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Comment by jaggederest | Hacker News Reader

I like the idea of stacking up a lot of 1 meter cubes of pure carbon (graphite, or diamond!) into nice shapes. Each cube is just over 2 metric tons (2266 kg) of carbon, or the equivalent of 8 metric tons of carbon dioxide. 20 cubic kilometers per year is enough to get us back to pre-industrial levels in no time, and build some interesting monuments while we're at it. A roughly 4-kilometer tall pyramid, anyone? Low low price of ~4 trillion dollars each.

Casually building pyramids out of the ~57 cubic kilometers of carbon blocks would be pretty neat. Three 4 kilometer tall square based pyramids would do it.

They would also be the largest structures ever built by humanity by an order of magnitude. If we did it in Australia, we could employ the entire country twice over, and they would be the 3 new tallest mountains in Down Under (by 1,772m).

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Its a wonderful image, but how do you propose sequestering the carbon? Without a powerful source of truly carbon-neutral energy, the losses incurred would simply see more carbon released downstream as a result of whatever process you choose to create such artful carbon chunks.

I still really enjoy the mental image of a post-industrial society in a few thousand years sitting on a foundation of diamond bricks. :)

Well, that's kind of down stream of what I was talking about - I am assuming that we can get to $250 per ton of direct carbon capture and then use something like a solar CO2 reduction system with a metal catalyst to strip the O2 off. But it's "merely a matter of money" at that point.

There's almost certainly some coking issues to overcome, but hey, we're already hypothetically taking on the largest industrial project of all time, roughly equivalent to all the effort spent to extract fossil fuels ever.

One thing I find particularly concerning in these plans is how people want to use them. Lots of people inevitably suggest under these posts that we just use DAC as counterbalance instead of reducing emissions. This is very much impossible as optimistic reduction scenarios still need trillions annually from every country and a no-reduction scheme would lead to hundreds upon hundreds of trillions of global DAC funding, far more than the GDP of the Earth is right now. This is the scale of the megaproject we need to undertake.

The only way we can make these things viable is massive funding and incredible carbon emissions reduction. This is very literally the largest industrial project that ever has happened, a re-terraforming of our own planet. There is absolutely no way we are going to succeed without full effort from all countries.

It's not terribly easy to overcome.

Honestly I don't expect it to happen. It's depressing, but I just don't think humanity collectively can take action on a scale like this without direct personal incentives, and I don't think there are any. I think we're going to drown in our waste products like yeast in a fermentation tank due to the tragedy of the commons.

Solar panels are relatively cheap now, and the intermittent nature of solar power is not a deal breaker for carbon sequestration.

That's highly dependent on what chemical process you use. Most industrial processes don't like intermittent power.

With a properly designed electricity grid with interconnects to other grids and using all those idle electric cars as batteries we surely can solve this problem. The wind is always blowing somewhere, the sun is always shining somewhere, and most electric vehicles are idle at night when the sun is not shining and they could be used to smooth out the peaks and troughs. Most private vehicles are idle for more than 90% of the time.

There are about 290 million private cars in the US (See https://hedgescompany.com/automotive-market-research-statist...).

If those were all electric with, say 50 kWh batteries they would be able to deliver an instantaneous power of something like 58 TW if the connectors could take it. But even if we assume that they are connected to only 7 kW charging points they could deliver 2 TW instantaneously. They could keep this up for an hour at the cost of losing less than 20% of a full charge.

Average US electricity consumption is about 500 GW so vehicle to grid plus an upgraded and properly interconnected grid should be able to solve the problem of intermittent generation.

I hope I haven't made a mistake in the arithmetic!

Also, we have lots of energy storage options that produce minimal amounts of waste.

Flywheels, molten salt, iron air batteries, literally dozens of alternative systems exist that are all viable and variably scalable power grid stabilization systems that can work harmoniously with renewable generation to keep electricity available to the consumer at both the individual and commercial level.

It needs a lot of financial and engineering investment to make headway, and these decisions would have to come from government leadership as otherwise there are too many cats to corral to ever make is succeed.

Retooling Australia into perpetual carbon pyramid building might be an improvement over current state of things...

How soon would we need a fourth?!

Oh, sorry, I was not specific, it's three per year, every year, until we get to 250ppm CO2 in the atmosphere.

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