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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

#61

Post by [deleted] »

marcuslima wrote: post #53
brilee wrote: post #49

I'm not sure I understand where the carbon savings comes from. The cement industry specifically needs lime, CaO. Lime is most easily obtained by burning CO2 off of limestone, CaCO3. As you point out, this is effectively "burning off" captured carbon dioxide and is bad. Where does the carbon savings come from when the ultimate destination is to just burn CO2 off and make the actual desired product, CaO? Is this proces…

Yep, exactly! The world needs CaO for cement. We have a carbon neutral process for making it. It's actually overall negative as not all carbonates we extract are usable in cement production. But as far as cement producers are concerned it's carbon neutral.

[deleted]

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

#62

Post by uranium »

rout39574 wrote: post #43
marcuslima wrote: post #13

Earlier quoted context omitted.

Our current cost per tonne is in the same order of magnitude when including the carbon value from the European ETS. The key success criteria for making large plants profitable will be connecting to cheap electricity at <$50/MWh we're in the black

What electricity sources have you identified as acceptable for this? Proximity of e.g. hydro to an ocean seems like a small set of sites. :) A naive glance suggests that solar capacity factor of 25% is going to put that particular source out of your budget.

+1

Can you handle intermittency in your power, or do you need to run continuously? What capacity factor do you assume in your cost model?

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

#63

Post by frederikvs »

If I understand correctly, you extract both Calcium and CO2 from ocean water, and use this as input for making cement. The ocean will absorb the CO2 from the air, and that's a win. Where does the Calcium in the oceans come from?

If your process is scaled up massively, will the oceans run out of Calcium? Or will they absorb Calcium from somewhere? What would that Calcium source be?

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

#65

Post by marcuslima »

frederikvs wrote: post #63

If I understand correctly, you extract both Calcium and CO2 from ocean water, and use this as input for making cement. The ocean will absorb the CO2 from the air, and that's a win. Where does the Calcium in the oceans come from? If your process is scaled up massively, will the oceans run out of Calcium? Or will they absorb Calcium from somewhere? What would that Calcium source be?

Well understood! The ocean is supersaturated in the ocean (ie. there is about 20x more of it dissolved than you would expect). In fact it's the single largest deposit of calcium in the world. Risk of running out is zero. Calcium in the ocean comes from dissolved limestone (this does not emit CO2)

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

#66

Post by LeifCarrotson »

marcuslima wrote: post #35
pmat wrote: post #34

Very cool! It sounds like your sorbent requires calcium to precipitate calcium carbonate from sea water. What would be the source of this calcium? Hopefully it won't come from reducing lime!

The calcium all comes from dissolved calcium bicarbonate - we trigger precipitation by shifting bicarbonate to carbonate ions, which are insoluble. Essentially we acceelrate the oceanic carbonate cycle

I understand that calcium salts and bicarbonate ions are common in the ocean, and are increasingly common as the oceans become more acidic, but have no idea how common that is.

How much seawater do you need to get one kg of CaCO3 precipitate?

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

#67

Post by marcuslima »

hwillis wrote: post #56
marcuslima wrote: post #53

Earlier quoted context omitted.

Yep, exactly! The world needs CaO for cement. We have a carbon neutral process for making it. It's actually overall negative as not all carbonates we extract are usable in cement production. But as far as cement producers are concerned it's carbon neutral.

why does removing carbonates cause the ocean to absorb more CO2, though? Calcium and magnesium oxide aren't just floating around the ocean waiting to absorb more CO2. Removing salts does not lower oceanic acidity.

The ocean and the atmosphere exist in an equilibrium there is a 'balance' of relative concentration of CO2. Because CO2 can dissolve in water as CO3 and HCO3 the concentration is skewed to a higher concentration in oceans. When we take out CO2 from the oceans we lower the relative concentration, so we shift it out of balance. So the entire ocean becomes the surface area for re-absorbing CO2 from the atmosphere to re-establish that balance!

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

#68

Post by marcuslima »

skohan wrote: post #54

Very cool project! A couple questions: 1. How does your synthetic limestone compare to natural limestone? Are there any important performance differences in terms of the material properties of the resulting concrete? 2. What are the biggest bottlenecks/obstacles in terms of scaling this to the point it could replace a significant portion of natural limestone used today? Edit: do you have any blog posts/more informati…

Thanks! 1. We are entering the product testing stage with our cement producing parnters in the next few months, so I'll have a better answer for you then. But from a chemical composition point of view, our product is purer than mined limestone and so should perform better. 2. Biggest bottleneck from our perspective is nailing planning permission to build our plants quickly enough to supply cement producers.

Unfortunately no blog post or anything like that just yet. Website is very light on details for now, we haven't prioritised updating (+ some patent considerations).

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

#69

Post by marcuslima »

cerved wrote: post #48
marcuslima wrote: post #30

Earlier quoted context omitted.

Thanks! Yeah, we think it will be. But more importantly, the old way isn't a viable option. It's effectively off the table. Sweden has already banned mining of limestone ( https://www.ribaj.com/products/cementa-limestone-mine-suspen... ) The product comes out as a really finely ground powder

to be specific, an application was not approved and the reason the court gave was insufficient proof that continued mining wouldn't effect the local groundwater

Yes, thanks for clarifying

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

#70

Post by marcuslima »

uranium wrote: post #60
marcuslima wrote: post #13

Earlier quoted context omitted.

Our current cost per tonne is in the same order of magnitude when including the carbon value from the European ETS. The key success criteria for making large plants profitable will be connecting to cheap electricity at <$50/MWh we're in the black

Will you be able to complete on cost without carbon credits, at scale?

We're competitive at scale. This does require us to hit our CAPEX targets and to capitalize on cheap renewable sources of electricity that are becoming prevalent
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