SAN787 From United States, joined Jun 2007, 616 posts, RR: 1 Posted (1 year 6 months 1 week 2 days 9 hours ago) and read 868 times:
Are the planes we are building today digging us are deeper hole for the future? While the NG aircraft and 787 are more fuel-efficient by design than ever before, it is still an old technology powered by a limited resource: oil. It is much simpler for us to keep the SUV in the garage, but what happens to airlines and their workhorses in the future when fuel is exponentially more than it is today?
I am trying to think outside the box and think of other ways to propel a 300-ton aircraft. Is hydrogen feasible in commercial aviation? What other alternative fuels could be used in the future?
Pdxcessna206 From , joined Dec 1969, posts, RR: Reply 1, posted (1 year 6 months 1 week 2 days 9 hours ago) and read 864 times:
Hydrogen isn't because it is too heavy. The only promising thing is a biofuel that doesn't freeze at high altitude; and they may have just found a way to to make it. It would be more helpful if the biofuel had more calories so the engine would use less to fly a longer distance.....Just like biodiesel does. It has more calories than petrodiesel. Ethanol on the other hand has less calories so it takes more to generate the same amount of energy.
Actually it's the lightest fuel on an energy equivalent basis. Hence it's use in the space shuttle. Hydrogen's problem is that it's too bulky.
Liquid methane is probably the best possible alternate fuel. I believe it beats Jet A on MJ/kg, but the cryogenic tanks would be something of a problem. I think it too has the volume problem, although not as bad as Hydrogen.
B6fll From , joined Dec 1969, posts, RR: Reply 3, posted (1 year 6 months 1 week 2 days 7 hours ago) and read 822 times:
How far out in the future are we talking befroe we see any of the biofuels actually being used...Im really starting to get nervous on how long I will last in this industry
PDXCessna206 From , joined Dec 1969, posts, RR: Reply 4, posted (1 year 6 months 1 week 2 days 7 hours ago) and read 805 times:
Quoting Thegeek (Reply 2): Actually it's the lightest fuel on an energy equivalent basis. Hence it's use in the space shuttle. Hydrogen's problem is that it's too bulky.
Rwessel From United States, joined Jan 2007, 944 posts, RR: 0 Reply 5, posted (1 year 6 months 1 week 2 days 7 hours ago) and read 778 times:
Quoting Thegeek (Reply 2): Liquid methane is probably the best possible alternate fuel. I believe it beats Jet A on MJ/kg, but the cryogenic tanks would be something of a problem. I think it too has the volume problem, although not as bad as Hydrogen.
Compared to Jet-A, LNG (which is close enough to pure Methane for this discussion), has about 25% higher energy density on a mass basis, but about a third less on a volume basis. As you pointed out the tanks are going to be an issue.
Frankly there's nothing really that matches the medium chain hydrocarbons for their combination of high energy content on both a mass and volume basis, and users that are very sensitive to both of those parameters are likely going to be using them for a very long time. Now whether that's traditional Jet-A refined from petroleum, bio-diesel (which comes fairly close to matching tradition kerosene on those parameters), or synthetic diesel derived from natural gas or coal, is anyone’s guess, but the airliner of 2058 will very likely be burning something very much like kerosene.
But that's not really a problem - the vast majority of applications are much less sensitive to that combination (IOW, doubling the size* of the fuel tank on a car, bus, truck or locomotive isn't really going to be a major challenge), and can more easily use alternatives - so you reserve the stuff with special properties for those uses that require them.
*Or taking a range reduction, or some other tradeoff
KennyK From United Kingdom, joined Apr 2005, 411 posts, RR: 0 Reply 6, posted (1 year 6 months 1 week 2 days 6 hours ago) and read 755 times:
The future for aviation will most probably be that in 50 years time we will still be using Jet-A. Aviation uses about 3% of World oil. Most of the rest goes on power generation, heating and other transportation. What needs to happen is a World switch away from oil in those sectors that don't really need it. Power generation from Hydro-electric, wind, other renewables and nuclear. Ground transportation by electric cars, railways etc. The plan being to use oil only where there is no real alternative i.e. aviation.
Bio-fuels are of only limited use as you would need the whole of the wheat growing areas of the US, Australia, Argentina etc just to make a small dent in world oil consumption. The only problem then is where do we get our wheat from? There is only so much land and the Worlds forests are getting the brown stuff kicked out of them all the time.
The future does not look Rosy I'm afraid when China, India and other developing nations also want an ever increasing slice of the cake.
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