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

461–470 of 589 posts

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

#461

Post by m1sta_ »

rlucas wrote: post #139
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!

If the alcohol upgrade to gasoline makes sense technically and economically for you, why is it not commonly done with (presumably much cheaper and extant in great volume) industrial alcohol today?

Ethanol mixed fuel is common in a lot of places.

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

#462

Post by jaggederest »

cure wrote: post #396
mr_toad wrote: post #299

Earlier quoted context omitted.

> cars will switch to electric Even once cars are all electric, I can’t see gas turbine engines in planes, trains and ships being replaced in a hurry. And rockets are never going to be electric. I assume you can make RP-1 with this process. I can imagine hydrocarbons being produced where electricity is cheap and practical, and being shipped to where it is expensive and impractical. In theory if it was efficient enoug…

> Even once cars are all electric, I can’t see gas turbine engines in planes, trains and ships being replaced in a hurry. Of course most (non-electric) train engines use Diesel-electric propulsion ( https://en.wikipedia.org/wiki/Diesel%E2%80%93electric_transm... ). That's mostly because of the flat torque curve of the electric motor. Some ships do too. I'm not sure why you think that battery-electric train engines or…

A fun usage of dimensional analysis:

Fuel capacity of a diesel electric locomotive: 6200 gallons

Energy density of diesel fuel: 40kWh/gal

Total energy capacity of full fuel load: 248 megawatt hours

Tesla battery pack weight: 540kg

Tesla energy capacity: 85kWh

Weight of equivalent battery pack for a diesel locomotive:

248 MWh / (85 kWh / 540 kg) = 1575 metric tons

Weight of a diesel locomotive: 196 metric tons

So you'd roughly 10x the weight of a locomotive by trying to make it run on batteries, leaving aside the challenges of actually trying to charge those batteries.

Another fun fact: that locomotive can run flat out at max power for 2.2 days without refueling.

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

#464

Post by ngold »

ossie wrote: post #126

The unit economics around this are by no means perfect but the BIG point here that should probably be in all caps is that fact that the thermal process is displaced by the use of electricity. We could argue on what is used to generate said electricity, but that is beside the point since this innovation opens up many more possibilities than are stated here. We could also argue about the comparative cost of produced en…

Or we could just run engines on alcohol.

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

#465

Post by hyperbovine »

rorykoehler wrote: post #433
garrettdc wrote: post #63

This is really cool! I hope that you can rise above the comments of the "this isn't good enough" or "zero carbon or bust" crowd. This type of innovation is what we need to move the needle in a realistic manner and that helps to build on the infrastructure that we already have in place. I'm excited to see what comes of this in the coming years!

I'm conflicted. This is clearly better than what we have but I was really hoping for a carbon negative future. I hope projects like this are a stepping stone and not a handbrake on progress.

This does not displace a carbon negative future. And zero minus current emissions is still a negative number.

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

#468

Post by SJSque »

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…

> who is paying $7/gallon for gas?

Today's price for standard gasoline here in the Netherlands is 1.83 EUR/litre, which is currently equivalent to 7.75 USD/gallon.

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

#469

Post by Grustaf »

harpastum wrote: post #43
Grustaf wrote: post #4

So you are competing with batteries? I suppose batteries have much higher roundtrip efficiency, but maybe there are other advantages to your technology, like being able to rely on combustion engine cars?

The energy density of gas makes it incredibly useful for storage and transportation as well. For example, Tesla's 50MWh battery installation in Australia has the same energy as only 1,500 gallons of gasoline. (It's not an apples to apples comparison, I just wanted to give an example of a "large" battery installation.) Obviously there are lots of benefits of batteries over gas, but being able to load up a standard 10,…

Sure, but how useful is the energy density in practice? 1. Very soon all new cars will be electric anyway (because that is better for other reasons) 2. I’m assuming range will not be an issue, almost all private driving is very local, so most cars don’t benefit from long range, as long as it’s easy to get long range vehicles when you need them. And of course trucks etc will need to be long range. 3. Driving a truckload of energy is cool but how useful is it? We can already deliver more energy than that instantly through the grid, and most populated places on earth are on the grid now so it seems like a niche use case.

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

#470

Post by agumonkey »

js2 wrote: post #382
sanj wrote: post #369

Earlier quoted context omitted.

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

And in so doing, reduces waste heat due to friction, which is likely what the parent commenter meant.

Some say it doubles the lifespan of brake pads.
Post reply on HN