Reply to: Carbon-neutral petrol

[Zigenare]

Ahem...

https://www.velocys.com/

[Lance]

Hydrogen is a potential fuel supply for the future, but it has some issues.

• It's fecking explosive
• It requires cryogenic storage to keep it for any length of time. That requires power input to keep it liquid.
• It leaks like chuff when gaseous (it's like really small molecules, of just 2 protons in H2, so is hard to contain in normal pressurized containers)
• It's explosive (did I mention that)

Whereas alcohol/methanol has none of those problems.
There are other chemicals that could be used. But I'll detail methanol for now


My reference material is How to Live on Mars: A Trusty Guidebook to Surviving and Thriving on the Red Planet , Zubrin, Robert - Amazon.com

Methanol (CH3OH) can be produced within a reactor with copper-on-zinc oxide pellets. Heat that to 250C and feed it CO and Hydrogen at 20 bar presuure.


So the yeast/sugar bit can be bypassed, although it would be more efficient.
The downside of using sugar is that it requires the use of human edible food sources.

[d000hg]

Sustainable fuels exist, biodiesel and such - F1 is going 100% sustainable fuel in the near future.

But it seems a bit daft, you're just making more problems to solve.

[WTFH]

I've seen someone claim it will produce NOx as a by product, used this way, which I find a little puzzling...

Unless you keep the temperature down, when you burn hydrogen in air the heat causes the nitrogen in the air to combine with oxygen to produce NOx

[malvolio]

True - low revving, high torque and heavily built ones. Not sure they would translate up to smaller units.

But hey, someone has to try it out!

Incidentally anyone noticed that "hydrogen" is sneaking into boiler adverts and road work notices...?

[vetran]

Not that easy. You can't put pressurised liquid hydrogen into an unmodified fuel system, plus you need a specialised regulator, but none of that is all that difficult to overcome. It's not as energy dense of petrol (very little is, actually) so you'll use a lot more by volume, but the end result is comparable.

I've seen someone claim it will produce NOx as a by product, used this way, which I find a little puzzling...

JCB seem to think it is a goer on bigger engines.

[malvolio]

initially with adapted engines, then as they develop via fuel cells. walk before you can run..

I agree Hydrogen is an easy drop in replacement.

Not that easy. You can't put pressurised liquid hydrogen into an unmodified fuel system, plus you need a specialised regulator, but none of that is all that difficult to overcome. It's not as energy dense of petrol (very little is, actually) so you'll use a lot more by volume, but the end result is comparable.

I've seen someone claim it will produce NOx as a by product, used this way, which I find a little puzzling...

[vetran]

Hydrogen is the way forward but as a combustion engine fuel rather than using expensive and fragile fuel cells to convert hydrogen to electricity

initially with adapted engines, then as they develop via fuel cells. walk before you can run..

I agree Hydrogen is an easy drop in replacement.

[tazdevil]

Doesn't matter where it comes from, if energy is dependent on combustion then you are back to square one. Hydrogen is the way forward, via fuel cell technology and is fairly simple to obtain (off peak electrolysis of water is hardly rocket science, you could do it at home ), it's the storage and distribution architecture that is the tricky bit. Then again I can fill my motorhome with pressurised LPG (barely less dangerous than liquid H2) at a conventional pump, so it's clearly possible. As California are proving.

Hydrogen is the way forward but as a combustion engine fuel rather than using expensive and fragile fuel cells to convert hydrogen to electricity

[OwlHoot]

Doesn't matter where it comes from, if energy is dependent on combustion then you are back to square one.

Sure, Again I wasn't claiming that combusting manufactured hydrocarbons would reduce the amount of CO2 in circulation just not add to it, hence the phrase carbon-neutral.

Hydrogen is the way forward, via fuel cell technology and is fairly simple to obtain (off peak electrolysis of water is hardly rocket science, you could do it at home ), it's the storage and distribution architecture that is the tricky bit. Then again I can fill my motorhome with pressurised LPG (barely less dangerous than liquid H2) at a conventional pump, so it's clearly possible. As California are proving.

I did read somewhere that hydrogen leaks terribly over time, so long-term storage is a big problem. But then if Count von Zeppelin could do a fair job of storing it over 100 years ago, they've probably ironed out the wrinkles by now.

Also, I take Lance's point about alcohol as an ICE fuel. But you'd have to adulterate it with some noxious combustion-neutral unextractable additive, to prevent idiots drinking it!

[malvolio]

It’s fiendishly difficult (energy intensive) to make hydrocarbons from the air.

you need to step back even further though. Why are hydro carbons useful?
1. Availability. Just drag it out if the ground.
2. distribution already in place.
3. long term storage is easy.

if you were to use another liquid chemical then 2&3 are covered. Alcohol does this already. And is far more efficient. You just need a source of sugar/carbohydrate and yeast.

Doesn't matter where it comes from, if energy is dependent on combustion then you are back to square one. Hydrogen is the way forward, via fuel cell technology and is fairly simple to obtain (off peak electrolysis of water is hardly rocket science, you could do it at home ), it's the storage and distribution architecture that is the tricky bit. Then again I can fill my motorhome with pressurised LPG (barely less dangerous than liquid H2) at a conventional pump, so it's clearly possible. As California are proving.

[Lance]

It’s fiendishly difficult (energy intensive) to make hydrocarbons from the air.

you need to step back even further though. Why are hydro carbons useful?
1. Availability. Just drag it out if the ground.
2. distribution already in place.
3. long term storage is easy.

if you were to use another liquid chemical then 2&3 are covered. Alcohol does this already. And is far more efficient. You just need a source of sugar/carbohydrate and yeast.

[OwlHoot]

Well the first problem is getting the CO2 separated into C and O2

Oh,hang on, you need a tree....

Otherwise it's a very strong bond that requires energy to break.

Of course. I wasn't suggesting you could produce hydrocarbons without requiring a fair bit of energy and suitable catalysts, speaking of which:

2017-06-05 Splitting carbon dioxide using low-cost catalyst materials

A promising avenue for the future of clean energy is to store it in the form of carbon-based fuels produced from renewable sources, effectively enabling the clean use of liquid fuels such as gasoline. A first step is the electrolysis of carbon dioxide into oxygen and carbon monoxide. But current CO-forming catalysts are either not selective enough or too expensive to be industrially viable. Now scientists have developed an Earth-abundant catalyst based on copper-oxide nanowires modified with tin oxide.

[jayn200]

Where are you going to capture emissions? This likely won't solve localized air pollution problems which no one talks about anymore but cause way more deaths than climate change.

[malvolio]

Well the first problem is getting the CO2 separated into C and O2

Oh,hang on, you need a tree....

Otherwise it's a very strong bond that requires energy to break.