We think of the power we generate as coming from all these different kinds of sources. Oil, gas, coal, nuclear, wind… so varied! And yet they all fundamentally come down to moving a gas through a turbine to actually spin up a generator and make some juice. Even some solar plants worked this way, using the sun’s energy to heat water into steam to spin some blades and keep the lights on.
A solar updraft tower works along these basic principles, too, but in a rather unique configuration. It’s not since the dawn of the Industrial Age that humanity went around building lots of big chimneys, and if this technology makes good sense, we could be due again. Let’s find out how it works and if it’s worth all the bluster, or if it’s just a bunch of hot air.
You Spin Me Right Up, Baby, Right Up
The concept of a solar updraft tower is relatively simple to understand. The idea is to create a large greenhouse-type structure surrounding a tall vertical chimney. As solar energy passes through the glass of the greenhouse, it heats the air inside as well as the floor and other contents. Since the greenhouse is, by and large, not completely open to the atmosphere, the heat cannot readily pass away by convection, and so the air within tends to become hotter than ambient temperature. That is, except for the chimney. As the air under the greenhouse grows warmer, it becomes less dense, and thus due to buoyancy forces, it wishes to travel upwards, and the only way out is via the chimney. It’s thus possible to install turbines in the base of the chimney to capture energy from this air as it travels up and out of the tower.
Beyond simple power generation, the solar updraft tower also offers some potential for energy storage, much like a hydroelectric dam. The sun can be used to heat the air under the greenhouse, but that air does not have to be immediately allowed to pass through the chimney. It can be stored for some time before passing it through the turbines and up the stack. Some concepts propose to further improve the storage capability by adding large water tanks as thermal sinks beneath the greenhouse. However, like all thermal storage, it’s time-limited, as the air in the greenhouse starts losing energy when the sun goes down and the ambient temperature drops.
Simple engineering tells us that the potential power output primarily relies on how much warm air you have to turn the turbine, and how much you can get it moving. Thus, a larger greenhouse collector area will have more power potential. So too will a taller chimney, which will create a greater pressure difference between the hot air at ground level and the cooler ambient air at the top. As you might imagine, there’s not a huge amount of energy packed in to air that’s just been warmed up a bit by the sun. Thus, to get significant output, you’d want a huge collector and a huge chimney. If you’re wondering about scale, you’d want to consider chimneys many hundreds of meters high, and greenhouses measured in square kilometers.
As a guide, one proposed project in Western Australia promised to generate 200 MW of power. The tradeoff? It involved a 1-km high tower and a collector 10 km in diameter, to be built at a cost of $1.67 billion. The engineering team behind the idea, Schlaich Bergermann and Partner, noted that solar updraft towers really only make sense at these massive scales. Smaller installations aren’t cost competitive with photovoltaic solar panels, but larger ones can be. Large facilities make enough power to offset the huge construction costs, and ongoing maintenance is cheap, as it really just involves keeping the turbines and generator up and running. There are no dirty panels to clean, for example.
By and large, solar updraft towers have remained largely conceptual, with few real-world projects built. The best example of an actual solar updraft tower was a small-scale effort built in Manzanares, a locale south of Madrid, Spain in 1982. It was built for an output of 50 kW, and intended to operate for just 3 years. It ran for 7 years in the end, before collapsing in 1989 due to storm winds and corroded guy wires holding up the 194-meter tower. The chimney was paired with a 244-meter diameter collector, using a combination of glass and plastic membranes to create the greenhouse.
More recently, other pilot projects have experimented with the technology. Researcheres in Botswana experimented with a small-scale build of just 22 meters height with a small 15-meter diameter collector. The country has instead looked to photovoltaic and concentrated solar power concepts since.
Chinese efforts got a little further, but not by much. In Jinshawan, a $200 million project saw the construction of a solar tower on desert lands back in 2010. It combined solar updraft generation with a special air entry door that let it capture power from prevailing winds as well. Big plans were to see the build expand in multiple phases to eventually generate 27.5 megawatts, but it never came close. It achieved just 200 kilowatts, and was plagued by glass panels shattering in the greenhouse collector. It was originally supposed to have a 200-meter high chimney, but a nearby airport meant that it could only be built to 50 meters instead. This greatly limited the pressure differential available to help generate power from the heated air. The project continued for several years, but has made little impression.
Solar updraft towers are an interesting concept, to be sure. They rely on simple physics and are easy to understand. However, to generate meaningful power, they require huge tracts of land and incredibly tall towers. They pose a great number of challenges, many of which are simply construction and land use related, and come with a great many unknowns.
In comparison, we’ve now learned how to stick solar panels on every flat surface going spare, and are able to generate huge amounts of power via that route. Heck, they’re even sticking them on water now. Few governments or businesses would want to accept a pie-in-the-sky power generation project involving construction on a massive scale when there are easier routes to go. It seems that technology has marched well past the point where solar updraft chimneys might be viable, but who knows! Maybe one day, someone with a great deal of money and a taste for megaprojects might just make one a reality once more.
> Large facilities make enough power to offset the huge construction costs, and ongoing maintenance is cheap, as it really just involves keeping the turbines and generator up and running. There are no dirty panels to clean, for example.
Sure, now you have square kilometers of glass (for your greenhouse) to clean instead. What an improvement!
A little bit of dirt on a solar panel has an outsized effect on its output in comparison to this. So yeah you have square kilometres to keep vaguely clean for good performance here vs very very clean in comparison for Photovoltaic (or you basically never clean either and PV efficency just drops off worse).
I really don’t see this as a great saving on that front though, the saving maintenance wise comes from how very very much cheaper to make and replace the bit of glass is compared to a solar panel in the array, so if anything like freakish football sized hail ever breaks some its easy to repair the whole structure cheaply and recycle the broken bits too.
Very much not convinced this system makes sense in its own right – it is just so much land to commit to a relatively low power generator. But as a combination project with agriculture perhaps it really could – the whole thing is still a greenhouse and while balancing electric power generation vs optimal plant growth conditions potentially does put the two factors at odds I’d think be possible to get good results for both. Though how the humidity that is certain around growing plants will change the function of the solar updraft is a little tricky too – the mass of the air will change as the water condenses, the water itself could pose a problem for the turbines etc.
Thing is, it’s a greenhouse in areas with significant solar radiation, which makes it into a hothouse – too warm to keep plants.
The evaporation of water takes massive amounts of energy and cools the air down.
>it into a hothouse – too warm to keep plants.
Too many variables to say that categorically – the concept will work to some extent anywhere in the world, so if its cold enough outside normally then its probably just a greenhouse no matter how much sun it catches. You can also regulate the temperatures to those required for the plants relatively easily, potentially even passively so it ends up staying warmer and productive overnight (plus wide range of plants some like it insanely hot).
Between a large greenhouse that produces only fruit/veg or electricity and one that can generate some of both, maybe even getting close to as much of both as the stand alone…
If it’s cold enough outside normally, then it’s probably not a place that gets a whole lot of sunlight through the year.
You could grow plants in the edge areas, where fresh air is already coming in at ambient temperature. You could bring air through underground pipes to inner sections to regulate the temperature for plants further in toward the chimney. The same effect is used in reverse to grow tropical plants in Nebraska greenhouses.
Why not both?
Wouldn’t the solar panels heat up and create a similar effect as glass panels? Could have a solar farm with the updraft collector as a means of passive cooling.
Because solar panels loose efficiency as they warm up. Putting a ring of PV around the outside and using the draft to cool them makes sense, but the middle of the area would probably be barren or unused.
One hailstorm and the greenhouse is toast.
Normal hail shouldn’t be a problem, or at least only one if you don’t build it to last 5 mins. Real freak weather is always possible, but that sort of freak weather can trash anything. At least this would be reasonably cheap to fix.
There are massive greenhouses in places that also have hailstorms now, and they seem to manage okay. The economics may not work out, but I doubt that it’s a complete showstopper.
Yes, the posters assume that greenhouses are sheathed in glass, but they could be sheathed resin or a glass resin sandwich, which would withstand hail impact.
Agriculture could happen under a double pane, though obviously to maximize power output opaque bottom surfaces, e.g. vanta black, for the energy collector would probably be optimal. Leading to a lot of barren land.
You may also still need to deal with “hurricane” speed winds both as a structural and as an agricultural consideration. These may be due to the draft effect as well as weather events.
For someone to write such an obvious lie as that quoted paragraph, it’s clear they either do not think about what they say or else they want to deceive to minimize huge flaws in the design. Yes of course it would cause massive ecological harm; anybody arguing otherwise is either fooling themselves or acting in bad faith.
You can argue that every single thing a human has ever done is ecological harm if you want to, and actually have a reasonably valid point.
But that paragraph you object to is talking about something that on ecological harm terms should work out really negligible compared to most human activity. For instance consider the resources consumed for us to have this discussion, high complexity chemical refinery, mining, silicon fabrication etc just to make the computers and networking gear before you even get to consuming electricity in the process of achieving very little…
Arguably we are ecological vandals just for being here to read the article. So yes it covers a large land area, and won’t be dirt cheap to build initially. However as it should then last and keep generating practically forever on a human timescale with only very basic input resources for the maintenance – making it as far as ecological harm goes pretty good for a human activity, and a bit like Hydro-electric or water reservoir dam it is a short duration major upset for a very local area that long term works out better for us and the local environment as the alternatives we would use are worse. Not sold the idea will really work out as a great choice – to me seems like there are other avenues that either reduce the demand or cohabitate with our cities etc , but theoretically it is sound enough to be a valid possible solution.
Covering a 10 km circle in glass to gain 200 MW is negligible?
There’s a reason new hydroelectric project face stiff opposition from the environmentalists: the dams destroy entire ecosystems and also generate methane.
and most environmentalists are ‘religious’ twits.
Solar thermal is not a new idea.
A hothouse is just an idiot’s solar collector.
Better designs have existed for decades.
You could build a couple of nuke plants in that same area and get a few gigaWatts.
Dam don’t really tend to destroy any ecosystem and can actually increase the amount of rarer ecosytem behind them long term – It is rather more moving an ecosystem. Drowning one river/lake adjacent area to usually just create a much larger amount of those ecosystems around the now much larger perimeter – short term pain but for a long term payout.
>Covering a 10 km circle in glass to gain 200 MW is negligible?
By human standards absolutely – we cover way more than that to get nothing but a flat surface to park our seats 4-12 but almost never transports more than 1 people vehicles. We flatten huge swathes of forest/jungle with no concern that the soil erosion now possible with the trees gone over such huge areas will damn nearly sterilise that land in short order so even more slash’n’burn it is, we dig giant open pits orders of magnitude bigger just to burn the really low grade coal contents…
Humans really are terribly destructive in so many ways, covering a circle in glass and building a tower to heavens won’t even register on that list for so long.
>By human standards absolutely
Think again. The world’s largest open pit coal mines are only about 4-5 kilometers across, or less than a quarter of the surface area of one of these monsters. And they’re worth much more than 200 MW so you don’t need nearly as many.
Even the Three Gorges Dam is only 2.3 kilometers wide and floods 632 square kilometers of land, and it also makes 18 Gigawatts of power. It gets the 200 MW out of just 7 square kilometers of land versus 79 square kilometers for the solar chimney.
In other words, you’d be bulldozing 10x more nature and worse building these things than building coal mines or hydroelectric dams to get equal amounts of power.
>Think again. The world’s largest open pit coal mines are only about 4-5 kilometers across,
yes and just how deep? And where does all the waste go – Orders of magnitude bigger they are even if the land footprint of the pit itself isn’t as large. And then just how far does the toxic byproduct crap and runnoff into the water ways end up spreading? Or the acid clouds created by the burning of such poor grade coal it is almost more nasty shit than actual coal in it…
A giant glass house and chimney to create an airflow by its very nature has to has lots of fresh air intakes so can’t really be kept free from wildlife even if you wanted too… Its going to be a different ecology in there no doubt about it, certainly not destruction free, but not the multiple decades of work after the fact to try and make the giant pit vaguely habitable for some form of life once its run dry… And nowhere near the the same wider effect.
You won’t get me arguing against Hydro power. But it doesn’t have a major flaw in requiring suitable geography in the first place. So if you can turn a field into a productive greenhouse and get electricity out of it for decades to come so cheaply, actually hard to argue against.
Maybe a different kind of glass.
https://youtu.be/LcCOj1b3ZwY
This problem has already been solved — Nuclear Power. Add to that backbone some other sources based on what makes sense at location (geo, hydro, …)
Next problem please …
The “sticking them on water now” link is broken.
You don’t hear much about these.
That project in Jinshawan has the smell of a corruption scam. Reducing the tower from 200 to 50 meters destroys any hope of getting some decent energy out of it. Even the 200meter Manzanares tower in Spain was considered a small proof of concept experiment. Once these towers get big enough, efficiency is further improved by the inherent temperature difference of air at different heights.
I do like the idea of funneling already available wind into the base of the tower to further improve differential pressure over the turbines and thus energy output.
As a variant, Once you have such a tower, you can also use them in reverse. In a downdraft tower, you can pump up water and evaporate it at the top of the tower. Then the cooler and denser air will flow down though the chimney
https://en.wikipedia.org/wiki/Energy_tower_(downdraft)
Still won’t work at night.
If you insulate the greenhouse efficiently, yes it will. It won’t collect additional energy at night but you could allow less air up the chimney during the day and then, at night, use the stored heat to continue generating. The lost heat would be offset by the atmosphere being cooler at night, improving the power that can be extracted from what heat is stored.
Kind of pointless to insulate something you are sucking cold air through.
Not at all if the insulation allows load smoothing. By insulation I mean double or triple glazing above, insulating mats below. This is much cheaper than batteries.
Umm… You can double and tripple glaze all you want. If you want air to go up the chimney and spin a turbine you have to suck in cold air to replace it.
Almost all of these renewable energy schemes are corruption scams. I don’t doubt that the climate is changing and pollution has ill effects, what I am saying is that this sainthood marketing a company immediately gets from a thousand creepy international NGOs if you say you’re doing renewables attracts scam artists like a beacon. They are flies on rotting meat with this stuff. For every one legit person putting in a lifetime of hard work to engineer something exceedingly difficult—generating megawatts without pollution—there are hundreds of charlatans.
Honestly there needs to be some kind of legislation to tax large NGOs out of existence for several reasons.
It’s the same problem with governmental organizations as well: lobbyists driving funding into projects that can be shown to produce little or no returns whatsoever with a simple back of the envelope calculation, get built in the name of “research and development” even though everyone knows it’s a dead end.
Like, “inductively charging roadways for electric vehicles”. It’s cool – you can make endless small scale demos to prove that it works, but once you consider how much copper it takes to make a mile of such road it’s instantly obvious why it will never be used. Still, publicly funded universities the world over are researching this technology with the excuse that it might be some day used – and politicians and bureaucrats fall for it every time.
Example:
https://www.caranddriver.com/news/a45989117/first-wireless-charging-road-north-america-debut/
“The quarter-mile stretch of road comes from a collaboration between the state of Michigan and the tech company Electreon. “
Small change.
Solyndra
Their key ‘innovation’?
They were putting solar cells inside glass cylinders, so they were pointed to the east and west as well as up. Reducing the daily power generation per cell. Giving up midday light to chase morning and evening light, while driving up production cost.
An idea you’d expect from a half smart middle schooler, right after perpetual motion. Smart middle schoolers will also have these ideas but will understand when you explain why ‘it won’t work’ (as your father explained to you).
A smart HS calc student could have worked the math and proved to them it was a terrible idea, ‘they’ wouldn’t have got it though.
DC is full of corrupt innumerate politicians. The checks cleared. Politicians love checks that clear, a lot! Like normal dudes love squishy p.
>Reducing the daily power generation per cell.
That daily generation peak wasn’t the goal though – put solar collection into the path of early morning and evening sun you get a much more productive solar setup using any average but mean for the whole day – its a smooth rolling hill on the graph not a needle that spikes really hard at midday with almost nothing for the rest of daylight hours. Which then nicely lines up with peoples actual consumption of that electricity – don’t need storage or to import electric over longer distances to the same extent when the local solar is actually working though the all the high demand hours better.
>you get a much more productive solar setup
No you don’t, because the sun is at a low angle and your collectors will shade each other. You have to space them further apart to remedy that, and you use twice the number of collectors to point east and west unless you use some tracking setup which also costs more money in maintenance.
It’s a good idea that some solar panels face east and some west, but that’s reducing the total output per panel area by a factor of two or worse, so your power prices double.
The little lens concepts don’t have to shade each other at an angle the solar panel would really have worked at all, and being usually transparent really can’t shade each other very much anyway Dude. You do lose some peak performance with those concepts, but now you get a good portion of the panels rated power even when the sun is at a very low angle – its solid state and static but with a power curve that looks rather more like it was sun tracking!
That is vastly more productive for most, even if the area under the graph would end up smaller with the lensed options you need less battery as the power is more reliably available through the day, and because its more reliable through a day it also works out more reliable in general – that big storm cloud that comes over at midday really buggers up the regular PV output for that day, but won’t make nearly as much difference for the lensed panel that can actually make good use of early morning light.
Flat panels make sense because they are cheap, really cheap even, and that is great when you have a big grid to connect to and lots of profits to make. Not really because they get a slightly higher lower output under ideal conditions. Lets put it this way the battery we have here is on any day it isn’t horribly overcast full long before midday. But was probably rather empty for breakfast (certainly would be if the grid connection did go down) when our flat solar panels are still achieving very little (though yes we have a very small battery really – wouldn’t actually be able to run the baseline load of the house for 10 hours).
>The little lens concepts don’t have to shade each othe
Yes they do. It’s just basic geometry.
>>The little lens concepts don’t have to shade each other
>Yes they do. It’s just basic geometry.
Read the whole damn sentence – AT THE ANGLE THE PANEL WOULD ACTUALLY DO ANYTHING ANYWAY! A panel kept nearly perpendicular to the correct direction does technically make some power off the ambient but it is virtually nothing, the good output spike comes only when you are very close to perfectly sunward pointing. So as these lens are not hugely tall opaque obstacle that cast massive shadows for hours. They are infact largely transparent and usually quite small lenses… They really don’t shade each other during the hours the panel would do anything much anyway. Look the the power curves of such concepts and you get something that looks like you had a sun tracking rig set up from a panel that doesn’t move! Clearly so very shadowing of each other… Yes you do loose the peak of that panels performance, there is absolutely a cost to it, but it turns a huge power spike for a few hours either side of midday into a really nice rather smooth rolling hill that actually produces good power through all daylight hours (assuming there is sun).
> Look the the power curves of such concepts and you get something that looks like you had a sun tracking rig set up
Those power curves are pure marketing. If you lay a panel flat down, the angle of the sun as it travels across the sky causes the solar flux density to change so it peaks in the middle of the day. If you want to make a smoother curve out of that, the only way to do it is to REMOVE power from the peak. That’s basically what they were doing in an elaborate and costly way.
A cheaper way to do that is to paint a grid of thin wires over the cells so they coincide with the mid-day sun and shade it a little bit, but let light through at other times. Saves you the cost. The idea of the lenses was to capture light from very off angles, from the early morning to late evening, but there wasn’t much light available there anyways and it was coming in at such a shallow angle that the lenses were in each other’s way.
The idea that the transparent lenses don’t shade each other because they’re transparent is bunk, because the whole idea of a lens is to bend light from off angles down into the panel. Either the lens won’t capture the light at all from a shallow angle, which means it misses the PV cell as well, or it does and it robs the light from the next lens down the line.
> you get something that looks like you had a sun tracking rig set up from a panel that doesn’t move!
That’s physically impossible, because the cross-section of the stationary panel against the solar flux becomes smaller as the sun goes lower in the sky. It simply receives less light. In a sun-tracking rig this isn’t the case, because the panel is always facing the sun, so the two power curves look very different.
No lens can magically catch the sun rays off the air where they don’t physically enter the lens.
Dude the lens concepts take a really really quite narrow arc the solar cell really kicks into high gear at and makes it a much much wider arc – yes the scattering of these lenses when you are not on the ideal axis for them does loose you some performance under idea conditions at noon, but it also means you get something very much closer to noon level performance in the earlier and later parts of the day. As you are now capturing and directing that light to the panel at an angle it works better.
And while yes its possible for lens to shadow a lens, what you’d end up with at the angles shallow enough some light hits one lens that is in the path first is that both that lens and the next on in the line work on that ray – the lens has bent the light and might steal some with internal reflections but lots of light still gets through to the next lens even off axis. Or are you arguing that your window glass is opaque at all times but when the light is coming in perfectly on axis?
>> you get something that looks like you had a sun tracking rig set up from a panel that doesn’t move!
>That’s physically impossible, because the cross-section of the stationary panel against the solar flux becomes smaller as the sun goes lower in the sky. It simply receives less light.
Yes, the area you are catching light matters, however sun tracking rigs still don’t do squat till the sun is high enough over horizon either and once it is you get a similar curve – I didn’t say they had the same output power, but the CURVE is very similar. And that is because these lens do improve the capture of early/late in the day light – a solar panel isn’t just a x light hits it makes y, the angle that x light hits the PV panel actually matters too! Which is why a lens on a solar panel might make that nominally 300w panel never be able to produce more than 200w, but will now when the uncovered flat panel would be producing say 40w with the lenses you are producing 140w. Its not just shaping the curve by blocking sunlight at noon!!!
Did they consider the impact of injecting lots of hot air up into the stratosphere on weather patterns and cloud formation?
What about the impact of injecting large volumes of hot air directly up people’s rear end, which is what they are actually doing. This is a hairdryer enema company
The lower edge of the stratosphere is around 7-20 km and I doubt the impact of a narrow 1 km tower of hot air would be measurable.
You mean, like every other chimney and cooling tower ever built?
You don’t need to build the tower straight up. You could, for example, build a tube up the side of a 1000m mountain. Straight up is more efficient as it’s the shortest way to achieve the required altitude difference, and the walls of the tube produce drag, but provided the whole thing is cheap enough, who cares?
Aren’t there some slightly irradiated deserts in Nevada with adjoining mountains which would be ideal for this?
Well if you like desert and radiation how about using low level nuclear waste to warm the air for the tower?
The main issue with that and anything like that is keeping idiots from stealing the slightly dangerous material used. Because it produces less power and requires a large area the cost of properly securing it goes way up.
I assume the previous comment mentioned the land being irradiated as a way to say, land that is unfit for normal use.
Also, if were building any sort of nuclear power, we should just build better versions of the traditional ones.
Could be feasible.
Sweden / Finland (or thereabouts) are finally building long term nuclear waste storage deep underground. If that stuff gives off enough heat, it can be used to keep ventilation going (for people working there) and if some energy can be extracted on top of that, then that is an extra bonus.
Science Fiction author (and Marine Biologist, PhD) Peter Watts described a somewhat similar arrangement in one of his books. Only his hive-mind non-aristotalian thinkers somehow constrained a tornado at the top to draw air through a shorter tower.
sounds like the Aeromine, which is a current small sized wind generator.
https://www.aerominetechnologies.com/
Man that guy is wacky. Great books, people should read Blindsight. His dialogue is a little meh but it’s a book you read for interesting concepts, not incredibly deep characters. His idea of what an interstellar intelligence would look like is probably more accurate than almost anyone else’s.
Sure hope the future doesn’t turn out like he predicts.
In the 1920’s a French physicist, Bernard Dubos proposed a solar updraft chimney generator using a “greenhouse” for warming the air, and a 6600 foot concrete chimney of about 30′ diameter to run up the side of a mountain to generate wind power. He had designed it thinking of North Africa as an ideal site for it.
Both the difference in temperature and the difference in atmospheric pressure should have generated a steady flow of air, at least during the day and when the air was heating.
But, there isn’t a difference in atmospheric pressure if the temperature is the same?
If I build a 5km high chimney on the moon and fill it with air until the bottom is at 1 ATM pressure, the top will be at 1/2 ATM (the same pressure as the air on earth at 5km) because the weight of the air above it is pressing down on it.
Or do you just mean that the height multiplies the pressure difference from the air being heated?
Edit: my analogy should have said “atmosphere-less, earth like planet” not “the moon”, because the moon’s gravity is different.
There are people who troll this site by pretending not to understand HS physics.
Their objective is to trick a geek into wasting time spoon feeding them.
They aren’t exactly creative. Last, I remember was demanding an explanation for why you couldn’t generate power between the pressure at the bottom of the sea and surface.
Then again. Site standards are ‘be kind and respectful’…could be a genuine…
It’s easy to assume malice if you forget that half the people have an IQ below 100.
Didn’t NewScientist’s Daedalus (aka David “perpetual motion” Jones) present this scheme sometime back in the last millennium? (recall, it was a humor piece)
I have thought about a similar system for years, start with some location with lota of hot atr to begin with, like death valley. Make the chimney as tall as possible but make it coaxial, channel sea water via a tunnel in from the ocean making the tunnel narrower as it goes so the water can make it to the top of the chimney where it is sprayed over the outer openings cooling the exiting air making it cooler so it drops down through a second set of turbines generating more power. the water evaporating causes desalinatio to occur with thesalt falling out the moist air could be harvested to use as drinking water or for agriculture salt sold as a byproduct. if the water was brought in thugh the tunnels by gravity thats energy saved with no pumps. 2 times the power, 2 side products, 4 income streams vs. one. So what am i missing? there has to be a got you here some place!
I may be misunderstanding this, but, I see a flaw. Isn’t all sea water located at sea level? And this would require the seawater to be at the top, right?
Pumping water up large heights is insanely energy intensive, so, wouldn’t that eat up almost all of your power generation ability to pump the water up?
How about a photovoltaic farm under the green house? Keeps the panels cleaner, and cools them. Heat might be about the same.
What are the economics like when sited in a climate too cold for crops, and using the area under the glass/plastic sheeting for farming as well?
It is a greenhouse after all.
Or, in a cold climate it could be used as an ‘outdoor’ heated park.
The massive fixed thermal column they create will change the regional weather patterns in hard to predict ways and that disruption could destroy sensitive ecosystems. Nuclear is much more ecologically friendly, even in worst cases case such as “three eyed fish” scenarios, which are entirely hypothetical anyway.
It’s a chimney. There are thousand of cooling tower/chimneys around the world, and their whole purpose is to funnel megawatts of heat into the sky. Any coal or nuclear plant, not mention factories and industry will have several (and the coal power stations are way worse because they also funnel radioactivity, sulfur, heavy metals and CO2 into the atmosphere!)
Dumb question/thought: could the energy generation of this be thought of as a giant hot air balloon? Such that the power output is the lifting capacity, the tower size is the balloon size, and the greenhouse temperature is the heater. Then to increase the power, you need to make the balloon bigger while keeping the temperature the same, or you need a bigger temperature difference for the same size.
Has anyone proposed using a source of heat other than solar, such as geothermal to heat the air? I assume that with those energy sources, it’s easier to just create electricity the old fashion way.
Can’t we just build these at a smaller scale over government buildings? Plenty of hot air there!
I remember reading years ago that in the 1800s a man built a solar chimney onto his house. It was like a traditional chimney but the south side of it was glass. A damper in the bottom of it opened into his house. As air heated up and rose it would draw air from the house. Fresh air from an underground passage was pulled in to replace the air traveling into and up the chimney. This was how he cooled his house. I wished someone in modern time to repeat this and measure how effective this actually was.
I saw a documentary a few months back showing how tribes in the Sahara have been making houses slightly below ground, but with tall chimneys to keep cool their homes. They had been doing this for centuries.
If you already have a source of cool air from an underground passageway, couldn’t you just stick a fan on it to pull the air?
So, the efficiency of the chimney would be whatever power the fan would have used before it was replaced by the chimney.
Gravity ventilation is what most houses and buildings used 100 years ago, and what many still use. It doesn’t require solar chimneys – just that there’s some heat source in the house to cause convection.
You’d have to build something like this on what we in the UK call (not sure whether the term is the same over the pond) “brown field” Sites. Tearing up more farmland or forest for this kind of thing would be a definite non-starter. We’re concreting over more and more of the planet on a daily basis, not to mention the “solar farms” that developers are throwing up all over the place.
Minimum 10km-wide collector? bwahaha.. that’s a ridiculous amount of land to waste for something like this.
It’s an interesting concept but if, in order for it to be cost effective, you need huge swathes of land for it to work, it’s a bust.
The politics of brownfield sites is weird. We’ve got one that has been sitting for 20 or more years, the state couldn’t find any solar investors, and now half of it is storage for CAT trucks. But the other brownfield site a couple miles away was purchased by an investor and they’re blitzing the cleanup and reconstruction. I think brownfield #2 is already zoned for industrial use which makes it easier to build on.
I don’t quite agree – while we don’t in the UK have the huge Polytunnel Growhouses of Spain we could have them. So cover over farming land with them and stick a honking great tower up the middle to gain some electric out of it. It would almost certainly be a change in the crops grown, but I don’t think it really has to mean taking productive land and making it unproductive. (though I do expect you would need to make some tradeoffs between optimal plant growth and electric production)
The real problem here would be the NIMBY’s that would complain anything other that open fields is spoiling their views…
All these crazy projects should never have passed the back-of-the-envelope stage. There are only a few effective ways to generate power:
nuclear, fossil fuels, weather(wind and solar), and geothermal/hydro if your country has the right geography for it. If you don’t have access to the last one and are opposed to the second one, then the only alternative is nuclear, you cannot reliably depend on the weather for power production.
I had to do the maths:
A quick google suggests (in the UK) you’d need 6-8 acres of land to generate roughly 1 MW of solar energy, so: 10km2 = 2471acres, 2471/8 = 308MW, likely significantly more if placed somewhere sunny like Australia.
Another cursory google suggests solar is about $200,000/MW installed and still dropping, 220k * 308 = a mere $62 million compared to the article’s $1.67 billion.
Does nobody run these mad ideas through even the most basic bulls*t checks?
Answer: you’re right, no one runs this by the BS detector.
Sadly, your math seems wrong. (Or that the proposed efficiency you’re using is less than 3%)
Wikipedia states that solar irradiance is about 1 kilowatt per square meter (when sunny, and it varies), and one square kilometer is 1 million square meters (1000×1000), therefore, your 10km2 area receives 10 million Kilowatts of energy from the sun or 10,000 MW (on a sunny day). If you only get 300 MW out of 10,000 MW possible, that would be 3% efficiency, which, compared to PV is abysmal.
You mentioned UK numbers being different, does that mean that the numbers you used are normalized for cloudy days and night times? Because PV solar would also not perform well in those conditions, so, it’s not a fair comparison.
All these comments and not one Daemon (Daniel Saurez) reference, I’m shocked.
I’m also shocked at all of the hail concerns. Glass is easy to recycle and replace, and tempered glass is a thing if you’re very worried
Glass is also highly energy-intensive to make and recycle, since it’s basically molten sand, and the cheapest way to do it is with gas furnaces.
The elephant in the room, and what everyone refuses to acknowledge with solar power is the cost of making it, because the major manufacturing costs come from refining silicon and refining glass, and the main point there is that both processes use massive amounts of energy.
So, solar power is cheap because fossil fuels are cheap. If you want high grade process heat to run a silicon refinery or a glass furnace, natural gas comes in at 1-2 cents per kWh straight off the pipeline. Renewable electricity out of the grid comes at the average system costs – because these aren’t the kind of processes that can just be started and stopped at will – which is 10x the price at 10-20 cents and more.
If the industry was forced to “eat its own dog food”, i.e. produce renewable power using renewable power instead of fossil fuels as inputs, it would fold in on itself and vanish.
It’s all relative.
A general statement like “glass manufacturing uses massive amounts of energy” is just wrong.
Proof: Check out recyclables every week. A huge amount of it is glass containers.
When ketchup no longer comes in glass bottles, I’ll be glad to revisit this…
Recycling glass is almost as energy-intensive as making new glass, because the main part is melting it. Whether you start from sand or ground-up glass bottles makes little difference here.
Re: Recycling glass is as energy intensive as new …
You’re totally missing the point. You’re making this grandious “elephant in the room” argument, that glass is sooo expensive.
If glass is so prohibitively expensive, how is it, it can be used as packaging for cheap goods?
I had read in Popular science years ago of a similar setup using heat output from nuclear and other generation plants to fuel the turbines. In that case it was meant as a secondary generation step using waste heat. Certainly beats using solar thermal and the space that would take up to create the source heat.
I like the multi use of this. Tower can be also used as communication tower or transmitter tower, and the greenhouse would house plant that would not survive outside in local climate or even homes that would save on heeating, just farther from the turbines. If one gets build and i get offer to live there or even work there as a engineer i would go for it.
One wonders if an effective absorbing material (maybe just a black painted box of sand) with embedded pipes would work better than large glass enclosures.
This is interesting: Wonderfully low tech requiring little more than 19th century capability, similar to a dam. But even a dam requires just the right geography and geology and, as mentioned, is quite destructive to its environment.
But look at a world atlas and check out all those vast areas of cold, dry desert in Central Asia. It seems to me the economics involved may be far more favorable to this kind of power generation compared to, say, wind power (though these would likely be combined).
While I’m very in favor of developing proper nuclear energy, for now our society seems unable to organize and regulate itself around anything other than maximizing profit (read greed of the few) from such investment, sacrificing safety and environment in the process. Nuclear economics also favors high density, high centralization of its consumers; just the opposite of what is found in Central Asia.
It’s past time we stop with the single-use structures. A tower? Chimney, cell antennae, broadcast antennae, gravity/mass energy storage system, wind turbine at the top… some combination of these and more make the undertaking far more economic (and concentrate the visual pollution instead of spreading it around).
Easier to design and maintain single-purpose structures? Sure it us. But look how exceedingly complex it is to build a fusion reactor, and we’re still chasing that. The Information Age is not over, it’s just becoming broader and more complicated.
https://en.wikipedia.org/wiki/Solar_updraft_tower