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Comment by opwieurposiu | Hacker News Reader

Depending on the type of rocks and how fine you want to grind them, the Specific Energy used is between 10-100(kWh/t). That leads me to guess $8-$25 per ton of electricity used for grinding rocks into sand. I was unable to find good numbers for the capital cost.

At an aggregate mine located in Brazil, the total expenses are $80-$160 per ton [1].

The price of sand at home depot is 5.96 for a 50lb bag, $238 per ton. My conclusion is you could make sand by grinding but it would cost 50%-100% more vs. digging up the beach.

[1] https://www.scielo.br/j/rem/a/8MW5dFZc5Vh6qMdnTqRKbfM#

Edit: Chat GPT thinks it would cost $62.25/per ton make sand from rocks.

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Land vs water/barge transport costs for bulk cargo may increase that by magnitude. Article suggest there will be 5x increase in demand and 5x increase in price at current stagnating availability. So that seems maybe doable.

I call shenanigans on the 5x price increase.

Marginal increases in commodity price can greatly increase supply as previously uneconomic deposits/production methods suddenly become very viable.

And while some processes critically depend on concrete, others will get pushed to other non-concrete methods if price goes up.

I think this might be case where cheap deposits are obviously geographically constrained. River sand near shores/blue water access for bulk transport to global markets. Once you expand to exploring/exploiting increasingly inland, the logistics of bulk cargo starts stacking up.

Sure, but when you double the acceptable transportation budget/distance, you square the coverage territory.

(Assuming an infinite number of routes and no change in cost per distance)

I think, unqualified speculation, transportation cost scales linearly because most economical exploitation past shores is along river/waterway sand, hence exploitation will be not be squared. Squaring coverage territory, as in getting sand from land introduces land shipping, which is even less efficient because cost per distance is subject to geography. Unless, engineered sand comes from coastal infra that takes regional inputs and pipes it strait onto barges, which also makes sense. But wild speculation on my part.

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