Turning CO2 to Stone

I was curious, so I did the math.<p>Total worldwide carbon production is 38.2 billion tons per year. Cost to sequester a ton of carbon is between $30 and $150, depending on who you ask and how you do it. Let&#x27;s assume a middle of the road price of $90&#x2F;ton. That&#x27;s $3.438 trillion a year, or about $478 per person. This is roughly equal to the US yearly federal spending, or 3% of the world GDP.<p>If you somehow pooled together all the world&#x27;s billionaires and got them to contribute their annual income (roughly $600 billion a year, averaging the past 7 years) to the effort, you could eliminate roughly 20% of carbon produced in the world every year.<p>-------------------------<p>Suddenly, it becomes crystal clear why finding new sequestration methods is incredibly important: if you can get the cost from $160 to $10 per ton, then suddenly all you&#x27;d need would be a coalition of half the world&#x27;s billionaires to stop the main cause of global warming.<p>Additionally, it&#x27;s important that people realize that CO2 production is in tons of CO2 per year. Tree offsets are a one-time deal, since when trees die they release CO2, and when new ones are born they absorb that CO2 again. After they&#x27;ve been planted, forests are generally carbon neutral. That&#x27;s why we can&#x27;t &quot;just plant trees&quot;: we&#x27;d have to be continuously planting new trees. The Earth is only 8% arable land, much of which already has stuff on it, or is undesirable for one reason or another. We&#x27;d run out of space pretty fast. Trees are good for other reasons: preventing climate change (different from global warming), preserving species diversity, being nice to look at, etc etc.<p>-------------------------<p>Mostly off-topic: when I was looking at estimates of land size, apparently the amount the US has shrunk from 2007 to 2015 (14,000 km2; went from 9,161,120 km2 to 9,147,420 km2) [0] is roughly equivalent to half the area of the Netherlands. Wow.<p>[0] <a href="http:&#x2F;&#x2F;data.worldbank.org&#x2F;indicator&#x2F;AG.LND.TOTL.K2" rel="nofollow">http:&#x2F;&#x2F;data.worldbank.org&#x2F;indicator&#x2F;AG.LND.TOTL.K2</a>

The net reaction goes like this: CaSiO3 + CO2 -&gt; CaCO3 + SiO2. Note that the products, silicon dioxide and calcium carbonate, are thermodynamically stable solids.<p>Crucially, the <i>activation energy</i> for the weathering of silicates to carbonates is low in the presence of water and carbon dioxide. Low enough that it happens spontaneously in nature on exposed rock surfaces. That means that the energy inputs required to reduce atmospheric CO2 via silicate weathering are <i>much</i> lower than a &quot;combustion in reverse&quot; process to turn gaseous CO2 into synthetic coal and bury it.<p>The other crucial issue is that the <i>kinetics</i> of silicate weathering are tremendously hindered in nature. A freshly fractured basalt surface weathers rapidly for a year or two and then develops a cation-depleted micron scale &quot;rind&quot; that drastically slows the weathering reactions with the rest of the bulk rock.<p>One way to accelerate the kinetics of silicate weathering is to use more concentrated materials, like the Iceland injection process: nearly pure CO2 plus water will react much faster than natural surface waters exposed to hundreds-of-ppm CO2 in the atmosphere. That works ok if you have a rich stream of CO2 like directly from a power plant&#x27;s stacks. It won&#x27;t work for dealing with CO2 already emitted to the atmosphere unless you add a complicated and energetically expensive pre-concentration stage to turn 400 ppm of atmospheric CO2 into a 950,000 ppm CO2 stream you can inject.<p>The other way to improve the kinetics of silicate weathering is to generate a lot more surface area: crush bulk stone into particles 100 microns or finer. Then there&#x27;s a lot of fast-reacting extra surface area that can react with CO2 at ambient concentrations. And even the slow weathering to the center of the particle will take maybe a century rather than multiple millennia. (If a century sounds unacceptably slow, I would venture that you have not fully internalized the vast timescales that unaided nature would take to restore the pre-industrial CO2 equilibrium.)<p>Putting crushed stone particles in near-shore ocean environments may further accelerate weathering by ensuring that natural wave action keeps abrading the rind from particles. Crushed stone rich in magnesium and calcium silicates can also be applied to acid sulfate soils in tropical agriculture. Raising the pH of acid soils increases agricultural productivity by preventing low-pH aluminum toxicity to plants and, unlike sweetening soil with limestone, it sequesters some carbon at the same time. The crushed stone accelerated weathering approach can offset all sorts of CO2 emissions: point or distributed sources, local or distant sources, present or past sources. Finally, it restores the historical pH balance of the oceans as well as getting rid of excess radiative forcing from CO2.<p>The amounts of stone required to offset historical emissions are vast, but any solution will be vast because the scale of the problem itself is vast. In terms of scalability, simplicity, energetics, and flexibility, I think that accelerated silicate weathering is the best shot at long term restoration of oceanic and atmospheric CO2 concentrations to the pre-industrial baseline.

It&#x27;s nice that we&#x27;re looking to alternative ways to capture and store atmospheric CO2, but at time it also does look like we&#x27;re working too hard to replicate a system that does that already (and has for a long time): plants.<p>Or does it mean that the time of planting trees and preserving forests is over now and we have to do it another (most often less efficient) way?

We have a great method of storing carbon. It is also technologically simple, very stable, and, would you believe it, completely free! It is called coal. It was already stored in the ground millions of years ago. We just have to not dig it up and burn it.<p>Also related: oil, peat.

Would be very interesting to see nuclear energy sources harnessed to split carbon dioxide into oxygen and carbon or generated into liquid fuels.<p>I can&#x27;t wait to see nuclear power plants selling oil and gasoline.

Not mentioned in these comments is the actual method they cite in capturing the solid CO2. The method involves bubbling CO2 through water and hydrogen sulfide, which is incredibly toxic. Not sure if there&#x27;s a better way to do it, but their current process is both economically infeasible and dangerous.

Just a reminder that the Iceland study result was unexpected, and while it is great that the media is publicizing the results, it would be nice to get additional confirmations before getting really excited.<p>Having said that, I&#x27;m still kind of excited. The basalt flood in Eastern Washington alone is in theory large enough to sequester hundreds of years of US emissions.

The best way to reduce emissions of CO2, is to develop sources of energy that are more economical than fossil fuels. If we had the huge surpluses of carbon emissions free energy implied by fusion, we&#x27;d be able to slash energy-related carbon emissions to a small fraction of the current level, while also drastically reducing the need to extract hydrocarbons as a chemical feedstocks. Fusion is probably even capable of providing enough energy to sequester excess carbon, beyond emissions.

Scaling up this technique to make it practical is going to be challenging. And it is not enough to simply compute the quantity of carbon not emitted; the full energy-life-cycle of the sequestration needs to be computed as well.

There is an entrepreneur I follow on Twitter working on this. Press Release: <a href="http:&#x2F;&#x2F;www.orica.com&#x2F;News---Media&#x2F;australian-research-pilot-plant-turns-co2-into-potential-green-construction-materials#.WIUS6vGGNhE" rel="nofollow">http:&#x2F;&#x2F;www.orica.com&#x2F;News---Media&#x2F;australian-research-pilot-...</a>

This made me appreciate how much a few degrees C of climate change matter:<p><a href="http:&#x2F;&#x2F;xkcd.com&#x2F;1732&#x2F;" rel="nofollow">http:&#x2F;&#x2F;xkcd.com&#x2F;1732&#x2F;</a><p>When the world climate was 4.3 degrees Celsius colder, Boston was covered under a mile-high sheet of ice.

I haven&#x27;t read this, but do people forget basic chemistry? We burn fossil fuels because the process is exothermic -- we extract usable energy from it.<p>Lithification of CO2 (to make up a word?) is, as far as I know, endothermic. It takes energy to accomplish. On the surface, tending towards counter-productive. Burn fossil fuels to lithify CO2 from burning fossil fuels. Or ramp up nuclear, with all its problems, for the same.<p>Fusion, sure -- but we are not there, yet.<p>Unless we look at the sun -- solar and wind. (The largest fusion reactor we are going to have -- up in the sky.)<p>&quot;Alternative&quot;, next-generation, &quot;renewable&quot; energy might allow us to divert part of its potential excess supply to lithification of CO2. At the &quot;tailpipe&#x2F;smokestack&quot; of conventional production, or even, if we can figure out effective capture, out of the sky.<p>You want CO2 dealt with, you&#x27;re going to need to find a way to package it into a stable solid state.<p>By the way, we already have one worldwide, extant system for lithification of CO2. Based upon solar energy. Photosynthesizing flora.<p>Trouble is, we are outracing its natural counterbalance while simultaneously reducing and eliminating the flora required for it.

On a very off-topic note, I wanted to know how human beings can colonize gas giants like Jupiter and Saturn assuming they somehow have access to huge amount of energy. One key problem that would be needed to solve is exactly this: converting gases like CO2 and methane to solids.

The optimal way of storing carbon is as coal.

Question: once this CO2 has been changed into a solid form, will we be able to burn the solids to produce energy?

What about methane, anyone got stuff for that?? It&#x27;s much more potent of a greenhouse gas than CO2.

I heard there&#x27;s also a way to turn CO2 into wood.

Storing co2 under the sea? Imagine what a leaking well will look like: a giant soda straw injecting c02 directly where it can do the most damage.<p>Carbon storage may be a stop-gap but, as with &quot;clean coal&quot;, is also used as a pr flag to justify continued fossil fuel expansion. With the price of solar dropping, that is where we should focus (and fusion).