Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

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

news.ycombinator.com

Post reply on HN
Print view View original

171–180 of 589 posts

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

#171

Post by s1512783 »

rmcginnis wrote: post #150
s1512783 wrote: post #138

Here's what I don't understand - You're taking CO2 out of the atmosphere using renewable energy sources. Thermodynamically, this will take at least as much energy as it took to burn them. You did not mention how energy efficient your energy storage method is right now (50-60% at maturity sounds really optimistic, when plants are only a few %), but, in the short term, while we're still mostly using carbon-based fuels,…

Demonstrated overall conversion efficiencies for CO2 to fuels are already in the 25-50% range, depending on the fuel. We are confident we can get to at least 50% for our process. We will not be taking renewable power away from other uses - in the short term we'll be using marginally useful power (wind at midnight, solar at noon, etc), as we need the power to be low cost, and any time it has higher value uses, it won'…

Thanks for the reply, I get the load balancing part now, I did not think about that.

I was thinking a lot recently about flying and how we could make it work in the (hopefully) greener future. This is definitely a more sensible way of doing it than electric jets, good luck with your company!

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

#173

Post by rmcginnis »

geofft wrote: post #101
ineedasername wrote: post #69

Earlier quoted context omitted.

With respect, that answer skirts the question of what happens to the water. You said you're using the nanotube membrane to separate petro products from the water. What do you do with the water left over? What state is the water in when the process is complete? Potable? In need of treatment by traditional water treatment facilities?

I think you're asking a different question from the one being responded to (and the one being responded to is more obvious to me): I will try to help this conversation by restating the questions, both of you should correct me if I've misread this. Your question is, in the distillation step, the nanotube membrane separates fuel from water, leaving some amount of water; what happens to that water in the process? The qu…

Correct!

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

#174

Post by beat »

s1512783 wrote: post #138

Here's what I don't understand - You're taking CO2 out of the atmosphere using renewable energy sources. Thermodynamically, this will take at least as much energy as it took to burn them. You did not mention how energy efficient your energy storage method is right now (50-60% at maturity sounds really optimistic, when plants are only a few %), but, in the short term, while we're still mostly using carbon-based fuels,…

Look at it from an economics standpoint... because of the efficiency loss, energy from this process would always be twice as expensive (or more) than freshly generated renewable electricity. So you'd only want to use it in places where grid electricity is impractical.

Vehicles are the obvious market. It took over a century for electric vehicles to become even remotely practical. But vehicles are necessarily disconnected from the grid.

And even for vehicles, this is only desirable when consumption needs or disconnect times are very high, like aircraft and oceangoing ships. That's because combustion is very wasteful. There are about 33.7 kwh of energy in a gallon of gasoline. A Tesla goes as far on three gallons' worth of energy as a comparable Mercedes goes in ten or more. That's because an electric drivetrain is 3x (or more) more efficient than a combustion one.

So using this process, it could cost 10x as much to operate a fuel-based vehicle as an electric one. You don't want to do that unless you have no other choice.

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

#175

Post by bluGill »

How much control over molecules do you have? Gasoline is a mix of things (which changes based on season). I know today you can buy synthetic diesel (last I checked 3x the price of pump fuel, but it has enough more energy to make the difference between a win/loss in a race).

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

#176

Post by zaroth »

bluGill wrote: post #142
zaroth wrote: post #102

Earlier quoted context omitted.

I don't know about you. I've driven the last 5 months / 5,000 miles without using a Supercharger once, except for the first day I took delivery just to try it out. It's there when I need it for the long road trip. But daily life is effectively refueling-free. What percentage of round-trips are under 200 miles? NHTS recorded the distance from ~750,000 car trips in 2009 and found the 95th percentile is 30 miles, and th…

I go on vacation a few times a year. Renting a car just for that is more expensive than extra cost of fuel. Not to mention most rental cars won't let me use my truck as a truck (putting rock in the back damages the bed, and a trailer is right out - both things I do only a couple times a year but I still own a truck for just those few times). IF this is as good as they claim I don't see electric cars as worth it as a…

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 trip experience, that's barely enough time for everyone to use the bathroom and pick out a beverage. [2]

[1] - https://www.tesloop.com/blog/2018/7/16/tesloops-tesla-model-...

[2] - https://twitter.com/privater/status/1103567772301193216/phot...

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

#177

Post by noonespecial »

If nothing else it would be a great technology for solar and wind plants to employ on-site to convert excess power into fuel that could drive standby turbine generators for the times there is no sun or wind.

Giant batteries are a pretty easy to beat cost and maintenance wise.

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

#178

Post by rmcginnis »

eanzenberg wrote: post #127
icebraining wrote: post #92

Earlier quoted context omitted.

If water is an input and not an output, that implies it's consumed, not left over.

Yes, one of the things that gets glossed over many times in this field (I used to do research in artificial photosynthesis) is that water gets consumed to create the fuel, and is released as vapor from every engine's exhaust. So to generate 10 million barrels requires about 10 millions barrels of pure water, per day, to satiate the US.

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.

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

#179

Post by amluto »

rmcginnis wrote: post #134
jvanderbot wrote: post #121

So, the goal is carbon-neutral gasoline. Short term, I suppose your target is feel-good gas burning vehicles. Longer term, do you envision this technology being used for clean(er) + carbon neutral municipal power generation, or is the fuel type just wrong for that? I ask because a stop-gap can easily become permanent, and it'd be unfortunate to continue dumping particulates (pm2.5/10), smog, etc into the air in major…

In the near term, we will remove the damage caused by fossil fuel use. Our fuel will burn much cleaner, so that's also helpful. In the medium to long term, cars will switch to electric, but now we'll have enough time to do that. As that happens, Prometheus will roll out new products made from CO2, like carbon negative building materials, etc. It's important to look not only at the end goal, but also the path!

Why will your fuel burn cleaner? Soot and NOx are fundamental to the combustion process. I guess you have no sulfur, which is worth something.

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

#180

Post by pcl »

apo wrote: post #125
rmcginnis wrote: post #115

Earlier quoted context omitted.

We could use the alcohols as fuels directly (in flex fuel vehicles), but this wouldn't address the much larger market for gasoline. It's a simple and inexpensive upgrade, so makes sense to do it. We will definitely take advantage of carbon credits, tax incentives, etc too!

Organic feedstocks (non-fuel), although smaller isn't exactly a tiny market. Depending on how much control you have over the fixation process you might be able to tap into some high-value alcohol markets. That's the main reason I added the follow-up to the original questions. In other words, the flow of material would look like: CO2 -> polymers, drugs, and other useful solid materials There would be no [product] -> C…

I believe that as long as we have a huge worldwide oil / diesel / gasoline infrastructure in place, from transport to refining to distribution to combustion, it makes a lot of sense to build reasonably-efficient carbon-neutral mechanisms to plug into that infrastructure.

In other words, for the next handful of decades, the worldwide fleet of cars, trucks, generators, boats, etc. are going to be burning carbon that comes from somewhere. Products like this provide a carbon-neutral means of supplying that demand.

It's like working on a huge existing codebase, but at much larger scale, and with geopolitics. People are working on rebuilding it all from scratch, but iterating within the existing infrastructure could also deliver huge wins.

And, if we somehow found ourselves in a world in which carbon-neutral petrochemicals were the norm, well, we can always generate a surplus and sequester that surplus, right?

Post reply on HN