# Audi creates "synthetic diesel" from air, water, and electricity...?

Discussion in 'General Science & Technology' started by Kittamaru, Apr 27, 2015.

1. ### KittamaruAshes to ashes, dust to dust. Adieu, Sciforums.Valued Senior Member

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https://www.audi-mediaservices.com/...tteilungen/2015/04/21/fuel_of_the_future.html

Well... that is interesting!

3. ### DaeconKiwi fruitValued Senior Member

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3,133
It's encouraging if it's true.

The cynic in me is whispering in the ear of my inner conspiracy theorist that "Big Oil (tm)" isn't going to like it...

5. ### exchemistValued Senior Member

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9,877
Why would "Big Oil" take a view on this that is any different from the view it takes on nuclear power or renewables?

Must admit though that I had to check it was not an AprilFool joke, when I saw the name of the minister quoted

.

7. ### billvonValued Senior Member

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18,679
We've known about this for almost a century. All the processes are well known - electrolysis, Sabatier, Fischer-Tropsch, RWGS. The process has a negative EROEI so it's not useful as a source of energy.

8. ### KittamaruAshes to ashes, dust to dust. Adieu, Sciforums.Valued Senior Member

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billvon - if it were made using, say, solar power as the primary method of creating the fuel, shouldn't it still result in a net gain (if only because of the reduction in fossil fuel consumption, if nothing else?)

9. ### billvonValued Senior Member

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18,679
Well, no - solar is only about 15% efficient best case. Then you add a hideously inefficient chemical process and you're down in the weeds.
You can ignore the solar conversion efficiency, of course, and say that the Sun is free so you can ignore its energy. However, in that case, you are still far better off using the electricity to drive cars, trucks and trains than trying to convert that electricity to fuel, to thermal energy and back to mechanical energy. It may find some limited application in critical missions (military aviation, spacecraft etc) but overall there are far better uses for solar electricity, and far better sources for liquid fuels.

10. ### KittamaruAshes to ashes, dust to dust. Adieu, Sciforums.Valued Senior Member

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Hm... fair enough I guess - I wonder what the byproducts of this synthetic fuel are (and what the emissions standards are for it)

11. ### spidergoatLiddle' Dick TaterValued Senior Member

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As long as I don't have to stop driving my car for any reason.

Would like to see some numbers on energy return over investment on this fuel.

12. ### FutilitistThis so called forum is a fraud...Registered Senior Member

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1,586
Hi billvon.

Good posts.

I never thought I would say this, but billvon is 100% correct in this case.

Although it sounds super techie cool, Audi e-diesel cannot save the world.

This thread has run it's course.

---Futilitist

Last edited: Apr 28, 2015
13. ### Beer w/StrawTranscendental Ignorance!Valued Senior Member

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What would it be like mixed with ethanol?

14. ### billvonValued Senior Member

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Basically you average the EROEI's and get the net EROEI.

15. ### Russ_WattersNot a Trump supporter...Valued Senior Member

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Agreed. This is just an inefficient, expensive, convoluted storage method. The only scenario where it could possibly make sense is if you had to use diesel, but it was ridiculously expensive. That is highly unlikely for anything other than airplanes, for which no reasonable alternatives exist. And the Peak Oil scenario that would drive it is decades away.

16. ### Russ_WattersNot a Trump supporter...Valued Senior Member

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It's a circular process: it is made from CO2 and H2O so the products of burning it are CO2 and H2O. For the car and the emissions standards governing it, nothing changes (though it is likely freer of other pollutants).

17. ### KittamaruAshes to ashes, dust to dust. Adieu, Sciforums.Valued Senior Member

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Actually... a thought.

What if, and I know it's a bit "out there"... but what if we could put a refinery in high-orbit... unfettered access to the sun for solar power generation. Draw CO2 from the space station (which, I believe, is currently just vented into space). As for the water - well, they don't actually need water, just the Hydrogen and Oxygen - could this be gathered from an ice-based comet?

Again, way, way out there in terms of feasibility... and probably not worth the cost of deployment and distribution.

That's what I was thinking... very cool, if impractical.

18. ### billvonValued Senior Member

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They are already doing something very similar. Water (transported from Earth) is split to create oxygen and hydrogen. The hydrogen is stored and the oxygen is breathed. The CO2 from the astronauts is then run through the Sabatier reaction to yield methane and water. The water is reused for oxygen; the methane is dumped.

Future versions may either save the methane for propellant (a small methane/oxygen engine for periodic orbital boosting) or break down the methane via pyrolysis to hydrogen and carbon. The carbon would be ejected and the hydrogen would be reused. This would allow a system where nothing needs to be imported from Earth other than food (and enough water to make up for the inevitable leaks.)

19. ### KittamaruAshes to ashes, dust to dust. Adieu, Sciforums.Valued Senior Member

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Huh... very cool! I didn't realize the system they had was that efficient!

Do they store excess/extra oxygen as well? I would presume they must in the event of a failure of the atmospheric system?

20. ### billvonValued Senior Member

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Yes, they have both bottled oxygen and perchlorate "candles" they can burn to release oxygen if they have problems.

21. ### KittamaruAshes to ashes, dust to dust. Adieu, Sciforums.Valued Senior Member

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perchlorate candles... very cool! Apparently these have been used previously:

http://www.space.com/1099-space-station-crew-ignite-oxygen-generating-candles.html

Another bit of tech I didn't know about... man, I'm slipping in my "old age" lol! Thanks Billvon, you've given me several new topics to investigate and learn about

22. ### Billy TUse Sugar Cane Alcohol car FuelValued Senior Member

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I don't know what the news is.
I am old enough to ride on Sao Paulo's buses for free, so often jump on one of the many* going my way if only riding for 2 or 3 blocks to their next stop. At least half have "ecodiesel" written on their side, and under it in finer print "15% diesel made from sugar cane." At current exceptionally low oil prices, there probably is no, or very little money saved, but until recently ecodiesel was cheaper than diesel only. I think only the newer buses can use it. (Older ones may not be "flex fuel".)

Perhaps the new ones have some sort of "glow plugs" as adding alcohol, if that is all that is done, reduces compression ignition ("knocking" in car, its called) - why Flex fuel" cars that use pure alcohol give a little more HP than when they use gasoline. Not sure, but think they have higher compression ratio and delay the spark or something when using only gasoline, which few do as that is more expensive and lower power, but you could make a trip of more than 300 miles without stopping for fuel. (Alcohol's one disadvantage is a tank full range is only 70% of that of gasoline's) The fuel mix is continuously sensed and the computer controls spark timing or fuel air ratio or something so a "flex fuel" car can use any mix from pure gasoline to pure alcohol.

Another thing more than half the buses have printed on their sides (when translated from the Portuguese) which pleases me, goes like:
"Transport - The citizen's right / the government's duty."

Buses have there own lanes** which taxis with a passenger may use too. - They are often faster than driving your own car as Sao Paulo traffic can be terrible - I walk a lot and note which car I started with; it is not rare that I get well ahead of it, but am not sure when it does not catch up to me, if that is because it turned off to a side street or that for many blocks I was going faster.

* I once counted 17 busses, one just after the other, in their bus lane. They are color coded telling the district they will go to, from a central one where many pass thru, as often they are so close to one another that you can only read their small description of their route printed on the side, near the door. Also, most will not stop where a few others will - you need to walk a couple of blocks to where one you want to use for a long trip will stop, but for my typical "short assist trip," I can take anyone at any bus stop if it stops there. One or two are usually stopped to take on & discharge passenger, so I never need to wait.

** Most roads in Sao Paulo are asphalt but in the last few years the bus lanes have become mainly concrete. Almost no one not entitled to use them does so. I got into one for less than a block to make a turn from it more easily and got a ticket! - about $70 as I recall. Sao Paulo may not be able to catch many crooks, especially the elected ones, but they have many traffic cops, at least one at major intersections, constantly writing up tickets - their only job with unique brown clothing to distinguish them from real cops. Their salaries are low, so I bet the$Ro\$I is greater than 1000!

Last edited by a moderator: Apr 28, 2015
23. ### KitemanSARegistered Senior Member

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624
Folks, the only thing that controls whether this process will ever be of benefit is the cost of the electricity. If someone ever throws of the yoke of fear and begins building LFTRs (Liquid Fluoride Thorium Reactors) in quantity, they could power this process and have it be comparable to petro-fuels.