6 ms·

Can anyone explain the assertion that “we’ll run out of land before ever can put in enough solar”. I’ve seen a lot of articles and interviews that say that, but

by doitLP 4y ago

Can anyone explain the assertion that “we’ll run out of land before ever can put in enough solar”. I’ve seen a lot of articles and interviews that say that, but then a whole bunch that don’t even mention the high amount of land use and seem to think that’s not a problem. Any explanation or good articles would be helpful.

deleted 4y ago
[deleted]
kQq9oHeAz6wLLS 4y ago
I don't have much to add here, other than a lot of land isn't suitable for solar. From not enough light to too much heat, there's less available land than you'd think.
- ncmncm 4y ago
  Yet, far, far more is available than could ever be needed. Orders of magnitude more.
- elihu 4y ago
  There's also a lot of land that is suitable for solar that is too dry or the soil too poor to be suitable for agriculture.
standardUser 4y ago
There's vastly more land than is needed for any reasonable mix of solar in a post-carbon world. There's just also lots of speculative and unreasonable scenarios one can dream up if they want to argue otherwise.
- ncmncm 4y ago
  As Hamlet said, "It's as easy as lying."
Aachen 4y ago
OWID says 19–13m²/MWh depending on the panel type, no idea for which location but let's go with 15 m² for a rough idea. We need about 900 TWh of energy in the country. A calculator tells me that's $ calc 900TWh/MWh\*(15m^2) (900 \* ((terawatt \* hour) / (megawatt \* hour))) \* (15 \* (meter^2)) = 13500 km^2 The country is about 42000 km² big. We won't want to get 100% of energy from photovoltaic, but also we'll need overcapacity to compensate for losses in storage and, to a lesser extent, transmission. Presumably, the land is currently not unused. I don't know what area is currently used by roofs and parking lots, that would be interesting to put this in perspective. I was under the impression that roofs are not enough by far; perhaps it works when we add parking lots and cover all roads, or perhaps my knowledge is outdated (also because batteries have evolved since I first heard that). Either way, we'd have to cover gigantic amounts of land with electronics. Not saying it can't be done (I don't know enough about it), but not having any hydro to speak of, little space far enough from villages for wind, and no nuclear in the mix for the sake of argument... it sure seems daunting.
- danielheath 4y ago
  > The country is about 42000 km² big It's not clear which country you're talking about; land area of the USA is 9.8 million km². Melbourne (Australia) is a moderately large city of just under 10,000 km² in area. I'd (very conservatively) estimate at least 10% of that is roof space, so 1000 km² of roof-mounted panels seems pretty achievable. Global electricity consumption (averaged over the year of 2019) is approx 2.7 terawatts (per statistica.com). Lets call it 100 terawatts (storage losses, switching oil heaters to electricity). It's straightforward to get 1 kilowatt per square meter from a solar panel, so you'd need about 100k km² of solar panels globally. That's the rooflines of 100 cities the size of Melbourne.
  - Aachen 4y ago
    > It's not clear which country you're talking about; land area of the USA is... You assume that when someone just speaks of "the country" without specifying, it's the place where people think they're the whole world. I left it out to see if exactly this would happen because I was curious. I'm surprised not one but two persons felt certain enough I must mean the USA to correct my figure for the USA in a comment. Goes to show. My username is a city in Germany but apparently that wasn't enough of a hint that it is, for once, not about the USA. Also the USA uses double the energy per capita and has twenty times more people, 900 TWh should also be a giveaway for those who know any country's energy consumption, or at least it was easy to check that I didn't merely take a wrong km² value (also, I'm using metric). Anyway, I'm glad we can supply global energy consumption this way. Now we just need a global government to distribute the produced energy to countries with higher population densities than the extreme examples you took like USA and Australia. That they can use solar effectively, both from the amount of unused land and favorable latitude, shouldn't surprise anyone. Oddly (no sarcasm here), I don't see them getting around to it either. I just looked up the landuse of my country and that's about 7% built-up area. https://www.clo.nl/en/indicators/en0061-land-use-in-the-netherlands https://www.clo.nl/en/indicators/en0061-land-use-in-the-neth... Even if we cover all of that, it's not enough, we'll need to take land away from agriculture which is already only barely enough to feed everyone in a pinch despite having a huge yield per unit area. Which is not to say we shouldn't do it. I just realized I might come across as "renewables will never work". No, with wind at sea and nuclear (easy to import from any country on Earth since it's so energy dense) we can be self sufficient even though we have enough independent neighbours that we needn't be anyway. It's just that the person I initially responded to wasn't far off, depending on which country they were talking about, and it's something people aren't being realistic about in counties near me. The reason that matters is that it influences policy: rooftop solar and wind are great, go go go, but don't stop there! Don't wait for that to complete, then discover we've replaced 2000's electricity use (not used for transportation or heating) and forgotten about the rest. That's what many countries are doing currently. See people being happy about headlines like "wind and sun were >50% of the energy mix last year!" when they really mean electricity mix and don't realize that this is about 10% of the total energy need.
scythe 4y ago
About 40% of US corn is used for fuel ethanol [1]. About 90 million acres of corn are planted in the United States [1]. So around 36 million acres of corn are used for ethanol. Solar farms generally require less than four acres to produce one GWh of electricity per year [2]. Therefore at least 9 million GWh of electricity per year are available by displacement of corn ethanol alone. Total annual US electricity consumption is presently around 4 million GWh [3]. In summary, "the assertion" is false. 1: https://www.ers.usda.gov/topics/crops/corn-and-other-feedgrains/feedgrains-sector-at-a-glance/ https://www.ers.usda.gov/topics/crops/corn-and-other-feedgra... 2: https://www.nrel.gov/docs/fy13osti/56290.pdf https://www.nrel.gov/docs/fy13osti/56290.pdf 3: https://www.eia.gov/energyexplained/electricity/use-of-electricity.php https://www.eia.gov/energyexplained/electricity/use-of-elect...
- ncmncm 4y ago
  And in fact actual food could be farmed in those acres at the same time, instead of fuel.
newyankee 4y ago
Back of envelope Math: According to linked calculation Solar PV needs 19 sq m per MWh per annum Per Wiki final total energy consumption is 7050 MTOE which translates to 610 TWH Multiple this by 10, 1.5 to account for energy losses,1.5 for capacity factor issues and 3.33 for growth in developing countries. Rounding up say the world needs 6000 per annum Area needed = 6000 * 10^6 * 20/10^6 = 120000 sq km Even in a densely populated country like India that is roughly 3% of the total land area The challenge off course is installing it cheaply and balancing demand, supply, transmission etc.
- ncmncm 4y ago
  Even that massively overblows the real numbers, because there is no need to use that land only for solar.
- curtisf 4y ago
  For reference, in 2010 the US was estimated to have 60,000 km² of road & parking lots https://persquaremile.com/2011/01/20/800-million-spaces-and-nowhere-to-park/ https://persquaremile.com/2011/01/20/800-million-spaces-and-... So we have experience building infrastructure of a similar scale, though probably not quite at the speed currently needed to meet carbon emissions targets solely by building photovoltaics. Of course, deserts, and not cities, are the best places to put solar power, especially since the shade generated can be useful for crops, and we have tons of desert in the US
deleted 4y ago
[deleted]
ncmncm 4y ago
It is a transparent falsehood. Besides that just the area already devoted to fossil fuel extraction would suffice, solar and wind coexist neatly with existing uses, so don't need to "use up" any land at all.

by doitLP 4y ago

deleted 4y ago

[deleted]

kQq9oHeAz6wLLS 4y ago

I don't have much to add here, other than a lot of land isn't suitable for solar. From not enough light to too much heat, there's less available land than you'd think.

ncmncm 4y ago
Yet, far, far more is available than could ever be needed. Orders of magnitude more.
elihu 4y ago
There's also a lot of land that is suitable for solar that is too dry or the soil too poor to be suitable for agriculture.

standardUser 4y ago

There's vastly more land than is needed for any reasonable mix of solar in a post-carbon world. There's just also lots of speculative and unreasonable scenarios one can dream up if they want to argue otherwise.

ncmncm 4y ago
As Hamlet said, "It's as easy as lying."

Aachen 4y ago

OWID says 19–13m²/MWh depending on the panel type, no idea for which location but let's go with 15 m² for a rough idea. We need about 900 TWh of energy in the country. A calculator tells me that's $ calc 900TWh/MWh\*(15m^2) (900 \* ((terawatt \* hour) / (megawatt \* hour))) \* (15 \* (meter^2)) = 13500 km^2 The country is about 42000 km² big. We won't want to get 100% of energy from photovoltaic, but also we'll need overcapacity to compensate for losses in storage and, to a lesser extent, transmission. Presumably, the land is currently not unused. I don't know what area is currently used by roofs and parking lots, that would be interesting to put this in perspective. I was under the impression that roofs are not enough by far; perhaps it works when we add parking lots and cover all roads, or perhaps my knowledge is outdated (also because batteries have evolved since I first heard that). Either way, we'd have to cover gigantic amounts of land with electronics. Not saying it can't be done (I don't know enough about it), but not having any hydro to speak of, little space far enough from villages for wind, and no nuclear in the mix for the sake of argument... it sure seems daunting.

danielheath 4y ago
> The country is about 42000 km² big It's not clear which country you're talking about; land area of the USA is 9.8 million km². Melbourne (Australia) is a moderately large city of just under 10,000 km² in area. I'd (very conservatively) estimate at least 10% of that is roof space, so 1000 km² of roof-mounted panels seems pretty achievable. Global electricity consumption (averaged over the year of 2019) is approx 2.7 terawatts (per statistica.com). Lets call it 100 terawatts (storage losses, switching oil heaters to electricity). It's straightforward to get 1 kilowatt per square meter from a solar panel, so you'd need about 100k km² of solar panels globally. That's the rooflines of 100 cities the size of Melbourne.
- Aachen 4y ago
  > It's not clear which country you're talking about; land area of the USA is... You assume that when someone just speaks of "the country" without specifying, it's the place where people think they're the whole world. I left it out to see if exactly this would happen because I was curious. I'm surprised not one but two persons felt certain enough I must mean the USA to correct my figure for the USA in a comment. Goes to show. My username is a city in Germany but apparently that wasn't enough of a hint that it is, for once, not about the USA. Also the USA uses double the energy per capita and has twenty times more people, 900 TWh should also be a giveaway for those who know any country's energy consumption, or at least it was easy to check that I didn't merely take a wrong km² value (also, I'm using metric). Anyway, I'm glad we can supply global energy consumption this way. Now we just need a global government to distribute the produced energy to countries with higher population densities than the extreme examples you took like USA and Australia. That they can use solar effectively, both from the amount of unused land and favorable latitude, shouldn't surprise anyone. Oddly (no sarcasm here), I don't see them getting around to it either. I just looked up the landuse of my country and that's about 7% built-up area. https://www.clo.nl/en/indicators/en0061-land-use-in-the-netherlands https://www.clo.nl/en/indicators/en0061-land-use-in-the-neth... Even if we cover all of that, it's not enough, we'll need to take land away from agriculture which is already only barely enough to feed everyone in a pinch despite having a huge yield per unit area. Which is not to say we shouldn't do it. I just realized I might come across as "renewables will never work". No, with wind at sea and nuclear (easy to import from any country on Earth since it's so energy dense) we can be self sufficient even though we have enough independent neighbours that we needn't be anyway. It's just that the person I initially responded to wasn't far off, depending on which country they were talking about, and it's something people aren't being realistic about in counties near me. The reason that matters is that it influences policy: rooftop solar and wind are great, go go go, but don't stop there! Don't wait for that to complete, then discover we've replaced 2000's electricity use (not used for transportation or heating) and forgotten about the rest. That's what many countries are doing currently. See people being happy about headlines like "wind and sun were >50% of the energy mix last year!" when they really mean electricity mix and don't realize that this is about 10% of the total energy need.

scythe 4y ago

About 40% of US corn is used for fuel ethanol [1]. About 90 million acres of corn are planted in the United States [1]. So around 36 million acres of corn are used for ethanol. Solar farms generally require less than four acres to produce one GWh of electricity per year [2]. Therefore at least 9 million GWh of electricity per year are available by displacement of corn ethanol alone. Total annual US electricity consumption is presently around 4 million GWh [3]. In summary, "the assertion" is false. 1: https://www.ers.usda.gov/topics/crops/corn-and-other-feedgrains/feedgrains-sector-at-a-glance/ https://www.ers.usda.gov/topics/crops/corn-and-other-feedgra... 2: https://www.nrel.gov/docs/fy13osti/56290.pdf https://www.nrel.gov/docs/fy13osti/56290.pdf 3: https://www.eia.gov/energyexplained/electricity/use-of-electricity.php https://www.eia.gov/energyexplained/electricity/use-of-elect...

ncmncm 4y ago
And in fact actual food could be farmed in those acres at the same time, instead of fuel.

newyankee 4y ago

Back of envelope Math: According to linked calculation Solar PV needs 19 sq m per MWh per annum Per Wiki final total energy consumption is 7050 MTOE which translates to 610 TWH Multiple this by 10, 1.5 to account for energy losses,1.5 for capacity factor issues and 3.33 for growth in developing countries. Rounding up say the world needs 6000 per annum Area needed = 6000 * 10^6 * 20/10^6 = 120000 sq km Even in a densely populated country like India that is roughly 3% of the total land area The challenge off course is installing it cheaply and balancing demand, supply, transmission etc.

ncmncm 4y ago
Even that massively overblows the real numbers, because there is no need to use that land only for solar.
curtisf 4y ago
For reference, in 2010 the US was estimated to have 60,000 km² of road & parking lots https://persquaremile.com/2011/01/20/800-million-spaces-and-nowhere-to-park/ https://persquaremile.com/2011/01/20/800-million-spaces-and-... So we have experience building infrastructure of a similar scale, though probably not quite at the speed currently needed to meet carbon emissions targets solely by building photovoltaics. Of course, deserts, and not cities, are the best places to put solar power, especially since the shade generated can be useful for crops, and we have tons of desert in the US

deleted 4y ago

[deleted]

ncmncm 4y ago

It is a transparent falsehood. Besides that just the area already devoted to fossil fuel extraction would suffice, solar and wind coexist neatly with existing uses, so don't need to "use up" any land at all.