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Launch HN: Prometheus (YC W19) – Remove CO2 from Air and Turn It into Gasoline

news.ycombinator.com

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Re: Launch HN: Prometheus (YC W19) – Remove CO2 from Air and Turn It into Gasoline

#361

Post by narrator »

What's your Energy Returned on Energy Invested (EROEI) on that?

Specifically, this means if you took the gasoline you made from this and put it into an efficient generator how much electricity would you get out of it vs how much electricity you put into it to make it in the first place? This would be very useful in comparing this technology to biodiesel as a method of carbon sequestration for example. Biodiesel has other problems too such as using arable land and depleting topsoil. This comparison would make a nice slide in your deck.

Re: Launch HN: Prometheus (YC W19) – Remove CO2 from Air and Turn It into Gasoline

#362

Post by rayiner »

Damorian wrote: post #19

How could the math possibly work out on this? If a gallon of gas holds 33.70 kWh of energy, and you can get cheap electricity for $0.1/kWh, you're looking at $3.37/gallon if you have a magical process that converts with 100% efficiency. Even if you hit your efficiency goal, which would be impressive, who is paying $7/gallon for gas? Just buy an electric car. This can only possibly be useful when all of the oil is gon…

> Just buy an electric car.

China’s EV goal is 20% of new vehicle sales by 2025. That is to say, 80% of sales in 2025 will still be gas. (So will the 100 million gas vehicles sold in China between now and then). We are a long ways away from not needing this tech.

Re: Launch HN: Prometheus (YC W19) – Remove CO2 from Air and Turn It into Gasoline

#363

Post by rmcginnis »

geedy wrote: post #355
rmcginnis wrote: post #333

Earlier quoted context omitted.

There are no limiting factors to us scaling now.

So is it fair to say that basically your only constraint is the price of your input electricity?

That is the main input. We also have to keep the capital costs low, but that looks good too.

Re: Launch HN: Prometheus (YC W19) – Remove CO2 from Air and Turn It into Gasoline

#364

Post by medunham97123 »

Rob,

I haven't seen anyone else ask this question, but I currently craft my own biodiesel and was wondering if the maker / private owner market would be able get access to buy fuel from this process?

I understand there might be tweaking of engine combustion profiles to make that happen, but I think this is exciting and would love to support by buying some of this amazing fuel without waiting for it at a gas pump...

Re: Launch HN: Prometheus (YC W19) – Remove CO2 from Air and Turn It into Gasoline

#365

Post by NortySpock »

_Nat_ wrote: post #332
rmcginnis wrote: post #322

Earlier quoted context omitted.

We want to get to >300 B gallons per year of gasoline, and only direct air capture will scale to that level.

Even in the long term, it seems like you'd want to grab CO2 from point-sources. Sure you might need to also grab CO2 from open-air if you reach such a scale, but even at that point open-air would just be a supplement rather than the sole source (unless there's a reason to favor open-air exclusively?). So why start with open-air capture? Just seems weird to burn cash on a more expensive way of accomplishing the same g…

It takes time to integrate technology with existing utilities or businesses, rather than just renting a building and opening a window.

I agree, they're going for the harder problem, but it's also the most scalable solution.

Re: Launch HN: Prometheus (YC W19) – Remove CO2 from Air and Turn It into Gasoline

#366

Post by zdragnar »

mikorym wrote: post #141
zdragnar wrote: post #96

Earlier quoted context omitted.

If the inputs are truly CO2 and electricity, and 100% gets converted to usable hydrocarbons, then there's no waste water; the catalyst and water remain behind. Assuming some water is lost due to electrolysis, you can top it off over time. If the catalyst breaks down, or some undesired reaction limits efficiency (i.e. generation of perioxide or other undesired chemicals that degrade or react with the membrane, electro…

There is no water left either—you forgot that oxygen is also produced.

I wasn't really sure how much of the o2 generated came from the co2 and how much came from the water. Either way, I don't see "waste water" to be as big an issue as the earlier posts i was replying to did.

Re: Launch HN: Prometheus (YC W19) – Remove CO2 from Air and Turn It into Gasoline

#367

Post by NortySpock »

rmcginnis wrote: post #162
amluto wrote: post #146

How small can you scale it? Net energy metering for small-scale solar is not particularly widespread, and the terms are getting progressively less favorable over time. If you can make an inexpensive unit to turn a few kW of excess production for a few hours a day into fuel at 50% efficiency, you might be able to sell it in some markets. Think of it as a 25% round-trip efficiency battery with immense capacity that can…

Our current prototype is the size of a refrigerator. One of the cool things about our tech is that it can work well at small scale. We don't have to get to a billion dollar plant to get the economics right. We could make a system to fit in your garage and make fuel at home. This isn't our focus right now because we want to solve the problem of CO2 emissions from fuel, so need to scale as fast as possible. That's the…

Still, "refrigerator-that-produces-fuel" would probably be a hit with those interested in living off the grid. Just an idea for a side market.

Re: Launch HN: Prometheus (YC W19) – Remove CO2 from Air and Turn It into Gasoline

#368

Post by rfrey »

alexeldeib wrote: post #358
dragontamer wrote: post #343

Earlier quoted context omitted.

> Pipeline compressor stations often generate 35MWth+ in waste heat, which we can use at about 20% efficiency to generate electricity. Can the waste heat be used for distillation instead? To heat up the fuel/water mix to separate the two cleanly? It would seem to me that the future of "waste heat" is to actually utilize the heat, instead of powering a relatively inefficient heat-engine. Perhaps instead of 20% efficie…

re: waste heat, I've been thinking forever that someone must capture this. I've generally assumed the economics don't work out or no one has cracked it outside of scenarios like regenerative braking. We waste so much energy that we could capture and put back to use.

Something like 55-60% of the thermal energy created by burning fossil fuels is currently wasted.

Re: Launch HN: Prometheus (YC W19) – Remove CO2 from Air and Turn It into Gasoline

#369

Post by sanj »

alexeldeib wrote: post #358
dragontamer wrote: post #343

Earlier quoted context omitted.

> Pipeline compressor stations often generate 35MWth+ in waste heat, which we can use at about 20% efficiency to generate electricity. Can the waste heat be used for distillation instead? To heat up the fuel/water mix to separate the two cleanly? It would seem to me that the future of "waste heat" is to actually utilize the heat, instead of powering a relatively inefficient heat-engine. Perhaps instead of 20% efficie…

re: waste heat, I've been thinking forever that someone must capture this. I've generally assumed the economics don't work out or no one has cracked it outside of scenarios like regenerative braking. We waste so much energy that we could capture and put back to use.

Regen braking doesn’t use waste heat. It converts mechanical energy back to electrical.

Re: Launch HN: Prometheus (YC W19) – Remove CO2 from Air and Turn It into Gasoline

#370

Post by effie »

maelito wrote: post #303

Correct me if I'm wrong, but planes look like a bad target for this fuel substitute : for 1 kg of CO2 emitted, estimates give a ~2 (or worse, 2.7 - 4) factor of radiative forcing (the potential for climate warming), due to the water vapor released at high altitudes. You'd have to capture 2 or 3 times more fuel that you'd burn in the sky for this to be "net zero climate", which is a better metric than "net zero carbon…

You seem to be right about the forcing of water being much higher [1], but CO2 has a nasty property as opposed to water: it stays in the atmosphere for much longer and contributes to warming for much longer than the water does. If temperatures get really bad in future, we can limit burning fuels and all the excess water will fall back down to oceans in few years. CO2 won't do such thing as fast. So even if we can't decrease forcing due to aviation burning fuel, it makes sense to make aviation use CO2 neutral fuels to keep the concentration of CO2 low.

[1] https://pubs.acs.org/doi/full/10.1021/es9039693

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