/10.1126/science.aai8878: “Crop plants protect themselves from excess sunlight by dissipating some light energy as heat, readjusting their systems when shadier conditions prevail. But the photosynthetic systems do not adapt to fluctuating light conditions as rapidly as a cloud passes overhead, resulting in suboptimal photosynthetic efficiency. Kromdijk et al. sped up the adaptation process by accelerating interconversion of violaxanthin and zeaxanthin in the xanthophyll cycle and by increasing amounts of a photosystem II subunit. Tobacco plants tested with this system showed about 15% greater plant biomass production in natural field conditions.” It isn’t certain that we can make this work at scale, though. See https://gmopromises.org/article/enhancing-photosynthesis-with-genetic-engineering/ https://gmopromises.org/article/enhancing-photosynthesis-wit...
_Microft 5mo ago
DARPA’s “Cornucopia” program has the same goal. https://www.darpa.mil/news/2023/food-air-water-electricity https://www.darpa.mil/news/2023/food-air-water-electricity
hulitu 5mo ago
> Once you realize how much more efficient solar panels are (compared to plants) You, and others, forgot to account for the growth of solar panels compared to plants: the energy required to make one solar panel.

by wcoenen 5mo ago

aaron695 5mo ago

[dead]

rubyfan 5mo ago

sounds delicious

IncreasePosts 5mo ago

AIUI plants are actually only responsive to a few wavelengths of light for most of their growth. I've wondered, if solar panels can collect energy over a broader spectrum, if it could actually be more efficient to drive LEDs tuned to just what plants need, driven by broad spectrum solar power. In this way you could, theoretically, power a 3d growing operation based solely on the solar panels on the roof.

zhivota 5mo ago
I love this idea and it's one of those ideas I categorize into the bucket of "when all the other lower hanging fruit has been picked", just because it's more complicated. When we've got actually braindead policy like ethanol fuel mandates, the ROI of switching a corn farm to solar is so incredibly high that solutions like this just aren't competitive. I wish some of our billionaire class would turn their attention to these things rather than building yet another rocket company. Maybe that's why Gates is buying up farmland, who knows.
- tbrownaw 5mo ago
  Maybe present it as proving out technology that could be helpful in building a self-sustaining Mars colony?
CGMthrowaway 5mo ago
Back of the envelope math: Solar panel captures energy from an 800nm wide range (300-1100nm) Plant captures energy from a 300nm wide range (400-700nm) The solar panel could reproject and amplify the 300nm range at (800/300=) 2.7X more power than the sun
- magicalhippo 5mo ago
  But solar panels are only about 30% efficient, so that kinda kills any gains.
  - pinkmuffinere 5mo ago
    Thanks, this is exactly the comment I was looking for. In addition to the 70% loss due to the solar panel efficiency, I think we should also lose some efficiency in the conversion to light via leds (although I expect that’s much more efficient, perhaps at like 80%). I’m curious what is physically possible, if we assume we can achieve the max possible efficiency. I’m guessing there’s behavior like a Carnot engine, and the energy transfer can only be up to ~86% efficient (but please correct me if I’m wrong!!). In that case, conversion from light to energy via solar panels -> conversation back to light via leds should be 0.86*0.86 = 73% efficient in best case. And the full effect should be (800/300)*0.73 = 1.94, about twice as good as growing plants with the sun’s direct light. I’m surprised that seems possible! p.s. My efficiency guesses are probably wrong. Please correct me.
    - magicalhippo 5mo ago
      By using multiple junctions and stacking them, top one converting the most energetic photons, then the second-most etc, one can approach the theoretical limit of about 95% or whatever it is. However in practice it's very expensive and difficult as I understand. AFAIK the current state of the art is about 6 stacked junctions at around 60% efficiency, at great cost. And as you say the LEDs aren't 100% efficient either, though both deep red and bright blue are among the most efficient, about 85% there. So that leaves you with about 50% overall just from those two.
    - 5mo ago
imtringued 5mo ago
Every vertical farming company says this in their advertising. That didn't stop them from going bankrupt. Conventional agriculture works much better. You can build acres of greenhouses and make a profit. Vertical farming is such an abject failure that every single vertical farm is biomass constrained, meaning that they have to stretch their biomass with water. This is why vertical farms generally only sell "leafy greens", a marketing term that tries to sweep the inherent technical failure of vertical farming under the rug.

imoverclocked 5mo ago

Efficiency is a funny thing to argue here; Plants do a lot more than just produce food for humans. Also, I'll wager that whatever "produced protein" is manufactured will be only edible/palatable with other additives and processes. It would be cool if we spent more time understanding our soils and all of the things living in them more instead of finding ways to require more artificial energy to sustain our civilization.

adrianN 5mo ago
If we reduce land use for food production, it's not like that land will turn into a parking lot. Other plants will grow there, hopefully with richer biodiversity than an agricultural monoculture.
- bitmasher9 5mo ago
  Also some locations do not have climates great for agriculture, but may have climates suitable for solar panels.
  - imoverclocked 5mo ago
    You are both ignoring the "soils" part of my comment; Even deserts have things growing in their soils. Putting solar panels into these places disturbs the natural soils. Transporting that energy requires infrastructure that also messes with habitats. Using it on-site requires different infrastructure and activity that is also disruptive. Just because the land is "virgin" or "barren" doesn't mean nothing is there biologically. Part of biodiversity is biodiversity in the soil itself. Much of that diversity hasn't been officially studied/documented. ie: We don't even know what we are killing off. Solar panels do have an ecological cost. Expanding to cover the entire planet is the wrong approach (IMO.) We have plenty of urban space and existing infrastructure that we can cover with solar without disturbing farm land or what's left of natural habitats. Beyond all of this, TFA was comparing corn vs solar. That implies we are talking about farmable land.
    - 5mo ago

downboots 5mo ago

Corn cyborgs, the future

anon84873628 5mo ago

Caves of Steel, here we come!

ZeroGravitas 5mo ago

There's also a startup that claims you can turn fossil fuels directly into butter and use less fossil fuels than you would going through the traditional process of farming.

AngryData 5mo ago
The first part we know is true, the Germans in WW2 fed some troops up to 800 calories a day of coal butter, which was black margarine synthesized from coal. Using less than needed for fertilizer for farming though seems unlikely, coal butter was born from desperation for immediate calorie source, not because it was cheaper or more efficient.

Someone 5mo ago

Another next logical question is whether we can engineer plants to get better at capturing solar energy. Turns out we (somewhat) can. See for example https://www.science.org/doi/10.1126/science.aai8878 https://www.science.org/doi/10.1126/science.aai8878: “Crop plants protect themselves from excess sunlight by dissipating some light energy as heat, readjusting their systems when shadier conditions prevail. But the photosynthetic systems do not adapt to fluctuating light conditions as rapidly as a cloud passes overhead, resulting in suboptimal photosynthetic efficiency. Kromdijk et al. sped up the adaptation process by accelerating interconversion of violaxanthin and zeaxanthin in the xanthophyll cycle and by increasing amounts of a photosystem II subunit. Tobacco plants tested with this system showed about 15% greater plant biomass production in natural field conditions.” It isn’t certain that we can make this work at scale, though. See https://gmopromises.org/article/enhancing-photosynthesis-with-genetic-engineering/ https://gmopromises.org/article/enhancing-photosynthesis-wit...

_Microft 5mo ago

DARPA’s “Cornucopia” program has the same goal. https://www.darpa.mil/news/2023/food-air-water-electricity https://www.darpa.mil/news/2023/food-air-water-electricity

hulitu 5mo ago

> Once you realize how much more efficient solar panels are (compared to plants) You, and others, forgot to account for the growth of solar panels compared to plants: the energy required to make one solar panel.