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

Dude, where's my fuel?

prometheusfuels.com

Post reply on HN
Print view View original

181–190 of 191 posts

Re: Dude, where's my fuel?

#181

Post by jabl »

coderenegade wrote: post #176
jabl wrote: post #127

Earlier quoted context omitted.

> Ammonia is certainly the best carbon-free fuel, the only real issue with it is its toxicity If we don't care about toxicity, might as well go with hydrazine, which is liquid at room temperature and has higher energy density than ammonia. ;) (No idea about the cost of hydrazine synthesis, though) > most sane options for an e-fuel are methanol and ammonia The article seems to say their process produces ethanol. If it…

"I'm pretty sure we can go through that iceberg." --Captain of the Titanic, probably. "Might as well go with hydrazine." --Unknown, heard before explosion. I missed the bit on ethanol when I skimmed through the first time, but you're right. That's actually fairly exciting if it's something that can be scaled. The part that baffles me is that if you have a workable fuel like ethanol, from an efficient process that doe…

> The part that baffles me is that if you have a workable fuel like ethanol, from an efficient process that doesn't compete with arable land, why try to make petrol from it? Ethanol is perfectly fine, and inherently cheaper than any hydrocarbon you would make from it.

Indeed. Even replacing the current usage of ethanol in the gasoline pool would be a huge market, and AFAIU most Otto engines can be relatively cheaply modified to work on up to E85 fuel.

Perhaps they're trying to fly under the radar of the corn ethanol lobby?

Re: Dude, where's my fuel?

#182

Post by Folcon »

molyss wrote: post #153
Folcon wrote: post #114

Earlier quoted context omitted.

> Bluntly? They are a running joke among anybody that has been around the renewable fuels space for longer than a couple years. > There are no shortcuts around the physics required to assemble a molecule. So the process is viable, but the cost is prohibitive?

I just don’t understand the answer. Seems to be conflating “energy cost” and “financial cost” under the same umbrella. I don’t think Prometheus is disputing the energy costs of “the physics required to assemble a molecule”. Current processes use heat+pressure, which are pretty wasteful, and often rely on burning fossil fuels in the 1st place, which will mechanically increase the financial cost” What I understand from…

Yes, the whole thing is a bit weird and so I honestly don't know which side is credible.

Re: Dude, where's my fuel?

#183

Post by ncmncm »

ncmncm wrote: post #169
adrian_b wrote: post #138

Earlier quoted context omitted.

Using excess ammonia might have the risk of releasing unburnt ammonia in the atmosphere. Fuel cells using ammonia seem much safer, but they are farther from being a commercially available solution.

The exhaust doesn't have ammonia. The nitrogen really likes to link up, giving up protons to do it. You would be left traces of unburnt hydrogen.

Note that hydrogen is itself a greenhouse gas, so you would want to tune the mixture carefully to leave minimal unburnt hydrogen. Hydrogen acts to promote a greenhouse effect by several mechanisms: 6x directly, but also by prolonging methane lifetime, and by promoting lower-atmosphere ozone, making its greenhouse impact up to 200x CO2.

Water vapor is itself another greenhouse gas, so it could be important for big users of hydrogen and ammonia fuels to make an effort to condense out exhaust vapor, e.g. by using it to warm incoming fuel, or air after the initial compression stage. Probably natural-gas burners should be doing it already, as burning methane produces copious water vapor.

Condensing exhaust water vapor from these systems could increase efficiency by creating a vacuum at the exhaust.

Re: Dude, where's my fuel?

#184

Post by archi42 »

scotty79 wrote: post #165
archi42 wrote: post #156

Earlier quoted context omitted.

That's a distraction: The extraction is only temporarily. The value of an amount of efuel is not in that it's made from captured CO2, it's in burning that efuel to drive some machine. So yeah, there will be some CO2 captured in storage and transit, but that's will be less than what we release every year. If you want to capture CO2 for good: Capture it, dump it somewhere and don't touch it ever again. The trick is to…

I think the only way to make capturing CO2 valuable is to tax the economy and pay for actually captured CO2 directly. Fuel manufactured out of CO2 might be easily verifiable proof of capturing CO2.

Maybe we have a little misunderstanding here? If you produce fuel from CO2, that CO2 will be released again once that fuel is burned. It's CO2 neutral, not negative.

So assume today we have 100t CO2 in the air. You capture 20t of that and make efuel from it. Now we have 80t of CO2 in the air. Which is great. However you went through all the effort so you could actually sell that efuel instead of sitting on it. So lets say I buy it from you. And then I'll burn some in my car and use some to heat my house. As a result, we now have 100t of CO2 in the air, again.

Would I use fossil fuel and heating oil, then we would have 120t of CO2 in the air. So non-ironic hooray, we prevented that. We're neutral. But once we're upgrading me to an electric heat pump and an electric car that energetic detour won't be necessary anymore, since I can use the electricity directly. That's also much more efficient: The heat pump by a factor of 4 to 9 (77kWh produces 1 gal efuel, which burns for 33.7kWh of heat; 77kWh used in a heat pump produces 154 to 308kWh of heat), and the car by a factor of 10 (math given previously).

If the goal was to have 80t in the air on the other hand, then at least it didn't make it worse; but until we dump CO2 somewhere it isn't released into the air again, we will never get to that goal.

It's not like I'm anti-efuel; for a long time to come and for some specialty use cases it will be a good solution to not make things worse (e.g. space rockets), but in the general case: It's a stop-gap, not a solution.

//edit: What we could do is tax people who release CO2 for the subsequent, necessary capture. That can then be scrubbed from the air again using the 36$ process the people on the linked page claim to use/have invented. Use that CO2 in an efuel and release it again, you pay to have it scrubbed again. To reduce the total amount of CO2 in the air, require that you not only pay to scrub the emissions, but some additional % (until the problem is solved, then just pay to scrub what was actually emitted). That's essentially a simplified & more strict CO2 certificate trade.

Re: Dude, where's my fuel?

#185

Post by Layke1123 »

ncmncm wrote: post #55
Layke1123 wrote: post #46

I see carbon nanotube tech and become immensely skeptical. I am under the impression that anything carbon nanotube still cannot be done at scale, and the article is very light on that part of the process. Following the rabbit hole leads to http links (in 2022?) and various publications from science journals I am unfamiliar with. Does anyone else get the smoke and mirrors vibe from this or am I just being overly skept…

Depends whether he actually delivered the thing in 2018.

Exactly? Did he? Looking at the site that is linked or quoted to doesn't exactly instill confidence. Is no one else drilling down and looking into all these details like me, or do they simply research it and then move on rather than comment leaving all the arm chair scientists to pontificate based on a flashy website?

Re: Dude, where's my fuel?

#186

Post by Iwan-Zotow »

nyokodo wrote: post #44
Iwan-Zotow wrote: post #37

Earlier quoted context omitted.

India and China are not losing any Russian imports

> India and China are not losing any Russian imports Russia cannot keep up production without the involvement of the likes of BP etc, so while China and India haven't boycotted Russia it won't matter before very long.

You know that e.g. BP production had fallen for last few years, right?

Re: Dude, where's my fuel?

#187

Post by nyokodo »

ncmncm wrote: post #179
nyokodo wrote: post #174

Earlier quoted context omitted.

> There is plenty of sunshine most places if you can bank fuel during off-season Energy storage is woefully insufficient yet to cover days let alone seasons so that is a very big "if."

You seem to be saying you think keeping liquid fuel in tanks does not qualify as storage. If that is what you mean, you will need to explain why you think that, because it makes no sense. If you mean we have not yet built out as much storage as we will ultimately need, because we anyway haven't enough renewable generating capacity built out yet to charge it from, then yes we know . The solution to that is obviously t…

> You seem to be saying you think keeping liquid fuel in tanks does not qualify as storage.

I just misread what you wrote. I didn't see "fuel" and thought you were referring to other means of renewable storage. Fuel as an efficient and much less geographically limited means of storage makes a lot of sense.

Re: Dude, where's my fuel?

#188

Post by Layke1123 »

scotty79 wrote: post #171
Layke1123 wrote: post #170

Earlier quoted context omitted.

Distilling doesn't make it more economical than traditional refining though, according to their whole position. Boiling involves ALOT of energy compared to passive membrane separation.

They still have a zero carbon liquid fuel so you can't compare it directly to refined fuel. Fossil fuels should be eventually taxed into oblivion. Even at current taxation level their distilled fuel would be competitive if tax exempt for example in Europe.

I didn't. The comparison is that this is claimed to be cheaper than normal fuel extraction from the ground. But that relies on tech such as the permiable membrane developed from CNT, which AFAIK, no major breakthroughs have been made.

It's a bit like investment madness, in which investors are being swindled because no one is doing their due diligence to vet the tech and instead throwing money in a blind panic in FOMO.

Re: Dude, where's my fuel?

#189

Post by scotty79 »

archi42 wrote: post #184
scotty79 wrote: post #165

Earlier quoted context omitted.

I think the only way to make capturing CO2 valuable is to tax the economy and pay for actually captured CO2 directly. Fuel manufactured out of CO2 might be easily verifiable proof of capturing CO2.

Maybe we have a little misunderstanding here? If you produce fuel from CO2, that CO2 will be released again once that fuel is burned. It's CO2 neutral, not negative. So assume today we have 100t CO2 in the air. You capture 20t of that and make efuel from it. Now we have 80t of CO2 in the air. Which is great. However you went through all the effort so you could actually sell that efuel instead of sitting on it. So let…

> It's CO2 neutral, not negative

Yes. But at the same time is displaced a product that would put out CO2 into the atmosphere. So you reduce the amount of CO2 that is being put out.

So while neutral, not negative, it initially has the same effect that a novel carbon negative activity might have that doesn't replace anything.

I agree with you that later orther solutions will be better.

Re: Dude, where's my fuel?

#190

Post by ncmncm »

jabl wrote: post #180
ncmncm wrote: post #160

Earlier quoted context omitted.

We do, in fact, care about toxicity, so do not e.g. expect to see ammonia powering cars. NASA and ESA are phasing out use of hydrazine because of its unfortunate handling characteristics. But solid hydrazone might still find uses. Among the chief attractions of ammonia is that it is very simply synthesized with free feedstock. You bond hydrogen stripped from water to nitrogen from air. Although toxic, it is a lot lig…

> NASA and ESA are phasing out use of hydrazine because of its unfortunate handling characteristics. I read about various 'green propellant' efforts over the years, but it seems in practice hydrazine is still used for orbital manouvering systems. Of course for those the volumes are small compared to the launch rockets themselves. For launch vehicles it seems only old Russian and Chinese designs still use hydrazine. >…

They still loft hydrazine on birds already designed, but plan to use a non-toxic, and otherwise actually better alternative in new designs.

Hydrazine is troublesome because it is readily absorbed through the skin, in liquid form, or the lungs, in vapor form, whence it destroys the liver and other internal organs. As vapor it is slightly heavier than air, so its vapor spreads out from point of release.

When you see dramatic videos of spilled ammonia, that is generally liquid, either boiling anhydrous or dissolved in water and spreading out on the ground. Purely gaseous leaks go up. But liquid spills can be pretty bad.

All that said, synthetic hydrocarbon fuels will clearly be better for small and consumer-grade use in places where batteries do not suffice.

Post reply on HN