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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

#521

Post by effie »

effie wrote: post #370
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 d…

Contrary to what I said above, it seems the effect of jet exhaust water is more complicated and hard to evaluate... the problem is that unless there is enough water for condensation, water molecule is lighter than oxygen or nitrogen molecule, which means the high altitude vapor isn't likely to fall down quickly.

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

#522

Post by simonh »

ossie wrote: post #516
simonh wrote: post #484

Earlier quoted context omitted.

So we bleed energy off a hydrocarbon fueled generator system that produces CO2, to power a machine for capturing CO2 to create hydrocarbon fuels. That seems a little pointless. The advantage of this system is you can use excess renewable energy sources to mitigate hydrocarbon energy generators. If you are running a hydrocarbon powered system, don't use energy to power this capture system at the same time. That's madn…

That is not what I was suggesting.

You said:

>Imagine power plant stack exhausts channeled through this technology

What's I'm saying is, if you have spare energy available to power the converter, you're better off reducing the hydrocarbon power plant output and replacing that output with your 'spare' energy supply. Doing so would be dramatically more efficient.

The only case this doesn't apply is if there is no way to substitute your spare available energy for the output of the hydrocarbon plant, but I can't think of such a situation, at industrial scale, off the top of my head.

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

#523

Post by D_Alex »

> we absorb CO2 and water vapor from the air into an aqueous electrolyte....to get the fuel out of the water...we have a carbon nanotube membrane

Considering the partial pressure of CO2 in the atmosphere is miniscule, the eventual concentration of the product will also be very low. And because the water molecule is the smallest, you will not be extracting fuel from the solution, but rather extracting water until the fuel concentration is sufficient. Together, this implies that the energy expended in separation must be high, and therefore the process must be inefficient. Is this correct, or have I made a bad assumption somewhere?

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

#524

Post by Zenbit_UX »

rmcginnis wrote: post #337
thereisnospork wrote: post #336

Earlier quoted context omitted.

Electricity costs more than heat, as a rule. (electricity = heat at pretty much 100% efficiency) Intermittent operation blows up CAPEX costs. There's no heat in the system until you start dumping electricity into the resistive heating of your cells - you won't ever be able to run at scale at room temperature. A gallon of gas per second unit - something nicely sized for intermittent operation at a gas station - would…

It's true that running part of the time is not as good as running continuously, but if the capital is low enough, it's ok to start out running intermittently until we get to the point where we have low cost dedicated power and can have a higher uptime. We will have to shed heat from the system to the environment, but that can be done passively. Current densities are likely going to be substantially lower, but our cap…

If you base yourself in QC you'll have access to cheap and 100% green hydro electricy 24/7.

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

#525

Post by Zenbit_UX »

rmcginnis wrote: post #514
phonebucket wrote: post #510

What happens with the gasoline after it’s made? Does it get burnt again? I’m guessing the energy released from burning that gasoline must necessarily be less than the energy used in creating it. Then the net is going back to square one with regards to CO2, but with a net loss of renewable energy? I may well be off the mark here, so would appreciate it if someone could tell me what I’m missing.

The energy content of the gasoline is less than the energy used to make it (only 50-60% efficiency), but the CO2 released is the same as the CO2 used. So the energy efficiency is low, but the net CO2 emission is still zero.

Is your device small enough that it could be placed to filter the exhaust emissions from a fuel burning car and reinsert the newly created gasoline into its fuel tank?

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

#526

Post by wazoox »

_Nat_ wrote: post #453
NortySpock wrote: post #365

Earlier quoted context omitted.

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.

> I agree, they're going for the harder problem, but it's also the most scalable solution. It's not really harder, just more expensive. When major point-sources give off CO2, it's more concentrated. Once it gets into the atmosphere, the entropy goes up, and that entropy cost must be repaid to capture it again. Technical challenges aside, it's still another cost to be paid, making it more expensive. I think people lik…

Investors financed total nonsense such as solar roads. You don't need to be efficient to get VC money, particularly nowadays with loads of free cash from the central banks and low interest rates.

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

#527

Post by bluGill »

kbutler wrote: post #349
zaroth wrote: post #176

Earlier quoted context omitted.

Battery replacement is not really a factor under any kind of "normal" use. One Tesla owner driving for Tesloop was able to burn out a battery after extensively (exclusively) Supercharging from low charge to 95-100% charge after about 350,000 miles. Maintenance cost over that time was calculated as $0.05/mile. [1] With V3 Supercharging, you can drop in with your Model 3 at 15% and be at 80% in 24 minutes. In my road t…

Interesting stats on the battery replacement, but if my family/youth groups/etc. routinely took 20+ minutes for a gas station bio break, there'd be words. Especially if we had to do it every 150 miles (80-15%).

I go both ways on that one. On the one hand I want to get there. On the other hand my doctor wants me to get out and take a 10 minute walk every hour anyway.

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

#528

Post by dzhiurgis »

pstuart wrote: post #413
rmcginnis wrote: post #178

Earlier quoted context omitted.

Yes, water is turned into fuel and oxygen. In most places the water can be obtained from moisture in the air (there is much more water than CO2 in air, and we are already mining the air, so we can get both). In the process the fuel is separated from the water, which remains in the reactor, and is topped off as it is used to make the fuel. No waste water.

Somewhat tangential, but does your crystal ball show when we will start seeing carbon nanotube desalination tech making it into the real world?

His startup was supposed to start shipping it last year...

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

#529

Post by frantzen »

Hello Rob, thanks for the post. I studied with Chichilnisky before founding, and have reviewed Thermostat. Has your company performed an energy return on energy invested (EROI) accounting for your process? Few companies (engaged in fossil fuels, renewables, or CCS) provide a comprehensive EROI and/or CO2 emissions accounting for their products. I know you explained that the inputs are low-carbon; however (1) “renewable” energy is still anywhere from 10-50 gram CO2 per kWh (effectively), and (2) the CO2 intensity of your capital equipment can be depreciated over the useful lifespan of said equipment and then allocated to each effective unit of energy (kWh? or Gallon?). I’m genuinely excited about your technology; your low capital costs, cheap materials, intermittent operations, and hopefully low maintenance cost all sound very promising.

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

#530

Post by frantzen »

Hello Rob, thanks for the post! Has your company performed an energy return on energy invested (EROI) accounting for your process? Few companies if any provide a comprehensive EROI and/or CO2 emissions accounting for their product(s). I know you explained that the inputs are low-carbon; however (1) “renewable” energy is still anywhere from 10-50 gram CO2 per kWh (effectively), and (2) the CO2 intensity of your capital equipment can be depreciated over the useful lifespan and then allocated to each effective unit of energy (kWh or Gallon?). I’m genuinely excited about your technology; your low capital costs, inexpensive materials, intermittent operations, and hopefully low maintenance costs all sound very promising.
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