Solar Powered CO2 Scrubber





Introduction: Solar Powered CO2 Scrubber

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We have extensively harmed our planet by following a careless and profligate lifestyle. But the Rubicon has not yet been crossed. If we act swiftly and boldly, we can still avert disaster. Among several other solutions, carbon dioxide scrubbing could help us move towards a greener and brighter future.

Carbon sequestration or carbon capture and storage are effective processes of extracting carbon dioxide gas from the atmosphere or from large point sources such as fossil fuel power plants, and storing it in underground reservoirs.

Although a brilliant concept, the present technology is still very expensive and not perfectly sound. So here's the concept of a solar-powered carbon scrubber that could be the key in bringing down CO2 levels in the atmosphere.

Solar CO2 Scrubber :

If you like this innovative project, do vote for it!

Step 1: Application

This solar-powered appliance can be installed anywhere, preferably in locations with high CO2 levels such as traffic congested areas or industrial areas. This infamous gas which is harmful to the environment, has also its positive side.

The carbon dioxide that is extracted from the atmosphere through thermosiphon can then be recycled and used in chemical processes like making soda water or in fire extinguishers. It can also be pumped into a greenhouse and help in the growth of plants. The best part is that this CO2 scrubber can be easily built by modifying a solar water heater.

Step 2: Process

Here's how the solar carbon dioxide scrubber works:


Using the passive heat exchange based on the thermosiphon principle, we let ambient air rise up the sloped glass case and bubble into a water container.


Next, by exploiting the varied solubility of gases, we separate carbon dioxide from the rest of the gases that constitute air. At 40C and at normal pressure conditions, about 600ml of carbon dioxide can dissolve in 1L of water while the solubility of nitrogen and oxygen is a mere 10ml and 20ml respectively. Refer here for details on solubility and here for calculations on the fluid dynamics.

So when air is bubbled into water, CO2 will dissolve in water while the rest of the air just bubbles out.


The CO2 rich water then trickles back down the sloped glass tubes where it is heated by the sun and rises up again. In this heating process, the solubility of CO2 drops drastically and the gas bubbles out. At this point it can be tapped and used.

Step 3: ​Further Improvement

So here's an innovative concept for capturing carbon dioxide from the atmosphere using solar power!

However due to the poor concentration of carbon dioxide in the air, this process may not be as effective as it sounds. Probably this concept needs to be combined with other regular thermo-chemical processes such as reacting CO2 with calcium oxide or sodium hydroxide.

This energy independent concept of cleaning up the atmosphere through CO2 scrubbing needs improvement but has a promising future.

Build it and find out for yourself if it works!

And do let me know :)



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    21 Discussions

    The ocean produces more CO2 tha all of humanity's technology combined... and plants use CO2, so if we were really producing enough to effect global change, jungles would be expanding, and the problem would be self regulating. Plant some trees and stop listening to Al 'Photoshop' Gore.

    3 replies

    Just look outside see a car ok now look at the ocean now whats producing more CO2 also the ocean sucks up CO2 when phytoplankton photosynthesize.

    I'm going to address three of the things you said, because they prove how little you understand.

    1. "Plant some trees..." The CO2 we've released has been in an underground carbon bank for tens of millions of years. Planting a tree locks carbon up in a tree for a number of decades, then re-releases it when the tree dies. The carbon is also re-released in the form of CH4 (methane), which greatly increases the greenhouse power of the carbon that, in the form of CO2, went in initially. Untill you permanantly remove the carbon from the atmosphere, as it was when it was locked in the Earth, you've done nothing. The atmospheric carbon concentration, which has historically oscillated between 180 and 280 PPM on a 100,000 year cycle, is currently at 400 PPM. It has spiked in the last century. You didn't know this, because your fantasy-forests would already be busting at the seams if you were right.

    2. Plants don't grow faster in the presence of excessive CO2. Where did you get this faulty idea? Other limiting factors, including nutrients and sunlight, would inhibit the expansion of forests. Think for just a second-- if the atmospheric availability of CO2 limited planet-wide tree growth, then a tree would die every time you planted one. Your forest-self-regulation fantasy is just that.

    3. The ocean's production of CO2 is part of a balanced system. How could you not realize this? When it comes to CO2, the ocean eats as much as it makes. This is why the NET production is near zero. When humans release formerly trapped carbon, the net production is 100%, because the process doesn't reabsorb carbon like the ocean does.

    To put it mildly-- You don't know what you're talking about. To put a finer point on it-- You have a profound and frightening ignorance that deludes yourself into thinking that you are somehow qualified to have an opinion. Please accept the startling depth of your ignorance, and leave such matters to experts.

    I am not convinced this carbon scrubber would have a measurable impact on CO2 levels at this small scale.

    However, you are misinformed regarding the ocean CO2 cycle. It is "photoshopping" to treat the ocean's CO2 outputs as net production, because all of it is consumed again. Hence the term "cycle" with net production = 0. Human emissions are indeed small relative to the natural cycle, but they are net positive and sum up over time. [Source: Sustainable Energy Without the Hot Air,]

    I see googled images, and a diagram that is missing a pump, recirculation and a heat-exchanger, but I can't seem to see any indication that you have actually done this...?

    5 replies

    If you took the trouble of reading through before commenting...I have mentioned that this is only a concept project and still needs to be tried out. You also seem to have missed the essence of the project. The first diagram (which I have designed and not googled) clearly depicts the process of thermosiphon which is the underlying principle behind my project. And thus no additional pump is required for this CO2 scrubber.

    The initial air-flow, bubbling into the water, needs to be pumped. It will not work otherwise.

    And if you took the trouble to look around this site, and to read some of the other projects here, you would realise that my comment was meant as a subtle reminder that Instructables are for showing things you have actually made or done. At an extreme, you may publish a part-built project if you cover an important technique in doing so.

    If you want to publish ideas, especially untried, unproven ideas, then you need to post in the Forums (I recommend either Green or Technology for this project), and be prepared for far more incisive criticism than any given so far.

    On a legal note, you have not shown that you have permission to use the images you have googled, not have you cited their source. That is a violation of the site's terms of service.

    Although I still think that it should be possible to pump air into water solely by means of thermosiphon, I agree with your observations and suggestions :)

    On a bit of a tangent here, but sticking with the carbon capture and storage that you were talking about. I believe I once saw a show about some scientist that were harvesting CO2 and then compressing it in to dry ice. They would then make a 6 foot torpedo shape of it and drop it in to the sea. I don't recall the depth that they were aiming for but obviously enough pressure to keep the dry ice from boiling away. They had instruments attached to it and I believe it worked from what I can recall. It's a neat idea but obviously not the solution otherwise i'm sure we would be hearing about it more.

    2 replies

    It takes a lot of energy to make a 6 foot CO2 dry ice torpedo - if the people harvesting it, making it, transporting and dropping it into the ocean were using conventional energy sources, I would not be surprised if the emission is bigger than the amount stored in the sea. All I'm saying is that many factors has to be counted in.

    This *may* work in a place with high CO2 concentration, but as the original poster writes it is unlikely to work under most conditions due to the low CO2 concentrations. One would have check what the breakthrough curves are for your system.

    Do you understand that you are exhaling co2, or that trees require it in addition to sunlight to produce oxygen? Push the agenda somewhere else.

    Well, let's suppose I make it in my house. And now, what can I to do with "my" CO2?

    Can the captured co2 be sequestered in plants?

    It can be used as shielding gas for welding, extra fuel for a greenhouse, make fizzy drinks fizzy .. that sort of thing.

    OK - so the used CO2 goes straight back into the atmosphere. In my view this is a bit much to 'harvest' at tiny bit of CO2, which goes back into the cycle anyway. I think the CO2 emmitted in the process of making the materials for this project is far bigger than the amount you'll catch from the air anyway. 'Don't burn fossil fuels' is the only real mantra here ;-)