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

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

#271

Post by progval »

sjg007 wrote: post #270
progval wrote: post #220

My most immediate question (after others you already answered in this thread) is about getting enough CO2. When you start absorbing CO2 from the air, won't the CO2 in the neighborhood be depleted very quickly? And I'm assuming you can't pump enormous amounts of air either for various reasons (noise, energy usage, other environmental issues). Of course there's wind to bring more CO2, but I'm curious about your computa…

Doesn't matter, air is a fluid, so diffusion works in your favor.

Yes, but does it work fast enough?

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

#272

Post by tommoor »

Damorian wrote: post #59
rmcginnis wrote: post #49

Earlier quoted context omitted.

We expect a gallon of gasoline to require approx. 60 kWh of electrical energy. If the price of that electricity is below 5 cents, the economics work. If the price is lower, the efficiency of the conversion could also be lower if that optimized other costs (like capital). Electricity is routinely below 5 cents now at utility scale (wholesale), which is where we will want to be.

Ah, that certainly explains it. I'm still highly skeptical of how widespread this will ever be, since electric cars will become even more compelling as electricity costs decrease, but you've convinced me to not dismiss this completely as impractical. Thanks for the context.

But liquids fuels like ethanol are used for MANY more things than just transport – plus the cost of fossil fuels can only go up on any reasonable timeline.

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

#273

Post by lucb1e »

rconti wrote: post #263
lucb1e wrote: post #257

It's never said explicitly and I couldn't find a question about it, but everyone talks as if we'll need solar input to power this. I assume this means the machine doesn't produce enough fuel to power itself? At any rate, amazing product. Can I (eventually) buy one of those machines or donate somewhere to make my area CO2 free?

Are you asking if this is a perpetual motion machine? Edit: Or close enough to perpetual motion that it only requires the occasional replacement of nanotubes and other materials

Please see the sibling thread that asked the same question a few minutes earlier (probably wasn't there when you loaded the page). I replied there: https://news.ycombinator.com/item?id=19844137

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

#274

Post by lucb1e »

wry_discontent wrote: post #265
lucb1e wrote: post #257

It's never said explicitly and I couldn't find a question about it, but everyone talks as if we'll need solar input to power this. I assume this means the machine doesn't produce enough fuel to power itself? At any rate, amazing product. Can I (eventually) buy one of those machines or donate somewhere to make my area CO2 free?

Wouldn't producing the necessary fuel to fuel itself lead to an infinite energy source, essentially making this a perpetual energy machine?

Please see the sibling thread that asked the same question a few minutes earlier (probably wasn't there when you loaded the page). I replied there: https://news.ycombinator.com/item?id=19844137

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

#275

Post by averros »

Well, producing solar panels and such also requires energy input, and these do have limited lifetime. What is the real full-cycle energy conversion ratio is?

Secondly... continuous distillation doesn't necessarily require lots of energy, since a lot of it could be recycled with counterflow heat exchangers and heat pumps instead of plain heaters (i.e. hot output and hot waste are used to heat up input to close to the proper fraction boiling temp, and the output and waste are only slightly warmer than the input mix). It still needs energy input to deal with losses and entropy reduction from mix to separate fractions, but this is also true about using any sort of membrane-based separation.

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

#276

Post by NortySpock »

ballenf wrote: post #75
mshron wrote: post #37

Earlier quoted context omitted.

Solar is already down to $0.065/kWh for industrial applications [1]. That's $3.90/gallon at today's prices, and solar prices continue to fall. The DOE's 2020 targets came three years ahead of schedule. Their 2030 target is $0.04/kWh [2], which would work out to $2.40/gallon. Mix in the fact that a bunch of countries (and US states) have implemented carbon taxes and you've got yourself a good long term investment. [1]…

Do those figures include gas taxes? Don't those make up a large part of the price at the pump?

In the US, gas taxes are low (I think I pay 15 cents per gallon tax on a total of $2.50 per gallon).

Taxes are low as here in the US (a) many people hate taxes and (b) with such a low population density, commerce is very reliant on road vehicles. So raising taxes has an outsized impact on commerce.

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

#277

Post by rmcginnis »

progval wrote: post #220

My most immediate question (after others you already answered in this thread) is about getting enough CO2. When you start absorbing CO2 from the air, won't the CO2 in the neighborhood be depleted very quickly? And I'm assuming you can't pump enormous amounts of air either for various reasons (noise, energy usage, other environmental issues). Of course there's wind to bring more CO2, but I'm curious about your computa…

This won't be a limiting factor. It won't be stagnant air, and the diffusion rate for gases is high.

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

#278

Post by lutorm »

averros wrote: post #248
lutorm wrote: post #188

Earlier quoted context omitted.

Why do you say ethanol degrades performance? Ethanol is an anti-knocking agent when added to gasoline, so it actually enables higher performance.

It degrades energy density of the fuel (by volume). In other words, today's gasoline in US takes you 4% less distance than gasoline from 70s. It also creates problems with internal corrosion (which is why it is not used in aircraft fuels), though modern auto engines are designed to deal with that (and are more expensive because of that, too).

Sure, the energy density is a bit lower, but that's not really what people mean when they talk about "performance". "High-performance cars" don't usually refer to cars that can go a long distance on a tank.

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

#279

Post by llukas »

qmanjamz wrote: post #105
llukas wrote: post #68

Earlier quoted context omitted.

ICE cars cant compete with convenience of: * not needing to refuel * less maintenance needed * not spewing particulates in air etc (if you care about what you breathe)

Bizarre comment. Being able to quickly refuel is one of the key advantages internal combustion engines have over electrics.

Depending on your assumptions.

For day to day use EV doesn't need trips for gas station to refuel - so you actually save time.

For long trips - yes.

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