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flyprivate
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Jet Engines That Run On Ethanol?

Tue Jun 06, 2006 12:10 pm

i was wondering..with all thats going on in the world with oil prices, and the future of ethanol powering cars, will airplane engines ever be able to run on ethanol? why havent any engine manufacturers looked into it yet?
 
D L X
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RE: Jet Engines That Run On Ethanol?

Tue Jun 06, 2006 1:36 pm

My understanding is that a jet engine can run on pretty much any kind of oil - allegedly even peanut butter. I know that the Abrams tank (which is powered by the same jet engine as in the F15) normally runs on jet fuel, but in a pinch, can and has been run on gasoline and cooking oil.

Of course, I doubt those other things are nearly as efficient as jet fuel.
 
brons2
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RE: Jet Engines That Run On Ethanol?

Tue Jun 06, 2006 1:39 pm

Let's hope not, as ethanol production is not sustainable without government subsidy. It uses more energy than it creates.
 
echster
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RE: Jet Engines That Run On Ethanol?

Tue Jun 06, 2006 3:06 pm

There was a discussion not so long ago in the military section. The USAF will be testing this soon on a couple B-52 engines.
NYTimes: Usaf Wants Alternative To Oil-based Fuel (by Pmg1704 May 13 2006 in Military Aviation & Space Flight)
 
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deltadawg
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RE: Jet Engines That Run On Ethanol?

Tue Jun 06, 2006 9:45 pm

Co-gen electric turbines, which are used to generate electricity built by GE, ABB/Westinghouse, Mitsubishi are essentially very large jet engines mounted in static housings. These units usually run off of several different fuels of which generally use the cheapest at the time. Most common fuel they usually use is Naptha, Gas/oil, sometimes jetfuel, gasoline and yes in the midwest I have seen ethanol used as an additive similar to 80/20 blend.
 
boeingforever
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RE: Jet Engines That Run On Ethanol?

Tue Jun 06, 2006 10:48 pm

so your saying that jet engines can run on ethanol?
 
Tod
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RE: Jet Engines That Run On Ethanol?

Tue Jun 06, 2006 11:05 pm

Quoting Boeingforever (Reply 5):
so your saying that jet engines can run on ethanol?

With modification, of course it could be done.

The problem is, to produce the same power, you would need to burn about twice the weight/volume of ethanol. In a weight and space sensitive industry, that's a non-starter.

Tod
 
PolymerPlane
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RE: Jet Engines That Run On Ethanol?

Tue Jun 06, 2006 11:05 pm

Energy content of ethanol is much lower than regular gasoline. I read somewhere, either in TIME or CNN, that car that runs on E85 (85% EtOH 15%gasoline) actually consumes more volumetric fuel per mile than when it uses regular gasoline.

This might post difficulties on aircrafts that are limited by the available fuel tanks. It will impose range penalty to the aircraft

Cheers,
PP
 
widebodyphotog
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RE: Jet Engines That Run On Ethanol?

Tue Jun 06, 2006 11:06 pm

Quoting Boeingforever (Reply 5):
so your saying that jet engines can run on ethanol?

Sure you can run turbine engines on ethanol...but ethanol has only 60% of the energy content per mass unit as Jet-A which means you have to use 67% more of it by mass to get the same energy output. You'll have to increase the fuel tankage of every aircraft by a fold if the engines are fueled by straight "E"...

The problem with so-called alternative energy use for turbine engines is that they pack much less energy density than Jet-A, and planes have to fly. These are mutually exclusive factors in my view. To move the same amount of material and people a given distance you need to burn substantially greater quantities of ethanol, for example, relative to petroleum fuels. "Cutting" petroleum fuel only lessens the degree of the disparity. For aviation "alternative" fuels must provide an energy density that is suitable for flying craft and/or bring a new paradigm to engines in terms of thermal efficiency.



-widebodyphotog
 
beefer
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RE: Jet Engines That Run On Ethanol?

Tue Jun 06, 2006 11:46 pm

Quoting Brons2 (Reply 2):
Let's hope not, as ethanol production is not sustainable without government subsidy. It uses more energy than it creates.

ABSOLUTELY FALSE!!!!!!!!!!!!!!!
 
boeingforever
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RE: Jet Engines That Run On Ethanol?

Wed Jun 07, 2006 12:04 am

cant they modify, or create engines to run better with ethanol than JET-A?
 
PPVRA
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RE: Jet Engines That Run On Ethanol?

Wed Jun 07, 2006 12:11 am

Quoting Echster (Reply 3):

NYTimes: Usaf Wants Alternative To Oil-based Fuel (by Pmg1704 May 13 2006 in Military Aviation & Space Flight)

Check out this link as well:

https://www.airliners.net/discussions/tech_ops/read.main/127922

BTW, this discussion is more appropiate in the tech/ops forum. A very interesting topic, nonetheless.

Cheers mate!
 
RichardPrice
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RE: Jet Engines That Run On Ethanol?

Wed Jun 07, 2006 12:11 am

Quoting Brons2 (Reply 2):
Let's hope not, as ethanol production is not sustainable without government subsidy. It uses more energy than it creates.

Brazil says otherwise - massive ethanol production for public consumption in vehicles, with majority of cars sold last year capable of running on ethanol.

Their ethanol production economy has no subsidy input from the government at all.

The energy production percentage depends on how you produce it, if you are losing energy in the process, you are doing it wrong.

[Edited 2006-06-06 17:12:39]
 
Oryx
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RE: Jet Engines That Run On Ethanol?

Wed Jun 07, 2006 12:13 am

Quoting Brons2 (Reply 2):
Let's hope not, as ethanol production is not sustainable without government subsidy. It uses more energy than it creates.

Only if you compare the energy content of the produced ethanol to the energy needet to produce it. Thereby you neglectd the energy content of the not fertilized parts of the used crops and of the residue from the fertilization.
 
Tod
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RE: Jet Engines That Run On Ethanol?

Wed Jun 07, 2006 12:25 am

Quoting BoeingForEver (Reply 10):
cant they modify, or create engines to run better with ethanol than JET-A?

Possibly, but you still can't get around the fact that the potential energy by weight or volume with ethanol is much worse than jet A

Tod
 
boeingforever
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RE: Jet Engines That Run On Ethanol?

Wed Jun 07, 2006 12:41 am

Quoting Tod (Reply 14):
Possibly, but you still can't get around the fact that the potential energy by weight or volume with ethanol is much worse than jet A

Tod

im sure modern technology can figure out how to make it work..no?
 
2travel2know
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RE: Jet Engines That Run On Ethanol?

Wed Jun 07, 2006 12:46 am

Maybe I should open a topic about Biodiesel aircraft engines...
 
FLY2LIM
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RE: Jet Engines That Run On Ethanol?

Wed Jun 07, 2006 1:01 am

Quoting Brons2 (Reply 2):
Let's hope not, as ethanol production is not sustainable without government subsidy. It uses more energy than it creates.

The only thing that is not "sustainable" is the rate of consumption of fossil fuels on this Earth. Therefore, we are some day going to RUN OUT of oil. It may be after everyone who reads this thread is dead and buried, but it will happen. So I would think that the airline industry must look into this, even if it's in support of the auto industry. Think about it; if the auto industry reduces/eliminates its need for oil, then the jet fuel can continue to be produced. Also, if an A380 was limited to 250 passengers, for example, but fuel was so cheap that airlines could fly 3 of them at a time for the same cost as one that uses jet fuel, isn't the problem basically solved?
Alternative fuels, like ethanol, are only restricted by the amount of agricultural land available for the production/growth of the materials needed, like corn.
Trust me, I am not an environmentalist, but this is what we will be facing.
FLY2LIM
 
widebodyphotog
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RE: Jet Engines That Run On Ethanol?

Wed Jun 07, 2006 1:11 am

Quoting BoeingForEver (Reply 15):
im sure modern technology can figure out how to make it work..no?

it may be theoretically possible to engineer super dense ethanol or some other type of fuel that presents an acceptable energy content for commercial aircraft applications. But at what cost?



-widebodyphotog
 
FLY2LIM
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RE: Jet Engines That Run On Ethanol?

Wed Jun 07, 2006 1:16 am

Quoting Widebodyphotog (Reply 18):
it may be theoretically possible to engineer super dense ethanol or some other type of fuel that presents an acceptable energy content for commercial aircraft applications. But at what cost?

Hey, remember when cell phones were so expensive that only rich people had them? Remember when only certain people could afford CD technology? With mass consumption comes lower costs. I think the world is still somewhat in denial, we'll get there soon.

FLY2LIM

PS, I think this second reply now gets me close to the "environmentalist" title, LOL.
 
RichardPrice
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RE: Jet Engines That Run On Ethanol?

Wed Jun 07, 2006 1:22 am

Quoting Widebodyphotog (Reply 18):
it may be theoretically possible to engineer super dense ethanol or some other type of fuel that presents an acceptable energy content for commercial aircraft applications. But at what cost?

Probably the other way around - more efficient engines offsetting the lower energy density of ethanol. Internal combustion engines designed specifically to run on ethanol are as much as 30% more efficient than gasoline based engines currently, so perhaps the same can be done for turbine engines - increases in efficiency for certain fuels only.
 
PolymerPlane
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RE: Jet Engines That Run On Ethanol?

Wed Jun 07, 2006 1:29 am

Quoting Widebodyphotog (Reply 18):
it may be theoretically possible to engineer super dense ethanol or some other type of fuel that presents an acceptable energy content for commercial aircraft applications. But at what cost?

Hmm.. if it were pure ethanol I am not sure how technology can achieve more dense ethanol since the density depends on the molecular interaction and the state of the liquid, i.e. temperature and pressure. You might be able to achieve higher density through molecular modification or blending, but even with blending, usually the density of the resulting fluid is only between the densities of each of its components.

When you hear now people are talking denser gasoline, I think it is achieved by blending or modifying the molecular structure, while EtOH is EtOH. If you modify the structure it is not EtOH anymore  Wink

Quoting RichardPrice (Reply 12):
Brazil says otherwise - massive ethanol production for public consumption in vehicles, with majority of cars sold last year capable of running on ethanol.

Their ethanol production economy has no subsidy input from the government at all.

The energy production percentage depends on how you produce it, if you are losing energy in the process, you are doing it wrong.

I have a friend, green environmentalist, who said that in the US the ethanol production is still heavily subsidized and potentially not profitable if it were not subsidized.

However, the difference between US and Brazil is that the primary source of carbon. In Brazil, the source of carbon is sugar cane, which is then processed to sugar, while in the US the primary source of carbon is corn. Sugar is a much much better source of carbon to be converted to ethanol because it is a much simpler carbohydrate, containing only two monomer. Starch, on the other hand, is a much more complex carbohydrate, requiring breaking down the longer chain before conversion to ethanol.

Just for your information, researchers at the University of Wisconsin-Madison, where I went for undergraduate, has managed to produce catalyst to convert glucose to longer carbon chain such as hexanes, with high yield and low CO and CO2 byproducts. I think this longer chain hydrocarbon has a better fuel properties compared to EtOH.

Still the problem is how to get a pure enough feedstock to allow the catalyst to convert it to desired product more efficiently.

Cheers,
PP
 
PolymerPlane
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RE: Jet Engines That Run On Ethanol?

Wed Jun 07, 2006 1:36 am

Quoting RichardPrice (Reply 20):
Probably the other way around - more efficient engines offsetting the lower energy density of ethanol. Internal combustion engines designed specifically to run on ethanol are as much as 30% more efficient than gasoline based engines currently, so perhaps the same can be done for turbine engines - increases in efficiency for certain fuels only.

Just curious, Is it really 30% more efficient than gasoline engine or it is more efficient because of reduction in the horsepower? I cannot really believe a ethanol engine is 30% more efficient than regular gasoline engine, while the hybrid technology offers only about that much more efficiency.

BTW EtOH is not the best alternative fuel available, since it is very hygroscopic and corossive. If you live in the US, earlier this year the gasoline distribution line has been having problem, especially in the northeast, because they have to set up a separate distribution line for EtOH. EtOH can only be mixed in the pump because of the corossion and hydroscopic problem.

Cheers,
PP
 
airmailer
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RE: Jet Engines That Run On Ethanol?

Wed Jun 07, 2006 1:39 am

Quoting Brons2 (Reply 2):
Let's hope not, as ethanol production is not sustainable without government subsidy. It uses more energy than it creates.

Please correct me if I am wrong, but doesn't practically all of Brazil run on Ethanol?

IIRC It's sugar based not corn based, maybe that's the difference.
 
airmailer
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RE: Jet Engines That Run On Ethanol?

Wed Jun 07, 2006 1:49 am

Quoting Widebodyphotog (Reply 8):
This might post difficulties on aircrafts that are limited by the available fuel tanks. It will impose range penalty to the aircraft

or... if you are say DL flying the 767 from ATL-MCO.
It's only a 500 mile (or so) flight, with that large of an aircraft couldn't they fit enough ethanol in the tanks to overcome the 60% less effecient power output?
 
widebodyphotog
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RE: Jet Engines That Run On Ethanol?

Wed Jun 07, 2006 2:04 am

Quoting AirMailer (Reply 24):
or... if you are say DL flying the 767 from ATL-MCO.
It's only a 500 mile (or so) flight, with that large of an aircraft couldn't they fit enough ethanol in the tanks to overcome the 60% less effecient power output?

You have to look at it in the entire picture. For an aircraft the heavier it is, the more fuel it burns. Simply putting the required additional mass of fuel is only part of the story. The airplane now requires additional mass of fuel to takeoff and fly at the heavier weight. Basically in a straight switch from Jet-A to ethanol you are talking about a 100% increase in the fuel requirement in actual operation. Can ethanol be made to cost half of what Jet-A cost and be delivered through the same infrastructure?

Quoting PolymerPlane (Reply 21):
Hmm.. if it were pure ethanol I am not sure how technology can achieve more dense ethanol since the density depends on the molecular interaction and the state of the liquid, i.e. temperature and pressure. You might be able to achieve higher density through molecular modification or blending, but even with blending, usually the density of the resulting fluid is only between the densities of each of its components.

I'm in agreement with you there, I just put it in the terms I did so as to not be too dismissive of the concept of ethanol for aviation...



-widebodyphotog
 
steeler83
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RE: Jet Engines That Run On Ethanol?

Wed Jun 07, 2006 2:10 am

Quoting 2travel2know (Reply 16):
Maybe I should open a topic about Biodiesel aircraft engines...

Do it! I'll be one of the first ones to respond  Smile
 
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Vasu
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RE: Jet Engines That Run On Ethanol?

Wed Jun 07, 2006 2:21 am

Funnily enough I thought the same thing a few hours ago, whilst revising for tomorrow's Chemistry A-level!
 
baroque
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RE: Jet Engines That Run On Ethanol?

Wed Jun 07, 2006 3:08 am

Quoting AirMailer (Reply 23):
Please correct me if I am wrong, but doesn't practically all of Brazil run on Ethanol?

Practically all of Brazil except the commercial air industry.

Quoting Steeler83 (Reply 26):
Quoting 2travel2know (Reply 16):
Maybe I should open a topic about Biodiesel aircraft engines...

Do it! I'll be one of the first ones to respond Smile

Turbines will run on pretty much anything as I remarked in a different thread. They have even been run on brown coal (Victoria in the late 1950s). They ran quite well, but in a very short time half the blades were covered with chemical build up and the other half were badly corraded (and possibly corroded as well).

Turbines will certainly run just fine on ethanol with minor modification. As far as large planes are concerned there are main two problems apart from making sure the plumbing does not get corroded.

First ethanol would be a much worse fire hazard compared with any current fuels.

Second, the presence of the OH group in the C2H5OH means that essentially part of the structure is already oxidised, and this results in a much lower specific energy when the molecule is burned to water and carbon dioxide.

You cannot compress ethanol significantly. You could dehydrate it to ethane C2H6 and then you have a higher specific energy than kerosene but unhappily you would end up with either ethane (a gas) or butane which boils at -0.5 deg C. Hexane would be better, it boils at 68.9 degrees C. Hexane would be less dense than kerosene but would have a slightly higher specific energy.

The fall off in energy production using ethanol, and hence the rise in fuel consumption, would mean that running planes on ethanol with the best of modern technology for fuel efficiency would be a bit like replacing the engines with those from about 1970. Not sure which date exactly and even that might understate the problem of lost energy, but about then. While ever there were kerosene powered planes, the ethanol ones would not be competitive.

Biodiesel is a different story. It is a potential substitute, given some constraints.

And the energy-input to energy-output of systems using cane sugar or corn as the source of the alcohol are a problem. There is the direct energy of tractors and harvesters and processing. Then you need to add the energy inputs (at present largely from oil or natural gas) to fertilisers and pesticides.

There are so many hidden subisidies in economic units involving farming that clearing them out would make sorting out the WTO case between Boeing and Airbus look like a Sunday picnic.

It seems unlikely that anybody has an accurate idea what the price of ethanol would be on a full cost recovery basis but it is clearly not cheap. It is most attractive where gasoline/petrol has high tax inputs. So it is less attractive in the US, and to some extent in Australia compared with most European countries.

It is certain that is some settings energy input is more than energy output depending on yields and crops used. But taxes on oil-based products may still make the ethanol appear cheap. But this type of substitution clearly makes the problem worse not better.
 
PPVRA
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RE: Jet Engines That Run On Ethanol?

Wed Jun 07, 2006 5:51 am

Quoting PolymerPlane (Reply 22):
Quoting RichardPrice (Reply 20):
Probably the other way around - more efficient engines offsetting the lower energy density of ethanol. Internal combustion engines designed specifically to run on ethanol are as much as 30% more efficient than gasoline based engines currently, so perhaps the same can be done for turbine engines - increases in efficiency for certain fuels only.

Just curious, Is it really 30% more efficient than gasoline engine or it is more efficient because of reduction in the horsepower? I cannot really believe a ethanol engine is 30% more efficient than regular gasoline engine, while the hybrid technology offers only about that much more efficiency.

Nope. A car with the same tank capacity on ethanol will have approx. 25-30% lower range. But it is still more cost-effective than conventional gas and have low environmetal impact.

Quoting AirMailer (Reply 23):

Please correct me if I am wrong, but doesn't practically all of Brazil run on Ethanol?

Not the case, either- at least not yet. When the program began something like 95% plus of all automobiles sold were ethanol powered; but after the the program went into ruins (ethanol prices dropped so much, farmers turned to the sugar market instead... IIRC the cause). The recent revival of the program has seen good numbers as well, they have also fixed a few technical issues, and the new engines are flex-fuel, meaning they can use gasoline or ethanol in any propotion.

Read the link on reply 11 with tons of facts and figures on the ethanol subject, including Embraer's experiment and already commercially available product.

Cheers guys!
 
StarGoldLHR
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RE: Jet Engines That Run On Ethanol?

Wed Jun 07, 2006 7:22 am

If planes cant create energy from solar and wind, then nothing else on earth can.

Maybe Solar/wind could generate some internal engergies.
 
Tod
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RE: Jet Engines That Run On Ethanol?

Wed Jun 07, 2006 7:46 am

Quoting PPVRA (Reply 29):
A car with the same tank capacity on ethanol will have approx. 25-30% lower range

In racing applications it is not uncommon for a methanol burning engine to product 30 percent more power than with gasoline, but burn twice as much fuel to accomplish that.

Tod
 
rmd11
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RE: Jet Engines That Run On Ethanol?

Wed Jun 07, 2006 8:17 am

Quoting 2travel2know (Reply 16):
Maybe I should open a topic about Biodiesel aircraft engines...

That could work but for jets wouldnt it be more like bio kerosene/#1 fuel
 
PPVRA
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RE: Jet Engines That Run On Ethanol?

Fri Jun 09, 2006 7:40 am

Quoting Tod (Reply 31):

In racing applications it is not uncommon for a methanol burning engine to product 30 percent more power than with gasoline, but burn twice as much fuel to accomplish that.

100% Correct. There is an increase in power output, but you use more fuel as well.
 
prebennorholm
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RE: Jet Engines That Run On Ethanol?

Fri Jun 09, 2006 9:03 am

Ethanol is a perfect fuel for turbine engines.

The only problem is that it takes 70% more ethanol to produce the same heat.

That means that today's 8,000 miles range planes would be turned into 4,000 miles planes. And current short range planes would hardly have tank capacity to more than what is needed as reserves for holding and diversions. (Range roughly zero miles).

Turbine engines (as well as piston engines) would easily produce the same power on ethanol. But at a much increased fuel flow.

Ethanol is best used for cars where weight of the fuel is much less of an issue.

If for a period of time we are going to use a mixture of crude oil and ethanol from sugar cane, then it would be stupid to use the ethanol on planes, because planes would spend a lot of extra energy just to haul along the heavy ethanol. While on the other hand it would not mean so much to fill 40 gallons ethanol on a car instead of 25 gallons gas or 20 gallons diesel oil.

It's quite natural. When looking at the structure of an ethanol molecule, then in the beginning it is rather similar to a hydro-carbon molecule (gas, kerosene, natural gas etc.), but in the end we see that it has already been partially "burned" with oxygen.

Another thing is simply "quantity". Brazil can chop down a few hundred thousand sq. miles of rain forest and grow sugar cane for ethanol production on that. And that way save a lot of fossil fuels.

But if ethanol should be a primary energy source to fulfill for instance Europe's current energy demand, then it would take a whole new planet with a few dozens of Brazils and their chopped down rain forests.

And I mean a NEW planet. Because chopping down the rain forests on planet Earth seriously affects our CO2 balance.
 
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lightsaber
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RE: Jet Engines That Run On Ethanol?

Fri Jun 09, 2006 9:17 am

As other have noted, Brazil makes Ethanol PROFITABLY. That's not possible if it were *energy negative* as some like to claim. Last I heard, the energy equivalent break even, at the pump was comparable to $55/bbl oil. I applaud Brazil for funding the R&D to make the current program a success. Heck, they've even sold huge quantities of Ethanol to Japan.

The US ethanol industry is still in incubation. We need to go to a cellulose based ethanol and away from corn derived ethanol. We'll get there. There is even *private* money funding the R&D. Like it or not, we're probably going to have to cut our gasoline with more ethanol. 20% is the limit without electronics that can compensate.

Quoting Widebodyphotog (Reply 18):
it may be theoretically possible to engineer super dense ethanol or some other type of fuel that presents an acceptable energy content for commercial aircraft applications. But at what cost?

First, you saved me a lot of typing with your description on ethanol.

What works better for aircraft is a bio-oil (say a vegitible oil). There are candidates that have an energy density close to JetA, but still reduced. What you can do is put bio-feedstock into a refinery and "crack" the feedstock into a higher energy fuel. The way this is done is by partially burning natural gas (theoretically, coal could work too) and using the radical hydrogens that are released to create longer chain bond hydrocarbons that have the required properties. To burn it straight has multiple issues:
1. Freeze point. Having all of the fuel in the wing go frozen mid flight would really suck...  flamed 
2. Energy content. The best fuels could have 95% to 97% of the energy content of JetA per pound (slightly worse volumentrically). So any "stretch run" couldn't be done. (e.g., SIN-LAX, or A320's coast to coast).

Quoting StarGoldLHR (Reply 30):
Maybe Solar/wind could generate some internal engergies.

To an airplane wind=drag. You could generate energy from the wind, but that would cost more fuel than its worth.

As to solar... The added weight of the panels (today) would cost more in fuel than the energy provided. Current solar panels have poor efficiency.

Quoting PPVRA (Reply 29):
Nope. A car with the same tank capacity on ethanol will have approx. 25-30% lower range. But it is still more cost-effective than conventional gas and have low environmetal impact.

 checkmark  Everyone, stop and think what world oil prices would be if Brazil didn't have their ethanol industry? With Ethanol, Brazil has freed up what, a tanker a day? (Maybe half a tanker of oil a day?) 1.5% to 3% less oil would mean.. 10% to 20% higher prices!  wideeyed 

Lightsaber
 
Boeing7E7
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RE: Jet Engines That Run On Ethanol?

Fri Jun 09, 2006 5:21 pm

This is the key. Get everything else... Off of Fossil Fuel.

Quoting FLY2LIM (Reply 17):
Think about it; if the auto industry reduces/eliminates its need for oil, then the jet fuel can continue to be produced.

A train can carry a tank car behind the locomotive of Ethanol/Hybrid Fuel if needed or be electric.

Transport Ships and Cruise Ships can be Nuclear Powered.

Every other vehicle can use ethanol or some other fuel source.
 
pavlin
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RE: Jet Engines That Run On Ethanol?

Fri Jun 09, 2006 5:40 pm

Even thought Ethanol has lower energy content per liter than kerosene. That doesn't mean it will cosume 60% more fuel. I thnik like 20-35% seems more realistic. In cars Ethanol consumption is only 10% higher
 
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lightsaber
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RE: Jet Engines That Run On Ethanol?

Sat Jun 10, 2006 1:43 am

To compare the energy of fuels you must compare the lower heating values.

Why lower heating values? Water comes out of the engine as steam (vapor) and not as a cold liquid.

Gasoline: 32MJ/liter; desnsity .73g/ml or 42.7 MJ/kg
Ethanol: 21.1MJ/liter; desnsity .79g/ml or 26.7 MJ/kg
Diesel (aka Petro-Diesel): 36.4 MJ/liter or 43 MJ/kg
Biodiesel: Up to 35.7 MJ/liter (but often less) and its fractionally denser than petro-diesel.

JetA is 44 MJ/kg (in round numbers)

Or ethanol has 60% of the LHV of JetA by weight


http://www.localenergy.org/pdfs/Docu...oenergy%20conversion%20factors.pdf
http://www.humanitarianinfo.org/darf...uel%20-%20helpdoc%20by%20UNJLC.pdf

Biodiesel can be made into a good Jetfuel but it will require refining "enhancement" to up the energy content per gallon and per pound. Unfortunately, that means consuming another fuel to get the required hydrogen.  Sad Ethanol? Maybe as stock to help upgrade the biodiesel, but not as the major fuel.

I belive a cellulose based ethanol system will work for producing ethanol economically. Something needs to be done to stretch the world's oil supply. Yes, I know a good part of that must be the US cutting consumption. You'll see more of that in the year's ahead.

As to the hydrogen economy... I work in the combustion world and know how dangerous many gaseous fuels can be. Ok, Natural gas (CH4) and Propane (C3H8) are easy and safe to handle. But take something like Hydrogen... ugh... I don't understand why a "hydrogen economy" has even been proposed! (Aerospace companies will pay techs to maintain gas systems, your average car owner? Good luck getting them to pay for that MX) There isn't any natural supply of H2 in any quantity...

I'm all for fuel cells. But CH4 fuel cells or even (I dream here) ethanol based fuel cells. But not yet... Not yet...

Lightsaber
 
antiuser
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Joined: Thu May 27, 2004 9:43 am

RE: Jet Engines That Run On Ethanol?

Sat Jun 10, 2006 2:31 am

Quoting Brons2 (Reply 2):
Let's hope not, as ethanol production is not sustainable without government subsidy. It uses more energy than it creates.

That is incorrect. As a matter of fact, most ethanol refineries in Brazil produce more energy than they consume and make extra profits from powering the neighbourhoods adjacent to the refinery.
 
PolymerPlane
Posts: 832
Joined: Thu May 11, 2006 1:12 am

RE: Jet Engines That Run On Ethanol?

Sat Jun 10, 2006 2:42 am

Quoting Lightsaber (Reply 38):
I belive a cellulose based ethanol system will work for producing ethanol economically. Something needs to be done to stretch the world's oil supply. Yes, I know a good part of that must be the US cutting consumption. You'll see more of that in the year's ahead.

Cellulose based ethanol will be great, but, breaking down cellulose is almost impossible. To break down cellulose chemically you have to have I think 1 M sulfuric acid solution with nitric acid, or something in that nature. That is why Brazil is successful with its ethanol industry because it uses sugar as the feedstock, simpler carbon than cellulose. You could probably do it using bio degradation, but the process is usually very slow, and very hard to scale up as the process is run on batch, while continuous reaction is much much desirable.

I do not know why people insist on using ethanol as their product. Long chain hydrocarbons such as hexane and octane are much better fuel, and you do not have to worry about the corrosion and hygroscopic nature of ethanol.

Cheers,
PP
 
Rottamo
Posts: 135
Joined: Tue Dec 06, 2005 1:45 pm

RE: Jet Engines That Run On Ethanol?

Sat Jun 10, 2006 3:36 am

I vote for:
http://www.radiationworks.com/flyingreactor.htm
I don't like idea that we have to cut rainforests.

Some wild speculation:
I guess that if (big if) solar panel technology is able to produce cheap enough electricity then we can use electricity/solar energy to produce liquid fuels even if it is not very efficient. Solar energy just have to be very cheap and we don't have technology now, but if solar cost of energy improves 4% per year then price of it should halve every 17th year.

Out of topic question. Does anyone have idea how much more expensive it is produce electricity using solar cell right now vs. oil?

There have to be break even point and I am just wondering is it at current levels, at level $150 per barrel or $300 per barrel or even higher.

Rottamo
 
phollingsworth
Posts: 759
Joined: Sat Mar 06, 2004 6:05 am

RE: Jet Engines That Run On Ethanol?

Sat Jun 10, 2006 4:05 am

Quoting Beefer (Reply 9):
ABSOLUTELY FALSE!!!!!!!!!!!!!!!

Either you support this or tone it down. Besides I don't think you read the actual text with respect to your response.

Quoting Brons2 (Reply 2):
Let's hope not, as ethanol production is not sustainable without government subsidy. It uses more energy than it creates.

You are quite correct, though I don't think you meant to say what you are saying. The only way that Ethonol would not use more energy than it produces was if all of the processes were fully reversible, that just isn't going to happen.

The argument that has been raging is not whether ethonolo uses more fuel than it produces. The argument is whether or not the production of ethonol uses more oil than it displaces from the market. To make this argument you must look at the whole fuel cycle. With petroleum it is easy, it is the energy cost of exploration, extraction, transportation and refining. With bio-fuels you have to look at the cycle including feartilizers and such. There seems to be some evidence that ethonol from feed materials, e.g. corn displaces more oil than it produces, but not by much. Other production techniques like cellulose based ethonol are not as efficient, but may use what is otherwise a waste product.

Quoting Antiuser (Reply 39):
That is incorrect. As a matter of fact, most ethanol refineries in Brazil produce more energy than they consume and make extra profits from powering the neighbourhoods adjacent to the refinery.

This says nothing about the overall energy balance of the fuel.
 
antiuser
Posts: 646
Joined: Thu May 27, 2004 9:43 am

RE: Jet Engines That Run On Ethanol?

Sat Jun 10, 2006 7:21 am

Quoting Phollingsworth (Reply 42):
This says nothing about the overall energy balance of the fuel.

I never went into the energy balance of the fuel. Brons2 implied that production of ethanol fuel is not economically feasible without government subsidies to power the refineries. I pointed out that it is, and refineries even have an energy surplus. Ethanol production is sustainable and feasible without government subsidies. It has been for many years now.

I think you were the one who misunderstood his post. You're talking about efficiency, I'm talking about sustainability.

[Edited 2006-06-10 00:31:29]

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