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Earth Power Science

A New Method To Produce Steel Could Cut 5 Percent of CO2 Emissions (technologyreview.com) 121

Posted by BeauHD from the cutting-carbon dept.
An anonymous reader shares an excerpt from a report via MIT Technology Review: A lumpy disc of dark-gray steel covers a bench in the lab space of Boston Metal, an MIT spinout located a half-hour north of its namesake city. It's the company's first batch of the high-strength alloy, created using a novel approach to metal processing. Instead of the blast furnace employed in steelmaking for centuries, Boston Metal has developed something closer to a battery. Specifically, it's what's known as an electrolytic cell, which uses electricity -- rather than carbon -- to process raw iron ore.

If the technology works at scale as cheaply as the founders hope, it could offer a clear path to cutting greenhouse-gas emissions from one of the hardest-to-clean sectors of the global economy, and the single biggest industrial source of climate pollution. After working on the idea for the last six years, the nine-person company is shifting into its next phase. If it closes a pending funding round, the startup plans to build a large demonstration facility and develop an industrial-scale cell for steel production. The process to produce steel results in around 1.7 gigatons of carbon dioxide being pumped into the atmosphere annually, "adding up to around 5 percent of global carbon dioxide emissions, according to a recent paper in Science," MIT Technology Review reports.

The electrolytic cell that Boston Metal developed was realized after it was proposed to be used to extract oxygen from the moon's surface. "The by-product was molten metal," the report says. "But producing something like steel would require an anode made from cheap materials that wouldn't corrode under high temperatures or readily react with iron oxide. In 2013, [MIT chemist] Sadoway and MIT metallurgy researcher Antoine Allanore published a paper in Nature concluding that anodes made from chromium-based alloys might check all those boxes."
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A New Method To Produce Steel Could Cut 5 Percent of CO2 Emissions More

A New Method To Produce Steel Could Cut 5 Percent of CO2 Emissions

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  • Sounds like aluminum refining (Score:4, Informative)

    by necro81 ( 917438 ) on Wednesday November 07, 2018 @08:25AM (#57605132) Journal
    The process sounds a lot like how aluminum gets refined. Aluminum doesn't exist in nature as a pure metal - the ores (primarily bauxite) are mostly aluminum oxides. To break apart (reduce) the oxides, huge electric currents are used: a battery in reverse [youtube.com]. (This is why a lot of aluminum refining happens in places with lots of cheap electricity - Canada, Iceland, etc.)

    In traditional iron smelting, the oxides are reduced by the addition of carbon in a blast furnace, producing CO and CO2 as a waste product. Replacing the chemical, carbon-based process with an electrical process would indeed be beneficial.
    • I did not realize that iron processing was such a big contributor to overall emissions. The EPA has an interesting breakdown: https://www.epa.gov/ghgemissio... [epa.gov]

      • But steel is an alloy of iron and carbon. So if they are not using a carbon fueled blast furnace, where is the carbon coming from? Are they adding it separately in some other way?

        • Blast furnaces are powered by coke (coal).

          • Yes, and coal contains lots of carbon, and part of that carbon becomes part of the steel. So if they are using electric energy to melt the steel, where is the carbon coming from?

            • I was assuming you are asking about conventional furnaces, not this new method. In the conventional ones, the carbon comes from the coke. As you said, only part of that carbon becomes part of the steel. Who is using electric energy to melt the steel? A furnace uses coke, not electricity.

              • Who is using electric energy to melt the steel? A furnace uses coke, not electricity.

                From the summary: "Instead of the blast furnace employed in steelmaking for centuries, Boston Metal has developed something closer to a battery. Specifically, it's what's known as an electrolytic cell, which uses electricity -- rather than carbon -- to process raw iron ore."

            • Re: (Score:2)

              by necro81 ( 917438 )
              Carbon, like any number of other alloying elements, can be added to the mix after the iron has been purified. In conventional steels, carbon accounts for 2%wt or less, so it's not like much needs to be added. (In alloy steels, the %carbon is much lower.) That is much, much less than the carbon used to reduce the iron oxides in the original ore. For instance, 2(Fe2O3) + 3(C) --> 4(Fe) + 3(CO2). In that case, it's 1.5 C for every 2 Fe on an atomic basis, or a mass ratio of 18:112, or about 1:6.

        • Presumably, just as with the other intentional impurities such as molybdenum, manganese, chromium, or nickel. The amount of carbon used in the alloy is insignificant compared to the amount used to generate the needed heat.

        • Re: (Score:2)

          by ceoyoyo ( 59147 )

          Most of it comes from the iron production. Iron ore is more or less iron oxide, so you need to convince the oxygen atoms to leave the iron and go somewhere else. For iron, this is usually done by heating up the ore with a source of carbon. The oxygen ditches the iron atoms and joins up with the carbon, producing carbon dioxide.

          It sounds like they've come up with a practical method to refine iron ore with electrolysis instead of thermally. They say it produces less carbon... I wonder if that's including the

          • The carbon is not just to take away the oxygen. Steel also needs to contain carbon for strength. But as others have replied, apparently they just add in the carbon afterwards. They tend to do that anyway: even with traditional furnaces, they target a little less carbon content than required, and then add some to get exactly the required amount. So in this case, they'll just have to add in a little more since the molten iron will hardly contain any at all.

            • Re: (Score:2)

              by ceoyoyo ( 59147 )

              Yes, but the alloyed carbon is a sink, not a source. The carbon you stick into steel is pretty much there for the long haul. The stuff you use to suck oxygen out during smelting goes up the stack as CO2.

              The alloyed carbon is also a pretty minor contribution. High carbon steel is under 1% carbon. Mild steel much less. If you were refining pure magnetite (Fe3O4) you'd expect to get two moles of CO2 for every three of iron.

    • Re: (Score:2)

      by Amtrak ( 2430376 )
      This is assuming that the electricity being produced isn't from fossil fuels. It would be interesting to see what is more efficient, this new process with a coal fired power plant vs just burning coke to make the steel directly. However, I can see how this process could be extremely useful if we ever get something like a moon base up and running. You could setup a large solar array or nuclear reactor and then use this process to produce oxygen to breath and steel to continue expanding the moon base. If tha

  • Assuming everything works out, can it produce iron from ore cheaper than existing carbon oxidation based processes? (Probably not.)

    Very little raw iron is made in the U.S. now. The iron production industry has moved to China and India, or Europe (including Russia). If it is a more expensive process then governmental action of various forms will be needed to achieve adoption in the places were pig iron is still being produced in quantity.

    BTW, most of U.S. coal export is metallurgical for making iron overseas

    • Since Trump's "Tariff War" several US steel plants are in the process of being taken out of Mothball status.

      • IIRC actual blast furnaces are all in China and Korea these days.

        Huge fuckers are now sunk costs, unless there is a process breakthrough, they are unlikely to be replaced.

        Steel mills in the west make boutique alloys, usually out of scrap.

  • Next: Cement (Score:1, Informative)

    by stereoroid ( 234317 )

    Another huge contributor of CO2 is the production of Portland cement for concrete: the current method produces about 10% of global CO2 emissions.

  • "adding up to around 5 percent of global carbon dioxide emissions"

    Don't get me wrong, reducing this is a good thing.

    But consider the fact that half of all the CO2 comes from cars. So in other words, improving fuel economy of cars by 10%, which we can do trivially, would have the same effect of reducing emissions in the steel industry by 100%, which is impossible.

    When solving a problem, you start with the biggest bang. That's cars.

    • Re: (Score:3)

      by b0bby ( 201198 )

      I agree that cars are important, but globally transportation only accounts for ~15% of CO2 emissions and even in the US it's ~28%. And that's all transportation, not just cars.

    • Re: (Score:2)

      by Ksevio ( 865461 )
      No reason not to take multiple paths to solving the problem. We're already moving to more electric cars which will solve that part, so it makes sense to also focus on industrial sources.

  • Where does the electricity come from?

    Probably coal.

    • Re: (Score:2)

      by Ksevio ( 865461 )
      Even if it is coal, that's a lot easier to switch to a different, cleaner source than it is to clean the manufacturing emissions

  • Someone forgot to mention in the lede, any electrolytic process is going to use scads of electricity, just like aluminum refining, and places with iron ore are like down by the seashore, where there is little or no cheap hydro power available. So you're going to have to build HUGE solar or middling nuke plants to refine steel this way. And price is still going to be an issue, as steel at aluminum prices isn't going to fly, not by a factor of 5 or worse,

  • same shit different decade

    https://www.newscientist.com/a... [newscientist.com]

    Elemental metal via electrolysis requires a hellish amount of electrical power, that's why aluminum is the easy win for recycling since 90% the energy saved.

    They could well up carbon emissions if China uses this method with all the lovely new coal plants they're building globally to fuel their offshore manufacturing.

    Remember kiddies, it doesn't really matter what the USA does any more for global carbon emissions, it matters a great deal what China's

    • Exactly. Every decade someone comes up with this same idea. If this idea worked and was viable it wouldn't need investor funding.

  • Kennicott mines in SLC burn CO2 albeit for copper. Inherently the incentive beyond copper is in gold. The slurry transport system deposits gold in the linings of its tubes which systematically are taken out of production to be processed for their value in gold.

    Find the incentive and the electric production method gets adopted FAST

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