Turbofans work by burning jet fuel to spin turbines, ultimately powering the massive fan you see in the front of the engine. Could you substitute the jet fuel with liquid hydrogen and, in theory, make a jet plane that produces no CO2

Yup.

http://planetforlife.com/h2/h2vehicle.html

But it will still produce con trails and probably NOX, both contribute to climate change

Personal opinion is Ammonia (NH3), less bulky, liquefies under pressure, no cryogenic freeze, but it's toxic, so handle with caution.

 

1 hour ago, Turbulent monkey said:

Turbofans work by burning jet fuel to spin turbines, ultimately powering the massive fan you see in the front of the engine. Could you substitute the jet fuel with liquid hydrogen and, in theory, make a jet plane that produces no CO2

Where did you get the Hydrogen?

You'd need a lot of solar panels or wind turbines (or whatever) to produce it.

That's easy. You can make hydrogen from fossil fuel.

C + 2 H₂O  --> 2 H₂ + CO₂

The plane doesn't make CO₂ (the hydrogen factory makes it).

The slight fly in the ointment is that the reaction also needs heat to drive it and that heat has to be supplied by burning additional fuel...

Ammonia is one way to transport "hydrogen". Methanol is another.

The fundamental problem is where do we get the energy from?
As a chemist, if you supply me with energy, I can make just about any fuel you like from things like air, water and CO₂.

Thanks for all the great replies! What are some other energy sources, besides solar and wind for their obvious deficiencies, that could be used to create the hydrogen necessary to realistically power a plane?

 

According to a Stanford study, it's possible to use WWS (wind water and solar) to power everything by 2050:

US:

https://news.stanford.edu/pr/2015/pr-50states-renewable-energy-060815.html

World:

http://www.thesolutionsproject.org/

http://thesolutionsproject.org/why-clean-energy/

 

 

11 hours ago, pzkpfw said:

Where did you get the Hydrogen?

You'd need a lot of solar panels or wind turbines (or whatever) to produce it.

Why not use the traditional hydrogen recipe; 

Zn + 2HCl --> ZnCl2 + H2

This way we can make hydrogen without making CO2.

Edited October 23, 20178 yr by Isila
Needed to add more.