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Comment by advisedwang | Hacker News Reader

Apparently burning petrol releases about 2.31 kg of CO2 per liter. At 100 USD per tonne of CO2 it would cost 0.23 USD per liter of petrol if we captured every bit of CO2 released. That's within the realm of possibility.

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Well that's a Holy Fuck moment for me.

I thought the parent here had made a off-by-orders of magnitude error - how can a liter of petrol (which itself is only a kg) produce 2.31kg of CO2 ... i mean work it out, all the carbon would have to attach to 2x oxygen ... ok that might just ... err ...

see this reference for a walk through of the calculation - http://ecoscore.be/en/info/ecoscore/co2

Every time I pour petrol into my tank I am basically pouring twice that weight of CO2 into the atmosphere.

I may be very dumb but I never thought if it like that before. I always assumed CO2 was a minor byproduct ... but like breathing.

oh dear.

Consider it this way. That entire liter turns to gas when burned, and in doing so it combines with O2 and other things in the air, resulting in the total weight of the liter + what it combined with entering the air.

> like breathing

When you eat 1kg of peanut butter, if I've done my math right, you'll breathe out about 2.3kg of CO2. Dry cereal would be about 1.5kg. Most foods have a lot of water in them, though.

Darn and that looked like a pretty decent breakfast :-)

I would think you're unlikely to produce sufficient bile to metabolise an entire kilogram of peanut butter at once. Most likely you'd get really nasty, oily runs at best, and quite possibly throw up.

Yes, but the weight of the oxygen is in the atmosphere already. And for a bonus, all the hydrogen you burn removes O2 from the atmosphere in the form of water, reducing the weight of the atmosphere (and therefor the greenhouse effect of the atmosphere). How much the reduction of O2 from H burning offsets the transformation of O2 to CO2 is left as a problem for the reader. If anyone knows of a paper that discusses this effect, I'd love to read it.

most of the weight is oxygen, by definition CO2

Carbon Atomic Mass: 12.0107 amu Oxygen, about 16

so carbon itself is really just 27% of CO2 12 / (32 + 12)

so you're not pouring "twice the weight of CO2" of petro, that would be wrong. Its taking 73% of the weight from the air, and putting it back, plus a little more.

The point is I am taking a locked down "harmless" fluid and doubling its weight as "harmful" gas - the weight thing surprised me.

it was just a human way to look at it

Yeah it seems pretty straightforward to just start taxing at that rate and be done with all the nonsense.

Except for the part that this process takes electricity to do. If the process can be turned off and on quickly, it would be a great use for excess wind and solar power.

One nice thing about this is that you could pull carbon out of the atmosphere from remote locations, in particular hydro electricity could provide abundant, inexpensive, and clean power.

Just what I was thinking. Like west Texas with wind where electricity prices go negative quite often in the middle of the night.

guys, capturing CO2 or not releasing it at a power plant are the easy and cheap part. It's what you do with the voluminous CO2 gas. Converting to fuel will be very expensive (although if the conversion process can be throttled quickly, which I highly doubt, we could use peak solar and wind, and treat fuel as a battery). The figures you calculate is meaningless, factories could always have been fitted with carbon capture for a relatively low energy cost. The reason this is not done at scale is there is zero demand for CO2! (unless you pay someone carbon credits to pretend to need CO2!!!)

Yes, at that scale, the price of CO2 approaches zero, especially with the caveat that it shouldn't be reintroduced (as with carbonated beverages and pressurized machinery).

Carbon dioxide sequestration or transformation is the next step. Getting the first step to be economical is also nice.

CO2 injection is already done in many oil fields for enhanced oil recovery. People already know how to pump it down into the earth and track where it goes. Put a decent price on removing CO2 from the atmosphere and people will quickly figure out how to do it for a nice profit. Lots of old oil wells in west Texas also.

A funny coincidence: the excise duty on petrol here consists of several "parts", one of which is the carbon dioxide tax, which is currently about 0.25 USD/litre (in total the fixed taxes amount to a bit over 1 USD/litre).

I assume "here" is USA, but you could be converting to dollars from local currency?

I'm converting because earlier messages used dollars as well. I doubt that taxes that high exist anywhere in the US (1 USD/litre being almost 4 USD/gallon after all).

This is a mind blowing concept. I mean, it makes sense when I read:

http://ecoscore.be/en/info/ecoscore/co2

But does this take into account catalytic converters or other emissions controls? Cats take the CO from the combustion process and turn it into CO2, the gas you're referencing. I'd just like to clarify because this is a big revelation in my way of thinking about pollution. Are we really releasing that much CO2 post emissions controls?

Emissions controls have no effect at all on CO2 emissions. They don't alter the fundamental stoichiometry of a pure octane combustion:

2C8H18 + 2502 -> 16CO2 + 18H2O

So yes, burning a liter of octane (6 moles) will use ~1600 liters of oxygen and emit ~1000 liters of carbon dioxide, or a little over two kilograms. In pure carbon terms, it produces (drumroll) the exact same amount as the input: 49 moles at 12 g/mol or 590 grams.

Yes, I would happily pay that for "carbon neutral" gas.

Considering the US has literally entered wars that cost trillions over oil disputes, I think you are pretty much alone.

Counter-example: I'd happily pay at least that much for carbon-neutral or carbon-reducing fuel.

Source: Am registered-voter citizen of the United States.

I'm not disputing that, just the the political climate makes that opinion a miniscule minority.

Sounds like others are paying a fairly high price in that case but just more indirectly

You are making the big assumption this article is accurate and scalable. I’m not so sure.

You’re also assuming that capturing everything scales linearly from capturing something.

Bill Gates has been funding this project since its inception and one of the founders is a world expert in global warming and a Professor at Harvard so you'll have to do better than unsubstantiated innuendo here. Roll out some real facts rather just than pulled out of your ear guesses.

You realize the argument you’re making (“Smart people are backing this!”) is exactly how Theranos and many other scams go on as long as they do right?

All I did was bring up some concerns. I did not state any facts, merely point out details that need to be addressed.

Chill out.

This may give you some reassurance.[1]

[1]https://arstechnica.com/science/2018/06/machines-that-suck-c...

Why would it? It’s just another one sided fluff piece. Basically a press release for the product much like the original article.

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