Algae carbon capture

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CCatalyst
TL;DR Summary
I want to save the planet.
I'm just devastated by the news of climate change as of late, and I knew it was worrying but I've never been more worried about it in my life than I am right now. Have we truly passed the point of no return? Are we all doomed?

Or do we still have time? Is algae carbon capture the way out? And also how do I turn into biofuel?

So I want to make my own algae tank and use it to absorb carbon dioxide. Any advise and suggestions? And how do I get started?

2milehi and Ivan Seeking

Summary:: I want to save the planet.

I want to make my own algae tank and use it to absorb carbon dioxide.
At individual level, there is very little chance that this will yield negative carbon footprint.

I suggest you plant some trees instead.

hutchphd, Astronuc and Ivan Seeking
Staff Emeritus
Gold Member
Summary:: I want to save the planet.

I'm just devastated by the news of climate change as of late, and I knew it was worrying but I've never been more worried about it in my life than I am right now. Have we truly passed the point of no return? Are we all doomed?

Or do we still have time? Is algae carbon capture the way out? And also how do I turn into biofuel?

So I want to make my own algae tank and use it to absorb carbon dioxide. Any advise and suggestions? And how do I get started?
Firstly, there is always hope. The choices are now more about how to best manage problems and through what means. Now we are likely looking at geoengineering solutions and not just reduced emissions.

I agree with Rive. In fact I actually started a company with an impressive team, with the intent to start producing fuel from algae at a competitive price, back around 2008. But there was still so much costly research needed it just wasn't practical for a small company to make a go of it. And one thing that becomes abundantly clear as one tries to design practical applications for this, is the scale of the problem. In my own model, I had to go to a 50,000 acre site before I could expect profitability. It is not an easy problem. And algae farming is not for amateurs.

Think globally. Act locally. Figure out how you can best contribute to the solution as part of the big picture.

hutchphd and Spinnor
Gold Member
More than ten years ago I visited an algae growing aquaculture facility in an arid area in California somewhere (don't remember where).
Its function was to make Spirulina algae for food production (humans and other things).
Besides the water maintaining equipment, it was mostly an oval shaped raceway of circulating water, maybe 20-50 feet wide but only a a foot or two deep. (The color was very green and the light probably wouldn't penetrate very far.)
The water circulation (due to paddle-wheel) keeps the algae in suspension. Otherwise it would create production problems.

This looks like a cement lined pond, but it might be cheaper to just dig a depression and use a pond liner.

This would be far more efficient than a set-up that does not use natural light.

It was a big set-up for the amount production, but was economically feasible due to the prices of the product, which would be hard to get in large pure quantities by other means.

I can't see something like this having much impact on global CO2 in the air.
When it comes to making fuel, it might be economically feasible, depending on the fuel produced.
One advantage of algae is that it can be fairly easily engineered genetically (being single cells). This could lead to production benefits.

Staff Emeritus
Gold Member
More than ten years ago I visited an algae growing aquaculture facility in an arid area in California somewhere (don't remember where).
Its function was to make Spirulina algae for food production (humans and other things).
Besides the water maintaining equipment, it was mostly an oval shaped raceway of circulating water, maybe 20-50 feet wide but only a a foot or two deep. (The color was very green and the light probably wouldn't penetrate very far.)
The water circulation (due to paddle-wheel) keeps the algae in suspension. Otherwise it would create production problems.
View attachment 285599
This looks like a cement lined pond, but it might be cheaper to just dig a depression and use a pond liner.

This would be far more efficient than a set-up that does not use natural light.

It was a big set-up for the amount production, but was economically feasible due to the prices of the product, which would be hard to get in large pure quantities by other means.

I can't see something like this having much impact on global CO2 in the air.
When it comes to making fuel, it might be economically feasible, depending on the fuel produced.
One advantage of algae is that it can be fairly easily engineered genetically (being single cells). This could lead to production benefits.

That is a classic raceway. The problem with using Spriulina and other nutritional supplments as a comparison to algae for fuel is that the end product for Spirulina sells for around $15 for 500 mg [$30 a gram]. Algae fuel needs to sell for [today] $4 for 7.2 pounds [one gallon]. It is a very different problem by two orders of magnitude. I am still convinced that algae is key to a renewable energy future. However, we need to grow about as much algae [by area] as we do corn. That is in the neighborhood of 90 million acres. Some companies were trying to start giant algae plumes in the ocean to offset the CO2 they produce in industry. I don't know the state of this. Given that ideally you can produce as much as 5000 gallons of fuel per acre-year of algae growth, that also suggests an upper limit for the CO2 one acre of algae can absorb in one year. Most of the carbon absorbed goes to either fatty acids [used for biodiesel] or sugar [used for ethanol]. Last edited: BillTre Staff Emeritus Science Advisor Gold Member Staff Emeritus Science Advisor Gold Member Spirulina sells for around$15 for 500 mg [$30 a gram]. Algae fuel needs to sell for [today]$4 for 7.2 pounds [one gallon]. It is a very different problem by two orders of magnitude.
Ack! Memory error plus a typo. Spirulina now sells for as little at $10 a pound but the point is the same. The markup in some "health foods" is crazy. BillTre Science Advisor Gold Member Thought that price was a bit high. Spirulina is a pretty pure product as far as I have seen. Maybe this is not such an issue in fuel production? Algae blooms can be made in some conditions just by adding iron to the water (which is pretty cheap I've been told). There are two arguments going on. One concerns doing things that would have a positive effect on climate change. The other is non-extractive fuel production. I guess that's because on the bipartite nature of this thread. I can see how this would remove CO2 from the atmosphere, and perhaps eventually sequestered to the bottom of the oceans, as dead things that have eaten the algae. However, if the carbon then just burned as fuel, I'm not sure it does anything for carbon balance. How you could harvest fuel from the algae you release into the ocean? Other than plankton netting or net penning the whole area where the algae are growing. That would not be popular with a lot of people. Done in tanks on land, these problems would not be problems. Staff Emeritus Science Advisor Gold Member Thought that price was a bit high. Spirulina is a pretty pure product as far as I have seen. Maybe this is not such an issue in fuel production? Algae blooms can be made in some conditions just by adding iron to the water (which is pretty cheap I've been told). There are two arguments going on. One concerns doing things that would have a positive effect on climate change. The other is non-extractive fuel production. I guess that's because on the bipartite nature of this thread. I can see how this would remove CO2 from the atmosphere, and perhaps eventually sequestered to the bottom of the oceans, as dead things that have eaten the algae. However, if the carbon then just burned as fuel, I'm not sure it does anything for carbon balance. How you could harvest fuel from the algae you release into the ocean? Other than plankton netting or net penning the whole area where the algae are growing. That would not be popular with a lot of people. Done in tanks on land, these problems would not be problems. Purity is a HUGE issue in fuel production. Firstly, most strains are not sufficient for producing fuel. And strains are being hybridized to maximize the yields. Strains tend to mutate from good producers to poor producers. So maintaining a high-yield strain is challenging. Also, algae is highly vulnerable to invasive algae species, bacteria, viruses, and parasites. These are but a few of the challenges in producing fuel from algae. Wild strains left to grow naturally will never produce enough fuel per acre-year to be competitive at the pump. For CO2 sequestration, the idea is to do what nature has done for millions of years. Algae in the ocean absorb CO2 to grow. They eventually die and sink in the deep ocean where it is preserved by the high pressure and low temperatures until eventually turned over and buried by tectonic motion. It turns out that a significant percentage of petroleum actually has it's origins in ancient algae. When used as a fuel, algae fuels can be carbon neutral. They can only release as much carbon as was absorbed to grow. Due to the vast amounts of water required to grow algae for fuel production, [note the number of hydrogen atoms per molecule of biodiesel] the only viable option I see is to grow the algae in closed bioreactors [essentially giant baggies] in the ocean and possibly large lakes. Abandoned oil platforms in the Gulf of Mexico would make excellent hubs for oceanic algae farms. And the infrastructure for fuel production is already in place. Ocean farming also helps to reduce the problem of excess heat, which is a challenge for land-based algae farming. Open raceways like that used for Spirulina are not acceptable for fuel production. They will certainly be closed batch systems. The purity of the strain could never be maintained for long in an open. continuous production system. And even running a paddle wheel in a configuration like that could eat up most of your energy gains from the algae produced. The key to starting an algae bloom is to dump vast amounts of nitrogen into the water. In fact nitrogen accounts of a significant percentage of the cost of farming algae. Runoff from farms and other sources rich in nitrogen such as sewage, often spawn wild algae blooms. Also, algae can be used to remediate nitrogen pollution in a controlled manner, rather than allowing wild blooms to choke off the oxygen supply for wildlife. When I first started looking into algae for fuel, perhaps as far back in 2006, biodiesel from algae cost up to$50 a gallon to produce. I have read recently that some producers are claiming to have broken the $5 per gallon barrier. Last edited: BillTre CCatalyst With all due respect, shouldn't removing carbon dioxide be of a higher priority than creating fuel? Sure it may be expensive but wouldn't it be worth it if it saves the whole planet? Also, couldn't we use algae and some other renewable in tandem? We would use solar and/or wind to circulate the algae and run the pumps to collect carbon dioxide and remove the oxygen. So couldn't that solve the problem? Also I think the sources (or at least the sources I've read) state that algae is a better if not the best at absorbing carbon dioxide. Or how well does it compare to other carbon capture methods? I know this may take some R&D but the fossil fuel industry had 50 years to do so. If they shared our concern they would have solved it by now. Instead they let their greed blind them and now we are looking down the barrel of the next mass extinction. We cannot let this happen. Ivan Seeking Science Advisor With all due respect, shouldn't removing carbon dioxide be of a higher priority than creating fuel? No. The first priority right now is to reduce carbon footprint. Any 'remove carbon' is just empty word till actual usage depends on fossil carbon and overall footprint is vastly positive. CCatalyst No. The first priority right now is to reduce carbon footprint. Any 'remove carbon' is just empty word till actual usage depends on fossil carbon and overall footprint is vastly positive. But won't removing carbon dioxide be an example of reducing our carbon footprint? And doesn't algae absorb carbon dioxide faster than trees? Answer this for me, how well does algae absorb carbon dioxide in comparison to oh say, magnesium oxide? Staff Emeritus Answer this for me, how well does algae absorb carbon dioxide in comparison to oh say, magnesium oxide? How about in comparison to a tree? Last edited: Rive and berkeman CCatalyst Mentor Note -- As a reminder, this thread is going okay so far, but please keep in mind the current PF rules about Climate Change discussions: https://www.physicsforums.com/threads/climate-change-global-warming-policy.757267/ Thanks. Fair enough, I think we can all accept that climate change IS real and it IS the result of human activity. After all we cannot fix the problem if we do not think it is happening. THAT debate should be over, we should be discussing how to fix it. How about in comparison to a tree? You tell me, that's why I'm here. But from a quick Google search, I was able to determine that algae can absorb 1 to 3 times its weight in carbon dioxide. Besides, don't trees have a very low metabolism? And aren't they burning causing less of them to be available to recycle the carbon dioxide? I'm not saying we should not be planting any trees, please do. I just don't think it will be enough. Can we plant trees faster than they are being burned down? Good luck with that. Is it not true that if we were to bring our net carbon dioxide output to zero, we would still be past the point of no return? The carbon dioxide in the atmosphere is still causing elevated temperatures, resulting in more forest fires, resulting in more carbon dioxide, resulting in more elevated temperatures, resulting in more forest fires and so on? Mentor and it IS the result of human activity. That is not what the PF rules say. we should be discussing how to fix it. Sure. Science Advisor we should be discussing how to fix it. But this particular topic seem to be about something different: Summary:: I want to save the planet. So I want to make my own algae tank and use it to absorb carbon dioxide. You were provided examples, hints and references about the difficulties regarding usage of algae. At home, there is no way you can make this even just comparable to trees. But from a quick Google search, I was able to determine that algae can absorb 1 to 3 times its weight in carbon dioxide. The end product of algae 'gardening' is a stinky, wet and 'dirty' goo. Especially if you do this at home. It requires quite amount of processing till it becomes either some kind of alcohol and/or some kind of oil/fat, ready for storage. Without processing (and circulating the waste), it quickly depletes the available nutrients, what you provided with quite a carbon footprint. Compared to the straightforward carbohydrate production of trees, it's just far more troublesome. Especially if you do this at home. If done big, that's a slightly different matter but still: the end product is 'dirty'. It's best to use it in an industry where this 'dirt' is called 'nutrients' instead and highly valued - food. But then it is no longer about carbon capture. Cool down and instead of pressing this dead end just listen to others. Last edited: BillTre and berkeman Science Advisor Gold Member Hi Ivan, I remember a long thread you had about this. Must have been on PF version 1. Maybe @Greg Bernhardt can find it. Ivan Seeking CCatalyst If done big, that's a slightly different matter but still: the end product is 'dirty'. It's best to use it in an industry where this 'dirt' is called 'nutrients' instead and highly valued - food. But then it is no longer about carbon capture. Cool down and instead of pressing this dead end just listen to others. Well fine but take a look at this. Algae might be a secret weapon to combating climate change It says that algae can be 400 times more effective than trees at absorbing carbon dioxide. Now everyone keeps saying it is difficult to scale up. But why is that exactly? Plus some people are making their own biodiesel from algae. Staff Emeritus Science Advisor Gold Member Hi Ivan, I remember a long thread you had about this. Must have been on PF version 1. Maybe @Greg Bernhardt can find it. Not that long ago. :) https://www.physicsforums.com/threads/algae-to-the-rescue.211274/ Near the end I spill my guts about some things we learned while researching this and in countless hours of discussions with experts. I had my company for about two years before we decided the cost of development was still just too high for a small company. The scale of the problem just keeps growing and growing, forgive the pun. Even ignoring much of the development cost, the first profitable point I could find using my model was a 50,000 acre farm. Note also that in addition to an algae biologist and a noted land use expert, I managed to recruit the chemist who was the nation's leading expert on biodiesel at the time. We had quite a team! This was a serious effort. I was most proud my solution for nitrogen. In short, nitrogen is a significant cost of farming algae. It turns out that diesel engines used to power the farm could be used to produce free nitrogen. I did the calculations and it appears that as much as 100% of the nitrogen might be produced onsite that way. Diesel engines are mass producers of oxides of nitrogen, which make acid rain- also known as nitrogen fertilizer. This also allow for much higher compression ratios in the engines, and therefore higher efficiencies in running the farm. Note that compression ratios are artificially limited to REDUCE the production of oxides of nitrogen. But we want to crank that up as high as we can and then use the nitrogen. There also are other tricks like increasing the size of the fuel droplets, and advancing the timing. In fact when you work through the practical aspects of farming algae, it becomes clear that the diesel engines can satisfy several critical roles and end up as the heart of the operation in a number of ways. As I said, I discuss all of this near the end of the thread linked. Last edited: dlgoff and berkeman Science Advisor Gold Member Not that long ago. :) https://www.physicsforums.com/threads/algae-to-the-rescue.211274/ Near the end I spill my guts about some things we learned while researching this and in countless hours of discussions with experts. I had my company for about two years before we decided the cost of development was still just too high for a small company. The scale of the problem just keeps growing and growing, forgive the pun. Even ignoring much of the development cost, the first profitable point I could find using my model was a 50,000 acre farm. I was most proud my solution for nitrogen. In short, nitrogen is a significant cost of farming algae. It turns out that diesel engines used to power the farm could be used to produce free nitrogen. I did the calculations and it appears that as much as 100% of the nitrogen might be produced onsite that way. Diesel engines are mass producers of oxides of nitrogen, which make acid rain- also known as nitrogen fertilizer. This also allow for much higher compression ratios and higher efficiencies in running the farm. Note that compression ratios are artificially limited to REDUCE the production of oxides of nitrogen. But we want to crank that up as high as we can and then use the nitrogen. In fact when you work through the practical aspects of farming algae, it becomes clear that the diesel engines can satisfy several critical roles and end up as the heart of the operation in a number of ways. As I said, I discuss all of this near the end of the thread linked. Thanks for the link Ivan. I've now got it bookmarked. That was back in 2008; a long time IMO. Ivan Seeking Staff Emeritus Science Advisor Gold Member Well fine but take a look at this. Algae might be a secret weapon to combating climate change It says that algae can be 400 times more effective than trees at absorbing carbon dioxide. Now everyone keeps saying it is difficult to scale up. But why is that exactly? Plus some people are making their own biodiesel from algae. Making fuel from algae is fairly easy. Making fuel from algae at a price that can compete with petroleum is extremely difficult. Most of these DIYers are probably paying$20-$30 a gallon for their fuel. When we can compete with the price of petroleum at the pump, we can easily convert to carbon-neutral fuels from algae. It is ALL about price. dlgoff Staff Emeritus Science Advisor Gold Member If done big, that's a slightly different matter but still: the end product is 'dirty'. The idea of starting huge blooms in the ocean is interesting. But the drawback is that a highly productive bloom, meaning one active enough to absorb vast quantities of carbon, also depletes the O2 from the water and creates a dead zone. I don't know if moderated algae growth is a reasonable option or not. I've never looked at the math for a sustainable bloom. We ruled out continuous production and opted for a high-yield batch process early on. One of the biggest mistakes DIYers make is they allow the algae to go anaerobic. That is when you get a big stinky mess. My algae all smelled like the fertilizer or it was mostly odorless. But you have to provide a great deal of aeration. Spinnor and BillTre Science Advisor Making fuel from algae is fairly easy. Making fuel from algae at a price that can compete with petroleum is extremely difficult. Well, I'll believe those youtubers only if/when they can take out their family car for a spin running only on that. I mean: repeatedly and without consequences. Till that it's just some lamp oil or so. And then, the carbon footprint. One would think that the lesson of other biofuels (many of them with bigger carbon footprint than classic oil) got learned by now. The idea of starting huge blooms in the ocean is interesting. The idea really looked like a big life saver back then. It's just when the few nutrients on short supply got boosted, the sinking algae/plankton from the bloom carried everything to the bottom, creating a short supply of all nutrients. So at the end you need to resupply all nutrients to keep the bloom go on... I still think the idea could be utilized somehow, but the recirculation of nutrients must be solved first, and we should somehow limit the harvest to the good old CHON(PS)... Feels so easy to talk about it Ivan Seeking and BillTre Staff Emeritus Science Advisor Gold Member Well, I'll believe those youtubers only if/when they can take out their family car for a spin running only on that. I mean: repeatedly and without consequences. Till that it's just some lamp oil or so. haha true. But it is fairly easy to make some oil... at$30 a gallon

And then, the carbon footprint. One would think that the lesson of other biofuels (many of them with bigger carbon footprint than classic oil) got learned by now.

This was one of the critical variables I found in researching all of this. Almost everyone I studied did not account for the energy required to grow the algae. I found that to be an incredibly difficult problem to beat. We need algae that produces 25-30% or more fuel by weight [either oil or sugar] for processing efficiency. But growing high-yield algae takes energy. Even running a paddle wheel as is typically done for raceways could kill most of the energy benefit of a batch. So design of the photobioreactors as well as the design of the farm are energy critical. Aeration is another big one; especially when you consider that you really need HEPA filters to avoid contamination. Even the energy required to process the nutrients such as nitrogen fertilizer, become important. That was another reason my solution for nitrogen was significant.

I was finally able to produce a model that was energy net positive but it was painstaking. In the end I was convinced that net 2000-2500 gallons per acre year was doable.

Rive and BillTre
But it is fairly easy to make some oil... at \$30 a gallon
Yeah, if somebody has some talent for chemistry then it can be done even from chickens

I was finally able to produce a model that was energy net positive but it was painstaking.
Quite a feat, I would say

Really rare to care about such 'small' details.

Ivan Seeking
Staff Emeritus
Gold Member
And then, the carbon footprint. One would think that the lesson of other biofuels (many of them with bigger carbon footprint than classic oil) got learned by now.
I sort of derailed this thought with my comments about energy. But they are essentially the same problem. If the system is truly energy net positive then it is likely carbon neutral. By closing the system and only powering the farm using fuel produced onsite, the idea of stealing energy and leaving a carbon footprint is mostly moot. But all inputs to the system have to be considered. And nitrogen was a big one!

And as it turns out, in my own efforts the generator engines become critical components of the system in several ways. For example, in addition to the nitrogen supply for fertilizer from the NOxs produced, we can capture additional CO2 needed to accelerate algae growth. The engine's high temps and pressures also act as an air purifier and kills any potential biological contamination. Everything coming out of the exhaust can be captured and recycled for the next batch of algae. This all helps to eliminate or reduce energy losses.

Keith_McClary and Rive
Staff Emeritus
Gold Member
Note also that the generator exhaust is significant. In all likelihood, half of the fuel produced is needed just to run the farm. So on the average, half of everything from the last crop is being burned in the generator engines and fed to the current crop as nutrients.

It may be reasonable to use the biomass [fiber] from the processed algae as another source of nutrients and energy through combustion. But that is also a high-quality feed for cattle. Either way an algae farm at scale will produce vast quantities of biomass that can be used or sold.

It may be reasonable to use the biomass [fiber] from the processed algae as another source of nutrients and energy through combustion. But that is also a high-quality feed for cattle. Either way an algae farm at scale will produce vast quantities of biomass that can be used or sold.
Difficulties at every corner. If you remove biomass from the loop, you need to replace the relevant nutrients (at a cost of increased footprint).
If you don't utilize the surplus biomass, then you run on deficit.
It may look good on first sight to incorporate the cattle into the loop, but bringing back the nutrients through manure into the loop is difficult since you have to avoid the biological contamination of your pools.

Compost heaps and the heterogeneous nature of soil life can cover up so many trouble in classical agriculture

Last edited:
Staff Emeritus
Gold Member
Difficulties at every corner. If you remove biomass from the loop, you need to replace the relevant nutrients (at a cost of increased footprint).

That is mostly carbon, oxygen, and hydrogen. So again the biggest concern is a water supply.

Staff Emeritus
Gold Member
It may look good on first sight to incorporate the cattle into the loop, but bringing back the nutrients through manure into the loop is difficult since you have to avoid the biological contamination of your pools.

Compost heaps and the heterogeneous nature of soil life can cover up so many trouble in classical agriculture

Yes, the use of something like animal fertilizer is impractical. The bacteria would run amok and contaminate the entire system. If the fertilizer is sterilized then you have probably just killed your energy budget.

Algae can be used to remediate contamination but that likely isn't going to be a high-yield strain.

That is mostly carbon, oxygen, and hydrogen.
Cattle just burn carbohydrates, but does not really live on it: the nutrients (missing from the pool) makes the difference.
If you can have (only) carbohydrates (you can sufficiently separate them), then maybe you can aim for alcohols instead, and keep the (still mostly sterile) nutrients within the loop.

Staff Emeritus
Gold Member
Cattle just burn carbohydrates, but does not really live on it: the nutrients (missing from the pool) makes the difference.
If you can have (only) carbohydrates (you can sufficiently separate them), then maybe you can aim for alcohols instead, and keep the (still mostly sterile) nutrients within the loop.

On the fatty acid side of things, some groups were having luck migrating the oil out of the algae without having to kill the algae. I believe they were using ultrasound. I have not heard of anything along those lines for the sugar. Also, I don't know how that affected later yields.

The biomass remaining after removing either sugar or oil is a source of protein.

Seaweed and microalgae are considered a viable source of protein. Some species of seaweed and microalgae are known to contain protein levels similar to those of traditional protein sources, such as meat, egg, soybean, and milk [3,4]. Algae use for protein production has several benefits over traditional high-protein crop use in terms of productivity and nutritional value. Seaweed and microalgae have higher protein yield per unit area (2.5–7.5 tons/Ha/year and 4–15 tons/Ha/year, respectively) compared to terrestrial crops, such as soybean, pulse legumes, and wheat (0.6–1.2 tons/Ha/year, 1–2 tons/Ha/year, and 1.1 tons/Ha/year, respectively) [5]. Terrestrial agriculture already requires approximately 75% of the total global freshwater with animal protein in particular requiring 100 times more water than if the equivalent amount of protein was produced from plant sources [6,7].
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5447909/

Staff Emeritus
Gold Member
Is it not true that if we were to bring our net carbon dioxide output to zero, we would still be past the point of no return? The carbon dioxide in the atmosphere is still causing elevated temperatures, resulting in more forest fires, resulting in more carbon dioxide, resulting in more elevated temperatures, resulting in more forest fires and so on?
I strongly suspect that the first, or one of the first attempts at geoengineering to reduce warming, will be to release substances into the upper atmosphere that will reflect some percentage of sunlight away before it can cause any warming of the planet. I remember that Alcoa Aluminum had a patent on a bright-white aluminum oxide powder that can be added to jet fuel. The jets fly at 30,000+ feet and release the powder in the engine exhaust. At that point the powder is light enough to stay aloft for up to two years or so. I did a quick search to find a report on that and didn't spot it yet.

What follows is from a recent effort to explore this technology. Environmental concerns have temporarily stopped the testing planned but this is just one example. This idea has been debated and planned for probably 30 years now.

Scopex is intended to better understand one form of solar geoengineering: injecting substances into the air to reflect some of the sun’s rays back to space and thus reduce global warming relatively quickly.

Solar geoengineering has long been a subject of intense debate among scientists and policymakers, often seen as a desperate, potentially dangerous measure that could have unintended consequences
https://www.nytimes.com/2021/04/02/climate/solar-geoengineering-block-sunlight.html

We may soon decide that the risk of not reducing warming is greater than the risk of spreading aluminium oxide, or other compounds, all over the planet.

​

https://www.space.com/global-warming-aerosol-reflector-block-sunlight

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dlgoff
Staff Emeritus