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Re:Launch HN: Heimdal (YC S21) – Carbon neutral cement by frederikvs on Monday August 02, 2021 @01:53PM (#28040187)
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 by marcuslima on Monday August 02, 2021 @02:09PM (#28040436)
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 by frederikvs on Monday August 02, 2021 @03:40PM (#28041630)
Could you elaborate on how dissolved limestone does not emit CO2? Limestone is CaCO3. The calcium gets dissolved, ready to be used by your process. The Oxygen, I don't care much whether it stays in the water or goes into the atmosphere. Where does the carbon go, if not into CO2?
Re:Launch HN: Heimdal (YC S21) – Carbon neutral cement by marcuslima on Monday August 02, 2021 @06:35PM (#28043541)
That's part of the CO2 saturation of the ocean. So when we remove that dissolved CO2 that equivalent amount is removed from the atmosphere
Re:Launch HN: Heimdal (YC S21) – Carbon neutral cement by foobiekr on Monday August 02, 2021 @06:41PM (#28043605)
I have the same question.
Re:Launch HN: Heimdal (YC S21) – Carbon neutral cement by pabs3 on Monday August 02, 2021 @11:41PM (#28045467)
How will reducing the amount of dissolved calcium and CO2 in the ocean affect organisms like shellfish and crabs. Could there be local zones around your extraction points where these organisms can no longer produce shells?
Re:Launch HN: Heimdal (YC S21) – Carbon neutral cement by marcuslima on Tuesday August 03, 2021 @04:19AM (#28046832)
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!
Re:Launch HN: Heimdal (YC S21) – Carbon neutral cement by hippari on Tuesday August 03, 2021 @07:13AM (#28047841)
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.

Re:Launch HN: Heimdal (YC S21) – Carbon neutral cement by sgc on Tuesday August 03, 2021 @11:24AM (#28050286)
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 by hedora on Monday August 02, 2021 @09:07PM (#28044644)
What sort of waste water do you produce? What is the local ecosystem impact?

Edit: Also, it’s great that your de-carbonating the ocean as part of this project. Ecological damage to the ocean is out of sight, and usually out of mind.

Re:Launch HN: Heimdal (YC S21) – Carbon neutral cement by marcuslima on Tuesday August 03, 2021 @04:29AM (#28046892)
All 'waste' we produce we either consume in our process or we're able to sell as a commercial product!

Not bad tackling ocean acidifcation to boot

Re:Launch HN: Heimdal (YC S21) – Carbon neutral cement by radicalbyte on Tuesday August 03, 2021 @05:31AM (#28047223)
I was just about to make this point: as I understood it, ocean acidification is a massive environmental problem.

Would your process reduce the local acidification significantly? Could there actually be a win-win situation here deploying around coral reefs? Especially given that such reefs are found in countries with massive solar potential (i.e Australia).

Re:Launch HN: Heimdal (YC S21) – Carbon neutral cement by hinkley on Wednesday August 04, 2021 @01:05PM (#28063498)
Coral reefs are having trouble with the ph of sea water. If you drop the calcium content then it’s probably more problems for them.

If you pull enough to dissolve more limestone, then they’re just mining limestone hydraulically, and they are mining it outside of the economic exclusion zone of their own country. This product plan is literally “I drink your milkshake.”

On the plus side Florida will fall into the ocean sooner.