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A Quest to Make Gasoline Out of Thin Air: Prometheus (YC W19)

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241–250 of 291 posts

Re: A Quest to Make Gasoline Out of Thin Air: Prometheus (YC W19)

#241
post #179

Earlier quoted context omitted.

This article has nothing to do with carbon recapture. The gasoline produced from carbon is then intended for burn... This is simply an alternative electricity/power storage mechanism. But great to reduce emissions but is not intended for negative emissions (for which there is other tech)

> The gasoline produced from carbon is then intended for burn... If it's captured from the atmosphere and then burnt then surely it's zero-sum (apart from the energy cost of capture). Is this not better than releasing historically captured fossil fuels with a larger net increase in atmospheric levels? If the capturing process is net-negative in terms of CO2 emmissions then perhaps we could invest in capturing more th…

That's all true, but it depends completely on the cost. Fuel is a fungible good: one barrel of, say diesel, is equivalent to any other (assuming they're the same "grade", etc.).

Stockpiling a barrel of fuel pulled from the air is the same as stockpiling a barrel of fuel dug out of the ground (assuming it would otherwise have been burned): both result in 1 barrel-of-fuel-worth of CO2 in a stockpile rather than the atmosphere.

It takes a lot of energy to extract fuel out of the air, so buying a barrel of fuel-from-the-ground is currently cheaper. Hence we can stockpile more of it for the same cost, and have a bigger effect on the climate.

We can go even further: fuel-from-the-ground was already stockpiled, as fuel-in-the-ground. Locating, extracting and refining it takes a lot of energy, so buying a barrel of fuel-in-the-ground and leaving it alone is much cheaper than buying fuel-from-the-ground or fuel-from-the-air. It's also has lower maintenance costs.

Activities like carbon sequestering or extracting fuel from the atmosphere are nothing more (or less) than methods for redistributing energy and costs.

This redistribution is useful for those cases where fuel is a necessity, e.g. jumbo jets. Extracting that fuel from the atmosphere using renewable power (carbon negative) would allow jumbo jets (carbon positive) to be overall carbon neutral. From a cost and energy perspective that would be hugely inefficient compared to simply powering the planes with renewable energy directly; the only reason it should be taken seriously at all is because electric jumbos are not an option (and won't be for a long time, due to physics, battery chemistry, etc.).

In any situation where renewable is a viable option (e.g. electricity grids, cars, etc.) then these redistribution schemes make no sense. Every step in a process loses some efficiency; since the whole point is to reduce atmospheric CO2, and atmospheric CO2 depends on energy usage, introducing inefficiencies to "clear our conscience" is counter productive.

Of course there are some nuances. For example, it might make sense to have nuclear plants pulling fuel out of the air for stockpiling (nuclear works best with a steady demand). We could think of this as plundering the nuclear fuel of future generations (the energy we leave in our stockpiled fuel won't match that of the nuclear fuel used to make it, due to inefficiencies). This may be desirable, if it's cheaper to spend that fuel fixing our climate mess now, than it would be for those generations to fix it themselves if we burden them with it.

(Note that burning any of that nuclear-aquired fuel-from-the-air also makes no sense if we could have just used the nuclear power directly)

Re: A Quest to Make Gasoline Out of Thin Air: Prometheus (YC W19)

#242
post #69
post #57

There is a water plant called Azolla that actually captured so much co2 long ago that many think it triggered an ice age. Why not incentivize natural carbon sequestration and just produce huge fields of this stuff everywhere? I would hope we find a fish that likes eating it, or find a way to convert it into other animal feed, if nothing else. I don't think carbon tax credits or whatever they are called are enough for…

If an animal eats it, wouldn't it be combusting the captured carbon to produce CO2/H20/energy? I don't think you'd want to feed it to anything, but just let it be buried or be pushed under the earth's crust.

[deleted]

Re: A Quest to Make Gasoline Out of Thin Air: Prometheus (YC W19)

#243
post #69
post #57

There is a water plant called Azolla that actually captured so much co2 long ago that many think it triggered an ice age. Why not incentivize natural carbon sequestration and just produce huge fields of this stuff everywhere? I would hope we find a fish that likes eating it, or find a way to convert it into other animal feed, if nothing else. I don't think carbon tax credits or whatever they are called are enough for…

If an animal eats it, wouldn't it be combusting the captured carbon to produce CO2/H20/energy? I don't think you'd want to feed it to anything, but just let it be buried or be pushed under the earth's crust.

Yes, they don't even need to eat it, just from decomposing versus growing corn you can measure the rising and falling cycles of co2 at different times of the year for north america. I think Azolla is still less effort to grow than most plants, which might still help out if it ends up being used for animal feed.

Re: A Quest to Make Gasoline Out of Thin Air: Prometheus (YC W19)

#244

Earlier quoted context omitted.

As soon as PV is cheap enough, lots of fleets will convert to liquid anhydrous ammonia. Sure it's different than petrol/diesel, but it's already in wide use as a fertilizer and no technological breakthroughs are required to get it burning in ICEs. It's not yet economical but if PV keeps getting cheaper it will be. So it seems like the effort described in TFA is barking up the wrong tree?

Ammonia? WOW! As at https://en.wikipedia.org/wiki/Ammonia#Combustion 4 NH3 + 3 O2 → 2 N2 + 6 H2O The stuff is darned dangerous, quite challenging to handle, highly regulated due to the dangers, with lots of potential for toxicity, and likely close to ammonium nitrate, one heck of an explosive, etc., but a little arithmetic might show some astounding energy per gallon. If it has a lot of potential, then I'd wonder why…

Sure there are issues but a lot of infrastructure and regulations already exist for dealing with this fuel. And it completely eliminates the problems with hydrocarbons: no greenhouse, exhaust is harmless, with cheap enough power it can be made literally anywhere. A lot of the problems with ammonia are easily dealt with in a fleet situation. People can be trained to safely refuel, you can have a centralized solar-NH3 production facility, etc.

Re: A Quest to Make Gasoline Out of Thin Air: Prometheus (YC W19)

#245
post #167

Earlier quoted context omitted.

Forgive me for pointing out the obvious, but we already have an existing supply of hydrocarbon based fuels which are relatively cheap compared to the proposed "quest."

They are destroying the environment on which we depend. They are also finite. To further point out the obvious. https://www.ipcc.ch

They are finite but the finite total is over five times the amount needed to utterly destroy the environment... so we need to refrain from using up that finite total.

Re: A Quest to Make Gasoline Out of Thin Air: Prometheus (YC W19)

#246

Earlier quoted context omitted.

Maybe cars, but the weight of batteries is a problem for larger vehicles that need long range, like a bus, truck, or plane. For those hydrogen might be better.

> the weight of batteries is a problem for larger vehicles that need long range, like a bus, truck, or plane. For those hydrogen might be better. China is already leading the world in electric busses. They work great. Busses are such good vehicles for batteries, that for some routes it may even make sense to run them with super-capacitors, with chargers embedded in the road at stops. Trucks are always going to be a p…

> China is already leading the world in electric busses. They work great. Busses are such good vehicles for batteries, that for some routes it may even make sense to run them with super-capacitors, with chargers embedded in the road at stops.

Alberquerque had to return electric buses because they didn't perform up to the range requirements.

Electric bus range goes down the moment you introduce any sort of elevation, which is why Shenzhen, a relatively flat city, has them, and Hong Kong, an extremely hilly and mountainous city, considered the pilot a failure.

Re: A Quest to Make Gasoline Out of Thin Air: Prometheus (YC W19)

#247

Earlier quoted context omitted.

> the weight of batteries is a problem for larger vehicles that need long range, like a bus, truck, or plane. For those hydrogen might be better. China is already leading the world in electric busses. They work great. Busses are such good vehicles for batteries, that for some routes it may even make sense to run them with super-capacitors, with chargers embedded in the road at stops. Trucks are always going to be a p…

> Busses are such good vehicles for batteries, that for some routes it may even make sense to run them with super-capacitors, with chargers embedded in the road at stops. I would think busses are a very poor fit for batteries: their economics favours driving around for as long as possible (switching drivers in shifts). Any time spent charging is a waste. This is less favourable than a consumer car, which sits around…

> they only need to last as far as the next charging point.

You had better hope that your bus doesn't get stuck in traffic on the way there, then.

Re: A Quest to Make Gasoline Out of Thin Air: Prometheus (YC W19)

#248
post #208

Earlier quoted context omitted.

Maybe cars, but the weight of batteries is a problem for larger vehicles that need long range, like a bus, truck, or plane. For those hydrogen might be better.

Some buses need long range, such as that from Munich to Baku. That's not the common case: the common case is more like line 59 in Munich, whose route is about 14km long. A lot more people take the 59 to work than take the bus towards Baku. Trucks: There are different kinds, but you can separate them into "ones that could be replaced by trains" and "ones that don't really need long range" and not be very wrong. There…

Presumably the bus running on line 59 doesn't run once a day; it makes lots of loops back and forth on line 59. Electric charging is not so fast that you can do it in the short amount of time that buses are required to turn around, which is usually measured in minutes.

A rail network rarely has capacity for both decent freight (America) and decent passenger service (Europe). There are some exceptions to this rule, like China. But on their end that necessitated building an entirely new national rail network so that they could make room for freight trains on the old one.

Re: A Quest to Make Gasoline Out of Thin Air: Prometheus (YC W19)

#249
post #165

Earlier quoted context omitted.

How would someone in China charge their electric car with clean electricity generated in the United States?

Whoosh... Nobody suggested what you are asking about. But it seems you are suggesting that rather than generating electricity locally by sustainable means, it would be a better idea to create synthetic gasoline in the US, then ship that to China for them to burn?

>Nobody suggested what you are asking about.

That is exactly what I was talking about it my original post. No matter how many cars in the US get replaced with electric ones, China is still going to be building and driving gas-powered ones, and we have limited influence on their domestic policy.

>But it seems you are suggesting that rather than generating electricity locally by sustainable means, it would be a better idea to create synthetic gasoline in the US, then ship that to China for them to burn?

Not at all. In fact, the very first prerequisite for what I'm talking about is that the US has switched entirely to nuclear, wind, solar, hydroelectric, and other non-CO2 emitting power. At that point, there's little the US can do further reduce global CO2 emissions, at which point generating extra electrical capacity and using it to synthesize ICE fuel starts to look really attractive.

And again, this isn't something that is necessary or even viable in the short term. Over the long run, however, it seems like an important way that more industrialized nations can lower the CO2 emissions generated by internal activity of less industrialized ones.

Re: A Quest to Make Gasoline Out of Thin Air: Prometheus (YC W19)

#250

Earlier quoted context omitted.

Maybe cars, but the weight of batteries is a problem for larger vehicles that need long range, like a bus, truck, or plane. For those hydrogen might be better.

There's a big difference between US, Canada or Australia, and say Europe regarding this. In Europe the majority of buses and trucks don't need to travel long distances. And as the population in Europe is generally much more dense soon there will be a local infrastructure of recharging stations available everywhere, so even those that need to cross long distances won't have a big problem recharging more often. The reg…

Buses travel long distances because they run the same route throughout the day, and the turnaround time of a bus is expected to be minimal.

Alberquerque, New Mexico had the not unreasonable requirement that a bus should have a range of 442 km, but the buses that were delivered could not reliably meet that goal on a route that has some elevation gain and in a hot climate. https://www.abqjournal.com/1246094/abq-rejecting-all-byd-art...

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