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Thu Feb 18, 2021, 07:32 PM

Vertical Farming Does Not Save Space

If the electricity for a vertical farm is supplied by solar panels, the energy production takes up at least as much space as the vertical farm saves.


The paradox of vertical farming
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.

Calculated at a yield of 175 kilowatt-hours per square meter of solar panel per year, the indoor cultivation of 1 m2 of wheat requires 20 m2 of solar panels. This is a underestimate because the calculations are based on the average yield of a solar panel. There is much less sunlight in winter than in summer. In reality, the vertical farm requires many more solar panels to keep operating all year round. There is also a need for an energy storage infrastructure, which costs money and energy too. Finally, solar panels’ production also requires energy, which would demand even more space if the production process itself were to run on solar panels.

All this criticism also applies to vertical farms where lettuce and tomatoes are grown. In this case, there is a significant reduction in water use. These companies are profitable, but only because the process relies on a supply of cheap fossil fuels. If solar panels supplied the energy, the extra costs and space for the energy supply would again cancel out the savings in terms of space and costs. The only advantage of a vertical farm would then be the shorter transport distances. Still, we could just as well make transport between town and countryside more sustainable.

The problem with agriculture is not that it happens in the countryside. The problem is that it relies heavily on fossil fuels. The vertical farm is not the solution since it replaces, once again, the free and renewable energy from the sun with expensive technology that is dependent on fossil fuels (LED lamps + computers + concrete buildings + solar panels). Our lifestyle is becoming less and less sustainable, increasingly dependent on raw materials, infrastructure, machines, and fossil energy. Unfortunately, this also applies to almost all technology that we nowadays label sustainable.


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Reply Vertical Farming Does Not Save Space (Original post)
Klaralven Feb 18 OP
Laelth Feb 18 #1
Binkie The Clown Feb 18 #2
GeorgeGist Feb 18 #3

Response to Klaralven (Original post)

Thu Feb 18, 2021, 07:55 PM

1. k&r for visibility. n/t


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Response to Klaralven (Original post)

Thu Feb 18, 2021, 08:03 PM

2. It makes sense.

Use sunlight directly, or convert it to electricity and then back to light with loss of efficiency in each of those steps.

With solar cells have a 15% to 20% efficiency, even if LED lamps were 100% efficient you still lose 80% to 85% of the original sunlight.

However, if vertical farms were to be built in places where regular farming is not possible, such as deserts, rocky or sandy soils, or even on barges out at sea, then it might be a better use of marginal land/sea, even if it is less efficient than is might theoretically have been if the region had been able to support agriculture

Another alternative would be to use mirrors to direct sunlight into the vertical farms directly with no conversion to electricity and back again.

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Response to Klaralven (Original post)

Thu Feb 18, 2021, 08:36 PM

3. One of the better comments, IMO ...

This criticism relies upon the false dichotomy of power coming from either solar or fossil fuels. Wind, tidal, or even nuclear avoids that issue. Furthermore even if powered with solar panels those panels do not need to be placed on fertile farmland, so there need not be a substitution.

Pertaining to the selection of crops, vertical farming does not need to grow every crop to be valuable. Farmland currently growing tomatoes or cucumbers could be switched to growing grains as those fruits are grown in vertical farms. Vertical farming would allow growing more grains and legumes on cropland currently devoted to cucumbers and peppers, significantly increasing the amount of land available for staple crops even if staple crops cannot currently be grown in vertical farms.

Distance is not the only consideration in transportation. Bulk goods like grains are not as perishable as cucumbers - logistics becomes much simpler when costly refrigeration and rapid transport is no longer a significant concern. If delicate perishables are grown in cities while only shelf-stable bulk goods are shipped in then the savings goes far beyond simple distance.

On a more speculative note, I would not expect staple crops to ever be grown in cities even in vertical farms. If bulk food production needs to be shifted into urban areas it would likely be in the use of large bioreactors for nutrient production while crops in vertical farms will still only be high-value fruits and herbs.

Posted by: Edmond | February 18, 2021 at 11:11 PM

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