PPVRA
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Mixing Ethanol In Aviation Fuel?

Fri Sep 16, 2005 3:17 am

For some 30 years now Brazil has had an ethanol program for automobiles. Some cars are 100% powered by ethanol, and some newer version have a dual-fuel engines (they can run on alcohol or conventional gas).

Beyond that history, which has it's own shares of issues only more recently mostly worked out, we also mix a certain percentage of ethanol in our fuel supply (I don't think for aviation fuel though). I believe Japan also does the same, some 5% or so of the mix they pump into their automobile is ethanol. I have no idea what the percentage we use, but I believe it's much greater.

NEIVA, an Embraer subsidiary, recently adapted an engine to 100% Ethanol use that powers their own designed/built aircraft (already certified by Brazilian authorities and available commercially); a small prop crop duster. The aircraft has been available for many years, with close to a thousand in operation in Brazil (av gas powered), and now many owners are asking NEIVA to convert their engines to Ethanol given that it is much cheaper than aviation fuel.

IIRC, they have hundred of orders (full a/c) and conversion requests for the Ethanol powered engine.

And now, even the Brazilian Air Force is looking into the possibility to convert their own turbo-prop fleet into Ethanol fuel.

So this begs the question:

With the cost of fuel sky-rocketing into space, and with no "re-entry" in sight, why not make Ethanol available for at least the worlds turbo-prop fleet? I don't know if it is possible to run jet's on it, so far no one has done it so I guess not, at least not viably, but can't we at least mix an X percentage into the fuel supply as to lower the overall costs? For jets and/or props?

Even if it is just 5% or so, those are some nice and very welcomed savings for our airline industry and hell, if applied for automobile use also, how much money would the U.S. save by reducing oil imports (think massive deficit)? Not to mention "foreign oil dependency."

This would also delay our supplies of oil from running out.

What you guys think?

Cheers,
PPVRA

Note: I posted this in this forum because I would like to hear some technical/economical responses. If I posted on the non-av, you know how it would have ended... lol
"If goods do not cross borders, soldiers will" - Frederic Bastiat
 
PPVRA
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RE: Mixing Ethanol In Aviation Fuel?

Fri Sep 16, 2005 4:00 am

Here are some numbers from NEIVAs website (unfortunately available only in portuguese it seems):

1. Friendlier towards the environment

2. The engine can run colder (not sure exactly what that means)

3. Engine can run longer without the periodic maintenace required

4. Increase in power output

5. Considerable lower operational costs


Considering a fleet of 600 Ipanemas (the name of the aircraft):


6. Eliminates a demand for 16.8 million liters of AvGas/year.

7. Generates a demand for 21.6 million liters of ethanol/year (Brazil produces well over a bilion liters/year)

8. Reduces in 13.5 million fleet operational costs yearly.

Note: Figures are all in USD.

I'm still going through the website, but the only disadvantage seems to be a decrease in range from 938km (AvGas) to 610km (Ethanol), a 35% reduction it seems, ouch, I know, but still: fuel costs much less and has many benefits.

Cheers

Edit: Here is the website with some pics if you're interested:

http://www.aeroneiva.com.br/site/content/home/

[Edited 2005-09-15 21:13:17]
"If goods do not cross borders, soldiers will" - Frederic Bastiat
 
Tod
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RE: Mixing Ethanol In Aviation Fuel?

Fri Sep 16, 2005 4:26 am

Downside:

To produce the same power as gas you need nearly the weight in ethanol.

Tod
 
Okie
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RE: Mixing Ethanol In Aviation Fuel?

Fri Sep 16, 2005 4:57 am

Basically a turbine engine can burn anything flammable.
Natural Gas to Bunker Oil.
Converting an existing turbine fuel system is a little more complicated than just switching to alcohol. There are problems with dealing with piping/tubing sizes, pumps, fuel controllers, and nozzles to deal with the 1/3 larger quantity of fuel. Alcohol is not compatible with many elastomers, gaskets, and sealants used in fuel systems. Severely limits range or payload to make up the difference in quantity used. Alcohol is very hygroscopic (absorbs water) making venting and storage of alcohol a major issue.

Even Bio-diesel has drawbacks as there is not any manufacturing facilities or a distribution system in place and not enough crop land on planet earth to produce a serious dent in the quantities of fuel used world wide.

So eventually you will start to see some splintering of fuels used either by regional logistics, industry, or application specific when the cost of dinosaur juice escalates to the point where other fuels become cost effective.

Okie
 
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TripleDelta
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RE: Mixing Ethanol In Aviation Fuel?

Fri Sep 16, 2005 5:32 am

There was an article about ethanol in general aviation in the July 2005 issue of Private Pilot. It is said that converting an avgas burning engine to an ethanol burning one is very simple, and the only major change is the addition of insulation for tubing and rubber components that could be affected by ethanol.

Another simple change concerns the mixture control and fuel injector unit, since the densities and specific weights of avgas and ethanol are a bit different. The article also states that converting the engine back to avgas is just a simple issue of tweaking the mixture to its previous setting - apparently, a screwdriver-only job.

The only drawback, according to the article based on the research of Dr. Max Shauck, is a 7-25% range decrease, a bit more optimistic than the Neiva figures. Apart from the Ipanema (the cropduster PPVRA was referring to), ethanol engines have been used on aerobatic aircraft as well (Shauck's Pitts S2B) and on a Velocity Max that Shauck flew over the pond back in 1994.

On a side note, converting the stock O-235 on the Cessna 152 to ethanol would in the end give about 20% increase in power, though again, application on the 152 would be questionable, as it already has restricted range...

Overall, it would be a very good and convenient interim measure until purpose-build ethanol (or in the shorter term diesel) engines become available in quantity and at a price that would not offset the lower price of ethanol. The question still remains, as always, how fast will the aviation community adapt to it. Logistical problems, such as those faced by natural gas-burning cars, will take time to iron out.

[Edited 2005-09-15 22:35:55]
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HiFi
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RE: Mixing Ethanol In Aviation Fuel?

Fri Sep 16, 2005 6:21 am

Quoting Tod (Reply 2):
To produce the same power as gas you need nearly the weight in ethanol.

Actually, output power is slightly higher with ethanol, as stated by NEIVA's website... That's true in cars also (the Ipanema is still a piston-engined aircraft, if I'm not mistaken). But the engine consumes more. The downside is really the resulting reduction in range, since fuel tank capacity is probably unchanged.

Quoting PPVRA (Reply 1):
2. The engine can run colder (not sure exactly what that means

In my opinion related to the difficulty one has in using ethanol in cold weathers. Some ethanol-powered cars carry a little gas tank in order to assist in starting the engine. Maybe the Ipanema has a solution to reduce cold weather inconvenience. Don't know how that would work on a jet engine, but I suppose it could at least be looked at..  Wink
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TripleDelta
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RE: Mixing Ethanol In Aviation Fuel?

Fri Sep 16, 2005 5:28 pm

Quoting PPVRA (Reply 1):
2. The engine can run colder (not sure exactly what that means)

As the article I mentioned says, the CHT (Cylinder Head Temperature) is significantly lower for ethanol burning engines, even though the EGT (Exhaust Gas Temperature) is similar, or almost the same.

Quoting HiFi (Reply 5):
Some ethanol-powered cars carry a little gas tank in order to assist in starting the engine. Maybe the Ipanema has a solution to reduce cold weather inconvenience.

100% pure ethanol is a nightmare at lower temperatures because it doesn't vaporize readily in cold weather, but, according to the article, that can be addressed by adding a denaturant to it to help it vaporize, something like, but not the same as, adding anti-freezing liquid to the cooler on a car to keep the water from freezing over in the winter.
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Tod
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RE: Mixing Ethanol In Aviation Fuel?

Fri Sep 16, 2005 11:20 pm

Quoting Tod (Reply 2):
To produce the same power as gas you need nearly the weight in ethanol.

Wow, that statement sounds stupid.
(probably shouldn't type before having that first cup of coffee)

What I meant to say was that to produce the same power for the same duration you will have a significant increase in fuel weight.

This is base on personal experience with automotive engines installed in boats so it may not be universally applicable.

Quoting TripleDelta (Reply 6):
CHT (Cylinder Head Temperature) is significantly lower for ethanol burning engines

To optomize performance we ended up decreasing the coolant flow rate through the heads.

Tod
 
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RE: Mixing Ethanol In Aviation Fuel?

Sat Sep 17, 2005 5:22 am

Quoting Tod (Reply 7):
What I meant to say was that to produce the same power for the same duration you will have a significant increase in fuel weight.

Now I got what you wanted to say! And you're right.. You're considering a fixed range (or time), so you need more fuel to get there. I considered a fixed fuel weight (assuming full tank), resulting in a more limited range. Just 2 ways of putting it.  Smile
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PPVRA
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RE: Mixing Ethanol In Aviation Fuel?

Sat Sep 17, 2005 6:32 am

Quoting HiFi (Reply 8):
Quoting Tod (Reply 7):
What I meant to say was that to produce the same power for the same duration you will have a significant increase in fuel weight.

Now I got what you wanted to say! And you're right.. You're considering a fixed range (or time), so you need more fuel to get there. I considered a fixed fuel weight (assuming full tank), resulting in a more limited range. Just 2 ways of putting it. Smile

I see

However, according to NEIVAs figures, they achieved a significant costs savings (well, we don't know the percentage, but 13.5 million USD yearly worth in AvFuel for crop dusters seems a lot! Even if for 600 of them!), so I assume they got the same amount of work done.

Question: Considering Tod's scenario, the extra fuel weight would only restrict payload, correct? How feasible is to have such a large increase in fuel tanks? Also, is ethanol lighter then Avfuel?

Airlines such as DL have extensive use of widebodies on domestic flights, well below it's max range, making ethanol feasible from my stand point. It lowers a bit pay load I guess, but it's only a short flight anyways.

Cheers
"If goods do not cross borders, soldiers will" - Frederic Bastiat
 
727EMflyer
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RE: Mixing Ethanol In Aviation Fuel?

Sat Sep 17, 2005 7:20 am

If the aviation industrial base would build it, I think the aviation user base would come. We can't exactly convert all our existing aircraft, but if the industry would make a commitment to the alternative fuel we could be fully integrated in a couple decades, I think. It would be like the switch from piston to turbine. We can phase out the fossil burners while bringing the new generation online. It would result in an entirely new school of thought in aircraft design since the planes would have to be optimized for similar performance while carrying a larger fuel capacity.... maybe incluing a rebirth of the turboprop or the development of some very large fans. We could see some really interesting models! It would change the airline route structure since some of our very long routes might no longer be feasible.... possibly a good catalyst to put an end to some of the super hubs that we all know are dinosaurs themselves.
I am all for alternative fuels. They offer a lot of exciting possibilities. The thing is though they won't "take off" unless industry makes a bold commitment to them.
 
TheSonntag
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RE: Mixing Ethanol In Aviation Fuel?

Sat Sep 17, 2005 7:33 am

I personally think that the more likely and much more practicable approach is to use Diesel Engines. The Thielert Centurion Diesel engine already exists as an alternative for the Lycoming on the Cessna (172 I think).

It only burns 14liters of Jet-A per hour at max speed. Diesel engines can in theory be powered with synfuel (synthetic fuel made out of virtually everything that includes hydrocarbons, like plants), ordinary Diesel fuel or FAME (fatty acid Methyl Ester, also known as "Biodiesel").

But we need certified fuel, so as far as I know, only Jet A may be used. Still, I think its better to burn 14litres of JetA per hour than 30+ litres of 100LL.

Michael
 
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TripleDelta
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RE: Mixing Ethanol In Aviation Fuel?

Sun Sep 18, 2005 4:47 pm

Looks like it'll be a stiff fight between ethanol and synthetic Diesel fuels, the only question would be which would offer more advantages:

- ethanol needs only an easily adapted avgas engine, while the Diesel has to be made virtually from the ground up

- Jet A is universally available (as well as synthetic Diesel fuels), while some countries still lack ethanol facilities

- despite that both Diesel and ethanol-powered light aircraft made it across the Atlantic in one hop (the Diamond DA-42 Twin Star and the Velocity XP respectively), the range of the Diesel is still greater, which may appeal to flight schools

- the Diesel requires a smaller fuel capacity than an ethanol engine for the same range

- Diesel engines are heavier than purpose-built ethanol engines

- ethanol engines can be easily adapted back to avgas

- Diesels can burn a wider spectra of fuels

But then again, we have to remember that both the Diesel developed by Thielert and ethanol-burner developed by Neiva are still new technologies in their first iteration. A few years for now, who knows what potential will both of them develop.

The present ethanol engines are adaptations of avgas engines - and an avgas engine running ethanol is still an avgas engine. If we built a purpose-built ethanol engine, it would differ from a standard avgas one:

- avgas produces much higher CHTs, meaning the cylinder walls themselves have to be thicker to withstand the heat. Also, significant cooling is required, achieved by increasing the area of the cylinder with rib structures, much like those on a home radiator - which adds weight and increases dimensions, as well as drag

- the properties of ethanol give it a higher horsepower output than avgas for the same engine cubic capacity. A 100 HP avgas engine may give 120 HP on ethanol, and on some planes those 20 HP might not be all that important. Reducing the cubic capacity of the engine would bring it back to 100 HP, as well as providing a smaller and lighter engine

all of which in the end, may provide some answers to the problems of ethanol engines, like increasing range because the engine is lighter, smaller and gives less drag - even though this would be evident only in the long run. However, frequent operators, like flight schools, may find this a good option.
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TheSonntag
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RE: Mixing Ethanol In Aviation Fuel?

Sun Sep 18, 2005 7:46 pm

We could also argue, however, that an aircraft equippet with a Diesel engine does not need nearly as much fuel, so it would (in theory) not be required to have as big a fuel tank as an ordinary engined aircraft, thus being lighter. This is not the case, I think, as the fuel capacity will be the same, but it is definately something that could be considered with new designs.

Anyway, I am very sceptical towards new fues like ethanol, because they require a complete new infrastructure and engines that are modified. Lets face it, today we have two kinds of fuel: Avgas 100LL and Jet-A. Diesel engines can use this existing infrastructure without problems and could also use new fuels like synfuel, while piston engines need to be modified for ethanol as far as I have heard. And I honestly do not see an advantage if you use ethanol if that increases the fuel consumption even further.

What we really need in aviation are modern engine designs that are no longer based on the 1940s. I think that the Diesel is the best alternative for today.

Michael
 
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TripleDelta
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RE: Mixing Ethanol In Aviation Fuel?

Sun Sep 18, 2005 8:25 pm

Quoting TheSonntag (Reply 13):
And I honestly do not see an advantage if you use ethanol if that increases the fuel consumption even further.

But then again, ethanol is even cheaper than Jet A. And you forget that Diesels are completely new engines, while ethanol burners are modifications of existing engines that solve an important problem in the near future - the availability of the engine and upgrade costs. People who have aircraft from the 70s, bought because of their simplicity and relatively low operating costs, will probably not buy a new engine when they can upgrade their existing engine at a fraction of the cost and take the range penalty, if they have ethanol available.

Quoting TheSonntag (Reply 13):
because they require a complete new infrastructure and engines that are modified

True, however, ethanol as such exists in quantity around the world (come on, it's 100% pure alcohol). As PPVRA stated with the example of Brasil, it would be a feasible enterprise since some manufacturing facilities, if only manufacturing processes, already exist and have been in widespread use as long as avgas. Adding ethanol into car gasoline is a widespread practice around the world and has been practiced for a while, again as PPVRA states.

Quoting TheSonntag (Reply 13):
We could also argue, however, that an aircraft equippet with a Diesel engine does not need nearly as much fuel, so it would (in theory) not be required to have as big a fuel tank as an ordinary engined aircraft, thus being lighter.

That is true I admit. But then again, everybody wants more more more...
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Dougloid
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RE: Mixing Ethanol In Aviation Fuel?

Mon Sep 19, 2005 7:02 am

Quoting Okie (Reply 3):
So eventually you will start to see some splintering of fuels used either by regional logistics, industry, or application specific when the cost of dinosaur juice escalates to the point where other fuels become cost effective.

I think you're probably right on this score...we use 10% ethanol in our mogas because we have the resources to manufacture it locally and the animals to eat up the distillers grain or slops as you like. Likewise we have enough soya to make a bit of biodiesel and the systems in place to use the residuals as feed or as tofu after further processing.

There are a few E85 (85 per cent ethanol) stations around and more production is coming on line daily.

Right now there are a number of people who are selling the necessaries to make biodiesel in your garage...the biggest expense is the methanol needed, but I figure that there is not enough restaurant spent fry grease to make a dent in the need, particularly as it's also good as an additive in poultry feed. If you want to make the stuff from new production soya oil the 20 year high was 33.9 cents per pound so figure near $2.50 per gallon.....it's still too expensive but the spread between soya and dino oil is narrowing....whether it's wise or prudent to be using a hig hquality food product to fuel tractors is another story.
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Okie
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RE: Mixing Ethanol In Aviation Fuel?

Mon Sep 19, 2005 11:40 am

Of course there is the possibility of the invention of the 10-20-30-40-50 turbine.

Weighs 10 kilos
Burns 20 gallons of fuel per hour
Has 30,000 hour TBO's
Produces 40,000 lbs of thrust
Costs $50,000


Okie
 
HiFi
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RE: Mixing Ethanol In Aviation Fuel?

Mon Sep 19, 2005 10:10 pm

Quoting PPVRA (Reply 9):
However, according to NEIVAs figures, they achieved a significant costs savings (well, we don't know the percentage, but 13.5 million USD yearly worth in AvFuel for crop dusters seems a lot! Even if for 600 of them!), so I assume they got the same amount of work done.

The engine's fuel efficiency is better with av gas than with ethanol, but ethanol is so much cheaper than it still means a cost reduction.

Quoting PPVRA (Reply 9):
Question: Considering Tod's scenario, the extra fuel weight would only restrict payload, correct? How feasible is to have such a large increase in fuel tanks?

Correct. In my opinion, this is why the range is reduced.
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KevinL1011
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RE: Mixing Ethanol In Aviation Fuel?

Fri Sep 23, 2005 10:06 am

Quoting Okie (Reply 3):
Alcohol is not compatible with many elastomers, gaskets, and sealants used in fuel systems

I believe this is a significant issue. I know for a fact here in Calif. we have up to 14% Ethanol in many fuels (since MTBE is outlawed). Ethanol is corrosive to nylon fuel pump impellers, causes seals to swell and intermittant fuel injector sticking on many older (pre 1998) vehicles. I'm not sure how applicable this is to aircraft fuel systems.

[Edited 2005-09-23 03:39:31]
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TripleDelta
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RE: Mixing Ethanol In Aviation Fuel?

Fri Sep 23, 2005 11:27 pm

Quoting Kevinl1011 (Reply 18):
I believe this is a significant issue.

That's why one of the main mods on ordinary avgas burners, when they're converted, is the reinsulation and refurbishing (and in rare cases replacement) of parts that could cause unfavorable chem reactions with ethanol.

EDIT: typos...  banghead 

[Edited 2005-09-23 16:27:58]
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