[skissane]

Converting silicon dioxide to elemental silicon is usually done by reacting with carbon, which produces carbon dioxide as a waste gas. However, in principle, the carbon dioxide could be captured and even recycled back into carbon to reuse in the initial reaction. I don’t think this is being done yet (at least not on a commercial scale), but there is no reason in principle why we couldn’t develop such a technology and combine it with nuclear/renewable power sources to reduce greenhouse gas emissions and fossil fuel consumption due to silicon refining to zero.

[diogenescynic]

Yes, but today we’re using coal to produce solar panels. Why even bother with such a fantasy hypothetical? Why not just go all the way to cold fusion if we’re just making stuff up that isn’t being done currently? This is what I meant about the left having a fantasy that one day technology will save us. We just cannot accept reality.

[skissane]

> Yes, but today we’re using coal to produce solar panels. Why even bother with such a fantasy hypothetical? Why not just go all the way to cold fusion if we’re just making stuff up that isn’t being done currently?

One obvious difference – the technology to capture waste CO2 gas is clearly feasible in principle. We already have lots of research into capturing and reusing CO2 (such as from coal-fired power stations) [1], and we already have known industrial processes which use CO2 as input [2]. So, the issue here is really (a) more R&D to finesse the technology, (b) its application to silicon refining specifically (other CO2 emissions sources are more significant and hence receive more focus) (c) getting the economics right. (On the last point, emissions trading schemes may help.) By contrast, most of the physics community doesn't believe cold fusion is a real phenomena, and the small minority who think it is can't explain how it works. You are comparing a technology whose physics and chemistry is well understood, and which basically just needs productisation, with a technology where there is disagreement on whether physics even allows it to exist.

[3] seems a particularly interesting approach - conversion of CO2 gas to graphite. The graphite in turn could potentially be reused in the silicon refining (which needs a carbon source, not coal/coke/wood specifically). Most current methods of procesing CO2 turn it into chemicals such as methanol (CO2 + hydrogen gas), urea (CO2 + ammonia), etc, which while useful, I'm not sure you could actually reuse those chemicals in silicon refining

[1] https://en.wikipedia.org/wiki/Carbon_capture_and_storage

[2] e.g. https://en.wikipedia.org/wiki/Methanol#From_synthesis_gas

[3] https://www.nature.com/articles/s41467-019-08824-8

> This is what I meant about the left having a fantasy that one day technology will save us

I'm not sure it is really "the left having a fantasy". I know plenty of right-leaning people with solar panels on their roofs. (I even know global warming sceptics with solar panels on their roof.)

[diogenescynic]

The fantasy is that you think that because carbon capture it's feasible in principle that someday our unsustainable way of life that currently relies on fossil fuels will somehow miraculously be converted to 100% clean energy. It just isn't happening--as much as I want it to. People are in denial.

[skissane]

Uh, I don't think that "our unsustainable way of life that currently relies on fossil fuels will somehow miraculously be converted to 100% clean energy".

I think fossil fuel use is going to decline over time. That's already happening in a lot of countries. It's going to be a gradual process, and I think eventually it is going to happen everywhere, but some parts of the world (e.g. Europe, US) are going to be ahead of others (e.g. China, India)

Is there such a thing as "100% clean energy"? I don't know if there ever will be such a thing, but so what. If you look at tonnes of CO2 emitted per a kilowatt-hour, over the life of a generator, then a solar farm is going to beat a coal power station, even when you include the CO2 emissions from the construction and the manufacturing of the equipment. Sure, the solar farm won't be "100% clean" (zero lifetime emissions), but it doesn't need to be, it just needs to be significantly better than the coal power station.

In some countries, coal power stations are being replaced by natural gas power stations. Natural gas obviously isn't 100% clean – it still emits CO2 and other pollutants. But it is a lot cleaner than coal. It emits less greenhouse gases for the same amount of power generated. We shouldn't let the perfect be the enemy of the better.