Zhengyao Lu, Lund University and Benjamin Smith, Western Sydney University
The world’s most forbidding deserts could be the best places on Earth for harvesting solar power – the most abundant and clean source of energy we have. Deserts are spacious, relatively flat, rich in silicon – the raw material for the semiconductors from which solar cells are made — and never short of sunlight. In fact, the ten largest solar plants around the world are all located in deserts or dry regions.
Researchers imagine it might be possible to transform the world’s largest desert, the Sahara, into a giant solar farm, capable of meeting four times the world’s current energy demand. Blueprints have been drawn up for projects in Tunisia and Morocco that would supply electricity for millions of households in Europe.
While the black surfaces of solar panels absorb most of the sunlight that reaches them, only a fraction (around 15%) of that incoming energy gets converted to electricity. The rest is returned to the environment as heat. The panels are usually much darker than the ground they cover, so a vast expanse of solar cells will absorb a lot of additional energy and emit it as heat, affecting the climate.
If these effects were only local, they might not matter in a sparsely populated and barren desert. But the scale of the installations that would be needed to make a dent in the world’s fossil energy demand would be vast, covering thousands of square kilometres. Heat re-emitted from an area this size will be redistributed by the flow of air in the atmosphere, having regional and even global effects on the climate.
A greener Sahara
A 2018 study used a climate model to simulate the effects of lower albedo on the land surface of deserts caused by installing massive solar farms. Albedo is a measure of how well surfaces reflect sunlight. Sand, for example, is much more reflective than a solar panel and so has a higher albedo.
The model revealed that when the size of the solar farm reaches 20% of the total area of the Sahara, it triggers a feedback loop. Heat emitted by the darker solar panels (compared to the highly reflective desert soil) creates a steep temperature difference between the land and the surrounding oceans that ultimately lowers surface air pressure and causes moist air to rise and condense into raindrops. With more monsoon rainfall, plants grow and the desert reflects less of the sun’s energy, since vegetation absorbs light better than sand and soil. With more plants present, more water is evaporated, creating a more humid environment that causes vegetation to spread.
Read more: Should we turn the Sahara Desert into a huge solar farm?
This scenario might seem fanciful, but studies suggest that a similar feedback loop kept much of the Sahara green during the African Humid Period, which only ended 5,000 years ago.
So, a giant solar farm could generate ample energy to meet global demand and simultaneously turn one of the most hostile environments on Earth into a habitable oasis. Sounds perfect, right?
Not quite. In a recent study, we used an advanced Earth system model to closely examine how Saharan solar farms interact with the climate. Our model takes into account the complex feedbacks between the interacting spheres of the world’s climate – the atmosphere, the ocean and the land and its ecosystems. It showed there could be unintended effects in remote parts of the land and ocean that offset any regional benefits over the Sahara itself.
Drought in the Amazon, cyclones in Vietnam
Covering 20% of the Sahara with solar farms raises local temperatures in the desert by 1.5°C according to our model. At 50% coverage, the temperature increase is 2.5°C. This warming is eventually spread around the globe by atmosphere and ocean movement, raising the world’s average temperature by 0.16°C for 20% coverage, and 0.39°C for 50% coverage. The global temperature shift is not uniform though – the polar regions would warm more than the tropics, increasing sea ice loss in the Arctic. This could further accelerate warming, as melting sea ice exposes dark water which absorbs much more solar energy.
This massive new heat source in the Sahara reorganises global air and ocean circulation, affecting precipitation patterns around the world. The narrow band of heavy rainfall in the tropics, which accounts for more than 30% of global precipitation and supports the rainforests of the Amazon and Congo Basin, shifts northward in our simulations. For the Amazon region, this causes droughts as less moisture arrives from the ocean. Roughly the same amount of additional rainfall that falls over the Sahara due to the surface-darkening effects of solar panels is lost from the Amazon. The model also predicts more frequent tropical cyclones hitting North American and East Asian coasts.
Some important processes are still missing from our model, such as dust blown from large deserts. Saharan dust, carried on the wind, is a vital source of nutrients for the Amazon and the Atlantic Ocean. So a greener Sahara could have an even bigger global effect than our simulations suggested.
We are only beginning to understand the potential consequences of establishing massive solar farms in the world’s deserts. Solutions like this may help society transition from fossil energy, but Earth system studies like ours underscore the importance of considering the numerous coupled responses of the atmosphere, oceans and land surface when examining their benefits and risks.
Zhengyao Lu, Researcher in Physical Geography, Lund University and Benjamin Smith, Director of Research, Hawkesbury Institute for the Environment, Western Sydney University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
HT/Michael D
Other non-negligible reasons listed here from :
https://sinovoltaics.com/technology/solar-panels-deserts-part-1-chances-risks-testing/
Extreme temperatures: Solar cells are subject to enormous climatic stress.
Resource-intense operations: require good and stable cooling, this often involves the use of water.
Costly maintenance: access to deserts is usually more challenging.
Sand storms: sand storms are a frequent and challenging occurrence in deserts.
Geographic limitations
Grid connection
Specific effects on flora and fauna
Complicated terrestrial conditions
Dangerous and costly construction work
Political instability: many of the world’s large deserts that are close to sizeable urban areas are in instable regions prone to political unrest, threats of terrorism and even war, that carry a huge risk premium on the overall project investment.
Hey, I’ve got it! How about, cover the entire moon with solar cells? It could supply the entire earth with plenty of electricity. And think of the jobs! All green, of course. Win-win!
Why-do-we-burn-coal-and-trees-to-make-solar-panels.pdf Planet of the Humans | By Jeff Gibbs, Executive Producer Michael Moore As Michael Moore made clear ordinary sand is not of the right quality to make solar panels you need quartz blue gem coal and highly refined carbon made from Canada Oil Tar sands facts which fanatical greens love to ignore.
Let’s be honest here and point out that this study too is based on computer models and therefore about as legitimate as all of the alarmist’s computer model predictions.
On the other hand, using their models to under cut one of their projects has a sense of poetic justice.
Electricity generation needs to be where the demand for electricity takes place, as close as possible to concentrated civilization.
No one lives in the Sahara Desert!
The Sahara comes pretty close to the inhabited coastal strip and Egypt… plus a HVDC line to Spain or Italy is quite within the bounds of feasibility.
But nobody, ever, is going to cover 20% of the Sahara with solar panels.
For once you said something I can agree with.
It seems the ‘solution’ is just about as simple as the problem. Ever play with those plastic strips of super-reflective stuff that is popularly attached to bicycle frames, warning signs, high-visibility coats and vests? I once worked at a place that stocked the stuff for private airplane owners. Some of it, no more expensive than most other roll plastic, was ridiculously reflective. BACK. Point a high-intensity flashlight (US) / torch (UK) at it, and something like 95% is reflected back at the source, more or less.
For environmental durability, bond this to the backside of glass. Panels of it. For every m² of solar cells, require 1 m² of the super-reflector to be put on the SAME industrial scale panel frames.
Net albedo change could be exactly zero.
And that’d answer the problem.
Head on.
But it would have to be mandated by tight regulation and tough cheαting consequences.
⋅-⋅-⋅ Just saying, ⋅-⋅-⋅
⋅-=≡ GoatGuy ✓ ≡=-⋅
First off….all the spare money on Earth can’t pay to cover 20% of the Sahara with PV cells much less infrastructure to move the electricity to point of use. Secondly their statements about the climate effects of condensation, offset rainfall in the amazon, etc….shows their “advanced Earth system model” is questionable to say the least….
Silicon solar cells have low absorption of infrared of wavelengths longer than 1,000 nm, which is about 20% of sunlight. This means about 35% of sunlight does not get converted to heat and about 65% does. Also green plants are highly reflective of most of the IR-A subset of infrared which is about 35% of sunlight and they reflect some green visible light, so about 65% of sunlight hitting green plants becomes heat, and not all of that 65% becoming heat at the time at the time the sunlight is absorbed because some becomes chemical energy at the time it is absorbed which becomes heat when the plants rot away or are burned. Soil is at least 65% absorbing of solar radiation reaching it, and most sand is about 40-50 % absorbing of solar radiation reaching it, so replacing bare soil with green plants or solar cells won’t increase heating of the land and replacing most sunlit sand with green plants or solar cells causes only a small increase of heating of the land. And if an increase in land heating increases rainfall in a desert, wouldn’t that be mostly beneficial with a decrease of daytime temperature?
So if all those dark panels cause climate issues, isn’t the unmentioned solution simply to paint the Sahara white ?
I don’t trust climate models predicting human global warming. Why would I trust these climate models?
since the greens define non renewable energy based on the fact that there is a “limited” supply of oil, gas and coal in the ground how does the same label not apply to wind and solar which need to be replaced every 20-30 years (actually sooner in reality)
the materials to build wind and solar are not unlimited … and the land required to install them is certainly not unlimited …
I see nothing “renewable” in wind and solar power …
How often do they plan to fly in workers and water in order to clean those panels?
There appear to be a number of solutions involving neither…
This Is How Solar Panels Panels Are Cleaned Regularly In The Desert (wonderfulengineering.com)
Another dumb solution
All of those “solutions” are going to scratch the heck out of the panels.
What you and others seem to be ignoring is the fact that such cleaning devices increase the cost of the installations and take power away from the already marginal energy-density solar panels.
They can use ‘Borate Bombers’ for wildfire fighting, off-season, to clean the panels. 🙂
The difficulty is that less than 0.01% of the world’s population lives in the Sahara. So for the rest of us, that electrical energy will have to be transmitted over wires to where people do live.
The Earth’s circumference is about 40,000km. Which means that the longest cable would be 20,000km.
Do these so called professors actually believe there will be any energy left after it is shipped that far?
If they are right, the panels will eventually terraform the sahara into a lush garden and everyone in europe will just move there.
Of course once its a lush garden the panels will be degraded by rain clouds and then it all collapses.
Like any ponzi scheme
All that extra water in the atmosphere is also going to dramatically cut down on the amount of energy those solar panels are able to capture.
“This massive new heat source in the Sahara reorganises global air and ocean circulation, affecting precipitation patterns around the world.”
That’s a tail-wags-dog argument. It is total bullshit. Northern Hemisphere insolation is far more dominant across a hemisphere, a hemispheric-latitudinal energy imbalance that redirects/shifts the ITCZ. That imbalance is hemisphere wide, not some localized heating sources like solar farms, even a large one. Someone should tell these rent-seking morons that we live on a water planet heated by the Sun.
This is as bad as talking about the “dark side of the moon!” However, it comes from The Conversation, which has publicly announced they will censor comments they don’t agree with — those are comments that challenge any of their authors. Thus, the authors don’t need to be concerned about peer review.
The uncited claim is like a zombie that won’t die. There are two related reasons that Arctic waters usually look dark, compared to, say, the Mediterranean or Bahamas; 1) the specular reflection is actually high (10-100%), but can only be observed and measured in the unique position of looking into the sun on the horizon, 2) with high surface reflectance, the amount of sunlight that actually enters the water is a small percentage (1-Reflectance), and thus there is little light available to be scattered back out by suspended sediment or plankton. Also, a ray of light that does enter the water will be refracted downward but continue in the same direction, increasing the chance that diffuse underwater scattering will be strongest in the forward direction, and weak in all other observing positions other than looking towards the sun.
By contrast, snow is a diffuse reflector that scatters light almost uniformly in all directions. (There is a strong forward lobe because the platelets of snow tend to have a sub-horizontal alignment.) Thus, no matter what viewing position an observer takes, or the position of the sun, snow will appear bright, and thus is said to have a high albedo.
This is another example of climastrologists speculating, based on what are essentially urban myths, on phenomena that are outside their areas of expertise.
Goebbels would be so proud of these climate scientists.
I’m wondering about all the roads and new power lines that will have to be built in order to accomplish such a vast engineering feat. That will only add to the environmental degradation of the desert ecology. What will the long term effects of that be?
Mathematical computer assisted onanism. If they don’t stop it, they will go blind.
After reading this I wonder what the effect the models calculate for vast areas of asphalt, concrete, roof tops, and so forth. My guess is that someone, possibly many, have made some calculations.
Should have performed an Internet search before writing.
I’d like to see the carbon footprint required to but this many panels and the extension or power cable required to get my local power source replaced.
Living in Colorado, that power line should start about as big around as a lumberjacks leg.
Seriously folks, the only conceivable use for solar energy is to power industrial processes that can work asynchronously.
What solar panels in the Sahara could do:
Mr Rotter the caption under the four solar parks lists one as Desert Sublight. It is Desert Sunlight which is located outside of Desert Center California
Why am I not surprised by this?
The percent of solar radiation that is converted is irrelevant. Either the power per square meter is worth it, or it is not.
How much power loss would there be in transferring from the source in Africa to the load in Europe?
Anyhow, seems like a good project for Google, as they have such an embarrassment of riches that they are willing to throw tons of cash at instruments of virtue signaling.
I don’t really know why, but every time an article title includes “here’s” I know it’s socialist drivel. It’s always “[statement] here’s why…” Or “[statement] here’s what you need to know” or similar.
What’s disturbing is that so many media outlets use this. It’s almost as if someone is co-ordinating the release of articles or something.
Just keep it in mind, and you’ll start to notice more of them.