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Diesel From Air & Water

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Audi just created a 'blue diesel' fuel from just air and water...imagine this fuel getting into aviation?  Still think diesel engines wont dominate aviation in time?

 

http://www.gizmag.com/audi-creates-e-diesel-from-co2/37130/?utm_source=Gizmag+Subscribers&utm_campaign=4f65f6819f-UA-2235360-4&utm_medium=email&utm_term=0_65b67362bd-4f65f6819f-91242709

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Perhaps if you had a modicum of scientific education you might know that this is nothing new.

The Fischer-Tropsch process was invented in 1925 and used during WW2 to create hydrocarbon fuels.

Chemistry really is quite wonderful!

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It's funny how I see a lot of innovation, then with minimal amount of effort, I discover it was invented a hundred years ago.

 

I think we're seeing a resurgence in a lot of these old techs because of the rising fuel costs. We already have a lot of tech that can replace oil as our primary energy source, but it's no where near as cost effective.

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It depends entirely on the cost of energy. The reaction to make a hydrocarbon from CO2 and H2O is pretty endothermic so needs a lot of energy input to make it work.

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It's funny how I see a lot of innovation, then with minimal amount of effort, I discover it was invented a hundred years ago.

 

I think we're seeing a resurgence in a lot of these old techs because of the rising fuel costs. We already have a lot of tech that can replace oil as our primary energy source, but it's no where near as cost effective.

 

It's not old tech.  If it were, we would see the stuff in gas stations right now.   I think the Germans are marching forward providing the world with a new future fuel.

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As I have a masters degree in chemistry I'll not be taking advice from you.

 

I also speak French and German - do you?

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It's not old tech.  If it were, we would see the stuff in gas stations right now.   I think the Germans are kicking butt and not taking any names while they march forward providing the world with a new future fuel.

 

Just like fracking, it was invented a long long time ago. We didn't see it in mainstream until recently because the only thing people care about is cheap (which is not always a good thing), so anyone that tried to make a business model based on this was pushed out of the market. This is an expensive process to complete.

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This is the first time that I have written to this forum. I have followed it for quite a while because I have a CTLS and would like to learn from all of you that have a lot more expieiences then I have but I don't enjoy personnel attacks that go on in this forum. Some tolerance should come in before you outright attack someone for their thoughts Evan if you adamantly disagree. I live and farm in Canada and fly out of my personal grass airstrip and enjoy the CTLS.

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Back to the original topic, all energy technologies only have one relevant question that needs answering: does the technology release more energy than the sum of the input energies used to produce it?

 

Hydrocarbons have been above that curve for over a century due to their plentiful quantities and relative ease of obtaining them. There is doubt as to how long they will stay that way, as more energy must be expended to reach each new barrel of oil.

 

the big question with this diesel producing tech is whether it can produce a gallon of diesel for significantly less than the chemical energy contained in a gallon of diesel fuel. I'm guessing the answer is no, or else all the energy problems of the world will have just been solved. It may be a technology worth pursuing and refining, but until it can break that threshold it will remain a research technology only.

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From the article:  "Sunfire claims that analysis shows the properties of the synthetic diesel are superior to fossil fuel."   But without the sulfur.    "The overall energy efficiency of the fuel creation process using renewable power is around 70 percent, according to Audi."

 

Since they are using solar and wind power to do the 'cracking' and mixing that with C02 harvested from 'ambient air' (presumed to be greenhouse gases man put there) the end result does seem too good to be true....

 

Wonder why Audi would stake it's corporate reputation on it?

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One gallon of diesel embodies ~37kWhr of energy, which means you can get 37kWhr of energy out by burning it, so long as all you want is heat. IC engines are only ~32% efficient at turning heat into motive force so 13kWhr of useful energy best case for spinning things like propellers. (See what that is in Li-ion batteries, just 10Whr for an 18650 cell and you'll understand why electric planes don't make much sense.) Anyway, if Audi's process is 70% efficient then they need inputs of 53kWhr to make a gallon of e-diesel. Electricity is a pretty useful fuel source to begin with and has generated costs of $0.04 and up (and that's only coal based)http://upload.wikimedia.org/wikipedia/commons/c/cc/LCOE_comparison_fraunhofer_november2013.svg, versus oil refining which generates diesel at ~$1.50 per gallon. If you start with coal, there are more efficient ways to turn coal into fuel without transitioning through electricity by making CO and H2 directly from Carbon via liquefaction for the Fischer Tropsch process. So wind generated electricity can optimistically be $0.06 and up meaning Audi could make diesel at just more than twice the cost of refining except they need a concentrated source of CO2 which is NOT the atmosphere (notwithstanding the pronounced greenhouse effect CO2 is just 0.35% of air) They would have to efficiently distill about 500m^3 of air just to get the 220mol of CO2 needed to make one gallon.

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Three things:

 

Firstly - my original reply to Hamburgers was intemperate and rude and for that I apologise.

 

Secondly - I reiterate that he is wrong in saying this is something new, it simply is not! I was going to go into great detail on the subject but I've just seen that Chanik has done it brilliantly - well done that man!

 

Finally I don't for a moment agree that Audi are "staking their corporate reputation" on this. They are taking a sensible step recognising that as the price of extraction of fossil fuel rises and the cost of electricity generation via renewable methods falls then this may well become viable. However, IMHO it will be quite some time before such a technology makes any impact on the volumes of fossil fuels currently extracted and refined.

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Propellers have losses too. Fortunately they are pretty darn efficient, converting around 90% of torque into forward momentum in cruise.

 

What I would find interesting is to see a resurgence in the use of turbo compound engines. Probably not going to happen since turbines are extremely expensive and maintenance intensive, but it's still interesting.

 

For those that don't know what a turbo-compound is: prior to the opening of the jet age, research was being conducted (and applied to a few of the military and propliners) in using exhaust gas driven turbines, connected via fluid coupling, to the crankshaft of the engine. It dramatically raised efficiency, but was very expensive and complex. Plus, you're most of the way to a turboprop at that point.

 

These turbines are called "power recovery turbines" by some vehicle engine manufacturers. Yet another technology touted as "new", but was actually invented a long long time ago!

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Kurt nailed it.  The issue is cost.  If the cost of the fuel made from CO2 and H2O is greater than the cost of other means of production, then the process has no commercial viability.  As the cost of existing sources increases (and the cost of the Fischer-Tropsch process decreases), then the economic viability improves.  

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I find it interesting to ask the question the other way around: How could it be viable.  First, crude would have to at least double in in price, but that day will surely come.  Audi's greenwashed version about grabbing atmospheric CO2 is warm, fuzzy bullshit.  But there are streams of concentrated CO2 to be had, mostly from refineries and gas/oil drilling.  Lot's of CO2 comes out with natural gas; often also with oil fields.  Also, wind power suffers from user-demand mismatch (much of the capacity generated at night is unused since electricity demand is massively lower).  So I could see a big windfarm in Bahrain or North Dakota augmenting fuel output.  Not so sexy a story but a much more practical one.  

All of this will be irrelevant, of course, once the water fueled engine comes to market if the automaker's/oil companies ever stop conspiring to keep the secret of chemically reasonant magnecule based oxyhydrogen production from getting out.

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Kurt nailed it.  The issue is cost.  If the cost of the fuel made from CO2 and H2O is greater than the cost of other means of production, then the process has no commercial viability.  As the cost of existing sources increases (and the cost of the Fischer-Tropsch process decreases), then the economic viability improves.  

 

They are using solar and wind for electrical energy and taking raw materials from water and the air...the recurring cost is near zero.

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You could capture a TREMENDOUS amount of CO2 from power plants too.

However burning fossil fuel to drive such a process doesn't make too much sense. Now wood fired with a short carbon cycle or better still nuclear is the way to go!

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They are using solar and wind for electrical energy and taking raw materials from water and the air...the recurring cost is near zero.

 

I encourage them to explore the options. But, pulling CO2 from the air is either going to be a very slow process if you want to use natural aspiration (don't even know if this will work), and CO2 purification needs expensive equipment. It's a step in the right direction, but it produces such small quantities of fuel.

 

However burning fossil fuel to drive such a process doesn't make too much sense. Now wood fired with a short carbon cycle or better still nuclear is the way to go!

 

No, but tacking it on to existing facilities does :).

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The only reason capturing flue gasses does not make sense is that if you have fuel to start with, coal or much better natural gas, then there are much more efficient, direct chemical process pathways to making diesel.  Rather than burning -> electricity (~40% eff) then capturing exhaust (~90%) then running electrolysis on CO2 and H2O (70% according to Audi).  That's 25% overall versus over 60% for modern FT process

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