Cyclonic From Australia, joined Jan 2005, 231 posts, RR: 2 Posted (7 years 11 months 5 days 18 hours ago) and read 1948 times:
I think some of you would've heard of biofuels such as Ethanol.
With biofuels becoming an alternative to petroleum and promising more performance, is there a possibility that such fuels could be adapted for use in the aviation industry, especially for jet flight?
With fuel costs being a driving factor, correctly engineered biofuels could bring enormous cost savings and be enviromentally friendly.
Mrocktor From United States of America, joined Jan 2005, 1661 posts, RR: 50 Reply 1, posted (7 years 11 months 5 days 17 hours ago) and read 1935 times:
While it is certainly possible to run jet engines off bio fuels (such as ethanol) they carry severe penalties. Compared to jet-A, all bio-fuels (and hydrogen as well) have either poor energy/mass or poor energy/volume ratios (or both).
A poor energy/mass ratio means that you need a lot more fuel to carry the fuel. Heavier fuel means more fuel is needed for the same route, and the progression is not linear, it's exponential.
A poor energy/volume ratio means that the fuel needed to complete a route just wont fit in existing aircraft. New aircraft would have to be designed with increased tankage - which would mean heavier aircraft, more fuel needed and enter the cycle described above.
All in all, aviation is one place where "enviromentally friendly" fuels actually are not. It would be much better to convert all automobiles to ethanol than to try to mess with planes.
Oryx From Germany, joined Nov 2005, 126 posts, RR: 0 Reply 5, posted (7 years 11 months 4 days 17 hours ago) and read 1859 times:
Quoting Wingscrubber (Reply 2): Present school of thought is that Cryoplanes will replace kerosene burning jet aircraft, using liquid hydrogen or more likely liquid natural gas.
Why? If you can make hydrogen, you can also produce hydrocarbons (i.e. kerosene) which are a lot easier to handle. If you take the carbon from crops it's even C0_2 neutral. Only disadvantage is you can't eliminate nitro-oxides from a kerosene flame like you could from a hydrogen flame.
Pyrex From Portugal, joined Aug 2005, 3627 posts, RR: 28 Reply 6, posted (7 years 11 months 4 days 17 hours ago) and read 1857 times:
Quoting Oryx (Reply 5): Only disadvantage is you can't eliminate nitro-oxides from a kerosene flame like you could from a hydrogen flame.
How come hydrogen wouldn't produce nitrous oxides? As far as I know all it takes is nitrogen and oxygen (both present abundantly in air) as well as very high temperatures (which you would still have in a hydrogen flame).
Read this very carefully, I shall write this only once!
Oryx From Germany, joined Nov 2005, 126 posts, RR: 0 Reply 7, posted (7 years 11 months 3 days 23 hours ago) and read 1814 times:
You have to compromise the layout of the combustion chamber between the production of unburned carbohydrates and nitro oxides. Without the presence of carbon in the fuel you can optimize for low nitro oxides with big improvements over present combustion chambers.