5 ms·

Aviation uses so much energy, it’s gotta be this or stop flying.

godelski 7y ago
Don't forget that ships aren't very efficient either. So there isn't really even a great alternative (though better, but also much slower). It is a complicated issue, unsurprisingly.
- jeffdavis 7y ago
  Ships are not efficient?
  - godelski 7y ago
    The problem is "what is efficient?" The quickest reference for emissions is Wiki [0] saying > Maritime transport accounts for 3.5% to 4% of all climate change emissions, primarily carbon dioxide. Aviation is about half that, but there is a lot less aviation, so we need to consider that. If we are saying "efficient" as a comparison, yes ships are. But that's not really the issue about climate change. The issue is that we have too much green house gasses in our atmosphere and are not slowing down (side bar: with sequestration the argument is that greenhouse gasses aren't inherently bad, but the levels are. So as long as net is zero or negative, who cares -- there is more nuance to this than suggested here). The issue is that we have to transport stuff. Sorry, but we can't live our current life unless we transport stuff globally. Doing otherwise would require drastic shift, which is needed, but come at a great cost. So do we solve it technologically or socially (I for one don't have faith in the social solution, but would love to be surprised). So the three ways we have of getting stuff across oceans (if we include Musk for entertainment value) are (in order of emissions): Shipping, Aviation, big fucking rockets (this isn't a linear scale and one of these dwarfs all the others). The issue is that we need to be at 0 or negative emissions (i.e. sequestering carbon). The short end of that argument is that US and EU combined is about 25% of global emissions and I don't know if we can trust other countries to be as aggressive as we are. (So obviously in favor of sequestration. What's the worst that can happen? We go too far and have to operate a few coal plants to balance out? LOL) The conversation is frequently a distracting one. We talk about energy, cars, and plastic straws. That accounts for <50% of a first world's carbon emissions, which energy needs are growing btw (keeping current levels of emissions is a difficult challenge alone!). Unless we have a serious conversation about this, we're never going to get to 0 emissions by 2100 (forget 2050, we've already given up on that. We're not willing to have a nuanced discussion about the issues and instead pretending paper vs plastic straws are an actual issue). [0] https://en.wikipedia.org/wiki/Environmental_impact_of_shipping https://en.wikipedia.org/wiki/Environmental_impact_of_shippi...
    - goodcanadian 7y ago
      Just a nitpick, really, but the plastic issue has little to do with climate change. It is a separate but also very important environmental problem.
hristov 7y ago
Aviation does not use that much energy. In fact if you look at it from pure energy point of view it would be very easy to generate the energy used by all aviation in the world by wind and solar. The problem with aviation is that it is hard to store energy for the actual planes. Since everything on a plane must be light, then the energy per weight (i.e., energy density) is crucial, and fossil fuels thus far have unparalleled energy density. So the solution is to make some kind of fuel that is similar to fossil fuels but is carbon neutral. What Rolls Royce is suggesting is that their nuclear plants will be perfect to power the factories that make this green fuel. But of course that is not true. Any grid connected generator can power these factories including renewables that are already much cheaper and safer than nuclear.
- darksaints 7y ago
  The specific energy (mass energy density) of pure hydrogen is 3x higher than the next best hydrocarbon fuel. It doesn't have the best volumetric energy density, but it could be good enough as liquid hydrogen. The big pushback with liquid hydrogen is that everybody thinks you need to have cryogenic storage. That's a lie. Mildly insulated tanks would work extremely well, as the fuel consumption rates of aircraft would easily exceed the evaporation rates of the fuel. It might be problematic if they sit on the runway for hours waiting for takeoff, but as long as the plane is flying, liquid hydrogen is a pretty damn good fuel.
eloff 7y ago
It's actually kind of small compared to terrestrial and sea transport believe it or not. In absolute terms, not per person. I think I read it was 1% of greenhouse gas emissions. Someone correct me if I'm wrong.
BurningFrog 7y ago
My theory is that people hugely overestimate the importance of things they see and touch. Flying is the most fossil fuel intensive thing regular people interact with, so we naturally assume it's the biggest energy user there is. Last I heard the number was around 2% of all CO₂ emissions.
- viburnum 7y ago
  Sure, but CO2 emissions need to be zero, so there has to be an alternative.
  - JumpCrisscross 7y ago
    > CO2 emissions need to be zero Net emissions. Planes burning fuel synthesised from electrolysed water and atmospheric CO2 is a closed carbon loop.
- mantap 7y ago
  CO2 emitted from an airplane at altitude isn't equivalent to CO2 emitted at ground level, in terms of global warming potential, so you have to adjust for that.
  - hollerith 7y ago
    I find that hard to believe. Can you provide a reference or a short explanation?
- duckymcduckface 7y ago
  Heating is actually the biggest user, accounts for 50% of global energy demand. This includes space heating as well as process heat.
  - markdown 7y ago
    In that case the answer is staring us in the face: we need to accelerate climate change in order to warm up the cold regions of the world and reduce our reliance on artificial heating.

Don't forget that ships aren't very efficient either. So there isn't really even a great alternative (though better, but also much slower). It is a complicated issue, unsurprisingly.

jeffdavis 7y ago
Ships are not efficient?
- godelski 7y ago
  The problem is "what is efficient?" The quickest reference for emissions is Wiki [0] saying > Maritime transport accounts for 3.5% to 4% of all climate change emissions, primarily carbon dioxide. Aviation is about half that, but there is a lot less aviation, so we need to consider that. If we are saying "efficient" as a comparison, yes ships are. But that's not really the issue about climate change. The issue is that we have too much green house gasses in our atmosphere and are not slowing down (side bar: with sequestration the argument is that greenhouse gasses aren't inherently bad, but the levels are. So as long as net is zero or negative, who cares -- there is more nuance to this than suggested here). The issue is that we have to transport stuff. Sorry, but we can't live our current life unless we transport stuff globally. Doing otherwise would require drastic shift, which is needed, but come at a great cost. So do we solve it technologically or socially (I for one don't have faith in the social solution, but would love to be surprised). So the three ways we have of getting stuff across oceans (if we include Musk for entertainment value) are (in order of emissions): Shipping, Aviation, big fucking rockets (this isn't a linear scale and one of these dwarfs all the others). The issue is that we need to be at 0 or negative emissions (i.e. sequestering carbon). The short end of that argument is that US and EU combined is about 25% of global emissions and I don't know if we can trust other countries to be as aggressive as we are. (So obviously in favor of sequestration. What's the worst that can happen? We go too far and have to operate a few coal plants to balance out? LOL) The conversation is frequently a distracting one. We talk about energy, cars, and plastic straws. That accounts for <50% of a first world's carbon emissions, which energy needs are growing btw (keeping current levels of emissions is a difficult challenge alone!). Unless we have a serious conversation about this, we're never going to get to 0 emissions by 2100 (forget 2050, we've already given up on that. We're not willing to have a nuanced discussion about the issues and instead pretending paper vs plastic straws are an actual issue). [0] https://en.wikipedia.org/wiki/Environmental_impact_of_shipping https://en.wikipedia.org/wiki/Environmental_impact_of_shippi...
  - goodcanadian 7y ago
    Just a nitpick, really, but the plastic issue has little to do with climate change. It is a separate but also very important environmental problem.

hristov 7y ago

Aviation does not use that much energy. In fact if you look at it from pure energy point of view it would be very easy to generate the energy used by all aviation in the world by wind and solar. The problem with aviation is that it is hard to store energy for the actual planes. Since everything on a plane must be light, then the energy per weight (i.e., energy density) is crucial, and fossil fuels thus far have unparalleled energy density. So the solution is to make some kind of fuel that is similar to fossil fuels but is carbon neutral. What Rolls Royce is suggesting is that their nuclear plants will be perfect to power the factories that make this green fuel. But of course that is not true. Any grid connected generator can power these factories including renewables that are already much cheaper and safer than nuclear.

darksaints 7y ago
The specific energy (mass energy density) of pure hydrogen is 3x higher than the next best hydrocarbon fuel. It doesn't have the best volumetric energy density, but it could be good enough as liquid hydrogen. The big pushback with liquid hydrogen is that everybody thinks you need to have cryogenic storage. That's a lie. Mildly insulated tanks would work extremely well, as the fuel consumption rates of aircraft would easily exceed the evaporation rates of the fuel. It might be problematic if they sit on the runway for hours waiting for takeoff, but as long as the plane is flying, liquid hydrogen is a pretty damn good fuel.

eloff 7y ago

It's actually kind of small compared to terrestrial and sea transport believe it or not. In absolute terms, not per person. I think I read it was 1% of greenhouse gas emissions. Someone correct me if I'm wrong.

BurningFrog 7y ago

My theory is that people hugely overestimate the importance of things they see and touch. Flying is the most fossil fuel intensive thing regular people interact with, so we naturally assume it's the biggest energy user there is. Last I heard the number was around 2% of all CO₂ emissions.

viburnum 7y ago
Sure, but CO2 emissions need to be zero, so there has to be an alternative.
- JumpCrisscross 7y ago
  > CO2 emissions need to be zero Net emissions. Planes burning fuel synthesised from electrolysed water and atmospheric CO2 is a closed carbon loop.
mantap 7y ago
CO2 emitted from an airplane at altitude isn't equivalent to CO2 emitted at ground level, in terms of global warming potential, so you have to adjust for that.
- hollerith 7y ago
  I find that hard to believe. Can you provide a reference or a short explanation?
duckymcduckface 7y ago
Heating is actually the biggest user, accounts for 50% of global energy demand. This includes space heating as well as process heat.
- markdown 7y ago
  In that case the answer is staring us in the face: we need to accelerate climate change in order to warm up the cold regions of the world and reduce our reliance on artificial heating.