[wcoenen]

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/S016777992...

[imoverclocked]

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]

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]

Also some locations do not have climates great for agriculture, but may have climates suitable for solar panels.

[imoverclocked]

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.

[subscribed]

Big farmland is effectively dead. It must be tiled and heavily fertilized to produce anything. It does NOT have healthy soils.

And remember the context: were talking of replacing corn grown for energy, monoculture with no insect or plant life, with the same land covered with solar panels, time for soil to recover, native plants to germinate and grow.

Putting solar panels instead of the industrial corn production is partially rewilding it - there are projects in the hotter countries where increased humidity and decreased sunlight actually allows for the more plants to thrive. There are projects using goats to trim the greens under the panels. Etc, etc.

Almost anything is better for the soil, biodiversity and life than industrial corn production.

[Gibbon1]

Worth noting you don't have to spray solar panels with pesticides and herbicides either. Nor do they require fertilizer. All of these have real negative effects.

Pesticides are causing a decline in insect populations and the animals that eat them. Herbicides what can say more than that. Fertilizer causes algae blooms and hypoxic conditions in lakes and streams. All three cause ground water pollution.

I'm a broken record, solar is 30 times more productive per acre than ethanol corn.

[tpm]

> without disturbing farm land

Farm land is heavily disturbed. All the fertilizer and other chemicals used, soil destroyed by all the things we do to it, and downstream disruption due to fertilizer runoff, animals that are fed and then we have to manage the manure, water that is depleted etc. Placing solar panels on farm land is actually very close to returning it to the nature (of course depending on how exactly you do it, how tightly placed they are, how high etc., but it's also possible to still grow trees under them like some pilot projects in southern Italy or to place them over animal pastures).

[pstuart]

Agrivoltaics is a viable path to have it both ways: https://en.wikipedia.org/wiki/Agrivoltaics

Obviously it won't work for everything but appears to be workable enough to do more of it.

That said, I absolutely agree that soil science and husbandry is dearly need to avoid depleting arable land. Farmers are catching on to this and with more support could hopefully make doing this a no brainer based on economics alone.

[adrianN]

Farm land has less healthy soil than if you stop tilling, fertilizing and pesticides and put solar panels on it. I also think you’re overestimating the area needed to cover our energy needs.

[palmotea]

> 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.

If current trends old, it will turn into data centers.

[foxyv]

I think it would be pretty cool if we could urbanize food production. Turning farm land back into wilderness would go a long way to reducing our impact on the environment.

[IncreasePosts]

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.

[imtringued]

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.

[CGMthrowaway]

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

[traes]

The reason plants capture energy from this range is because that's where most of sunlight's energy is concentrated, which is going to drop this quite a bit further. Glancing at a solar radiation spectrum curve makes it look a lot closer to ~1.5x. Combine that with inefficiencies of both the panel and the LEDs and it really doesn't look that good.

[magicalhippo]

But solar panels are only about 30% efficient, so that kinda kills any gains.

[pinkmuffinere]

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]

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.

[ben_w]

You're basically fine about PV, but nobody's corrected the real error which is wildly over-estimating the efficiency of photosynthesis in plants, which is 0.1-4.3%, with crops in particular being 1-2%: https://en.wikipedia.org/wiki/Photosynthetic_efficiency#Typi...

[benj111]

I thought that efficiency was governed by the wavelengths they absorb? Ie absorb all wavelengths == 100% efficiency.

So that would imply they are inherently more efficient just looking at the figures provided.

[zhivota]

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]

Maybe present it as proving out technology that could be helpful in building a self-sustaining Mars colony?

[_Microft]

DARPA’s “Cornucopia” program has the same goal.

https://www.darpa.mil/news/2023/food-air-water-electricity

[Someone]

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:

“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-wit...

[anon84873628]

Caves of Steel, here we come!

[hulitu]

> 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.

[ZeroGravitas]

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]

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.

[downboots]

Corn cyborgs, the future

[rubyfan]

sounds delicious