Oil use: Air transport Vs. all other?

[robertbartsch]

Anyone know what percentage of all oil that is used for transportation is used for air transportation/travel?

I would assume, as time goes by, that many forms of ground transport (cars, buses, trains, ships, etc.) will become greener and use solar or wind generated electricity for power, but I assume there is no future technology that is planned to replace jet engines that run from kerosene/jet fuel (e.g., oil).

Thanks.

[XPMorten]

If I recall correct, about 3% of world total CO2 emissions come from air travel.

[spud3]

Just throwing out what I think I read, about 80% of greenhouse gas is from coal and oil electrical generation, about 20% from transportation. Close to what XP said, I heard 4% is from aviation, leaving 16% for other transportations. That's not only oil though, add coal to the electrical generation.
But robert, think of this. Doesn't liquid hydrogen have more energy per pound than avgas? Makes it ideal for airplanes that must generate the lift to carry the weight of their fuel, unlike trucks, cars

[Dan Winterland]

''I would assume, as time goes by, that many forms of ground transport (cars, buses, trains, ships, etc.) will become greener and use solar or wind generated electricity for power, but I assume there is no future technology that is planned to replace jet engines that run from kerosene/jet fuel (e.g., oil).''

I'm writing an article about this in my part time job as a journalist. (Actually, I should be but I'm not right now. I'm on PPruNe procrastinating and ignoring the editor's e-mails about passed deadlines.) It's mainly about ships going back to wind power, but I offer alternatives to other forms of transport. I reckon land vehicles will rely on electricity powered by batteries and/or fuel cells, ships by liquid fuels and or wind power, and large aircraft will have no alternative but to use liquid fuels. Bio fuels have been experimented with, 747s have been flown with an engine fueled by a kerosene substitute made from vegtable oils. The most promising so far being a Diamond Twin Star with deisel engines powered by bio-fuel refined from Algae.

[Intruder]

Doesn't liquid hydrogen have more energy per pound than avgas? Makes it ideal for airplanes that must generate the lift to carry the weight of their fuel, unlike trucks, cars

Energy per pound of raw fuel is one thing. Then there is the tankage required... What kind of tanks would be required for liquid H2, and how durable would they be?

BTW, water vapor is as much a greenhouse gas as is CO2, if not worse...

[Dan Winterland]

Liquid hyrogen is very hard to handle. The Russians flew a hydrogen fuled TU154 about ten years ago, but the risks involved would be too high for commercial operations.

[BillS]

Liquid hyrogen is very hard to handle.

In a hybrid airship the hydrogen would not necessarily be liquid.

[XPMorten]

In a hybrid airship the hydrogen would not necessarily be liquid.

Then you get a volume problem. The problem is that while hydrogen supplies three times the energy per pound of gasoline it has only one tenth the density when the hydrogen is in a liquid form and very much less when it is stored as a compressed gas. This means that hydrogen fuel tanks must be large. In addition they need to be insulated.
Even an insulated tank will leak about 2% energy pr day.
So, you get a storage and logistical problem on on the ground as well.

Large tanks in an aircraft means either
- Less payload
- More volume -> more drag & mass

XPM

[jefferybond]

Another problem is where to get the hydrogen from?

Most of the hydrogen around us has already been 'burnt', (ie. water)

Jeff

[BillS]

In a hybrid airship the hydrogen would not necessarily be liquid.

Then you get a volume problem.

Not a problem in an airship - an advantage!


And as you burn off fuel load, you decrease the lift.

[XPMorten]

No, dis-advantage there as well. Due to huge drag, airships travel at
low speeds compared to airliners. So Airships would only be good for short flights and
most people would then prefere a highspeed train which travels faster instead..

XPM

[robertbartsch]

I thought I read that hydrogen is the perfect fuel; very clean and effecient. Unfortunately, in order to produce hydrogen, you currently need to use lots of hydrocarbons to convert the raw material (H2O ??).

The stats on air transport using only around 4% of hydros is surprising to me. I would have guessed much higher - say 20%.

So the real problem with limiting fossel burns is to find a viable alternative to oil/gas for ground transport.

...interesting.

[XPMorten]

So the real problem with limiting fossel burns is to find a viable alternative to oil/gas for ground transport.

China opens a new coal power-plant each week. One of those emits
about the same amount as the entire private population in a small
european country including their air travel...

XPM

[5LY]

The real effort should be directed towards using the our hydro carbon resources more efficiently. We're not going to stop using them anytime soon, but in N. America, for example, we could be more than self sufficient if we did it efficiently, and think of the security bonus.

I've heard that the reciprocating engine that we all use is about 30% efficient. In other words, about 70% of the stored energy in a volume of fuel goes out the tail pipe. If we used the oil and coal to make and store fuel more efficiently and developed the infrastructure accordingly, we'd have something. Make hydrogen, or electricity, or whatever, and then use a more efficient method to change it to noise and motion.

[stilton]

The R2800 used a lot.


Blew a bunch over the side as well..

[MG23]

Originally Posted by 5LY

I've heard that the reciprocating engine that we all use is about 30% efficient. In other words, about 70% of the stored energy in a volume of fuel goes out the tail pipe. If we used the oil and coal to make and store fuel more efficiently and developed the infrastructure accordingly, we'd have something.

I believe electrical generation from fossil fuels is around 30% efficient too, so that doesn't help. In fact, if you then convert from electricity to an intermediate form like hydrogen, it's actually worse... the only real use for hydrogen as a power source is for a means of storing renewable energy by, say, using solar power to split water either electrically or thermally.

Interestingly I was reading about a British hypersonic aircraft design from the 60s at the weekend and that included comparative drawings of a kerosene version vs hydrogen powered... the hydrogen version was enormous in comparison. Lockheed also considered hydrogen for the Blackbird but again from what I remember the huge fuel tanks and difficulty of refueling convinced them that relatively conventional fuels were the way to go.

What you can do with a fossil fuel power plant is to exploit the waste heat in a useful manner, for example by heating houses or greenhouses. That's harder to do in a plane or a car, though electric cars are going to have to work pretty hard to warm up the passengers on a typical -40 winter's day here, while fossil-fueled cars can just use the waste heat to do so.

[TyroPicard]

Anyone know what percentage of all oil that is used for transportation is used for air transportation/travel?

Using the figures for greenhouse gases in this thread the answer seems to be: about 20%.