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Dude, where's my fuel?

prometheusfuels.com

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Re: Dude, where's my fuel?

#81

Post by simulate-me »

10u152 wrote: post #42
Manuel_D wrote: post #26

Earlier quoted context omitted.

Those examples aren't actually capturing carbon from the atmosphere. They're capturing carbon produced as a byproduct of industrial processes. There's a massive difference when you're already working with concentrated carbon dioxide and when you're trying to capture it from the atmosphere.

If it’s capturing co2 that would otherwise go into the atmosphere…does it matter ?

It makes the burning of fossil fuels more efficient, e.g. you can X tons of coal to produce Y MW of power and get Z additional gallons of gas. But it's really a stretch to call this carbon neutral.

Re: Dude, where's my fuel?

#82

Post by simulate-me »

DennisP wrote: post #28
elil17 wrote: post #27

Can anyone explain to me why their DAC is so cheap?

From the article: > The main energy cost is in getting the CO2 to release from the absorbent — to desorb. And that’s when things get really expensive, because this requires a lot of energy...we don’t make or need pure CO2 gas, so we don’t need to desorb it. Therefore, we avoid the vast majority of this cost. Instead, we capture CO2 in water and then use it in water to make fuel. ARPA-E refers to this as “reactive CO2…

How good is water at capturing CO2 compared to the other absorbents? My guess, not as good. So is more CO2 released because they're capturing with water?

Re: Dude, where's my fuel?

#83

Post by tastyfreeze »

alex_young wrote: post #69
ncmncm wrote: post #63

Earlier quoted context omitted.

Tractor fuel produced at the foot of a wind turbine in the middle of a farmer's field, that doesn't need to be transported from a refinery, would have immediate value. Fences made of double-sided solar panels mounted a bit more than tractor-width apart, running N-S, coexist nicely with row crops, and cut water loss, improve conversion efficiency (via evaporative cooling), and often increase yield besides (via reduced…

Why not just make electric tractors? The energy efficiency of converting wind -> electricity -> fuel -> mechanical power has to be less efficient than wind -> electricity -> mechanical power right?

It is easier and cheaper to store liquid fuel. Making liquid fuel would allow fuel to be made and stored in the off season in a greater quantity than could be reasonable be stored in batteries.

Re: Dude, where's my fuel?

#84

Post by coderenegade »

All the best to them, but I'll believe it when I see it.

I'm also skeptical that petrol / diesel / long chain hydrocarbons are even the right fuel to make. If the average length of the carbon chain for something like diesel is around eight, you can make roughly eight times the number of methanol molecules for the same carbon input. Hydrogen requirements are also lower, so the cost limitation there is reduced as well. It just seems like an inherently cheaper $/kWh pathway for storing energy, especially when you consider that there are already amateurs doing methanol conversions for cars for a few thousand dollars.

Obviously this doesn't work for aviation, but the calculus there is a bit different. LH2 has a number of advantages for aircraft, and depending on how much cheaper it is than synthetic kerosene, it may prove to be the better option.

On the subject of direct air capture -- have any studies been done on its efficacy relative to fast growing plants? Some seaweeds can grow at a rate of a meter a day, which obviously requires pulling carbon from the water (i.e. indirectly from the atmosphere). Similarly, it seems like there are pre-existing (and potentially cost effective) pathways for shorting the carbon cycle by, for example, using sewerage as a source, since all of that carbon was at one time pulled from the atmosphere by a vegetable.

Re: Dude, where's my fuel?

#85

Post by throwaway894345 »

ncmncm wrote: post #79
alex_young wrote: post #69

Earlier quoted context omitted.

Why not just make electric tractors? The energy efficiency of converting wind -> electricity -> fuel -> mechanical power has to be less efficient than wind -> electricity -> mechanical power right?

Tractors are very expensive. Farmers will not replace them just for this. And, they need to operate all day long, which would take a hell of a lot of battery. Retrofitting with ammonia tankage and plumbing (making them cheaper to run) is an expense they might prefer to avoid until they have a reliable secondary supply of ammonia.

They need to run all day and all night for ~2 weeks straight twice a year and then they can sit idle most of the rest of the time. But during those 4 weeks charging for one out of every three hours (I’m assuming that a big tractor pulling a big implement is going to deplete even a really big battery fast and charging a battery that large is probably going to take a long time) isn’t going to be tolerable.

Re: Dude, where's my fuel?

#86

Post by throwaway894345 »

LgWoodenBadger wrote: post #76
alex_young wrote: post #69

Earlier quoted context omitted.

Why not just make electric tractors? The energy efficiency of converting wind -> electricity -> fuel -> mechanical power has to be less efficient than wind -> electricity -> mechanical power right?

With the amounts of extra weight farmers often add to their tractors, and their general hatred of DEF and regen cycles, electric tractors seem like a billion dollar idea just waiting for someone to pick it up and run with it.

I doubt batteries are up to the task. Tractors and implements are big, so the battery is going to have to be huge, which is going to further increase the weight of the tractor and so on. Plus if you’re in the middle of harvest season (you have a narrow window to get crops out of the ground and you work around the clock for a week or so), you can’t afford to wait an hour to charge your tractor after driving it for an hour or two. Anyway, you would have to have electricity in ample supply on site or else you’re taking your tractor offline for even longer while you drive it to and from your field for a charge.

Re: Dude, where's my fuel?

#87

Post by ur-whale »

Unless I missed it, there is no mention of the environmental cost of the process itself.

What I mean by that is all the chemistry / electrolysis / carbon nanotube stuff, they do mention that this is where the main cost is, but what happens when that equipment needs to be replaced?

What is the environmental impact of the equipment itself?

Re: Dude, where's my fuel?

#88

Post by ncmncm »

nyokodo wrote: post #80
alex_young wrote: post #69

Earlier quoted context omitted.

Why not just make electric tractors? The energy efficiency of converting wind -> electricity -> fuel -> mechanical power has to be less efficient than wind -> electricity -> mechanical power right?

> The energy efficiency of converting wind -> electricity -> fuel -> mechanical power has to be less efficient than wind -> electricity -> mechanical power It depends on how efficient it is to use existing ICE tractors vs creating new electric tractors. If tractors are like other ICE vehicles then something like half the energy they take over their lifetime is used in their production so if you want to get to Net-0 s…

Efficiency is secondary. Cost is primary. As the cost of generator capacity continues on down, people worry less about efficiency. The top-line input, sunshine, is free. So it is a question of capital cost amortized over energy produced.

Re: Dude, where's my fuel?

#89

Post by ncmncm »

coderintherye wrote: post #75
alex_young wrote: post #69

Earlier quoted context omitted.

Why not just make electric tractors? The energy efficiency of converting wind -> electricity -> fuel -> mechanical power has to be less efficient than wind -> electricity -> mechanical power right?

Solectrac is making electric tractors in production. They are available today (though waiting period between deposit and delivery).

Boutique item, maybe unless the batteries can be replaced while it operates. They would need a hell of a lot of spare batteries, and somebody running around replacing them. Presumably today people are driving out to fill up fuel in existing tractors after some number of rows.

Re: Dude, where's my fuel?

#90

Post by Manuel_D »

10u152 wrote: post #42
Manuel_D wrote: post #26

Earlier quoted context omitted.

Those examples aren't actually capturing carbon from the atmosphere. They're capturing carbon produced as a byproduct of industrial processes. There's a massive difference when you're already working with concentrated carbon dioxide and when you're trying to capture it from the atmosphere.

If it’s capturing co2 that would otherwise go into the atmosphere…does it matter ?

Yes, because Prometheus fuels is trying to extract from atmosphere. Scavenging industrial CO2 byproduct is something you can only do opportunistically.
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