21 ms·

More energy on less land: The drive to shrink solar’s footprint

73 points by RickJWagner 4y ago

monkeydust 4y ago
So where are we with practical deployment of perovskite solar cells?
- ncmncm 4y ago
  Perovskites are lately in the position of needing to prove longevity, which takes a long time. In the meantime, they are quite a lot cheaper to make, so in many uses it would not matter so much if they did fail faster. In some uses, like aerospace, their lighter weight and better areal efficiency are essential, and forgive a lot.
  - moffkalast 4y ago
    > they are quite a lot cheaper to make, so in many uses it would not matter so much if they did fail faster Hard disagree on that, their current longevity is comparably tiny so you'll have lots of overhead in installation costs. Not to mention the amounts of toxic lead trash you'll need to pay to dispose of, the thing is basically poison after all. Makes far more sense to invest in multilayer tech even if it costs more since it'll last longer by an order of magnitude and use far less area to function which is a big benefit for vehicles too.
    - ncmncm 4y ago
      Perovskites do not need to have any lead in them at all. The thin films amount to very little mass, and in any case may be incinerated and the ash used as feedstock. Longevity is already up to years. In many uses that is plenty, especially when you can just roll it out, instead of needing to bolt it up.
      - moffkalast 4y ago
        > Perovskites do not need to have any lead in them at all. Well that's news to me, I thought that was part of the core functionality.
        ncmncm 4y ago
        Many of the best chemistries have lead, but it is still early days. "Perovskite" refers to lattice structure. Tin has also been used.
- ZeroGravitas 4y ago
  https://pubs.acs.org/doi/full/10.1021/acsenergylett.2c00698 https://pubs.acs.org/doi/full/10.1021/acsenergylett.2c00698 is an overview, seems like for places where you could use silicon, but are limited by space and need high output then thy hybrids from Oxford PV seems ready, but I'd guess that's going to be a tiny share compared with people who just want it cheap and at scale. https://www.oxfordpv.com/news/towards-better-understanding-lifecycle-environmental-impact-perovskite-silicon-modules https://www.oxfordpv.com/news/towards-better-understanding-l... But hopefully that is enough for it to get proved out and scaled up.
  - monkeydust 4y ago
    https://sauletech.com/ https://sauletech.com/ Recall seeing a video of their factory printing solar cells. Looked great but nothing on their site suggests they have a product unless anyone knows different? They are listed on Warsaw stock exchange (and having a miserable time of it as the price would suggest).
deleted 4y ago
[deleted]
adrianN 4y ago
If Germany switched all the land that is currently used for "energy crops" to PV, it could cover a large fraction of its primary power demand. I assume it's similar in other countries. Wind is even a bit more space efficient in Germany. Land use is really not a problem for renewables.
- belorn 4y ago
  I find the issue of land use for renewables (especially wind) to be similar as land use for rail and highways. Technically they don't use up a lot of land, but when it is time to actually build there tend to be a lot of problems finding land that people are willing to sell. Either because of noise, or because current utilization of that land would be hindered in some way. Eminent domain is a common tool to solve this, and it is also used for mining. It is however not very popular.
  - adrianN 4y ago
    A wind turbine "uses" very little land. The area under the turbine can be used for many other things. That doesn't stop NIMBYs.
    - QuarterReptile 4y ago
      Presumably you mean farming? And,more particularly, industrial farming since the turbines would probably scare animals and endanger birds near it. Or are there examples of more intensive uses under wind turbines?
      - ncmncm 4y ago
        "Industrial" farming? You mean using tractors instead of mules?
      - lostapathy 4y ago
        Crops grow just fine around a wind turbine, regardless of farm size. And they don't get scared of it either.
ZeroGravitas 4y ago
Yale360 seems to cover renewables issues as if the reader already has some very weird ideas about them. Probably a sensible and sadly necessary approach. But in reality, land use has never been a problem for Solar. It's great that lots of people are working on the issue and improving it. Just as lots of people are working on making them cheaper, or more environmentally friendly or easier to finance or a thousand other metrics. But none of those were ever fundamental problems with the tech. Their own source of data about the 'problem' puts Ground-based PV at about the same land use as Coal. They also missed out 'floatovoltaics' (PV on water) and building integrated PV as well as solar PV as a paving solution. Probably all of which are likely to be bigger than ground mount PV, given the trend to bifacial panels.
- mech987 4y ago
  Is PV at the same land use as coal currently on a per-watt basis or on a total land use basis?
  - ncmncm 4y ago
    Since solar may use up exactly zero acres, its watts per acre may be infinite. Wind, also, coexists easily with other uses. Solar farms are often sited, stupidly, in deserts, not because it is a good idea, but because ignorant investors think it is a good idea.
    - QuarterReptile 4y ago
      >Solar farms are often sited, stupidly, in deserts, not because it is a good idea, but because ignorant investors think it is a good idea. Perhaps indulge our ignorance about deserts for a moment?
      - ncmncm 4y ago
        Deserts are hot and dusty. Efficiency falls quickly as temperature rises, and more as dust accumulates. Panels degrade exponentially faster as peak temperature increases. (Precisely: each fixed increase in temperature doubles rate of degradation.) Siting panels on water and on farmland reduces operating temperature. Mounting vertically, in fence-rows, keeps off dust, collects more during morning and afternoon demand peaks, aids convective cooling, and protects crops from harshest afternoon sun.
ncmncm 4y ago
> Ground-based solar is land-intensive, however, with utility-scale arrays often spanning hundreds of acres. Wind farms have their own sprawling land needs. This is stupid. The article leads with the solution to this non-problem. There is no shortage of pasturage to site solar in. Likewise, of reservoirs and canals. Both places get net benefit from the dual use, even discounting the extra revenue.
- montalbano 4y ago
  Do you have some references on this? I would probably agree if you are referring to USA. But I would be skeptical that the same is true in the UK.
  - ZeroGravitas 4y ago
    https://www.nfuonline.com/updates-and-information/solar-farms-and-the-british-landscape/ https://www.nfuonline.com/updates-and-information/solar-farm...
  - cheeko1234 4y ago
    They're quite wrong about 'this being stupid'. It is true, that the amount of solar needed to power the entire US is about 0.5% of the land. That doesn't mean there's no benefit in increasing the efficiency of panels and get dual use of the land. It also has the benefit of allowing for solar in more places where it's needed for more decentralized power.
    - ncmncm 4y ago
      Better efficiency, in dollars per watt, is always good. Pretending there is some sort of shortage of land to site solar in is not a valid reason to court efficiency. There are other, legitimate reasons.
    - ZeroGravitas 4y ago
      On the question of this being stupid or not, I think that a sentence saying "Ground-based solar is land-intensive, however, with utility-scale arrays often spanning hundreds of acres. Wind farms have their own sprawling land needs" that links to a source that says: > Solar energy is one example where the context and type of material matter a lot. Solar panels made from cadmium use less energy and materials than silicon panels, and therefore use less land per unit. It also matters a lot whether you mount these panels on rooftops or on the ground. Rooftop solar obviously needs much less additional land; we’re just using space that is already occupied, on top of existing buildings. However, they do need some land over their life-cycle because they still require mining of the materials to make them, as well as the energy (mostly electricity) used in refining the silicon. Finally, the density and spacing of the panels also makes a difference. > Wind is the most obvious electricity source that we should consider differently when it comes to land use. You find it separated from the other sources, at the bottom of the chart.3 There are several reasons for this. First, offshore wind takes up space, but it’s marine, not land area. Second, onshore wind is different from other electricity sources because you can use the land between turbines for other activities, such as farming. This is not the case for a coal, gas or nuclear plant. This means the land use of wind farms is highly variable. I have calculated the land use of 22 of the world’s largest wind farms [you find my calculations here]. > Take the Roscoe Wind Farm in Texas, which uses 184 m2 per MWh. This is a large project, where farmers can generate additional income through electricity production while they continue their farming operations between the wind turbines. The wind farm is almost a secondary land use. This contrasts with much more dense wind farms, such as Fântânele-Cogealac in Romania, or the Tehachapi Pass in California, where energy production is the primary land use. These can have a small land footprint of just 8 m2 per MWh. Seems pretty stupid to me. Though if someone get sucked in by the headline, reads the article and moves from thinking "we don't have enough room for renewables" to "there are lots of ways to dual use land with renewables" then maybe it's all for the best.
JoeAltmaier 4y ago
Orbital Power Stations! All the real estate there you could ever want. 9X the solar flux. Little or no "night". Direct delivery via lasers to any point in the hemisphere.
- ncmncm 4y ago
  Or, we could hire children to pedal stationary bicycles attached to generators. Where cost doesn't matter, everything gets easy.
  - JoeAltmaier 4y ago
    Real estate near major metropolitan centers is not cheap either. With modern orbital delivery dropping by orders of magnitude, the entire equation changes. Get with the modern agenda! The advantages of orbital are nearly 20X generation per panel to start with, even before considering support structures (none) and weather-proofing (none). That leaves lots of room in the cost equation.
    - ncmncm 4y ago
      Real estate already generating revenue that may have solar added without reducing that revenue is not expensive. It has, instead, negative cost. Solar panels do not need to be "near major metropolitan centers". Modern transmission lines move power efficiently, silently, and reliably. It would be impressive for your orbital panels to get out 4x as much energy as the light they intercept carries, but getting a patent on your perpetual-motion apparatus might be difficult. Maybe do some elementary cost analysis. All the numbers are easy to find. Don't forget to figure in conversion loss from electric power on orbit to laser light emitted, losses scattering in the atmosphere, and conversion again from laser light received to electricity on the ground. You would better loft many-square-km aluminized-mylar mirrors to reflect sunlight to solar farms on the ground. Keeping them pointing the right direction would be tricky.
      - JoeAltmaier 4y ago
        That's so far a pipe dream, dual-purpose 'negative cost'. Also transmission lines need right-of-way and are not free. Solar flux outside the atmosphere is 9X sea level. Go ahead, look it up. Then there's the periodic eclipse called 'night' that doubles orbital efficiency again. Look that up too. Conversion losses of 20% seem normal? Both in orbit and on the ground. Which halves what you collect, well within the budget of 20X reducing it to around 10X.
anonymousiam 4y ago
The article is very light on the technology. (Quad Junction) GaAs cells have been produced with >40% conversion efficiency. That's more than three times the efficiency of Si or anything else in common use. The GaAs cells have thus far only been used for space-based applications. Somebody should be working on getting production costs down and deploying these things terrestrially. https://arxiv.org/pdf/1905.08024.pdf https://arxiv.org/pdf/1905.08024.pdf https://boeing.mediaroom.com/2010-11-01-Boeings-Spectrolab-Produces-3-Millionth-Multi-junction-Space-Solar-Cell https://boeing.mediaroom.com/2010-11-01-Boeings-Spectrolab-P... https://www.spectrolab.com/photovoltaics.html https://www.spectrolab.com/photovoltaics.html
- ncmncm 4y ago
  40% is not, in fact, 3x, or even 2x, current best efficiency of Si or CdTe panels. And, the important efficiency measure is W/$, where GaAs trails well back. Perovskites may exceed 40% conversion efficiency, and also have good prospects to offer much better W/$. Their endurance has grown encouragingly quickly.
  - johnday 4y ago
    If we are talking about solar installations on land, rather than in the built environment, the W/$ also needs to factor in the cost of the land itself, which is at a premium in many places including across Europe. On that basis there is scope for an increased efficiency to lower the cost delta.
    - ncmncm 4y ago
      You have clearly missed the point that siting solar has no need to interfere with other, simultaneous uses of the land.
  - anonymousiam 4y ago
    If you looked at the first link I cited, they claim 47% efficiency is possible. That is more than 3x the efficiency of many Si panels on the market today. Unlike perovskites, which to date have only achieved ~25% efficiency, GaAs cells have been produced with efficiencies approaching 70% (under laser illumination). https://www.ise.fraunhofer.de/en/press-media/press-releases/2021/record-efficiency-68-9-percent-for-gaas-thin-film-photovoltaic-cell.html https://www.ise.fraunhofer.de/en/press-media/press-releases/... W/$ goes down with manufacturing efficiency. Nobody has done large scale manufacturing of multi-junction GaAs cells.
greggeter 4y ago
fredgrott 4y ago
Something interesting to calculate if you like math and biology. Why is it that Trees can generate more energy via absorbing light than implied by the surface area of leaf coverage of the outer branches? Hint, yes has to do with light spectrums and their behaviors and the benefits of chloroplasts using more than one light frequency
- ncmncm 4y ago
  Conversion efficiency of most plants, trees included, is around 2% or less. A few species, including certain cereal crops, have got up to 4%.
wolfi1 4y ago
why not use the parking lots and malls and one story buildings?
- jandrese 4y ago
  Parking Lot solar makes a huge amount of sense. Not only does it create power, but it creates shade for the parked vehicles and cuts down on the amount of heat absorbing blacktop visible to the sun. The suburbs are absolutely covered in parking lots that could be converted. Nobody is going to complain that the solar array is despoiling the aesthetics of the suburban parking lot either. Really the only downside is that people will crash their cars into the support structures. It is inevitable, and needs to be accounted for in the design.
  - ssully 4y ago
    I am not saying this to be pedantic, but people will 100% complain about solar arrays in parking lots. Green energy is a politicized and having solar parking lots will be used as a political talking point. It already happens with electric cars, wind farms, and much more.
    - jandrese 4y ago
      Well yes, there are always cranks to complain about everything. But as long as they are just the usual cranks it's not really a problem, especially if you can make them look foolish in front of the planning committee by showing a "before" picture of the hideous parking lot.
    - colordrops 4y ago
      If not pedantic, then what are you trying to communicate? We shouldn't abort good ideas because stupid people are politicized into hating them.
ZetaZero 4y ago
Here in the US, we could power the entire country with solar panels by just using 1% of the land now dedicated to agriculture.
- whichquestion 4y ago
  I wonder if it would be a possibility to relay electricity across the US with large battery stations from big solar farms, or if the loss in transit + the expense of the batteries would make something like that intractable.
  - bburrito 4y ago
    So Cal has Sunrise Power Link which is high voltage transmission lines specifically designed to bring in power from the solar and wind farms in the desert. The proliferation of solar farms in the desert is a clear indicator of how that has gone.
    - HideousKojima 4y ago
      Growing up in San Diego I hilariously remember environmentalists protesting the Sunrise Power Link. The reason given by my high school classmates who were involved in the protesting was that it threatened some desert tortoise's habitat or something like that. There were also some NIMBY types protesting the transmission lines. From the gas and oil companies' perspective, with enemies like these, who needs friends?
- masklinn 4y ago
  And the US has plenty of literal deserts to use for that anyway. The issue is really mostly the difficulty of smoothing production over consumption. And transmission.
  - jandrese 4y ago
    I've been wondering lately if it wouldn't make sense for power companies to offer a battery incentive program to homeowners. They'll cover 1/2 the cost of a battery but mandate that the system be set to draw from the grid when production is high (middle of the day mostly) and be used to power the home in the evening when demand is high but production is tailing off. Some companies do Time of Use contracts which do this to a degree, but flat incentives (cut a one time check to the homeowner) seem much less complicated. The grid gets smoothing and the homeowner gets to keep the lights on when the power goes out and doesn't have to spend nearly as much on the install. The power company doesn't have to manage a big bank of batteries somewhere and saves on distribution costs. Plus the homeowners technically own the systems so when something goes wrong the power company doesn't have to roll a truck to fix it. The only real problem with this scheme is that the battery market is already squeezed with so many companies jumping into the electric vehicle business and production lagging behind demand. However, this is likely to be a short term problem, so hopefully in the next couple of years something like this will be practical.
codereviewed 4y ago
I just don't see how land use is an issue worth worrying about right now, climate emergency and all. The federal government owns _huge_ swaths of sunny arid desert land in the west. It is largely not suitable for crops, livestock, suburbs, etc. We could install millions of acres worth of current solar tech out there and generate enough power for everyone. The real difficulty lies in the infrastructure it would take to get the power to where people are. What we should be focusing on is transmission and distribution, those are the really hard problems. We could have all the power we want but if our grids can't handle the rapidly increasing demand it does nothing for us. And as more people go 100% electric for transportation, heating, and cooking the integrity of power distribution becomes even more important because we will have put all our energy eggs in the electricity basket. The only place land use seems relevant is for smaller scale off-the-grid cases where someone's property is small but they want to generate all their own electricity.
- deleted 4y ago
  [deleted]
- einpoklum 4y ago
  > just don't see how land use is an issue worth worrying about right now 1. In small(ish), densely-populated countries, land is in short supply, regardless of any socio-economic-political considerations. 2. In many countries, land is private, or has been fully "divvied up" in some form or another, despite being only sparsely used. In these countries, reallocating land is a headache - politically, economically and legally. But I agree that storage, transmission and distribution are important things to focus on. Or rather - the important thing to focus on is to actually deploy lots of solar instead of fossil (which the recent US federal legislation makes even harder than before).
  - robomartin 4y ago
    > the important thing to focus on is to actually deploy lots of solar Why? What do you think, expect or hope this will accomplish?
    - 4y ago
jefurii 4y ago
Anidolic lighting could be used to provide diffuse light beneath solar panels.
thedougd 4y ago
Curiosity question for the large scale pros. How is rainwater runoff handled in these large solar farms? Trenches and drains to retention ponds? Or do they somehow try and redirect the water under the panels to utilize the surface area under them? Impacts to watersheds are the biggest environmental issues of any small or large scale building projects in my neck of the woods. I’m only allowed 12 percent of my land for impervious surfaces.
- Schroedingersat 4y ago
  The panels are only a few m apart. The only difference between that and a fallow field is going to be slightly lower evaporation, and maybe a hair more erosion until grass establishes itself
  - thedougd 4y ago
    Found motivation to look it up. This document suggests leaving enough space between the rows to accomodate the runoff. "EMLR allows solar panels associated with ground-mounted solar farms to be considered pervious if they are configured in accordance with the recommendations in this chapter. These recommendations promote sheet flow of stormwater from the panels and natural infiltration of stormwater into the ground beneath the panels." ... "In general, the minimum disconnection length between two rows of solar panels is equal to the width of each row, as shown in Figure 1. However, some panel layouts include horizontal gaps between individual modules that allow stormwater to drip off the panels at intervals much smaller than the width of each row. In these instances, the solar farm can be designed with a smaller disconnection length, provided that they will not cause concentration of stormwater runoff." https://deq.nc.gov/media/12043/download https://deq.nc.gov/media/12043/download
aaron695 4y ago
Schroedingersat 4y ago
Solar land use is such a non-issue. Consider tokyo as an example of a space where area is at an absolute premium. There are around 7000 people per km^2 Shrink it down to a single block. Tokyo's blocks are a little smaller, but a common size is 100x200m for ease. At 0.7kWh/day/m^2 there are 14,000kWh/day available in this area shared between 140 people. This is about 100kWh/day each. This isn't quite enough to be as absurdly wasteful as someone from Australia or the US, but it covers the total per capita energy consumption of people living pretty much anywhere else. Note that this is just the net solar electricity available in a high density metropolis as an input vs all energy (including thermal) used everywhere. As soon as you add in medium density towns or industrial areas there is an abundance of space for panels so long as we stop being exponentially more wasteful with the available energy. Anyone bringing it up is a fossil fuel or nuclear shill.

73 points by RickJWagner 4y ago

monkeydust 4y ago

So where are we with practical deployment of perovskite solar cells?

ncmncm 4y ago
Perovskites are lately in the position of needing to prove longevity, which takes a long time. In the meantime, they are quite a lot cheaper to make, so in many uses it would not matter so much if they did fail faster. In some uses, like aerospace, their lighter weight and better areal efficiency are essential, and forgive a lot.
- moffkalast 4y ago
  > they are quite a lot cheaper to make, so in many uses it would not matter so much if they did fail faster Hard disagree on that, their current longevity is comparably tiny so you'll have lots of overhead in installation costs. Not to mention the amounts of toxic lead trash you'll need to pay to dispose of, the thing is basically poison after all. Makes far more sense to invest in multilayer tech even if it costs more since it'll last longer by an order of magnitude and use far less area to function which is a big benefit for vehicles too.
  - ncmncm 4y ago
    Perovskites do not need to have any lead in them at all. The thin films amount to very little mass, and in any case may be incinerated and the ash used as feedstock. Longevity is already up to years. In many uses that is plenty, especially when you can just roll it out, instead of needing to bolt it up.
    - moffkalast 4y ago
      > Perovskites do not need to have any lead in them at all. Well that's news to me, I thought that was part of the core functionality.
      - ncmncm 4y ago
        Many of the best chemistries have lead, but it is still early days. "Perovskite" refers to lattice structure. Tin has also been used.
ZeroGravitas 4y ago
https://pubs.acs.org/doi/full/10.1021/acsenergylett.2c00698 https://pubs.acs.org/doi/full/10.1021/acsenergylett.2c00698 is an overview, seems like for places where you could use silicon, but are limited by space and need high output then thy hybrids from Oxford PV seems ready, but I'd guess that's going to be a tiny share compared with people who just want it cheap and at scale. https://www.oxfordpv.com/news/towards-better-understanding-lifecycle-environmental-impact-perovskite-silicon-modules https://www.oxfordpv.com/news/towards-better-understanding-l... But hopefully that is enough for it to get proved out and scaled up.
- monkeydust 4y ago
  https://sauletech.com/ https://sauletech.com/ Recall seeing a video of their factory printing solar cells. Looked great but nothing on their site suggests they have a product unless anyone knows different? They are listed on Warsaw stock exchange (and having a miserable time of it as the price would suggest).

deleted 4y ago

[deleted]

adrianN 4y ago

If Germany switched all the land that is currently used for "energy crops" to PV, it could cover a large fraction of its primary power demand. I assume it's similar in other countries. Wind is even a bit more space efficient in Germany. Land use is really not a problem for renewables.

belorn 4y ago
I find the issue of land use for renewables (especially wind) to be similar as land use for rail and highways. Technically they don't use up a lot of land, but when it is time to actually build there tend to be a lot of problems finding land that people are willing to sell. Either because of noise, or because current utilization of that land would be hindered in some way. Eminent domain is a common tool to solve this, and it is also used for mining. It is however not very popular.
- adrianN 4y ago
  A wind turbine "uses" very little land. The area under the turbine can be used for many other things. That doesn't stop NIMBYs.
  - QuarterReptile 4y ago
    Presumably you mean farming? And,more particularly, industrial farming since the turbines would probably scare animals and endanger birds near it. Or are there examples of more intensive uses under wind turbines?
    - ncmncm 4y ago
      "Industrial" farming? You mean using tractors instead of mules?
    - lostapathy 4y ago
      Crops grow just fine around a wind turbine, regardless of farm size. And they don't get scared of it either.

ZeroGravitas 4y ago

Yale360 seems to cover renewables issues as if the reader already has some very weird ideas about them. Probably a sensible and sadly necessary approach. But in reality, land use has never been a problem for Solar. It's great that lots of people are working on the issue and improving it. Just as lots of people are working on making them cheaper, or more environmentally friendly or easier to finance or a thousand other metrics. But none of those were ever fundamental problems with the tech. Their own source of data about the 'problem' puts Ground-based PV at about the same land use as Coal. They also missed out 'floatovoltaics' (PV on water) and building integrated PV as well as solar PV as a paving solution. Probably all of which are likely to be bigger than ground mount PV, given the trend to bifacial panels.

mech987 4y ago
Is PV at the same land use as coal currently on a per-watt basis or on a total land use basis?
- ncmncm 4y ago
  Since solar may use up exactly zero acres, its watts per acre may be infinite. Wind, also, coexists easily with other uses. Solar farms are often sited, stupidly, in deserts, not because it is a good idea, but because ignorant investors think it is a good idea.
  - QuarterReptile 4y ago
    >Solar farms are often sited, stupidly, in deserts, not because it is a good idea, but because ignorant investors think it is a good idea. Perhaps indulge our ignorance about deserts for a moment?
    - ncmncm 4y ago
      Deserts are hot and dusty. Efficiency falls quickly as temperature rises, and more as dust accumulates. Panels degrade exponentially faster as peak temperature increases. (Precisely: each fixed increase in temperature doubles rate of degradation.) Siting panels on water and on farmland reduces operating temperature. Mounting vertically, in fence-rows, keeps off dust, collects more during morning and afternoon demand peaks, aids convective cooling, and protects crops from harshest afternoon sun.

ncmncm 4y ago

> Ground-based solar is land-intensive, however, with utility-scale arrays often spanning hundreds of acres. Wind farms have their own sprawling land needs. This is stupid. The article leads with the solution to this non-problem. There is no shortage of pasturage to site solar in. Likewise, of reservoirs and canals. Both places get net benefit from the dual use, even discounting the extra revenue.

montalbano 4y ago
Do you have some references on this? I would probably agree if you are referring to USA. But I would be skeptical that the same is true in the UK.
- ZeroGravitas 4y ago
  https://www.nfuonline.com/updates-and-information/solar-farms-and-the-british-landscape/ https://www.nfuonline.com/updates-and-information/solar-farm...
- cheeko1234 4y ago
  They're quite wrong about 'this being stupid'. It is true, that the amount of solar needed to power the entire US is about 0.5% of the land. That doesn't mean there's no benefit in increasing the efficiency of panels and get dual use of the land. It also has the benefit of allowing for solar in more places where it's needed for more decentralized power.
  - ncmncm 4y ago
    Better efficiency, in dollars per watt, is always good. Pretending there is some sort of shortage of land to site solar in is not a valid reason to court efficiency. There are other, legitimate reasons.
  - ZeroGravitas 4y ago
    On the question of this being stupid or not, I think that a sentence saying "Ground-based solar is land-intensive, however, with utility-scale arrays often spanning hundreds of acres. Wind farms have their own sprawling land needs" that links to a source that says: > Solar energy is one example where the context and type of material matter a lot. Solar panels made from cadmium use less energy and materials than silicon panels, and therefore use less land per unit. It also matters a lot whether you mount these panels on rooftops or on the ground. Rooftop solar obviously needs much less additional land; we’re just using space that is already occupied, on top of existing buildings. However, they do need some land over their life-cycle because they still require mining of the materials to make them, as well as the energy (mostly electricity) used in refining the silicon. Finally, the density and spacing of the panels also makes a difference. > Wind is the most obvious electricity source that we should consider differently when it comes to land use. You find it separated from the other sources, at the bottom of the chart.3 There are several reasons for this. First, offshore wind takes up space, but it’s marine, not land area. Second, onshore wind is different from other electricity sources because you can use the land between turbines for other activities, such as farming. This is not the case for a coal, gas or nuclear plant. This means the land use of wind farms is highly variable. I have calculated the land use of 22 of the world’s largest wind farms [you find my calculations here]. > Take the Roscoe Wind Farm in Texas, which uses 184 m2 per MWh. This is a large project, where farmers can generate additional income through electricity production while they continue their farming operations between the wind turbines. The wind farm is almost a secondary land use. This contrasts with much more dense wind farms, such as Fântânele-Cogealac in Romania, or the Tehachapi Pass in California, where energy production is the primary land use. These can have a small land footprint of just 8 m2 per MWh. Seems pretty stupid to me. Though if someone get sucked in by the headline, reads the article and moves from thinking "we don't have enough room for renewables" to "there are lots of ways to dual use land with renewables" then maybe it's all for the best.

JoeAltmaier 4y ago

Orbital Power Stations! All the real estate there you could ever want. 9X the solar flux. Little or no "night". Direct delivery via lasers to any point in the hemisphere.

ncmncm 4y ago
Or, we could hire children to pedal stationary bicycles attached to generators. Where cost doesn't matter, everything gets easy.
- JoeAltmaier 4y ago
  Real estate near major metropolitan centers is not cheap either. With modern orbital delivery dropping by orders of magnitude, the entire equation changes. Get with the modern agenda! The advantages of orbital are nearly 20X generation per panel to start with, even before considering support structures (none) and weather-proofing (none). That leaves lots of room in the cost equation.
  - ncmncm 4y ago
    Real estate already generating revenue that may have solar added without reducing that revenue is not expensive. It has, instead, negative cost. Solar panels do not need to be "near major metropolitan centers". Modern transmission lines move power efficiently, silently, and reliably. It would be impressive for your orbital panels to get out 4x as much energy as the light they intercept carries, but getting a patent on your perpetual-motion apparatus might be difficult. Maybe do some elementary cost analysis. All the numbers are easy to find. Don't forget to figure in conversion loss from electric power on orbit to laser light emitted, losses scattering in the atmosphere, and conversion again from laser light received to electricity on the ground. You would better loft many-square-km aluminized-mylar mirrors to reflect sunlight to solar farms on the ground. Keeping them pointing the right direction would be tricky.
    - JoeAltmaier 4y ago
      That's so far a pipe dream, dual-purpose 'negative cost'. Also transmission lines need right-of-way and are not free. Solar flux outside the atmosphere is 9X sea level. Go ahead, look it up. Then there's the periodic eclipse called 'night' that doubles orbital efficiency again. Look that up too. Conversion losses of 20% seem normal? Both in orbit and on the ground. Which halves what you collect, well within the budget of 20X reducing it to around 10X.

anonymousiam 4y ago

The article is very light on the technology. (Quad Junction) GaAs cells have been produced with >40% conversion efficiency. That's more than three times the efficiency of Si or anything else in common use. The GaAs cells have thus far only been used for space-based applications. Somebody should be working on getting production costs down and deploying these things terrestrially. https://arxiv.org/pdf/1905.08024.pdf https://arxiv.org/pdf/1905.08024.pdf https://boeing.mediaroom.com/2010-11-01-Boeings-Spectrolab-Produces-3-Millionth-Multi-junction-Space-Solar-Cell https://boeing.mediaroom.com/2010-11-01-Boeings-Spectrolab-P... https://www.spectrolab.com/photovoltaics.html https://www.spectrolab.com/photovoltaics.html

ncmncm 4y ago
40% is not, in fact, 3x, or even 2x, current best efficiency of Si or CdTe panels. And, the important efficiency measure is W/$, where GaAs trails well back. Perovskites may exceed 40% conversion efficiency, and also have good prospects to offer much better W/$. Their endurance has grown encouragingly quickly.
- johnday 4y ago
  If we are talking about solar installations on land, rather than in the built environment, the W/$ also needs to factor in the cost of the land itself, which is at a premium in many places including across Europe. On that basis there is scope for an increased efficiency to lower the cost delta.
  - ncmncm 4y ago
    You have clearly missed the point that siting solar has no need to interfere with other, simultaneous uses of the land.
- anonymousiam 4y ago
  If you looked at the first link I cited, they claim 47% efficiency is possible. That is more than 3x the efficiency of many Si panels on the market today. Unlike perovskites, which to date have only achieved ~25% efficiency, GaAs cells have been produced with efficiencies approaching 70% (under laser illumination). https://www.ise.fraunhofer.de/en/press-media/press-releases/2021/record-efficiency-68-9-percent-for-gaas-thin-film-photovoltaic-cell.html https://www.ise.fraunhofer.de/en/press-media/press-releases/... W/$ goes down with manufacturing efficiency. Nobody has done large scale manufacturing of multi-junction GaAs cells.

greggeter 4y ago

fredgrott 4y ago

Something interesting to calculate if you like math and biology. Why is it that Trees can generate more energy via absorbing light than implied by the surface area of leaf coverage of the outer branches? Hint, yes has to do with light spectrums and their behaviors and the benefits of chloroplasts using more than one light frequency

ncmncm 4y ago
Conversion efficiency of most plants, trees included, is around 2% or less. A few species, including certain cereal crops, have got up to 4%.

wolfi1 4y ago

why not use the parking lots and malls and one story buildings?

jandrese 4y ago
Parking Lot solar makes a huge amount of sense. Not only does it create power, but it creates shade for the parked vehicles and cuts down on the amount of heat absorbing blacktop visible to the sun. The suburbs are absolutely covered in parking lots that could be converted. Nobody is going to complain that the solar array is despoiling the aesthetics of the suburban parking lot either. Really the only downside is that people will crash their cars into the support structures. It is inevitable, and needs to be accounted for in the design.
- ssully 4y ago
  I am not saying this to be pedantic, but people will 100% complain about solar arrays in parking lots. Green energy is a politicized and having solar parking lots will be used as a political talking point. It already happens with electric cars, wind farms, and much more.
  - jandrese 4y ago
    Well yes, there are always cranks to complain about everything. But as long as they are just the usual cranks it's not really a problem, especially if you can make them look foolish in front of the planning committee by showing a "before" picture of the hideous parking lot.
  - colordrops 4y ago
    If not pedantic, then what are you trying to communicate? We shouldn't abort good ideas because stupid people are politicized into hating them.

ZetaZero 4y ago

Here in the US, we could power the entire country with solar panels by just using 1% of the land now dedicated to agriculture.

whichquestion 4y ago
I wonder if it would be a possibility to relay electricity across the US with large battery stations from big solar farms, or if the loss in transit + the expense of the batteries would make something like that intractable.
- bburrito 4y ago
  So Cal has Sunrise Power Link which is high voltage transmission lines specifically designed to bring in power from the solar and wind farms in the desert. The proliferation of solar farms in the desert is a clear indicator of how that has gone.
  - HideousKojima 4y ago
    Growing up in San Diego I hilariously remember environmentalists protesting the Sunrise Power Link. The reason given by my high school classmates who were involved in the protesting was that it threatened some desert tortoise's habitat or something like that. There were also some NIMBY types protesting the transmission lines. From the gas and oil companies' perspective, with enemies like these, who needs friends?
masklinn 4y ago
And the US has plenty of literal deserts to use for that anyway. The issue is really mostly the difficulty of smoothing production over consumption. And transmission.
- jandrese 4y ago
  I've been wondering lately if it wouldn't make sense for power companies to offer a battery incentive program to homeowners. They'll cover 1/2 the cost of a battery but mandate that the system be set to draw from the grid when production is high (middle of the day mostly) and be used to power the home in the evening when demand is high but production is tailing off. Some companies do Time of Use contracts which do this to a degree, but flat incentives (cut a one time check to the homeowner) seem much less complicated. The grid gets smoothing and the homeowner gets to keep the lights on when the power goes out and doesn't have to spend nearly as much on the install. The power company doesn't have to manage a big bank of batteries somewhere and saves on distribution costs. Plus the homeowners technically own the systems so when something goes wrong the power company doesn't have to roll a truck to fix it. The only real problem with this scheme is that the battery market is already squeezed with so many companies jumping into the electric vehicle business and production lagging behind demand. However, this is likely to be a short term problem, so hopefully in the next couple of years something like this will be practical.

codereviewed 4y ago

I just don't see how land use is an issue worth worrying about right now, climate emergency and all. The federal government owns _huge_ swaths of sunny arid desert land in the west. It is largely not suitable for crops, livestock, suburbs, etc. We could install millions of acres worth of current solar tech out there and generate enough power for everyone. The real difficulty lies in the infrastructure it would take to get the power to where people are. What we should be focusing on is transmission and distribution, those are the really hard problems. We could have all the power we want but if our grids can't handle the rapidly increasing demand it does nothing for us. And as more people go 100% electric for transportation, heating, and cooking the integrity of power distribution becomes even more important because we will have put all our energy eggs in the electricity basket. The only place land use seems relevant is for smaller scale off-the-grid cases where someone's property is small but they want to generate all their own electricity.

deleted 4y ago
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einpoklum 4y ago
> just don't see how land use is an issue worth worrying about right now 1. In small(ish), densely-populated countries, land is in short supply, regardless of any socio-economic-political considerations. 2. In many countries, land is private, or has been fully "divvied up" in some form or another, despite being only sparsely used. In these countries, reallocating land is a headache - politically, economically and legally. But I agree that storage, transmission and distribution are important things to focus on. Or rather - the important thing to focus on is to actually deploy lots of solar instead of fossil (which the recent US federal legislation makes even harder than before).
- robomartin 4y ago
  > the important thing to focus on is to actually deploy lots of solar Why? What do you think, expect or hope this will accomplish?
  - 4y ago

jefurii 4y ago

Anidolic lighting could be used to provide diffuse light beneath solar panels.

thedougd 4y ago

Curiosity question for the large scale pros. How is rainwater runoff handled in these large solar farms? Trenches and drains to retention ponds? Or do they somehow try and redirect the water under the panels to utilize the surface area under them? Impacts to watersheds are the biggest environmental issues of any small or large scale building projects in my neck of the woods. I’m only allowed 12 percent of my land for impervious surfaces.

Schroedingersat 4y ago
The panels are only a few m apart. The only difference between that and a fallow field is going to be slightly lower evaporation, and maybe a hair more erosion until grass establishes itself
- thedougd 4y ago
  Found motivation to look it up. This document suggests leaving enough space between the rows to accomodate the runoff. "EMLR allows solar panels associated with ground-mounted solar farms to be considered pervious if they are configured in accordance with the recommendations in this chapter. These recommendations promote sheet flow of stormwater from the panels and natural infiltration of stormwater into the ground beneath the panels." ... "In general, the minimum disconnection length between two rows of solar panels is equal to the width of each row, as shown in Figure 1. However, some panel layouts include horizontal gaps between individual modules that allow stormwater to drip off the panels at intervals much smaller than the width of each row. In these instances, the solar farm can be designed with a smaller disconnection length, provided that they will not cause concentration of stormwater runoff." https://deq.nc.gov/media/12043/download https://deq.nc.gov/media/12043/download

aaron695 4y ago

Schroedingersat 4y ago

Solar land use is such a non-issue. Consider tokyo as an example of a space where area is at an absolute premium. There are around 7000 people per km^2 Shrink it down to a single block. Tokyo's blocks are a little smaller, but a common size is 100x200m for ease. At 0.7kWh/day/m^2 there are 14,000kWh/day available in this area shared between 140 people. This is about 100kWh/day each. This isn't quite enough to be as absurdly wasteful as someone from Australia or the US, but it covers the total per capita energy consumption of people living pretty much anywhere else. Note that this is just the net solar electricity available in a high density metropolis as an input vs all energy (including thermal) used everywhere. As soon as you add in medium density towns or industrial areas there is an abundance of space for panels so long as we stop being exponentially more wasteful with the available energy. Anyone bringing it up is a fossil fuel or nuclear shill.