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Peer review paper: https://www.cell.com/device/fulltext/S2666-9986(24)00235-7

Executive Summary: Solar heater that can work at temperatures close to 1000C by using semi-opaque materials to absorb solar energy and minimise radiative losses. Not even a proof of concept of an improved smelter.

Article text in PopMech is exaggeration of paper and headline is a further exaggeration on top of that.

The paper itself mentions the usefulness of the 1000C threshold:

Solar process heat at above 1,000°C can decarbonize key industrial applications such as cement manufacturing and metallurgical extraction.

The article is just running with that theme.

> decarbonize key industrial applications such as cement manufacturing and metallurgical extraction

... so what's the reducing agent, if not carbon?

There's a proposed entirely-thermal iron reduction process that uses sodium as the reducing agent. This produces sodium oxide, which apparently can be decomposed back to sodium and oxygen by vigorous heating. I have my doubts about the overall feasibility of this scheme, but it doesn't involve any electrical energy input.
Can you explain the chemistry pieces vs. the thermal inputs pieces?
The main tasks in converting iron ore to steel is as follows: reduce the iron (which requires a redox reaction), drive out existing impurities (both other metals present in the ore, such as magnesium or aluminum, and other nonmetals like sulfur or phosphorous), and introduce new ones (predominantly, uh, carbon). Note that these don't necessarily all occur at the same time, in the same furnace (steelmaking is a multistep process). These processes require the necessary chemical reagents to cause the necessary chemical reactions to occur.

There are multiple roles for heat. Most notably, most of the necessary chemical reactions require high heat to occur at a time. Furthermore, outright melting gives the advantage that impurities tend to sort themselves by density, and your impurities are typically less dense than your main metal (i.e., the slag will float on top of the molten iron). There's also the advantage that high heat can make volatile impurities (e.g., sulfur dioxide) boil out.

Historically, the reducing agent was largely charcoal, where you burn the wood in oxygen-poor environment to produce high purity carbon-rich material. The industrial revolution replaced charcoal with coke, where you burn coal in oxygen-poor environment to produce high purity carbon-rich material. In both cases, the furnace converts the fuel largely into carbon monoxide, which is the main actual reducing agent in contact with the iron (whereupon it forms carbon dioxide). The decarbonization assumption has been to replace carbon with hydrogen gas, but as far as I'm aware, hydrogen-based reduction furnaces have only existed in pilot plant form.

Ah - a greenhouse that can almost melt copper, though I think you need a mirror to get the "135 suns" input radiation.
> Fighting against climate change means building, whether that’s large solar arrays, sprawling wind farms, or powerful fission reactors

Can we, maybe, consider using fewer resources? Are we past the point of imagining that we could possibly get by with a sustainable lifestyle?

> Can we, maybe, consider using fewer resources?

I'm not optimistic about schemes that require almost everyone to sacrifice for the common good, but which (implicitly) reward parties that cheat.

More specifically, I don't see how this would ever work at an international level, due to trade / military competition.

I think it's part of the tragedy of human nature.

You're asking a large number of people to substantially reduce their standards of living. Think of the sheer amount of energy required daily in even a "sustainable" lifestyle in a modern developed economy.

And then of course there are the powerful financial incentives to not care about sustainability at all, or what's worse to spend more energy than before on products that are meant to seem sustainable (but aren't), because actual sustainable practices aren't good business on the scale of shareholder lifetimes.

Maybe it should happen, but it's a long uphill battle.

Not with electric cars slowly coming, our current infra at its max here in Switzerland ain't enough for any serious mass electrification. They dwarf all combined electricity usage by huge margin. And somebody has to generate all of it.
I think this is unintentionally falling into the trap that the parent commenter is railing against. Lowering consumption does not mean going from fossil cars to electric cars, it means going from cars to modes of transportation that aren't so inherently wasteful and inefficient as cars.
You have a source on that? Sounds a lot like oil company fud.

Couple of results from the top 5 when searching for this:

https://www.scientificamerican.com/article/why-electric-vehi...

https://www.virta.global/blog/myth-buster-electric-vehicles-...

https://www.eia.gov/energyexplained/us-energy-facts/images/c...

Transportation in the US consumed ~27.5 quadrillion BTUs, electricity consumption was ~13.3 quadrillion BTUs, about ½ transportation use.

Are you willing to feed your family at the low level currently available to the poorer humans on this planet? And convince your parents to not access healthcare that might use quite a large amount of resources to deliver?
This isn't a reasonable response. They didn't propose cutting out basic needs.
Privileged delusional fools propose sustainable lifestyles totally ignoring that there are 8,113,289,337 humans and a large percentage of them do not have basic needs met at the moment.

Humanity requires better technology to provide modern healthcare and food to everybody.

Yes, let's propose fundamentally altering human nature. This is an approach that cannot help but be successful, with zero chance of horrific side effects in its implementation!
I mean honestly war is a fundamental part of human nature, and if we just got a little bit better at that we could solve the rest of our resource consumption issues quickly. Might be a little ancillary damage but you can't make an omelette if you don't break a few eggs!

What you might be calling "human nature" is different from country to country. For instance while 5-10% of Americans are vegetarian, 30% of Indians are. Imagine the change in resource consumption if that same number applied to the U.S.

Bottom line is humans talk a big game of having more complex reasoning and and problem solving abilities compared to other, less self-aware species, but when it comes down to not mistreating the earth we at HN have a new mantra of "you can't change human nature." To me it just sounds like people throwing in the towel so they can keep consuming 80% of the world's resources.