File:solar-land-requirements.png - Revision history

Conversion script: Conversion script moved page File:Solar-land-requirements.png to File:solar-land-requirements.png: Converting page titles to lowercase

2022-08-26T19:47:23Z

Conversion script moved page File:Solar-land-requirements.png to File:solar-land-requirements.png: Converting page titles to lowercase

← Older revision	Revision as of 15:47, 26 August 2022
(No difference)

Elie: /* Would your city need solar farms? */

2022-08-07T07:45:33Z

Would your city need solar farms?

← Older revision		Revision as of 03:45, 7 August 2022
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	Simple heuristic:		Simple heuristic:
	* If your city's ''population density'' is greater than ~~the~~ number above, then yes.		* If your city's ''population density'' is greater than this number above, then yes.
	* Otherwise, all energy could be generated within the city (rooftops, probably).		* Otherwise, all energy could be generated within the city (rooftops, probably).

	But this is be an oversimplification.~~<br />~~		But this is an oversimplification. Some things to consider:
	Some things to consider:
	* Every city defines its borders differently - this could bias the official stats of "population density".		* Every city defines its borders differently - this could bias the official stats of "population density".
	* If [[factories]] are in some industrial area outside the city, their solar panels could be there instead.		* If [[factories]] are in some industrial area outside the city, their solar panels could be there instead.

Elie: /* Methodology */

2022-08-07T07:19:39Z

Methodology

← Older revision		Revision as of 03:19, 7 August 2022
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	==Methodology==		==Methodology==

	~~Land~~ required for solar panels, if		Area required for solar panels, if
	* all energy came from solar photovoltaics, and		* all energy came from solar photovoltaics, and
	* everyone on Earth lived a "first-world" lifestyle.		* everyone on Earth lived a "first-world" lifestyle.
Line 116:		Line 116:

	Divide this by the Earth's surface (510072000 km^2), and you get '''0.8%'''.		Divide this by the Earth's surface (510072000 km^2), and you get '''0.8%'''.





	==Would your city need [[solar farms]]?==		==Would your city need [[solar farms]]?==

Elie at 07:18, 7 August 2022

2022-08-07T07:18:51Z

← Older revision		Revision as of 03:18, 7 August 2022
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	Map projection: equirectangular		Map projection: equirectangular

	Not counted in this map: The land that would be needed for {{p2\|extracting the minerals\|you can [[Talk:minerals\|help calculate this]] - analyze your favorite battery chemistry and solar panel chemistry}} needed to make both the solar panels and [[energy storage]].

	{{dp		{{dp
Line 145:		Line 143:

	If we want something really accurate, we might have to analyze things on a city-by-city basis.		If we want something really accurate, we might have to analyze things on a city-by-city basis.

			Not counted in this map: The land that would be needed for {{p2\|extracting the minerals\|you can [[Talk:minerals\|help calculate this]] - analyze your favorite battery chemistry and solar panel chemistry}} needed to make both the solar panels and [[energy storage]].

Elie at 07:14, 7 August 2022

2022-08-07T07:14:57Z

← Older revision		Revision as of 03:14, 7 August 2022
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	\|<nowiki>20%</nowiki>		\|<nowiki>20%</nowiki>
	\|<nowiki>How much of the land is suitable for placing solar panels</nowiki>		\|<nowiki>How much of the land is suitable for placing solar panels</nowiki>
	\|<nowiki>We're trying to keep the solar panels as close to humans as possible - including on city land. But cities have limited space to put solar panels - in general, rooftops are the way to go. An educated guess says that rooftops are about 20% of city land. 20% is also a good compromise outside the city - you don't want to block out all the sun in the ecosystems.</~~nowiki><br /><~~nowiki>		\|<nowiki>We're trying to keep the solar panels as close to humans as possible - including on city land. But cities have limited space to put solar panels - in general, rooftops are the way to go. An educated guess says that rooftops are about 20% of city land. 20% is also a good compromise outside the city - you don't want to block out all the sun in the ecosystems.</nowiki>
	}}		}}

Line 78:		Line 78:

	# load files		# load files
	pop << data/population.data-float64-8640x4320		pop << data/[[:File:population.data-float64-8640x4320\|population.data-float64-8640x4320]]
	earth << data/blue-marble-posterized.png		earth << data/[[:File:blue-marble-posterized.png\|blue-marble-posterized.png]]

	# convert 'pop' to population density (people per km^2)		# convert 'pop' to population density (people per km^2)
	pop @@ quantity_to_density		pop @@ quantity_to_density

	# resize 'pop' to fit the 'earth' background		# resize 'pop' to fit the 'earth' background
	pop :: earth.r		pop :: earth.r

	# make 'pop' represent "for each pixel, what fraction of the land is solar land"		# make 'pop' represent "for each pixel, what fraction of the land is solar land"
	pop *= 0.~~00053790025~~ # km^2 per person needed for solar		pop *= 0.00053790026 # km^2 per person needed for solar
	pop @@ spread		pop @@ spread

	# darken the background		# darken the background
	earth.r *= 0.5		earth.r *= 0.5
	earth.g *= 0.5		earth.g *= 0.5
	earth.b *= 0.5		earth.b *= 0.5

	# show the solar land in white		# show the solar land in white
	earth.r += pop		earth.r += pop
Line 103:		Line 103:
	earth.g <= 1		earth.g <= 1
	earth.b <= 1		earth.b <= 1

	# save		# save
	earth >> data/solar-land-requirements.png		earth >> data/solar-land-requirements.png
Line 115:		Line 115:
	From the "stats" output from the last line:		From the "stats" output from the last line:
	Sum: 4293152.303951		Sum: 4293152.303951
	This means there is ~~8575041~~ km^2 of solar land.		This means there is 4293152 km^2 of solar land.

	Divide this by the Earth's surface (510072000 km^2), and you get '''0.8%'''.		Divide this by the Earth's surface (510072000 km^2), and you get '''0.8%'''.
Line 124:		Line 124:

	==Would your city need [[solar farms]]?==		==Would your city need [[solar farms]]?==
	{{calc\|		{{calc
	\|solar_land_per_capita		\|1 / solar_land_per_capita
	\|people per km^2		\|people per km^2
	}}		}}
Line 133:		Line 133:
	* Otherwise, all energy could be generated within the city (rooftops, probably).		* Otherwise, all energy could be generated within the city (rooftops, probably).

	But this is ~~a gross~~ oversimplification.<br />		But this is be an oversimplification.<br />
	Some things to consider:		Some things to consider:
	* Every city defines its borders differently - this could bias the official stats of "population density".		* Every city defines its borders differently - this could bias the official stats of "population density".
	* If [[factories]] are in some industrial area outside the city, their solar panels could be there instead.		* If [[factories]] are in some industrial area outside the city, their solar panels could be there instead.
	* ~~And also...~~		* Other factors, shown in the next section:


	==Limitations of this analysis==		==Limitations of this analysis==

Elie: World map: If all energy came from solar panels, how much land would we need? The land is shown in white. We would need approximately 0.8% of Earth's surface. Just for comparison, crop land is about 2.9% of Earth's surface, and pasture land is about 5.4% of Earth's surface. ==Methodology== Land required for solar panels, if * all energy came from solar photovoltaics, and * everyone on Earth lived a "first-world" lifestyle. Map projection: equirectangular Not counted in...

2022-08-07T06:59:23Z

World map: If all energy came from solar panels, how much land would we need? The land is shown in white. We would need approximately 0.8% of Earth's surface. Just for comparison, crop land is about 2.9% of Earth's surface, and pasture land is about 5.4% of Earth's surface. ==Methodology== Land required for solar panels, if * all energy came from solar photovoltaics, and * everyone on Earth lived a "first-world" lifestyle. Map projection: equirectangular Not counted in...

New page

== Summary ==
World map: If all energy came from solar panels, how much land would we need?

The land is shown in white.

We would need approximately 0.8% of Earth's surface.

Just for comparison, crop land is about 2.9% of Earth's surface, and pasture land is about 5.4% of Earth's surface.

==Methodology==

Land required for solar panels, if
* all energy came from solar photovoltaics, and
* everyone on Earth lived a "first-world" lifestyle.

Map projection: equirectangular

Not counted in this map: The land that would be needed for {{p2|extracting the minerals|you can [[Talk:minerals|help calculate this]] - analyze your favorite battery chemistry and solar panel chemistry}} needed to make both the solar panels and [[energy storage]].

{{dp
|<nowiki>oecd.energy.tfc</nowiki>
|<nowiki>3784.37 Mtoe/year</nowiki>
|<nowiki>OECD countries - energy usage - total final consumption</nowiki>
|<nowiki>Key World Energy Statistics 2020 (IEA report)</nowiki> <nowiki>
- Page 49: OECD energy balance, 2018</nowiki>
}}
{{dp
|<nowiki>oecd.population</nowiki>
|<nowiki>1372683615</nowiki>
|<nowiki>Number of people living in OECD countries</nowiki>
|<nowiki>Population, total - World Bank Data</nowiki> <nowiki>
data.worldbank.org › indicator › SP.POP.TOTL </nowiki> <nowiki>
</nowiki> <nowiki>
Using data from 2020</nowiki> <nowiki>
</nowiki> <nowiki>
OECD countries are: Austria, Australia, Belgium, Canada, Chile, Colombia, Costa Rica, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Israel, Italy, Japan, Korea, Latvia, Lithuania, Luxembourg, Mexico, the Netherlands, New Zealand, Norway, Poland, Portugal, Slovak Republic, Slovenia, Spain, Sweden, Switzerland, Turkey, the United Kingdom and the United States.</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>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> <nowiki>
https://www.newport.com/t/introduction-to-solar-radiation</nowiki> <nowiki>
http://www.ftexploring.com/solar-energy/insolation.htm</nowiki>
}}
{{dp
|<nowiki>area_suitable</nowiki>
|<nowiki>20%</nowiki>
|<nowiki>How much of the land is suitable for placing solar panels</nowiki>
|<nowiki>We're trying to keep the solar panels as close to humans as possible - including on city land. But cities have limited space to put solar panels - in general, rooftops are the way to go. An educated guess says that rooftops are about 20% of city land. 20% is also a good compromise outside the city - you don't want to block out all the sun in the ecosystems.</nowiki> <nowiki>
}}

First we estimate how much energy would be needed per person: {{p|this is a conservative overestimate. People in warm climates might actually need slightly less energy because they don't need [[heating]]. The difference is not a lot though}}
{{calc
|oecd.energy.tfc / oecd.population
|kWh/year
|energy_per_capita
}}

Then we estimate how much area that would take
{{calc
|energy_per_capita / (area_suitable * sunlight_average * solar_panel.efficiency)
|km^2
|solar_land_per_capita
}}

Now we use that to generate an [[isochromic]] map:

[[Code:isochromic.c|Image generator]] code:

# load files
pop << data/population.data-float64-8640x4320
earth << data/blue-marble-posterized.png

# convert 'pop' to population density (people per km^2)
pop @@ quantity_to_density

# resize 'pop' to fit the 'earth' background
pop :: earth.r

# make 'pop' represent "for each pixel, what fraction of the land is solar land"
pop *= 0.00053790025 # km^2 per person needed for solar
pop @@ spread

# darken the background
earth.r *= 0.5
earth.g *= 0.5
earth.b *= 0.5

# show the solar land in white
earth.r += pop
earth.g += pop
earth.b += pop
earth.r <= 1
earth.g <= 1
earth.b <= 1

# save
earth >> data/solar-land-requirements.png

# How much solar land is needed in total?
pop @@ density_to_quantity # make 'pop' represent "for each pixel, how many km^2 of solar land"
pop @@ stats

From the "stats" output from the last line:
Sum: 4293152.303951
This means there is 8575041 km^2 of solar land.

Divide this by the Earth's surface (510072000 km^2), and you get '''0.8%'''.

==Would your city need [[solar farms]]?==
{{calc|
|solar_land_per_capita
|people per km^2
}}

Simple heuristic:
* If your city's ''population density'' is greater than the number above, then yes.
* Otherwise, all energy could be generated within the city (rooftops, probably).

But this is a gross oversimplification. 
Some things to consider:
* Every city defines its borders differently - this could bias the official stats of "population density".
* If [[factories]] are in some industrial area outside the city, their solar panels could be there instead.
* And also...

==Limitations of this analysis==
* Not all cities have the same <code>area_suited</code> for solar panels.
* Solar panel output varies by latitude.
* Energy requirements for [[heating]] depend on latitude.

If we want something really accurate, we might have to analyze things on a city-by-city basis.