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<!DOCTYPE html>
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<title>Making silicon carbide in the desert</title>
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<meta name="description" content="Carbon sequestering manufacturing process for Silicon Carbide" />
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<h1><a href="/">Mohamed Koubaa blog</a></h1>
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<li class="active"><a href="/category/inventions.html">Inventions</a></li>
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<h1 class="entry-title">
<a href="/silicon-carbide-desert.html" rel="bookmark"
title="Permalink to Making silicon carbide in the desert">Making silicon carbide in the desert</a></h1>
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<div class="entry-content">
<footer class="post-info">
<abbr class="published" title="2020-07-07T15:57:00-05:00">
Published: Tue 07 July 2020
</abbr>
<br />
<abbr class="modified" title="2020-07-10T21:43:00-05:00">
Updated: Fri 10 July 2020
</abbr>
<address class="vcard author">
By <a class="url fn" href="/author/mohamed-koubaa.html">Mohamed Koubaa</a>
</address>
<p>In <a href="/category/inventions.html">Inventions</a>.</p>
<p>tags: <a href="/tag/inventions.html">Inventions</a> <a href="/tag/silicon-carbide.html">Silicon Carbide</a> <a href="/tag/climate-change.html">Climate Change</a> </p>
</footer><!-- /.post-info --> <h1>Carbon Sequestration</h1>
<p>In the modern era - CO<sub>2</sub> is getting more plentiful in the atmosphere, leading to
<strong>catastrophic</strong> climate change. But what can be done about this? Of course, there are multiple
vectors to come at this issue. One of these - which this post will delve into - is carbon capture.
(Now, I am by no means claiming that carbon capture is more important than reducing emissions or
any other vector)</p>
<p>Carbon capture simply means to pull carbon out of the atmosphere and <em>capture</em> it somewhere so that
it will not simply return to the atmosphere. There are many promising candidates for these carbon
<em>jails</em>. First, the most obvious is in living things, after all, we are all made of carbon. This
is where much of the earth's carbon is currently captured. Our animals, forests, plankton, and
even little diatoms have a huge capacity to sequester carbon.</p>
<p>I think we can and should all be planting trees. It is a remarkably low-tech, distributed, and
cheap portion of the overall solution if a solution exists. With modern drones and autonomous
vehicle technology, the scale of tree planting can even be increased significantly. That being
said, trees need to be planted on <strong>land</strong>, which itself can be thought of as a finite and scarce
resource. The fact is, land use is increasing in many places of the world. Ultimately, I think
vertical farming and lab-grown meat has the potential to <strong>significantly</strong> reduce the land use
required by humans to be self-sustaining at an eventual population of 10 billion, which is the
projected asymptote for human population increase (citation needed). I am all for giving land back
to apex predators and large mammals, to restore the ecosystem to something close to pre-human
expansion.</p>
<p>Short of planting trees, what other organic carbon <em>jails</em> could be grown by human activity? One
other possibility is dropping large structures onto the ocean floor, encouraging ecosystems to
develop around them. This happens with shipwrecks. It remains unclear (to me) if this can be
done at a scale that can significantly curb climate change.</p>
<p>Aside from organic carbon <em>jails</em>, there must also exist inorganic carbon <em>jails</em>. For instance,
some companies are commercializing inserting carbon dioxide into underground cavities where it will
hopefully remain forever. Another option is of course as a raw material in objects that we humans
find useful. We are already doing this for organic chemistry compounds and industrial materials.
The opportunity here is that often the industrial materials are using carbon extracted from the
earth. We could just as well use carbon extracted from the atmosphere if it can be done
economically.</p>
<h1>Silicon carbide</h1>
<p>Silicon carbide is an extremely useful substance, with uses in many industries ranging from
automotive to semiconductors. While not extremely cheap, its manufacturing process is
remarkably simple. And I believe it is worth exploring whether it can be done using carbon from
the atmosphere.</p>
<p>First let's discuss the proposed chemical process. The chemical process to produce both silicon
carbide and graphite is the <a href="https://en.wikipedia.org/wiki/Acheson_process">Acheson process</a>.
Essentially, silicon dioxide is mixed with carbon in its elemental form, such as powdered coke.
Then, in a (usually electric) furnace, the mixture is heated to 1700-2500 °C. There are four
chemical reactions involved:</p>
<ol>
<li>C + SiO<sub>2</sub> → SiO + CO</li>
<li>SiO<sub>2</sub> + CO → SiO + CO<sub>2</sub></li>
<li>C + CO<sub>2</sub> → 2CO</li>
<li>SiO + 2C → SiC + CO</li>
</ol>
<p>Silicon dioxide might seem like some exotic substance, but its literally just sand. As for coke,
this ingredient is slightly more controversial. Usually, coke is produced by burning coal, which
is clearly not environment friendly.</p>
<p>The carbon capture here is going to be essentially to suck CO<sub>2</sub> out of the atmosphere and
converting it to its to elemental carbon, which will be substituted for coke in the Acheson process.
The process to convert CO<sub>2</sub> into elemental carbon is known as the
<a href="https://en.wikipedia.org/wiki/Bosch_reaction">Bosch Reaction</a>. Really there are two reactions:</p>
<ol>
<li>CO<sub>2</sub> + H<sub>2</sub> -> CO + H<sub>2</sub>O</li>
<li>CO + H<sub></sub> -> C + H<sub>2</sub>O</li>
</ol>
<p>Basically, using hydrogen, CO<sub>2</sub> can be converted to elemental carbon. In the process,
water is also produced. Elemental hydrogen is a by-product of the petrochemical industry and is
cheap. It can also be produced by the following reaction:</p>
<p>CH<sub>4</sub> -> C + 2 H<sub>2</sub></p>
<p>So why am I talking about these almost trivially basic chemical reactions? The reason is that there
exists and increasingly economically viable way to produce silicon carbide at industrial scale in
a carbon-negative manner. Silica can be found abundantly in deserts, where coincidentally solar
power is also highly cost-effective.</p>
<p>My proposal is simply to design a Silicon Carbide manufacturing facility in the desert using sand
and solar power. As an added plus, water <strong>and</strong> heat are byproducts which can be used to provide
the facility with water and reduce the solar energy required to power the Acheson process. The
only piece of this puzzle which must be supplied is hydrogen, unless a naturally occurring natural
gas reservoir happens to be in the neighborhood.</p>
<h1>Scale</h1>
<p>You may be thinking that this will not sequester enough carbon to make a difference, and you're
probably right. But just tree planting is critical despite the fact that any individual tree does
not sequester enough carbon to make a difference, small to medium scale carbon negative
industrial enterprises can also be on the critical path to net-zero or negative emissions. The
fact is, industry will continue whether it is carbon positive or negative, and to design carbon
negative industrial applications that are cost-competitive with traditional methods will be
necessary. In fact, if governments begin to place a price on carbon emissions, they may just as
well place bounties on carbon capture, meaning a cost-competitive carbon-negative operation may
become highly profitable.</p>
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<h2>links</h2>
<ul>
<li><a href="https://getpelican.com/">Pelican</a></li>
<li><a href="https://www.python.org/">Python.org</a></li>
<li><a href="https://palletsprojects.com/p/jinja/">Jinja2</a></li>
<li><a href="#">You can modify those links in your config file</a></li>
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<h2>social</h2>
<ul>
<li><a href="#">You can add links in your config file</a></li>
<li><a href="#">Another social link</a></li>
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