Nuclear Airplane

[Mudcat]

As far as commerical aviation goes, even if technically possible it is economically unfeasible. I would hate like hell to be in charge of a marketing campaing to get people to buy tickets on a plane with nuclear reactor on board............

I'm glad I'm not the only one who sees that.

 

[Trakar]

I'm glad I'm not the only one who sees that.

Actually, the novelty (at first) would probably attract far more than it would repel.

 

[Travis]

What started this was me thinking of how with cars we can eventually convert them to electric operations and thus eliminate internal combustion engines. But with jet liners the problem is much more complicated. How do we get all electric jet liners that don't use up precious fossil fuels or exhaust greenhouse gases?

A nuclear powered plane was one of the only things I came up with.

Taking this another direction: if the government banned the use of jet fuel in jetliners what would be the technology that would replace them?

 

[shuttlt]

Taking this another direction: if the government banned the use of jet fuel in jetliners what would be the technology that would replace them?

I thought somebody was supposed to be inventing hyperloop transport any day now...?

 

[Mark6]

What started this was me thinking of how with cars we can eventually convert them to electric operations and thus eliminate internal combustion engines. But with jet liners the problem is much more complicated. How do we get all electric jet liners that don't use up precious fossil fuels or exhaust greenhouse gases?

Use electricity from solar or nuclear power plants to synthesize hydrocarbons out of CO2 and water. Use these hydrocarbons in jet engines. Also in internal combustion engines.

 

[ElMondoHummus]

Mr. Fusion it is then

Love it, but it'd be a pain to have to haul the garbage up a ladder every time you needed to refuel.

 

[catsmate]

What started this was me thinking of how with cars we can eventually convert them to electric operations and thus eliminate internal combustion engines. But with jet liners the problem is much more complicated. How do we get all electric jet liners that don't use up precious fossil fuels or exhaust greenhouse gases?

A nuclear powered plane was one of the only things I came up with.

Taking this another direction: if the government banned the use of jet fuel in jetliners what would be the technology that would replace them?

Peanut oil and other biofuels. Butanol perhaps, produced from bacterial consumption of organic waste.

 

[TjW]

Hydrogen has very poor energy density, the whole craft would need to be fuel tanks- high pressure, heavy tanks.

But hmmm, liquid rocket fuel of some kind, using nuke electricity to make? There has got to be something renewable with a huge energy density. Not as hazardous as rocket fuel, because it can still use atmospheric oxygen.

If only there were some way to bond the hydrogen with some other chemical -- say, carbon -- that would result in an easy to handle liquid fuel.

 

[Mitchell314]

As far as commerical aviation goes, even if technically possible it is economically unfeasible. I would hate like hell to be in charge of a marketing campaing to get people to buy tickets on a plane with nuclear reactor on board............

On the bright side, getting the world's attention won't be hard. That's half of the marketing job done right there. Just don't call it a nuclear plane. More like . . . Transmutational Translation Technology.

 

[smartcooky]

Love it, but it'd be a pain to have to haul the garbage up a ladder every time you needed to refuel.

I give you The Solution

The MK1 Nuclear Aircraft Refueller from Fusion Industries

 

[Trakar]

What started this was me thinking of how with cars we can eventually convert them to electric operations and thus eliminate internal combustion engines. But with jet liners the problem is much more complicated. How do we get all electric jet liners that don't use up precious fossil fuels or exhaust greenhouse gases?

A nuclear powered plane was one of the only things I came up with.

Taking this another direction: if the government banned the use of jet fuel in jetliners what would be the technology that would replace them?

There is no reason to ban jet fuel, but a ban on fossil fuel systems doesn't necessitate electric powered systems, flying nuclear power systems, nor even any revolutionary change in current designs. It is rather simple to produce kerosene without using fossil fuel feedstocks. Additionally, there are many potential biofuel systems that could replace fossil-sourced kerosene.

 

[pteridine]

There are ways to take CO2 and water and make Methane with electric power. Then you can make the Methane into a long-chain Furan and that will burn in an engine just fine and has an acceptable power density.

It is simpler to reduce CO2 with hydrogen from electrolysis of water using nuclear generated electricity. Look up Fischer-Tropsch reaction [CO + 2H₂ -> [CH2]_n] The South Africans made jet fuel and diesel using this reaction after gasifying coal to produce the synthesis gas. This was when the world was castigating them and not selling them petroleum. The only problem is cost of hydrogen. This is the show stopper every time someone thinks that they have an original idea when they suggest reducing CO₂ to make "valuable products." The cost of hydrogen swamps everything else.
The net result of schemes to produce fuel from CO2 is that hydrogen is combusted using carbon as a carrier. This is actually a much better way to go than to try to use gaseous or liquid molecular hydrogen.

Making methane into a "long chain furan" wouldn't be easy. What substituted furan did you have in mind? Have you confused this with something else?

 

[Travis]

I thought somebody was supposed to be inventing hyperloop transport any day now...?

There will be a hyperloop from America to Japan?

Use electricity from solar or nuclear power plants to synthesize hydrocarbons out of CO2 and water. Use these hydrocarbons in jet engines. Also in internal combustion engines.

Peanut oil and other biofuels. Butanol perhaps, produced from bacterial consumption of organic waste.

There is no reason to ban jet fuel, but a ban on fossil fuel systems doesn't necessitate electric powered systems, flying nuclear power systems, nor even any revolutionary change in current designs. It is rather simple to produce kerosene without using fossil fuel feedstocks. Additionally, there are many potential biofuel systems that could replace fossil-sourced kerosene.

Wouldn't all those produce CO2? Maybe I wasn't clear but the idea was to ban all air travel that produces CO2 as well.

What would be a viable airliner that could take 300+ people from LA to Sydney without producing greenhouse gases?

 

[Brian-M]

Wouldn't all those produce CO2? Maybe I wasn't clear but the idea was to ban all air travel that produces CO2 as well.

What would be a viable airliner that could take 300+ people from LA to Sydney without producing greenhouse gases?

You quoted some of the solutions. Make jet fuel out of biofuels, or synthesize it using nuclear or solar (or tidal, hydro, geothermal, wind, ect).

Remember, any CO2 the jet puts into the atmosphere by burning the non-fossil fuel was first taken out of the atmosphere to produce the fuel. The result is a net increase of atmospheric CO2 level of zero.

 

[lpetrich]

One needs a high power-to-weight ratio to be a good airplane engine. Keeping weight-to-everything-else down is absolutely critical in designing an airplane and its systems.

The Boeing 777 uses two General Electric GE90 turbofan jet engines. (Orders of magnitude (power)^WP, General Electric GE90^WP, Boeing 777^WP).

Engine power: 75 megawatts (not sure whether this is thermal or mechanical)
Engine mass: 7.55 metric tons (megagrams)

For 777-200:
Airplane empty mass: 134.5 mt
Airplane max landing mass: 201.84 mt
Airplane max takeoff mass: 247.2 mt

About 40 mt per engine, using landing mass, since the plane must land with its engines.
Power/mass: 1.875 MW/mt


After some searching, I discovered: Power to Overall Weight Ratio of the 2013 Hyperion Power Nuclear Reactor
Mass: 20 mt
Thermal power: 70 MW
Electrical power: 30 MW
Power/mass: 3.5 MW/mt (thermal), 1.5 MW/mt (electrical, mechanical)


So a nuclear reactor could just about make it as an airplane engine.

 

[lpetrich]

Battery-powered airplanes are totally impractical, from considering releasable energy per unit mass. Energy density^WP has a nice table.

Gasoline, kerosene, and diesel fuel have around 46 MJ/kg, leaving out the oxygen from the air.

Hydrogen is even better, at 123 MJ/kg, but it's difficult to store.

Lithium-ion batteries are about 0.72–0.875 MJ/kg, and lead-acid ones are about 0.17 MJ/kg. The best case for batteries is about 1/50 that of typical fuel hydrocarbons.


But as some of the other posters here have pointed out, it's possible to make liquid hydrocarbon fuels from a variety of sources.

As to making hydrogen, electrolysis has the problem of needing platinum for its electrodes, though I've found some research on alternatives to platinum. I've also found a thermal cycle that runs at about 1000 - 1500 C:

Around 1000 C:
Fe2+ to Fe3+
2FeO + H2O -> Fe2O3 + H2

Around 1500 C:
Fe3+ to Fe2+
Fe2O3 -> 2FeO + (1/2)O2

Team Weimer
Efficient Generation of H2 by Splitting Water with an Isothermal Redox Cycle

 

[Trakar]

There will be a hyperloop from America to Japan?

Wouldn't all those produce CO2? Maybe I wasn't clear but the idea was to ban all air travel that produces CO2 as well.

What would be a viable airliner that could take 300+ people from LA to Sydney without producing greenhouse gases?

The idea is to ban the addition of GHGs that come from previously geologically sequestered carbon sources. Carbon that is already in the active planetary carbon cycle which is converted into fuel and subsequently burned is carbon-neutral in its environmental impact. If you really want to take a proactive stance you could require that a % of the carbon captured from the atmosphere used to create such carbon-neutral fuels be converted to longer-term stable forms and sequestered from the environment, thereby making the process create a carbon-negative fuel. Probably not a winning solution for automobile fuels, but certainly viable as a specialty use aviation fuel.

 

[Brian-M]

Hydrogen is even better, at 123 MJ/kg, but it's difficult to store.

Awesome, so liquid hydrogen would make a great airplane fuel!

(ETA: But not the most efficient fuel. It takes a lot of energy to liquify hydrogen.)

As to making hydrogen, electrolysis has the problem of needing platinum for its electrodes, though I've found some research on alternatives to platinum.

Why would you need platinum?

I suppose if you don't want to replace the electrodes due to corrosion on a regular basis, platinum might come in handy. But what's wrong with carbon electrodes or gold-plated electrodes?

 

[Trakar]

Awesome, so liquid hydrogen would make a great airplane fuel!

(ETA: But not the most efficient fuel. It takes a lot of energy to liquify hydrogen.)

Low volume density.

Look at a rocket's LH tanks. Liquid H2 is a very low mass substance.

Compare picture 5 on page 11 of this pdf
http://ftp.rta.nato.int/public//PubFullText/RTO/EN/RTO-EN-AVT-150///EN-AVT-150-14bis.pdf

with a more normal airliner as depicted
http://en.wikipedia.org/wiki/File:Jet-liner's_main_fuel_tanks.PNG

Difficult if not impossible to build cryo tanks into wings of H2 aircraft.

Don't get me wrong H2 aircraft are certainly possible, just not an easy or cheap solution to the problem.

 

[Travis]

Didn't Lockheed try to use Hydrogen as a fuel on the Blackbird project?