Vertical farming - Revision history

Elie at 00:03, 14 April 2025

2025-04-14T00:03:58Z

← Older revision		Revision as of 20:03, 13 April 2025
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	==See also==		==See also==
	* [[Food]] - a general overview, including better solutions for feeding the world.		* [[Food]] - a general overview, including better solutions for feeding the world.

			==External links==
			[https://solar.lowtechmagazine.com/2021/02/vertical-farming-does-not-save-space/ Vertical Farming Does not Save Space]

Elie: /* But what if the energy came from renewables? */

2023-09-02T02:43:40Z

But what if the energy came from renewables?

← Older revision		Revision as of 22:43, 1 September 2023
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	Uranium is far too scarce to power the grow lights with [[nuclear\|nuclear fission]]. Maybe [[fusion]] power could do it someday. Until then, vertical farming is just a bad idea.		Uranium is far too scarce to power the grow lights with [[nuclear\|nuclear fission]]. Maybe [[fusion]] power could do it someday. Until then, vertical farming is just a bad idea.

			====But solar panels could be on non-arable land?====
			So could [[greenhouses]] (which would use the non-arable land more efficiently compared to laying down solar panels to power vertical farms). {{x\|In the case of desert, maybe it's too hot for greenhouses, but it's also too hot for vertical farms (and too far away for power lines to reach, if the vertical farms are in non-desert areas).}}

	=====But doesn't it take energy to ship food from farm to city?=====		=====But doesn't it take energy to ship food from farm to city?=====

Elie at 22:22, 12 March 2023

2023-03-12T22:22:10Z

← Older revision		Revision as of 18:22, 12 March 2023
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	[[File:vertical-farm-1.jpg\|thumb]]		[[File:vertical-farm-1.jpg\|thumb\|Inside a vertical farm]]
	Vertical farming is the idea that [[food]] could be grown in ~~tall towers~~ with multiple floors~~, which~~ is supposed to save space and use less [[land]] - thus saving more of the environment - but on close examination we see that it doesn't.		Vertical farming is the idea that [[food]] could be grown in buildings with multiple floors/levels. This is supposed to save space and use less [[land]] (thus saving more of the environment) but on close examination we see that it doesn't.

	==Not a solution to feed the world==		==Not a solution to feed the world==
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	<small>		<small>
	To convert...		To convert...<br />
	: sunlight → electricity → back to light again		&emsp;sunlight → electricity → back to light again<br />
	can never be as efficient as...		can never be as efficient as...<br />
	: just using the sunlight directly.		&emsp;just using the sunlight directly.
	</small>		</small>

	The land requirements for [[wind]] power would be even higher. Keep in mind that wind power is still indirectly a kind of solar power: winds are caused by the sun heating the air.		The land requirements for [[wind]] power would be even higher. Keep in mind that wind power is still indirectly a kind of solar power: winds are caused by the sun heating the air.

	Uranium is far too scarce to power the grow lights with [[nuclear]] ~~fission~~. Maybe [[fusion]] power could do it someday. Until then, vertical farming is just a bad idea.		Uranium is far too scarce to power the grow lights with [[nuclear\|nuclear fission]]. Maybe [[fusion]] power could do it someday. Until then, vertical farming is just a bad idea.

	=====But doesn't it take energy to ship food from farm to city?=====		=====But doesn't it take energy to ship food from farm to city?=====

Elie: Elie moved page Draft:Vertical farming to Vertical farming without leaving a redirect: Published

2023-03-12T22:07:51Z

Elie moved page Draft:Vertical farming to Vertical farming without leaving a redirect: Published

← Older revision	Revision as of 18:07, 12 March 2023
(No difference)

Elie: /* See also */

2023-03-12T21:58:48Z

Elie at 21:55, 12 March 2023

2023-03-12T21:55:40Z

← Older revision		Revision as of 17:55, 12 March 2023
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	[[File:vertical-farm-1.jpg\|thumb]]		[[File:vertical-farm-1.jpg\|thumb]]
	Vertical farming is the idea that [[food]] could be grown in tall towers with multiple floors, which is supposed to save space and use less [[land]] (thus saving more of the environment), but on close examination we see that it doesn't.		Vertical farming is the idea that [[food]] could be grown in tall towers with multiple floors, which is supposed to save space and use less [[land]] - thus saving more of the environment - but on close examination we see that it doesn't.

	==Not a solution to feed the world==		==Not a solution to feed the world==
Line 10:		Line 10:

	{{dp		{{dp
	\|~~photosynthesis~~.~~spectrum_of_sun~~		\|sunlight.visible_fraction
	\|		\|43%
	\|How much of the sun's energy spectrum can ~~plants~~ use for photosynthesis		\|How much of the sun's energy is in the visible part of the frequency spectrum
	~~\|By factoring~~ this in, we'~~re being very charitable~~ to ~~vertical farming~~, by ~~assuming~~ the LED ~~lights~~ (~~unlike sunlight~~) ~~are entirely frequencies~~ of ~~light~~ that ~~plants use~~.		\|[https://sos.noaa.gov/catalog/datasets/climatebits-solar-radiation/ ClimateBits: Solar Radiation - Science On a Sphere - NOAA]
			}}
			{{dp
			\|sunlight.photosynthesis_fraction
			\|sunlight.visible_fraction
			\|How much of the sun's energy is in the "photosynthesis-friendly" part of the frequency spectrum
			\|We factor this into the equation because we assume that grow-lights are targeted at the frequencies that plants can use most efficiently for photosynthesis.<br />
			<br />Due to lack of data, we have to assume this is roughly equal to the 'visible light' fraction of sunlight.
			<br />Plants may somewhat make use of infrared as well, but this is offset by their lower utilization of green light (which isn't ''that much'' lower (according to [http://www.esalq.usp.br/lepse/imgs/conteudo_thumb/Which-regions-of-the-electromagnetic-spectrum-do-plants-use-to-drive-photosynthesis.pdf this source]) - as long as the plant has enough leaves, it will still ultimately absorb most of the green light it receives).
			}}
			{{dp
			\|<nowiki>crop_land</nowiki>
			\|<nowiki>15000000 km^2</nowiki>
			\|<nowiki>Agricultural land used for growing crops - global total</nowiki>
			\|<nowiki>https://ourworldindata.org/land-use</nowiki>
			}}
			{{dp
			\|<nowiki>sunlight_average</nowiki>
			\|<nowiki>200 watts per m^2</nowiki>
			\|<nowiki>Solar irradiance, averaged over a whole year INCLUDING nights, cloudy days, etc.</nowiki>
			\|<nowiki>Note: This varies by region.</nowiki><br /><nowiki>
			https://www.newport.com/t/introduction-to-solar-radiation</nowiki><br /><nowiki>
			http://www.ftexploring.com/solar-energy/insolation.htm</nowiki>
			}}
			{{dp
			\|<nowiki>solar_panel.efficiency</nowiki>
			\|<nowiki>17%</nowiki>
			\|<nowiki>Efficiency of an average solar panel</nowiki>
			\|<nowiki>Some solar panels are more efficient than this, but they tend to be expensive and contain more rare metals.</nowiki>
			}}
			{{dp
			\|<nowiki>led.efficiency</nowiki>
			\|<nowiki>58%</nowiki>
			\|<nowiki>Energy-efficiency of a typical LED light</nowiki>
			\|<nowiki>Kusuma, P., Pattison, P.M. & Bugbee, B. From physics to fixtures to food: current and potential LED efficacy. Hortic Res 7, 56 (2020). https://doi.org/10.1038/s41438-020-0283-7</nowiki><br /><nowiki>
			https://www.nature.com/articles/s41438-020-0283-7</nowiki><br /><nowiki>
			</nowiki><br /><nowiki>
			"Blue LEDs are now 93% efficient, phosphor-converted “whites” are 76% efficient, and reds are 81% efficient when run at the near-optimal conditions of 100 mA mm−2 and a junction temperature of 25 °C."</nowiki><br /><nowiki>
			...but then...</nowiki><br /><nowiki>
			"Typical fixture efficacy</nowiki><br /><nowiki>
			Using more typical parameters:</nowiki><br /><nowiki>
			1. Drive current achieves 90% of the reported LED efficacy.</nowiki><br /><nowiki>
			2. Temperature management achieves 90% of the reported LED efficacy (at 25 °C).</nowiki><br /><nowiki>
			3. The LED driver is 90% efficient.</nowiki><br /><nowiki>
			4. Protected LEDs in the fixture achieve 92% optical efficiency.</nowiki><br /><nowiki>
			The resulting fixture efficacy would be 0.90 × 0.90 × 0.90 × 0.90 = 67% of the reported efficacy of the LEDs."</nowiki><br /><nowiki>
			</nowiki><br /><nowiki>
			I decided to average 'ideal' red & blue efficiencies, and then multiply by the 'real world' stuff. Result: 58%</nowiki>
			}}
			{{dp
			\|<nowiki>energy.tfc</nowiki>
			\|<nowiki>9937.70 Mtoe/year</nowiki>
			\|<nowiki>Global energy usage - total final consumption (TFC)</nowiki>
			\|<nowiki>Includes: fuel (80.7%) + electricity (19.3%) AFTER it is generated.</nowiki><br /><nowiki>
			</nowiki><br /><nowiki>
			Does not include the fuel used in generating electricity. See [energy.tes] for that.</nowiki><br /><nowiki>
			</nowiki><br /><nowiki>
			Citation: "Key World Energy Statistics 2020" IEA</nowiki><br /><nowiki>
			- Page 47 - Simplified energy balance table - World energy balance, 2018</nowiki>
	}}		}}
	{{calc		{{calc
	\|crop_land * sunlight_average * ~~solar_panel~~.efficiency * led.efficiency ~~/ photosynthesis.spectrum_of_sun~~		\|crop_land * sunlight_average * sunlight.photosynthesis_fraction / led.efficiency
	\|energy.tfc		\|energy.tfc
	}}		}}

	In other words, we would need _ times more energy than the world currently consumes!		In other words, we would need '''168 times''' more energy than the world currently consumes!

	Since most energy currently comes from fossil fuels, this would be disastrous for the environment.		Since most energy currently comes from fossil fuels, this would be disastrous for the environment.

	=====But what if the energy came from renewables?=====		=====But what if the energy came from renewables?=====
	We already have a [[energy#Limits to other energy sources\|hard enough time scaling up renewables]] - but let's imagine it was easy. Still, vertical farms would defeat their entire purpose: They wouldn't save land.		We already have a [[energy#Limits to other energy sources\|hard enough time scaling up renewables]] - but let's imagine it was easy. Still, vertical farms would defeat their entire purpose: They '''wouldn't save land.'''

	<!-- The amount of land needed for [[solar]] panels would vastly outweigh the amount of crop land saved. -->		<!-- The amount of land needed for [[solar]] panels would vastly outweigh the amount of crop land saved. -->
	{{calc		{{calc
	\|~~photosynthesis~~.~~spectrum_of_sun~~ / led.efficiency / solar_panel.efficiency		\|sunlight.photosynthesis_fraction / led.efficiency / solar_panel.efficiency
	\|		\|
	}}		}}
	In other words, to grow an acre worth of plants{{x\|and I'm not talking about the footprint of the building. By "grow an acre worth of plants", I mean for example having a 1/8 acre building with 8 storeys}}, you would need over _ acres of solar panels!		In other words, to grow an acre worth of plants{{x\|and I'm not talking about the footprint of the building. By "grow an acre worth of plants", I mean for example having a 1/8 acre building with 8 storeys}}, you would need over '''4''' acres of solar panels!

	<small>		<small>

Elie: Created page with "thumb Vertical farming is the idea that food could be grown in tall towers with multiple floors, which is supposed to save space and use less land (thus saving more of the environment), but on close examination we see that it doesn't. ==Not a solution to feed the world== ===Powering the grow lights=== Natural sunlight is proportional to land{{x|Sure, technically you could argue that a tall building captures more sun than the land..."

2023-03-12T20:22:01Z

Created page with "thumb Vertical farming is the idea that food could be grown in tall towers with multiple floors, which is supposed to save space and use less land (thus saving more of the environment), but on close examination we see that it doesn't. ==Not a solution to feed the world== ===Powering the grow lights=== Natural sunlight is proportional to land{{x|Sure, technically you could argue that a tall building captures more sun than the land..."

New page

[[File:vertical-farm-1.jpg|thumb]]
Vertical farming is the idea that [[food]] could be grown in tall towers with multiple floors, which is supposed to save space and use less [[land]] (thus saving more of the environment), but on close examination we see that it doesn't.

==Not a solution to feed the world==
===Powering the grow lights===
Natural sunlight is proportional to [[land]]{{x|Sure, technically you could argue that a tall building captures more sun than the land it sits on, but that's just because it obscures the sun on the land beside it.}}. In vertical farms, the amount of real sun is quite limited. Grow-lights are needed:

====Thought experiment====
If all crops were grown in vertical farms, how much [[energy]] would be needed to power all the grow lights?

{{dp
|photosynthesis.spectrum_of_sun
|
|How much of the sun's energy spectrum can plants use for photosynthesis
|By factoring this in, we're being very charitable to vertical farming, by assuming the LED lights (unlike sunlight) are entirely frequencies of light that plants use.
}}
{{calc
|crop_land * sunlight_average * solar_panel.efficiency * led.efficiency / photosynthesis.spectrum_of_sun
|energy.tfc
}}

In other words, we would need _ times more energy than the world currently consumes!

Since most energy currently comes from fossil fuels, this would be disastrous for the environment.

=====But what if the energy came from renewables?=====
We already have a [[energy#Limits to other energy sources|hard enough time scaling up renewables]] - but let's imagine it was easy. Still, vertical farms would defeat their entire purpose: They wouldn't save land.


{{calc
|photosynthesis.spectrum_of_sun / led.efficiency / solar_panel.efficiency
|
}}
In other words, to grow an acre worth of plants{{x|and I'm not talking about the footprint of the building. By "grow an acre worth of plants", I mean for example having a 1/8 acre building with 8 storeys}}, you would need over _ acres of solar panels!

<small>
To convert...
: sunlight → electricity → back to light again
can never be as efficient as...
: just using the sunlight directly.
</small>

The land requirements for [[wind]] power would be even higher. Keep in mind that wind power is still indirectly a kind of solar power: winds are caused by the sun heating the air.

Uranium is far too scarce to power the grow lights with [[nuclear]] fission. Maybe [[fusion]] power could do it someday. Until then, vertical farming is just a bad idea.

=====But doesn't it take energy to ship food from farm to city?=====
Yes. Just nowhere near as much as what vertical farming would take.

=====But what about shade crops?=====
Shade crops could already be [[polyculture|grown in the shade of full-sun crops]]. Most of the crops that feed the world require full sunlight. This is because calories & protein require [[energy]] in the form of light shining on the plants.

There might be a very small niche for growing low-calorie greens in vertical farms in the city, just so people can enjoy herbs at their absolute freshest.

==Cases where vertical farming might actually be a good idea==
===Growing mushrooms===
[[Mushrooms]] don't get their energy from the sun - they get their energy from fiber. Since food crops have [[biomass waste|inedible fibrous parts]], there is plenty of material to cultivate mushrooms on. Mushrooms could be grown in tall buildings or deep basements with no light at all.
===Disambiguation===
Some people use the term "vertical farming" to refer to something different: a rich layered [[polyculture]] - no multi-storey buildings involved. This type of "vertical farming" actually has good potential to feed the world.

==See also==
* [[Food]] - a general overview, including better solutions to feeding the world.

← Older revision		Revision as of 17:58, 12 March 2023
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	==See also==		==See also==
	* [[Food]] - a general overview, including better solutions to feeding the world.		* [[Food]] - a general overview, including better solutions for feeding the world.