131–140 of 464 posts
Artificial lighting saves land because plants can be grown above each other, but if the electricity for the lighting comes from solar panels, then the savings are canceled out by the land required to install the solar panels. The vertical farm is a paradox unless fossil fuels provide the energy. In that case, there’s not much sustainable about it. This entire piece is based on the assumption that the only sources of…
Way overshooting the confidence on fusion here.
Earlier quoted context omitted.
Yes, please include the cost of nuclear power in the considerations. (The joke here is that the true cost is undefined because we here in the US have no method to store the long-term hazardous waste it produces. Current cleanup costs for just the military reactor waste are estimated at $500B, for civilian reactors the costs are said to be higher.)
In the short term nuclear energy is expensive, but in the long term nuclear energy is one the cheapest sources of energy available. Source - https://www.youtube.com/watch?v=cbeJIwF1pVY (this is even more true when you consider the cost of externalities)
Today is the long term, and the costs are still uncontrolled.
Earlier quoted context omitted.
1. We have nuclear waste already 2. We will continue to have nuclear waste if we want to have nuclear weapons 3. You can store all the waste you need to store in a football field ( https://www.energy.gov/ne/articles/5-fast-facts-about-spent-... ) Nuclear waste management is messy, but it's something we need to solve no matter what. It is now a sunk cost we have to deal with because of what we have already done and wh…
I have this giant pile of nuclear waste that's stored haphazardly and needs to be dealt with at a cost of $XXX billions of dollars. I know! I'll keep shoveling more waste into the haphazard piles! Perfect!
As an aside, if you must snark, it's best to do it when you're following the thread of the conversation.
> Artificial lighting saves land because plants can be grown above each other, but if the electricity for the lighting comes from solar panels, then the savings are canceled out by the land required to install the solar panels. This doesn't have to be the case. Plants don't use all the sunlight that hits them, because available light isn't generally the bottleneck in plant growth. Note how most plants are green, whic…
Say a plant needs 1/10th of actual full sun during the day, could you theoretically remove the electricity step entirely but "just" (putting "just" in quotes because I'm sure it wouldn't be easy) having some sort of fancy mirror setup on a 10 storey building to send 1/10th of the sunlight hitting the roof to each floor?
The 'fancy mirrors' required would simply be a prism. You'd separate out the red and blue light and aim it at the plants, and send the green and infrared light to solar cells, to be used for running red and blue LEDs. (Or you could use flourescence if you had something that glowed red or blue when exposed to green or IR light).
Check out this spectral plot for chlorophyll-a and -b:
http://hyperphysics.phy-astr.gsu.edu/hbase/Biology/ligabs.ht...
and compare it to this plot of the solar irradiance at Earth's surface:
http://hyperphysics.phy-astr.gsu.edu/hbase/vision/solirrad.h...
There are peaks in the clorophyl absorption spectrum at 400-500 and 600-700 nm (blue to UV and red), but the sunlight provides energy in an atmosphere-attenuated blackbody curve everywhere from 300-1000nm.
In theory, by providing illumination with just 10% the energy of the sunlight's full spectrum in a narrow band from 420-430nm where photosynthesis is most efficient, you could have plants receive the same amount of energy.
Unfortunately, solar cells have the exact same problem: Just as the proteins in chlorophyll only use certain spectral energies, so too the semiconductors only make efficient use of certain energies. Multi-bandgap solar cells can help:
https://en.wikipedia.org/wiki/Multi-junction_solar_cell#/med...
but in both chemical and electrical solar energy extraction, you're working with a particular photon energy and there's going to be waste.
Artificial lighting saves land because plants can be grown above each other, but if the electricity for the lighting comes from solar panels, then the savings are canceled out by the land required to install the solar panels. The vertical farm is a paradox unless fossil fuels provide the energy. In that case, there’s not much sustainable about it. This entire piece is based on the assumption that the only sources of…
Yeah, don’t bother with reading articles that exclude the largest source of clean energy in US. Such articles have an ideological bias.
Artificial lighting saves land because plants can be grown above each other, but if the electricity for the lighting comes from solar panels, then the savings are canceled out by the land required to install the solar panels. The vertical farm is a paradox unless fossil fuels provide the energy. In that case, there’s not much sustainable about it. This entire piece is based on the assumption that the only sources of…
Way overshooting the confidence on fusion here.
Vertical farming mostly feels like a solution in search of a problem. It uses relatively expensive technology to produce low-value products. Putting seeds in the ground, tilling, and waiting is absurdly cheap compared to building growhouses. For some perspective, what farms actually do extend growing seasons is put "greenhouses" around cold-sensitive crops like tomatoes, but a "greenhouse" in this case is a wire hoop…
Vertical farming optimizes water and transport.
I admit that I'm not entirely convinced about vertical farming, but I'm confident it has a future. I'm still curious about using leds and yield.
Earlier quoted context omitted.
1. We have nuclear waste already 2. We will continue to have nuclear waste if we want to have nuclear weapons 3. You can store all the waste you need to store in a football field ( https://www.energy.gov/ne/articles/5-fast-facts-about-spent-... ) Nuclear waste management is messy, but it's something we need to solve no matter what. It is now a sunk cost we have to deal with because of what we have already done and wh…
Rarely does one hear the sunk cost fallacy advocated so enthusiastically.
Earlier quoted context omitted.
The problem with talking about photosynthetic efficiency is that there are different endpoints you can talk about. The more efficient plants (C4 plants like sugarcane and maize) have something like 4% efficiency converting sunlight to biomass, but they actually absorb a 53% of the incoming light based on spectrum, and lose about 24% of the energy because photons with shorter wavelengths have excess energy which the p…
> It’s worth remembering that the reason why plants only absorb certain parts of the spectrum is the same reason why photovoltaic panels only absorb certain parts of the spectrum Plants are green because they value light consistency instead of total energy . Green light has too many peaks and valleys and can overload the photosynthesis systems so they reflect a lot of it. It's the "renewables without batteries" probl…
This doesn’t make any sense to me. Why would peaks and valleys overload something? Why would green light have more peaks and valleys?
I was a bit sloppy with the way I phrased that—what I really meant was “the reason why plants use specific quanta of light is the same reason why photovoltaics absorb specific quanta of light” but I didn’t put much thought into how worded it.
Plants absorb light near two different spectral peaks. This is not entirely dissimilar to the idea of a multijunction photovoltaic cell. The color of light between the two peaks is green.
Earlier quoted context omitted.
> lot of land that isn't suitable for farming We're talking about powering a hydroponic greenhouse. The alternative to "Solar Powered LEDs" isn't "plant things in the ground". Its "make a glass window on your roof". -------- "Plant things in the ground" is also cheaper, though it does suffer from potentially poor soil conditions. Still, it seems to me that spreading fertilizer across soil (and conditioning the soil i…
> lot of land that isn't suitable for farming > We're talking about powering a hydroponic greenhouse. The alternative to "Solar Powered LEDs" isn't "plant things in the ground". Its "make a glass window on your roof". I think what they were getting at is that you can take land wholly unsuitable for farming or greenhouses (e.g. severe slopes), apply solar panels, and then funnel that energy to a vertical farm. Since t…
I severely doubt that.
Solar panels are maybe 30% efficient. So 10-acres of glass-roofs need to be replaced by 30-acres of solar panels just to account for this inefficiency (let alone other inefficiencies: such as wiring, inverter, batteries, and LEDs). Maybe 50-acres of solar panels to be anywhere close to comparable against 10-acres of glass roofs once we include other inefficiencies.
