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

141–150 of 589 posts

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

#141

Post by mikorym »

zdragnar wrote: post #96
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?

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.

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

#142

Post by bluGill »

zaroth wrote: post #102
calvinmorrison wrote: post #81

Earlier quoted context omitted.

* not needing to refuel no, we're taking Soothing30MinuteRelaxingBreaksAt200MileIntervalsAwesomeHappy™ brought to you by Tesla™ instead

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 first car. They are slightly cheaper for an in-town only commuter car, but the downsides of electric cars (expensive battery replacement, limited range without long recharge times) are something that fans hate to acknowledge. Note that I said first car, once you have decided to have a second car electric is probably better.

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

#143

Post by teraflop »

34k5jo3i4toig wrote: post #109
tathougies wrote: post #85

Earlier quoted context omitted.

Can you elaborate how gasoline is 'dirty' if the outputs were converted back into the fuel via carbon neutral means? Such technology would make gasoline have no output, since the ouptuts would be reabsorbed. If anything, electric cars, due to the massive environmental damage due to rare earth mineral mining, would be more of an environmental disaster.

Every cycle has a 50% cost in renewable power. This is close to being carbon neutral, but it is not entirely. Its not a closed loop. You have a growing loss every cycle. Its digging yourself deeper every time.

It is not energy neutral, but it is carbon neutral (if the electricity input is from a zero-carbon source).

It sounds like you're suggesting that burning the fuel releases more carbon than was used to produce it, which isn't possible.

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

#145

Post by gmanley »

crankylinuxuser wrote: post #132
qmanjamz wrote: post #105

Earlier quoted context omitted.

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

If the ev car companies got their shit together, they could have used swappable battery packs. You can wait around for 12h to charge, or you can turn in your cores and pay for 100% capacity batts now. And the swap would be quicker than standing around filling up a tank. But no. Each ev is different and proprietary. The chargers aren't even the same.

I mean the battery technology for EV companies is their special sauce. If they are all the same that takes away their differentiator. I agree it would be better for customers but it's understandable why that isn't something they want to do.

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

#146

Post by amluto »

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 supply winter heat or vehicle power.

edit: for some applications like this, alcohol might be a better end point than gasoline.

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

#149

Post by skunkworker »

How is this different from what the US Navy has been trying to accomplish with turning seawater into Jet fuel? I know that they are extracting CO2 from the water instead of the air, but I believe the last I heard they had large inefficiency issues. And for them they plenty of power from their onboard reactor.

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

#150

Post by rmcginnis »

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't be cheap enough. So we are not removing it from other beneficial use. Also, as we scale, we will cause much more solar and wind power to be available as we will be buying a lot of it. In the long term, aviation and shipping are likely to still use liquid fuel, yes.
Post reply on HN