Oil's energy contribution has declined by about 12% since 1999. The world's economies have also declined by about 12%. (Using conventional metrics, which are time delayed determinations, this will only be seen in hind sight). The massive destruction of asset values now occurring testifies to it happening.
Peak is well behind us, world economies have peaked and will continue to decline.
Hydrogen can also power conventional turbofan, turboprop and turbojet egines with even higher potential efficiency than kerosene. The problem is production, storage and transport of fuel to the aircraft. Same problem as for autos.
Joined: Mar 22, 2005 Posts: 30 Location: Idaho, USA
Posted: Wed Mar 23, 2005 11:12 am Post subject:
Hydrogen isn't feasible. Cracking the water molecule is easy, but requires much electricity. This results in a net loss of energy.
But, you do get valuable oxygen, also...
As far as biodiesel, it's great on a small scale, but the entire continent of Africa would need to be converted to soybean farms to replace oil in our society and we'd still need oil for fertilizers. If it was scalabe, it would be done, but nothing we have discovered gives the energy return for energy invested like oil: 30:1
Nothing even comes close. Remember, we aren't concerned that oil will run out, but that cheap oil will be a thing of the past. All other forms of energy production are, in comparison to oil, very expensive. _________________ They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety.
-Benjamin Franklin
Joined: Oct 12, 2004 Posts: 1012 Location: In the suburban sea of strangers
Posted: Wed Mar 23, 2005 12:56 pm Post subject:
Air travel makes sense when time is valuable and fuel isn't. In a future of high unemployment and underemployment (lots of idle time) and precious fuel; bus, rail, and ocean vessel transport will return as air travel declines.
We will spend the remainder of the century slowly wearing out the existing fleet of aircraft at much lower volumes of travel, and they will use the same fuel as ever.
I imagine in the next century whatever flying still occurs will be based on some sort of bio-fuel. I heard Brazil is now manufacturing alchohol fueled small aircraft.
Or that's what I'm guessing will happen.
Has the sun set on my catapult idea? _________________ "When you understand why you dismiss all the other possible gods, you will understand why I dismiss yours." - Stephen F Roberts.
Posted: Wed Mar 23, 2005 1:39 pm Post subject: Re: How else can commercial aviation continue without oil?
Chachi wrote:
I can see how alternative fuels can provide power for almost all types of transport, but how can a jet engine create thrust to propel a plane without jet fuel or another petroleum based byproduct?
It's called biojetfuel. (I know, it doesn't sound like a very creative name). It's being developed as we speak.
Presentations on biojetfuel will be given at the 14th European Biomass Conference, to be held in Paris, october 17-21: Conference _________________ The Beginning is Near!
I imagine in the next century whatever flying still occurs will be based on some sort of bio-fuel. I heard Brazil is now manufacturing alchohol fueled small aircraft.
I read that also. Small aircraft (turbo-props) will likely make a comeback. I read that they are 2x as fuel efficient compared to jets. They are slower (200 mph to 300 mpg) but they are much lighter and fuel efficient.
Not as many people will get to fly anywhere in the future, but flight will continue with ethanol (corn, sugar, cellulose).
The return of the Zeppelin! I have always been a big fan of Zeppelins, sure they fly much slower but imagine an old-school Hindenburg-liner only this time filled with Helium and powered by solar energy, floating majesticly over beautiful landscapes while you sit in a comfortable leatherchair in front of huge panorama windows, sipping your martini! I seriously think this could be one example how, when we are forced to increase energy efficiency, this could at the same time turn out to be a booster of living quality...
Also for cargo-lifting Zeppelins would be great. Sadly enough one german company who tried to build them types of Zeppelins just went broke, but I am sure this idea will have a great comeback....
Also, when you absolutely need to get from point A to B the fastest possible way (business people), I think there are solutions beyond flight.
Consider this: The swiss are planning a gigantic "subway", consisting of underground vaccum tubes with magnetic rails, where trains would almost reach the speed of planes while using almost no energy! (because there is almost no friction, so you basically only need the energy for acceleration, and when you are slowing the train you can even gain back part of the energy from that!)
Joined: Aug 14, 2004 Posts: 2069 Location: San Diego, Ca.
Posted: Sun Apr 10, 2005 5:22 pm Post subject:
Quote:
I know about Scramjets and hydrogen, but these have to be flying faster than the speed of sound before the scramjet can work.
How many scram jet planes are in operation? We have had supersonic commercial planes (Concord & Tu-144) but they are all retired with no replacement in sight.
The aviation industry is in decline and its decline will accelerate after Peak Oil. I expect a regression in aviation technology. In the future, I expect complicated/expensive systems (airframe, engines, avionics, etc.) to be replaced with cheaper, simpler systems. Who is going to continue to buy 747-400s, 777s & A380s in a forever shrinking (collapsing?) economy?
Eventually, commercial aviation will only be available for the rich/upper class due to high costs.
When you think about aviation, think about the entire system (especially the energy required...it is not just the jet fuel folks):
-Aircraft manufacturing/maintenance
-Pilots, stewardesses, mechanics
-The Air Traffic Control system equipment & personnel
-Airport maintenance & infrastructure (parking lots, runways, crash/fire crews, navigation/electronic equipment, all the jobs associated with airports, etc.)
-Security personnel
-GOVERNMENT SUBSIDIES!
-CUSTOMERS!
It is a huge and complex system which requires heavy inputs of money and energy. Both of which may be in short supply after Peak Oil.
If you think "big picture" rising jet fuel costs aren't that big of a deal. It is effect that Peak Oil has on the economy that is/will be the primary factor regarding the demise of the industry.
Finding a substitution for fossil-jet fuel is not going to solve anything. The entire infrastructure & economy has to be adequately supplied with cheap energy or the entire system will decline and/or collapse. _________________ "Peak oil isn't more than an interesting industry factoid and doesn't have anything to do with the hysterics speculated on ad nauseum around here!" ReserveGrowthRulz
The return of the Zeppelin! I have always been a big fan of Zeppelins, sure they fly much slower but imagine an old-school Hindenburg-liner only this time filled with Helium and powered by solar energy, floating majesticly over beautiful landscapes while you sit in a comfortable leatherchair in front of huge panorama windows, sipping your martini! ... Also for cargo-lifting Zeppelins would be great. Sadly enough one german company who tried to build them types of Zeppelins just went broke, but I am sure this idea will have a great comeback....
Also, when you absolutely need to get from point A to B the fastest possible way (business people), I think there are solutions beyond flight. ...
I think you are on to something. Maybe not Zeppelins but aircraft design has emphasized speed for many decades. If fuel is the primary criteria airplanes will become very much slower. Aerodynamic drag, and therefore fuel inefficiency, goes up as the square of velocity. _________________ We're all entitled to our own opinions...but we have to share the facts.
I agree with one of the previous posters. For short-range travel over untraversable terrain, lighter-than-air will be the way to go. For international travel, Sea power will make a big comeback. Heck, why not sailing ships?
Land travel will probably dominated by trains & human-powered vehicles. Electrical vehicles too if electrical power (nuclear?) goes online rapidly enough.
One thing that passed my mind is that demand on the grid changes over the day (the lowest being at night) which is, I assume, the usual time cars would get recharged. Maybe there's a possibility of playing with that.
Joined: Apr 13, 2005 Posts: 53 Location: Kingston, ON, Canada
Posted: Fri Apr 22, 2005 1:35 pm Post subject:
Liquid hydrogen can fuel a plane. Sure it's expensive, but at least it'll work. Some things to consider: Electrolysis of water is energy intensive because there are lots of processes that occur including compression and if you want liquefied H2, then you have to reduce the temperature to about 30 Kelvin, that's -243C. Liquefied H2 also leaks from a lot of containers (more so than compressed hydrogen gas).
There is a way that I've heard of making H2, which is direct cracking of the water molecule. This requires very high temperatures and can be done with a nuclear reactor. Note that this is not electrolysis and it is apparently much more efficient. I think work in Japan is being done on this.
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