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(In case it gets changed the current title is: Burning sand as renewable power supply)

Where to even start, sigh.

You are not burning sand. And it's not in the slightest renewable. Or CO2 neutral or any of the other nonsense in the article.

At best silicon can be used as a battery of sorts if you burn the silicon.

It's not an energy source, and it has no impact whatsoever on CO2.

Flagged. I think it should be killed, but if it stays at least change the title to "Using silicon as an energy carrier by burning it and then reducing it".

I didn't even catch that bit about burning "sand" in the title. It's the precise _opposite_ of burning sand. Oxidation, reduction... details.
How is it not CO2 neutral? It isn't using carbon as an energy carrier like fossil fuels so no CO2 should be released unless I'm missing something.

It is renewable to some extent although it sound like on subsequent uses the media would become less effective.

I agree with you on the title. Not accurate.

> How is it not CO2 neutral?

It's not CO2 neutral, positive or negative. It has nothing whatsoever to do with CO2. It's an energy carrier not a source.

The amount of CO2 released depends on the energy source.

Hydrocarbon fuels can also be CO2 irrelevant if you make the hydrocarbon from some other energy source (you can make gasoline from air + energy). But usually you get the hydrocarbon from the ground and then it's not just a carrier, it's also a source.

> It is renewable to some extent although it sound like on subsequent uses the media would become less effective.

"Renewable" is not a concept that applies here because it's not an energy source. The media can be used as much as you like, it doesn't get used up, it just changes and changes back. Rechargeable is probably the better word here, but it starts as already full discharged (sand) so you have to charge it with something.

"It's not CO2 neutral, positive or negative. It has nothing whatsoever to do with CO2."

If it doesn't involve CO2, it is, by definition, CO2 neutral. As in, it doesn't produce CO2 (unlike fossil fuels). Yes, I realize it is an energy carrier (in concept). The media is less useful on subsequent uses. The sun is the source of the energy. Which I suppose makes you technically correct. As far as I know, the sun isn't "renewable".

> If it doesn't involve CO2, it is, by definition, CO2 neutral.

No, CO2 neutral is an energy source that does not release any extra CO2 into the air (like growing a plant and burning it). (CO2 negative removes CO2 from the air.)

This is not an energy source, the CO2 measure of this depends only on the source. The silicon is completely irrelevant to that.

> The media is less useful on subsequent uses.

And that's the 3rd time you've said that, and I still have no idea where you are getting this erroneous concept.

> The sun is the source of the energy. Which I suppose makes you technically correct. As far as I know, the sun isn't "renewable".

No, the sun is not the source of the energy. This proposal does not include an energy source. I keep telling you that, but you don't seem to get it. This is an energy carrier. There is no energy source involved here.

(And you can ignore the words "solar panel" in the article. You can use a solar panel for anything, it has absolutely nothing to do with this.)

Yes, the sun is absolutely the energy source. The silicon/sand is the carrier.

Why did I mention recycling the media? It's mentioned in the article. Twice in fact.

Read the article.

> Yes, the sun is absolutely the energy source.

The sun can also be an energy source to make syn-gas (to make synthetic gasoline for cars), or charge a battery, or make hydrogen, or pump water uphill.

What does that have to do with silicon as a carrier? Absolutely nothing. You can also make silicon if you burn some coal. The sun is completely irrelevant.

> Why did I mention recycling the media? It's mentioned in the article. Twice in fact.

Just because it's in an article doesn't make it correct. This article is really bad. It has just enough truth to make it seem plausible.

The crust of this entire planet is made of silicon, it's not something that needs recycling anyway.

>The sun can also be an energy source to make syn-gas (to make synthetic gasoline for cars), or charge a battery, or make hydrogen, or pump water uphill. What does that have to do with silicon as a carrier?

It has to do with using the sun to produce the energy that the "carrier" will carry.

Nobody said the Sun only has this particular application -- just that is one more application of Solar energy (on sand, and with using silicon as a carrier).

>Just because it's in an article doesn't make it correct. This article is really bad. It has just enough truth to make it seem plausible.

Seems like someone didn't read it.

Everyone keeps accusing me of not reading the article - but I did. The whole thing (despite eye rolls the entire time).

> just that is one more application of Solar energy (on sand, and with using silicon as a carrier).

You seem to have gotten lost in the argument here. I'm objecting to claiming that using by silicon somehow we reduce CO2 emissions.

We don't. Silicon has nothing to do with it. Sure by using the sun we reduce CO2 - but that's orthogonal to using silicon.

If you want to talk about using silicon as a load balancer, or a kind of rechargeable battery, then sure it's an interesting idea.

But don't start claiming it's some sort of super clean fuel or something like that because it's not.

This is about energy transportation, nothing about energy supply. The silicon is produced using solar power in this article. You could just as easily put it in a flywheel, put it in lithium ions, or use it to reduce sodium and burn the sodium instead.

edit: also, understatement of the century:

"restricting factor here is that the SiO2 oxidation product remains with the silicon and partially restricts its subsequent oxidation"

Exactly...

From the articles comments: "It's no more unreasonable than, say, storing solar power as a highly-linked hydrocarbon liquid and then burning it in a miniaturized power plant."

Putting it in a flywheel is cool but you can't practically transport that. I think the point is... there is a lot of sand. So if you only use it once maybe that's ok.

Did you understand that sand is the waste product? Not the fuel? It's much harder to burn silicon than you seem to be expecting. A miniature plant has no hope of doing it.
Yes, I understand sand is the waste product. So, it can be recycled through the same process but less efficiently (according to TFA).

I'm not expecting it is hard nor easy. Nor practical either.

"but less efficiently"

This is the second time you said that. Where are you getting that idea?

"This inert silicon dioxide might be recycled back to a silicon smelter or used locally in land fill."

Edited: "A restricting factor here is that the SiO2 oxidation product remains with the silicon and partially restricts its subsequent oxidation."

did you even read the article?

Yes, I read the article. And in what way does what you wrote imply "less efficient" on reuse?

To reply to your edit:

> "A restricting factor here is that the SiO2 oxidation product remains with the silicon and partially restricts its subsequent oxidation."

Do you even understand what you posted here? I really don't think you do. This is not "on reuse" this is a problem on the first use. And it's such a big problem that silicon is unlikely to ever actually be used this way.

If you read the article, then you failed at reading comprehension. The drop in efficiency on recycling is mentioned twice.
No it's not. And if you think it is go ahead and copy it here.
Here's one of them:

"The only waste product from silicon power stations would be large amounts of solid silicon-dioxide “ash” but this could be recycled back to the smelters to be reduced to silicon again."

So, if ash is a 'waste product' then it cannot be produced with 100% efficiency as the 'non-waste' is the goal of the process and not the 'waste' itself. Also, if you take that 'waste' and 'recycle it back to smelters', another round of inefficiency is introduced (as no physical process is 100% efficient).

Is there something wrong with that reasoning?

(comment deleted)
The comment I mention was by the AUTHOR of the article.

Why do you have to run the process in reverse? This apparently can be done to some extent by why not discard it instead? There is plenty more where it came from. Maybe build an island or something ... IDK.

"Sand is a stupid energy storage medium" Ok.. probably so.

(comment deleted)
This is a solution to the energy storage (transportation) problem that I've never heard. But if we're going to talk about this, could we start with a more honest title and a discussion of it in comparison to other storage technologies?
A nice piece of lateral thinking: use the desert sun to turn desert sand into silicon, take the silicon to where power is needed, and burn it.

Are there any chemical engineers who can comment on this? Is it an old idea that's been kicking around for years? Is it feasible?