Turning carbon dioxide into a solid and generating energy

The gloom and doom predictions of some are not good for those who are led to believe that scientists are powerless to stop whatever name anyone wants to give to so-called climate change. Not only have scientists found a way to turn atmospheric CO2 into a solid, but with a chemical reaction, it can be turned into two useful substances and generate heat.



And there’s more:





If I understood my chemistry classes ok, it would necessarily take more energy to turn gaseous CO2 into a solid than one could get out of it. So, nice idea, but just wishful thinking.

So I read the article, and the idea is that lithium nitride (Li3N) reacts with CO2 to give a couple of inorganic carbon minerals.

My question is, where do we get lithium nitride from? Is this something you can mine? Or how much energy does it take to produce?

I’ve heard it proposed to take CO2 from the air and turn it into methanol or other organics, which can then be burned as fuel, re-generating CO2. That’s a loser if you ask me; thermodynamics guarantees that you’ll lose energy in the process.

With this Li3N trick - the only way it could possibly be beneficial is if Li3N is available in large quantities in nature, which I would doubt, if it’s reactive enough to react with atmospheric CO2. If it has to be manufactured, chances are that it’s something that will take quite a bit of energy to produce. The more familiar example of reducing nitrogen to the -3 oxidation state is production of ammonia, which to put it mildly is an energy hog, I think this process (for producing fertilizer) by itself accounts for something like 5% of global energy consumption.

So… we can burn fossil fuels (and generate CO2) to create Li3N to fix CO2 from the atmosphere. Most likely that’s a loser (thermodynamics again). Or we use renewable energy, or nuclear power, or something like that, to make Li3N to fix CO2 from the atmosphere. But under that scenario, it’s probably better to just use the renewable energy or nuclear power to displace the same amount of fossil fuel use. The whole Li3N-CO2 thing seems like a parasitic drain on the system.

Note - I just checked Wikipedia, lithium nitride is prepared from Lithium metal & nitrogen gas. I think elemental lithium is itself pretty hard to come by - similar to sodium; lots of it around but it’s in ionized state, and reducing the ion to the metal (zero oxidation) state takes a lot of energy.

Doesn’t look like it can be mined. It’s quite rare and I can’t find a place that mines it. That makes sense though, since it reacts with water, so simply exposure to moisture in the air would break it down.

As for it’s components, Nitrogen is quite common, but Lithium is not. Lithium is actually running so low in supply, that people have had to begin to look for an alternative to it for treatment of people who are bipolar or schizophrenic. And even if we had Lithium in large supply, it is extremely flammable and highly reactive. It’s really quite dangerous to work with.

And apparently reacting Li3N with CO2 would produce tons of heat itself, so using it to counteract the warming of the planet would be ineffective short term.

On the upside, the byproducts of the reaction might be useful. C3N4 looks like it has several applications and if it can be produced in the right structure(has yet to be done), is actually harder than diamond. Li2O is used in batteries. (and as a ceramics glaze. Yay cobalt blue!)

Still, we don’t have nearly enough Lithium. It would have to be recycled and reused over and over again. Ultimately, it isn’t practical. And there is the fact that you have to put in more energy than you can get out of it, so that’s self defeating by itself.

This could perhaps be part of the mix of strategies, but we shouldn’t slack off on our own efforts to reduce our pollution and greenhouse gases thru energy/resource efficiency/conservation and going on alt energy when feasible.

Another strategy could be BIOCHAR (tho there are also some questions about it*). It basically takes organic waste (like garbage, yard & agri waste) and burns it with very low oxygen & very low CO2 emissions in a process known as pyrolysis. The products include high carbon charcaol that make a very good soil amendment, increasing crop production, while storing the carbon in the soil. So the plant life used for it draws CO2 down from the atmosphere, but instead of being released during decomposition, most of it is stored in biochar and sequestered for 100s, maybe 1000s of years. Terra Preta (biochar created by ancient civiliations) is still in the ground 1000s of years later. The pyrolysis process also produces heat energy that can be turned into energy (like a cogeneration principle), and some biofuel that can also be used as fuel.

See: en.wikipedia.org/wiki/Pyrolysis & en.wikipedia.org/wiki/Biochar & en.wikipedia.org/wiki/Terra_preta

Since our area generates a tremendous amount of yard waste, which is collected by the city, that might be an ideal place for biochar operations – then it could be sold or given to farmers as a soil amendment.

Another problem in our area that could be used as a solution is carrizo cane, which grows along the Rio Grande River, which smugglers and undocumented people use as cover; it is an invasive species, which environmentalists dislike. Homeland Security started areal herbicide spraying of it 3 years ago, endangering the health of us who live along the border, and it was stopped. But I’m thinking that with some mobile pyrolysis units, they could turn carrizo cane into biochar, then sell it at low price to farmers. That might work out more cost-effective than their newer hand-cutting it & herbicide plan (they could subcontract it out to small business people, by providing them with the equipment).

*One of the concerns about biochar is the transport and application of it possibly involving black soot escaping into the atomsphere and causing environmental problems (like climate change) and the eventual release of the carbon back into the atmosphere, and it should not be used as a “carbon off-set” assuming we ever get involved in some kind of Cap&Trade (which I don’t see happening anyway). See biofuelwatch.org.uk/docs/biocharbriefing.pdf

I think the ultimate solution is going to be many solutions from many different angles. I hope this lithium nitrade works out, along with some 100s or 1000s of other solutions (like taking a hanky to wipe hands in public restrooms or using the blank side of used paper, and 100s of more things we can do)

As soon as I get the impulse drive fixed, I’ll take a federation shuttle and my tricorder and go find us a nice big lithium asteroid. (Heck, while I’m at it how about some DiLithium crystals? :slight_smile: )

Until then, the laws of thermodynamics still stand as a barrier against such schemes. Sorry.

Fascinating! Thanks for the link!

That it’s an exothermic reaction is amazing in its potential for capturing waste heat!

There’s another mechanism that creates solid from CO2. Actually several. One is called photosynthesis. :wink: The other is carbonate rock formation. Both very big climate drivers. Cutting down all the darn trees doesn’t help!!!

Personally I like this idea better than all the fancy ways to turn biomass into liquid fuels, e.g. ethanol from corn, cellulosic ethanol (from switchgrass, etc), biodiesel from algae, etc. The biochar sounds pretty simple on the process side, which is where a lot of the liquid biofuels fall short.

This reminds me of an idea I had back in high school - one of these “future problem solvers” assignments. We suggested we could collect yard waste and feed it to cows. We actually got a response from the USDA or something like that, essentially saying it would never work, but thanks for suggesting it. But maybe the yard waste to biochar to soil amendment idea would work, to add organics back to soil. Similar to manure I guess. I wonder how the nitrogen content looks. The other part of the soil amendment picture are the beneficial microbes that you get with manure & compost; I don’t know if any of those would be in biochar, but maybe you mix 1 part manure, 1 part compost, 1 part biochar, something like that?

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