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Launch HN: Heimdal (YC S21) – Carbon neutral cement

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Re: Launch HN: Heimdal (YC S21) – Carbon neutral cement

#201

Post by froh »

marcuslima wrote: post #181
froh wrote: post #105

Earlier quoted context omitted.

so there is no more additional burning of limestone needed? instead your process directly produces the lime, CaO? and that then binds the CO2 when curing? to my limited understanding cement production emits CO2 in two ways: by splitting limestone into lime and co2 and by burning carbon based fuels to split the limestone. your method addresses both sources of co2 from cement production? or just one of them?

Our process produces calcium carbonate, CaCO3, which cement producers can then burn to make quicklime, CaO. This does release CO2 but that CO2 has been captured from the atmosphere in the process of making that calcium carbonate. We only address process emissions (ie. splitting CO2 from CaCO3), but we do also produce hydrogen on-site, which can be used to replace fossil fuels in generating the requisite heat

ok so your cement does not expose additional co2 from the lime-to-quicklime transformation, instead it takes co2 from the oceans. that is released to zhe athmosphere during cement production. and that co2 from the air is then recaptured by the ocean. so your process creates a ocean-co2 -> air -> ocean cycle.

and when and where the hydrogen is replacing some carbon based fuels, somehwere, that counterbalances the carbon based fuel used in the cement furnace.

now I get how it becomes carbon neutral overall.

do you guys have data points at hand how long it takes for an ocean to recapture the co2?

Re: Launch HN: Heimdal (YC S21) – Carbon neutral cement

#202

Post by brilee »

thereisnospork wrote: post #175
brilee wrote: post #157

I did some lengthy analysis behind the chemistry / economics and wrote it up here. https://www.moderndescartes.com/essays/carbon_neutral_concre... TL;DR: ignoring all sources of overhead/inefficiency and purely on consideration of thermodynamic costs, $70 of electricity can generate $100 of lime, $300 of chlorine gas, and $75 of hydrogen gas. Much more details on the chemistry and economics in the blog post...

Some comments and expansion on your analysis, which I enjoyed reading and provided a nice excuse to dust some mental cobwebs. I'd also like to clarify up front that I'm limiting my analysis to the proposed electrochemical mechanism, and have no information on the specifics of Heimdal's proposed implementation - which may vary significantly and materially: The theoretically minimum electrical energy input (often) wind…

Thanks for the comment, I also had to dust off some mental cobwebs for this analysis :)

You're pointing out the crux of the issue: "Ultimately making CaCO3 this way (and CaO) winds up substituting a 400$/tonne product in NaOH for an approx 40$/tonne product in CaCO3."

I calculated that Heimdal's process has 7x reality factor overhead, whereas chloralkali has 2x reality factor. This is seemingly in opposition to your statement. I think the diff comes from considering all the other energetics - precipitation of CaO from the hydroxide is thermodynamically quite favorable, reducing the overall theoretical cost by 65% relative to the chloralkali process. So to the extent that Heimdal can usefully harness that energy gradient, that's the difference.

Re: Launch HN: Heimdal (YC S21) – Carbon neutral cement

#203

Post by m12k »

marcuslima wrote: post #188
brilee wrote: post #157

I did some lengthy analysis behind the chemistry / economics and wrote it up here. https://www.moderndescartes.com/essays/carbon_neutral_concre... TL;DR: ignoring all sources of overhead/inefficiency and purely on consideration of thermodynamic costs, $70 of electricity can generate $100 of lime, $300 of chlorine gas, and $75 of hydrogen gas. Much more details on the chemistry and economics in the blog post...

Impressive analysis! Missed out on a couple details, but I'll take that as a thoroughly researched/analyzed endorsement. Most importantly, we'll be scaling up a lot faster. Our current 1t/yr is just a demo. Our current roadmap is scaling up to a 300t/yr pilot in the next few months before setting up building a commercial plant (10kt+) in the second half of next year. Any chance we can poach you from Google? ;)

What's the status on your current 1t/yr demo? (i.e. is it fully operational?) What did you learn from it and what are the technical challenges to scale it up to bigger plants?

Re: Launch HN: Heimdal (YC S21) – Carbon neutral cement

#204

Post by tablespoon »

robinsoh wrote: post #163
tablespoon wrote: post #160

Earlier quoted context omitted.

> one would have had to expend energy to extract that CO2 from the ocean and that energy would have generated emissions as well. I suppose they could planning to use renewable energy? > If the output of this is just CaCO3 again, then I fail to see how this is a better solution than carbon capture using a clay geopolymer technique that goes directly to a concrete like structural material. I don't have a horse in this…

They'd also need a significant source of Calcium. > one possibility is that concrete is a better understood material than some novel "concrete like structural material," so it's more acceptable in safety critical situations (e.g. people know how it fails, how to detect failures, how to remediate problems, etc.). Your explanation and argument looks correct to me. However, I should point out that concrete structures fa…

I think the difference between materials and software through is that with materials, there's definitely a better understanding that comes with actual aging that you can't really get otherwise.

With some new material, they'd probably need to rely significantly on accelerated aging tests (at least for a few decades), and there's always the question with those of how accurately those actually model real aging under real conditions.

That's not to say they shouldn't try new materials, just that the rollout probably should be slower, and maybe not so good for tackling climate change. For that reason, I can see the benefit of a less carbon intensive way to produce an existing material, since that could be rolled out/scaled up immediately without some of the concerns of alternatives.

Re: Launch HN: Heimdal (YC S21) – Carbon neutral cement

#205

Post by blacksqr »

brilee wrote: post #202
thereisnospork wrote: post #175

Earlier quoted context omitted.

Some comments and expansion on your analysis, which I enjoyed reading and provided a nice excuse to dust some mental cobwebs. I'd also like to clarify up front that I'm limiting my analysis to the proposed electrochemical mechanism, and have no information on the specifics of Heimdal's proposed implementation - which may vary significantly and materially: The theoretically minimum electrical energy input (often) wind…

Thanks for the comment, I also had to dust off some mental cobwebs for this analysis :) You're pointing out the crux of the issue: "Ultimately making CaCO3 this way (and CaO) winds up substituting a 400$/tonne product in NaOH for an approx 40$/tonne product in CaCO3." I calculated that Heimdal's process has 7x reality factor overhead, whereas chloralkali has 2x reality factor. This is seemingly in opposition to your…

According to their web site, one of their premises is that renewable electricity is now cheap and plentiful. If that's so, I'm led to wonder if there is a more direct way to reduce CO2 emissions in cement manufacture, namely, use resistive or carbon-arc heating to fire the ovens, thus replacing fossil fuels in the manufacturing process.

Sorry I don't have the chops to work out if that's economically feasible.

Re: Launch HN: Heimdal (YC S21) – Carbon neutral cement

#206

Post by sgc »

hippari wrote: post #195
marcuslima wrote: post #176

Earlier quoted context omitted.

The ocean is 20x supersaturated with calcium and is constantly being replenished by geological stores of the stuff coming in through rivers. As long as the ecosystem remains supersaturated this shouldn't be a problem for any marine life. Though a slight dislcaimer there is i'm not a marine scientist!

I think the diffusion rate of Ca and CO2 is also important. Even though the ocean is supersaturated *globally*, the local area around your plant might not have enough concentration. Hope you can get someone to check that. Might have to spread your plants across multiple regions, or place it around somewhere with low impact to marine life I think.

They can reduce that risk by having very long tubes that can be re-positioned from the surface using ships to take water from different locations while the currents replenish the other locations. Or just have several tubes to draw from. Like rotating a pasture. No doubt they will need to actually monitor and plan for this or they will likely create a disaster.

Re: Launch HN: Heimdal (YC S21) – Carbon neutral cement

#207

Post by coryrc »

blacksqr wrote: post #205
brilee wrote: post #202

Earlier quoted context omitted.

Thanks for the comment, I also had to dust off some mental cobwebs for this analysis :) You're pointing out the crux of the issue: "Ultimately making CaCO3 this way (and CaO) winds up substituting a 400$/tonne product in NaOH for an approx 40$/tonne product in CaCO3." I calculated that Heimdal's process has 7x reality factor overhead, whereas chloralkali has 2x reality factor. This is seemingly in opposition to your…

According to their web site, one of their premises is that renewable electricity is now cheap and plentiful. If that's so, I'm led to wonder if there is a more direct way to reduce CO2 emissions in cement manufacture, namely, use resistive or carbon-arc heating to fire the ovens, thus replacing fossil fuels in the manufacturing process. Sorry I don't have the chops to work out if that's economically feasible.

The thing you are firing in the oven (limestone) releases CO2. Fossil fuels aren't the only source of CO2.

We need zero CO2.

Re: Launch HN: Heimdal (YC S21) – Carbon neutral cement

#208

Post by coryrc »

marcuslima wrote: post #178
robinsoh wrote: post #142

Earlier quoted context omitted.

I'm probably missing something obvious. > The world needs CaO for cement. We have a carbon neutral process for making it vs > We make synthetic limestone using atmospheric CO2, such that when it is used to make cement, the process is carbon neutral. Do you make CaO or CaCO3?

We make CaCO3, I mention CaO here because that's what cement producers ultimately need. They heat up limestone (CaCO3) to make CaO

Is there a reason not to make quicklime instead of limestone?

Re: Launch HN: Heimdal (YC S21) – Carbon neutral cement

#209

Post by thereisnospork »

brilee wrote: post #202
thereisnospork wrote: post #175

Earlier quoted context omitted.

Some comments and expansion on your analysis, which I enjoyed reading and provided a nice excuse to dust some mental cobwebs. I'd also like to clarify up front that I'm limiting my analysis to the proposed electrochemical mechanism, and have no information on the specifics of Heimdal's proposed implementation - which may vary significantly and materially: The theoretically minimum electrical energy input (often) wind…

Thanks for the comment, I also had to dust off some mental cobwebs for this analysis :) You're pointing out the crux of the issue: "Ultimately making CaCO3 this way (and CaO) winds up substituting a 400$/tonne product in NaOH for an approx 40$/tonne product in CaCO3." I calculated that Heimdal's process has 7x reality factor overhead, whereas chloralkali has 2x reality factor. This is seemingly in opposition to your…

>This is seemingly in opposition to your statement. I think the diff comes from considering all the other energetics - precipitation of CaO from the hydroxide is thermodynamically quite favorable, reducing the overall theoretical cost by 65% relative to the chloralkali process. So to the extent that Heimdal can usefully harness that energy gradient, that's the difference.

I guess the crux of my argument is that it is impossible[0] to capture the energy from CaO precipitation. E.g.[1] one has to spend 2J of electrical to create the hydroxide in Ca(OH)2, but the 1.5J get released on precipitation of CaO comes as heat[2], rather than a reduction in energy input.

So, in summary, Electrochemical CaCO3 would have [approximately] equal theoretical electrical demand to chloralkali and, to borrow your term, a higher reality factor overhead[3], to make a product an order of magnitude cheaper than NaOH.

[0]For a loose definition of impossible, to be fair reality's never quite so black and white.

[1]Made up numbers.

[2]And heat in sub-boiling water is not useful for doing work.

[3]I broadly agree with your position on reality factor overhead, just made less of an emphasis on it trying for 'equivalent but worse and creates less value'

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