Is there any future technology that can replace the jet engine?

[whowhatwhy]

I was just watching a debate on all this carbon neutral issue and aviation was cited again and again as a big contributor to global CO2 levels (I know that it's not, compared to say...industrial USA or China, but it got me thinking)

Is there ANY future (less harmful to the environment) engine / propulsion system that is in the pipe line that may one day replace the jet turbine engine? I'm not talking scramjet technology, but rather something completely different?

[jake-the-peg]

I would imagine a hydrogen fuelled jet engine would be the most likely contender.

I can't see electric planes taking off


......I'll get me coat!

[Llamatron]

Giant catapults.

[Space]

this?
www.newscientist.com/.../dn1027.html

[lord molly]

a Swiss/German company hae been working on a fuel cell aircraft, due to be on sale in 2010

[lord molly]

jake-the-peg


the space shuttles use hydrogen fuel, and combust it with pure oxygen to leave only water. the engines them elves are super efficent, but extracting pure H2 and O2 require huge ammounts of electricity. although some electricity may be used via solar cells, this does not provide the ammount of voltage required to carry out the extraction. unfortunatly for the enviroment, the mane source of the power used in the extraction is from the combustion of fossil fuels. the reason why NASA use these fuels is due to the massive ammount of energy release when the two combust.



hydrogen fuel cells are far more enviromentally friendly, again producing only water as a bi-product, and no using the vast ammount of electricity to sepetare the two elements.