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Author Topic: 100% biofuel for jet engines  (Read 2379 times)
brackwell
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« on: October 15, 2016, 10:21:39 AM »

US navy successfully tested 100% biofuel.http://cleantechnica.com/2016/09/22/100-percent-invisible-biofuel-powers-us-navys-green-growler/

This could be hugely important but it does not go into costs or pollution levels of the burnt fuel.
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M
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« Reply #1 on: October 15, 2016, 01:10:14 PM »

Hiya Ken.

That is very interesting, both the aviation fuel and the testing of naval bio-diesel. If the pilots and mechanics don't any problems/issues then hopefully the only way is up!  Tongue

Fingers crossed the costs and scalability are good.

Mart.
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Just call me Mart.     Cardiff: 5.58kWp PV - (3.58kWp SE3500 + 2kWp SE2200 WNW)
Countrypaul
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« Reply #2 on: October 15, 2016, 02:00:08 PM »

If the only source for the process is vegetable oil (or possibly animal fats) there is a significant risk that the food chain could again be adversely affected.

It would be even more beneficial if the feedstock could use materials that would otherwise be sent to landfill such as polystyrene and other difficult to rescycle plastics. I know these are still dino oil based, but re-using them would be far better than dumping them in the ground and would also put less pressure on the food chain.  I know a number of plces were looking at ways to recycle plastics and other materials to generate a form of crude oil that could be sent through conventional refineries but I have not seen anything recently. Given that aircraft look as though they will be on oil based fuel for considerably longer than land transport, everything that can be done to reuse oil based products and other materials that would decay just contributing to the output of CO2 should be considered imho.

It worries me that there is a philosophy from some that if they can make an aircraft run on bio - derived fuel that the problem of CO2 generation is solved - without thinking of the consequences of where that bio - fuel source will actually come from.
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spaces
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« Reply #3 on: October 15, 2016, 10:03:39 PM »

If nothing else, the exhaust gases would be a good deal less dirty, but if it uses extra land to grow fuel then surely it's a daft idea? Then again, more and more people are eating more and more meat, I suppose these things depend on where in the spectrum of acceptability individuals place them.
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pdf27
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« Reply #4 on: October 16, 2016, 05:40:48 PM »

Realistically longer range aircraft are never likely to run off batteries, simply because the power density (both of the energy storage and the conversion from stored to mechanical energy) is too poor. Right now electric motors are at best a few kW/kg for the motor alone, while high bypass turbine engines are ~10 times that including the fan system and still improving.
That means diesel-type fuels for the foreseeable future, which could come from mineral, bio- or synthetic sources. Right now synfuels are a long way from being ready for mass use, so biofuels are the only plausible near-term way to replace mineral fuels for air travel.
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M
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« Reply #5 on: October 16, 2016, 05:55:03 PM »

Hiya pdf. Can aircraft use engines that run on methane or hydrogen? Are these fuels (in compressed form) practical/safe for such use? Obviously I'm thinking of producing aviation fuel from excess RE.

Mart.
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Just call me Mart.     Cardiff: 5.58kWp PV - (3.58kWp SE3500 + 2kWp SE2200 WNW)
Countrypaul
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« Reply #6 on: October 16, 2016, 06:31:29 PM »

Can aircraft use engines that run on methane or hydrogen? Are these fuels (in compressed form) practical/safe for such use?

Problem with both of those is that you need a very heavy container in which to store them on the aircraft, and hydrogen always leaks out as it can pretty much pass through most materials although in small quantities. Conversion of methane to longer chains - ie. synfuels would be a much more likely way to approach use for an aircraft.

Jet engines can be run on methane (obviously changes in the fueling system compared to normal aircraft jet engines), not sure about using hydrogen in them, though in principle it should work.

 
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pdf27
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« Reply #7 on: October 17, 2016, 11:18:46 AM »

Methane has certainly been done, and burning it is easy - there are plenty of aeroderivative jet engines use as land based power stations burning methane. The problem is that it's really, really bulky to carry around. It has been tried, but you have to cool it down and carry it in a liquefied state to get anything like the weight and volumetric efficiency needed, and even then the bulk is enough that you really need to go for a blended wing-body design (which has a lot of otherwise unusable internal volume before it starts to make sense.
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freddyuk
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« Reply #8 on: October 18, 2016, 10:20:59 AM »

Reminds me of my first post on this site........http://www.navitron.org.uk/forum/index.php/topic,8700.0.html
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