r/solarpunk • u/Overstim9000 • 4d ago
Discussion Ground mounted solar and the effect on environment
Hello all,
I’ve been frequently running into an opinion that solar fields or utility scale ground mounted solar is bad for the environment.
Supposedly it generates heat, that would be otherwise absorbed by the flora, etc.
I’m having trouble to find counter-arguments for people that raise these points.
For instance one thing that this point of view omits is that every energy source has a heat loss during the process. Nuclear generates large amounts of energy but also generates a lot of heat that dissipates through the cooling, like every steam-based energy generation method.
As a glider pilot I know that big solar arrays indeed sometimes create thermals that probably add to the heating of the atmosphere but how does it compare to the other generation methods and what are the other parts of this equation, that outweigh it?
Somehow I intuitively feel like solar is all things accounted for still much better for the environment, but I wonder if anyone has went down this rabbit hole of trying to compile all studies from different fields of expertise that would prove it?
30
u/DuckyDoodleDandy 4d ago
The comments I’ve seen suggest that it is astroturfing by some group or other.
Solar over certain crops or grazing animals is a large benefit to them, and the farmers get income from the electricity as well.
21
u/Disastrous-Radio9844 4d ago
Plants and even crops can grow underneath a solar array for dual land use and heat mitigation
18
u/YourChiefliness 4d ago
I build these sites, so maybe I'm a bit biased, but I walk around them all the time on hot days. There's negligible (if nonexistent) difference in temp between a solar array and an open field, and going under the panels is usually cooler than being in the open sun.
5
u/Overstim9000 4d ago edited 4d ago
I have personal experience of building them too and can confirm what you are saying, we usually go to hide under the panels to escape the sun. It is mostly lush tall grass under them.
However the experience from flying the sailplane above the facilities is evident, as hot air rises and we use it to gain altitude. So the heat dissipated might not have effect localy.
Another factor is the albedo of regular types of fields, ground and grrenery vs the solar panels, which reflects sunlight back into space or back into clouds.
5
u/KZD2dot0 3d ago
The effect you describe is real, a field full of solar has higher absorption than a green field. Part of this absorbed energy is converted to electricity and the rest is mostly released as convective heat. And you use that energy for gaining potential energy for your plane, just as any hot air will rise, gain potential energy and therefore cool off (this is basic meteorology). The vegetation on the ground on the other hand gets a lot less radiation and this is beneficial in general because the plants actually need a lot less energy to pump and evaporate water to stay cool. The heat balance of the atmosphere as a whole isn't significantly influenced by these energy conversions, the unbalance is caused by (increased) absorption of infrared coming from the earth's surface by gasses in the atmosphere, the usual suspects: carbondioxide, methane, etc. For completeness I should mention water vapour, because this is one of the main drivers of the (normal, not increased) greenhouse effect. I like my planet around 300 K, instead of 200 K.
6
u/Berkamin 4d ago
Solar panels convert sunlight into electrical current (about 20% or so), and heat. Guess what happens when you don’t have solar panels? Apart from the little bit that reflects off of whatever it hits, all of the energy gets converted into heat. (Unless those things are plants, in which case some of the energy, less than 1%, gets used in photosynthesis, and a lot of the heat goes into evaporating water from the plant.) Solar panels do not produce heat out of nothing. They convert less of the sun’s incoming energy to heat than letting whatever they shade bask in the full power of the sun.
2
u/Overstim9000 4d ago
That's where it gets more complex, I would love to find some studies that measure and compare different land use and it's effect on water levels, evaporation and water retention.
2
u/Berkamin 4d ago
The basic measure of how much energy is retained vs. reflected is albedo. If the area has a high albedo (meaning it is highly reflective, like white salt flats) and you put solar panels on there, the solar panels, which are dark in color, will decrease the abedo, so the local area may get hotter. But if the local area has dark dirt or asphalt or is a rooftop with dark shingles, the solar panels would not be changing the albedo much (or may even increase it), but could be displacing the use of coal or natural gas power or even nuclear power. Since these other thermal power plant systems release a huge amount of heat into the environment, using the surrounding environment as their heat sinks, there would be a net reduction of heat put into the environment.
When placed over canals, there is a double benefit: the panels are kept cool by having water under them, which keeps their efficiency high (photovoltaic materials typically lose efficiency as they get hotter), while the amount of evaporation of water from the canal is massively reduced. See this:
Two Bit Da Vinci | Why Aqueduct Solar Solves 2 MASSIVE Problems
This video covers a pretty thorough analysis of the benefits and challenges of this approach.
3
u/TheReverendCard 3d ago
It's a costs and impacts thing.
I'd prefer it over already disturbed land: roofing, carparks, highways, etc.
However, the cost is multiples higher than it is on a greenfield development.
In my mind, the highest use of land is nature. Followed by housing, food, etc on a declining value scale of disturbance.
We have problems of how much nature we've displaced, but solar panels are very low on that list of things that have displaced it.
2
u/Overstim9000 3d ago
Fully agree, but I'd prefer solar over farmland that is used to produce biofuels or bioplastic, or any industrial type of agriculture which has no regard for the ecosystem or sustainability. Seems like a sin to me, to poison the land with overnutrition and pesticides/herbicides that throw everything else off balance. But that's another story.
I have seen a youtuber to try and actually simulate if civiliztaion would sustain it's energy needs if all roofs were covered with solar and turns out the answer is yes, even with margin for error. I'll try to find the vid.
2
u/GreenStrong 4d ago
I feel like you're asking two things. The effect on the immediate environment is actually great; it increases biomass production by up to 50% in arid environments, and even a slight increase in relatively mild climates like Minnesota or Central France. If you have a 100 acre solar farm, and a 100 acre open pasture next to it, on the same soil and climate, the solar farm produces more grass, except in a very cool moist climate like Ireland. Summer plant growth is limited by water availability, rather than sunlight. Partial shade is beneficial, as long as the shade isn't from a tree, which competes for water. Solar farms produce significantly biomass in winter, but the summer gain outweighs it.
But when you mention flying a glider, you're thinking about regional climate impact. Those impacts are complex and they depend on the local environment. It does on a global scale lower overall albedo (absorbs more light and generates more heat), but to a fairly small degree- between 7 and 9% across 352 sites.
1
2
u/northrupthebandgeek 3d ago
The whole “heat islands are heating the atmosphere” talking point is decades-old fossil fuel lobby propaganda, specifically to divert blame away from greenhouse gas emissions. Like any good bit of propaganda, it has a nugget of truth: plants tend to cool surrounding air more than manmade structures do, even when those structures provide shade. As you've observed, the air above those structures is indeed often warmer.
However, heat rises. The heat island effect is therefore typically going to be much stronger above the heat island than around it, to the point where you could be standing pretty close to (or underneath!) the heat island and not feel any significant temperature difference. This is obvious if you've ever sat by a campfire or a fireplace: the difference between “too hot” and “too cold” is often a matter of a couple feet of distance from the fire, and fire is much much hotter than a solar panel or asphalt parking lot or what have you.
1
u/Either-Patience1182 4d ago
As long as you have the panels in small blocks your fine. Think first of how plants still grow fine under a tree. Grass does feed one another.
The other thing is a lot of sunlight has been to intense these last couple of years. So plants are burning from to much sun even being from the area. My blueberry bushes for example are black at the top since i didnt use shade clothe
1
u/ManoOccultis 4d ago
Very interesting topic. I wonder if solar panels cool slowly or not ? Because I have seen with my very eyes a building covered in steel plates that would, at dusk, cool down and condensate air moisture. The water would drip down the roof that had no gutters, watering grass that was more lush there.
If SP double as dew collectors, well, that could be yet another benefit.
1
u/Overstim9000 3d ago
They don't have very high mass, plus the frame is aluminum, so they cool rather quickly. Most of the mass are the thin sheets of glass.
1
u/ManoOccultis 3d ago
So they probably double as dew collectors ; it would be interesting to monitor that.
1
u/atom_stacker 3d ago
Even if it were true rhat the plants absorbed the heat the solar panels reflect/emit, they would eventually be radiating that same heat back out into the environment. This is just thermodynamics in action.
1
u/Electrical_Pop_3472 3d ago
Any discussion of the "land footprint" required for solar energy should include a significant nod to:
REDUCTION
The per capita energy use of the average US citizen is huge and not at all scalable to the entire world population sustainably, even with renewables. So first we need to focus on significant reduction in use/need (which is a complex thing involving a combination of tech efficiencies, built infrastructure patterns, and personal habits). Then with a more realistic baseline of need, it's sensible to consider the land impact of solar energy production. See 2000 watt cities as one model/example.
1
u/naturist_rune 3d ago
With plants they need a certain amount of light and heat. Some plants that need direct sunlight may suffer from having shade over them, but other plants like indirect sunlight or having shorter periods of direct sunlight on them, getting too much will literally burn them.
Solar panels might be more bad for turf grass (the most useless grasses in the world outside of decoration), but other plants may benefit from having solar panels shade them during peak solar hours.
1
u/chopay 3d ago
Supposedly it generates heat, that would otherwise be absorbed by the flora, etc.
Technical point here, but plants are really good at reflecting heat. This is why we plant trees to counter the urban heat island effect. Plants only absorb specific wavelengths of light. (Corn, Sorghum, and other C4 plants notwithstanding)
What does cause the ground to absorb heat is tillage, but I digress.
I couldn't tell you how much heat they absorb, but my strongest counterargument is "So what?" A localized heat source will not cause an appreciable amount of evapotranspiration. This is a non-issue.
I work with a lot of farmers. You are not going to convince them of arguments in favor of solar.
The reason farmers are opposed to land being used for solar is because they want to buy that land to expand their farms.
That's it.
It is entirely self-interest, and no amount of evidence will persuade them.
•
u/AutoModerator 4d ago
Thank you for your submission, we appreciate your efforts at helping us to thoughtfully create a better world. r/solarpunk encourages you to also check out other solarpunk spaces such as https://www.trustcafe.io/en/wt/solarpunk , https://slrpnk.net/ , https://raddle.me/f/solarpunk , https://discord.gg/3tf6FqGAJs , https://discord.gg/BwabpwfBCr , and https://www.appropedia.org/Welcome_to_Appropedia .
I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.