4 ms·

Net win or loss on carbon emissions? Planes are awful fuel-wise but ships use bunker fuel...

thatfrenchguy 5y ago
No matter how you look at it and what you compare it against, flying is always going to emit more carbon because... flying is hard compared to moving on the ground.
version_five 5y ago
My guess is that bunker fuel is (way) worse for other pollutants - sulphur compounds etc, but overall much higher efficiency when used to drive a giant container ship, so much lower CO2 per unit of freight overall.
- AnimalMuppet 5y ago
  I'm not sure bunker fuel is worse for other pollutants. There's going to be much more jet fuel. If jet fuel emits 1% as much sulphur but there's 100x as much burned, then it's a wash.
missedthecue 5y ago
Bunker fuel is relatively low in terms of CO2 emissions, requires far less energy and emissions to refine, and its use is disallowed anywhere near land. Given this, aside from pollution being something we don't like to do in general, there's no particular reason why bunker fuel is worse than something else. Emitting NOx thousands of kilometers from people, plants, or animals isn't really harmful.
- mym1990 5y ago
  What about the ocean?
  - missedthecue 5y ago
    What about it? Since the major sink of methane in the atmosphere is by reaction with OH radicals, the NOx emissions from ship travel leads to a net global cooling, according to Wikipedia. The main threat of NOx is to the respiratory tract of mammals, very few of whom find themselves in the middle of Pacific.
  - op00to 5y ago
    It all evens out. As the glaciers melt and sea levels rise, that will dilute the acidification from bunker fuel. (sarcasm)
  - dredmorbius 5y ago
    SO2 and NO2 are fairly concentrated along shipping routes, and degrade fairly rapidly in the atmosphere. Concentrations over most regions are fairly limited, though concentrations in coastal regions (which tend to be where marine life congregates) is higher than the average. Their principle risk to humans is as lung irritants when concentrated in air near large populations. As is clear here, the concentrations even along shipping routes are far lower than in urban regions. SO2 (fuel contaminant, notably in bunker fuel and coal): https://earth.nullschool.net/#current/chem/surface/level/overlay=so2smass/winkel3/loc=84.568,2.392 https://earth.nullschool.net/#current/chem/surface/level/ove... NO2 (a result of any combustion using atmospheric air which is 70% nitrogen, not merely a fuel contaminant): https://earth.nullschool.net/#current/chem/surface/level/overlay=no2/winkel3/loc=84.568,2.392 https://earth.nullschool.net/#current/chem/surface/level/ove...
    - mym1990 5y ago
      I appreciate the thorough response! I was genuinely interested in the effects :)
      - dredmorbius 5y ago
        NB: not my specialty, so I've likely missed other effects. Searching scholarly literature for "SO2 impacts on marine life" and "NO2 impacts on marine life" could be illuminating. Sulfur dioxide in particular produces sulfuric acid. Small changes to pH and specific acid/base concentrations of seawater, even if limited to a narrow vertical column, could have large impacts. Say, non floating plankton, especially primary producers. There's also the potential for positive "seeding" effects by introducing limiting nutrients to water, though my understanding is that iron and carbon are more likely to play these roles.
- JCharante 5y ago
  I was under the impression that animals live in the ocean.
  - missedthecue 5y ago
    As it happens, fish seldom travel to the upper atmosphere to take a breath.
jjk166 5y ago
In terms of carbon emmissions way way worse. Like not even close. A cargo ship consumes about 91 times as much fuel as a plane per trip, while transporting about 6000 times as much cargo, meaning the plane burns about 66 times as much fuel per unit of cargo. Jet fuel and marine bunker fuel both produce between 3.1 and 3.2 kg of CO2 per kg of fuel; jet fuel is slightly less dense at .74 kg/L vs .86 kg/L for marine bunker, but still planes are producing about 56 times as much CO2 per unit of cargo. Marine bunker has way higher sulpher content, which is a whole other issue, but as of earlier this year not by as much. Until this year, sulphur for marine fuel was capped at 3.5% by weight, now it's down to 0.5%. Jet fuel, for comparison, is required to be under 0.3% by weight. It should be noted though that planes release their emissions at higher altitudes, where both CO2 and sulphur do more damage, and ships can carry scrubbers to be cleaner (though many still don't) because they are not nearly as sensitive to weight as a plane. While in absolute terms there are larger sources of pollution, per unit of utility flying is one of the most polluting things humans do.
- beambot 5y ago
  > It should be noted though that planes release their emissions at higher altitudes, where both CO2 and sulphur do more damage [...] Stratospheric sulfur aerosols are largely considered one geoengineering solutions for global warming. How does this jive with your statement? https://en.wikipedia.org/wiki/Stratospheric_sulfur_aerosols https://en.wikipedia.org/wiki/Stratospheric_sulfur_aerosols
  - jjk166 5y ago
    Considered and widely rejected due to issues like acid rain, ozone depletion, and decreased photosynthesis. Maybe if carefully distributed at optimal locations and altitudes you could maximize the cooling effects while minimizing damage, but random emission from flights in no way optimized for that purpose? No, it's just pollution.
  - kortex 5y ago
    Seconding what jjk said, also airliners cruise in the troposphere, not the stratosphere. > From the planetary surface of the Earth, the average height of the troposphere is 18 km (11 mi; 59,000 ft) in the tropics; 17 km (11 mi; 56,000 ft) in the middle latitudes; and 6 km (3.7 mi; 20,000 ft) in the high latitudes of the polar regions in winter; thus the average height of the troposphere is 13 km (8.1 mi; 43,000 ft). Airliners cruise around flight level 310-380 (31-38,000', about 5.9 to 7.2 miles).
epolanski 5y ago
This is an environmental disaster.
freeflight 5y ago
Afaik ships can realistically run on LNG or hydrogen, there is no reason they have to use bunker fuel except it being the cheapest.
- Ekaros 5y ago
  I think there was some recent studies that LNG might not be that great sort term solution due to losses in handling it. That is higher methane emissions and with methane having higher green house effect. After all handling a gas is harder than handling liquid. So some of it tends to leak in many parts of use negating some of the gains.

No matter how you look at it and what you compare it against, flying is always going to emit more carbon because... flying is hard compared to moving on the ground.

version_five 5y ago

My guess is that bunker fuel is (way) worse for other pollutants - sulphur compounds etc, but overall much higher efficiency when used to drive a giant container ship, so much lower CO2 per unit of freight overall.

AnimalMuppet 5y ago
I'm not sure bunker fuel is worse for other pollutants. There's going to be much more jet fuel. If jet fuel emits 1% as much sulphur but there's 100x as much burned, then it's a wash.

missedthecue 5y ago

Bunker fuel is relatively low in terms of CO2 emissions, requires far less energy and emissions to refine, and its use is disallowed anywhere near land. Given this, aside from pollution being something we don't like to do in general, there's no particular reason why bunker fuel is worse than something else. Emitting NOx thousands of kilometers from people, plants, or animals isn't really harmful.

mym1990 5y ago
What about the ocean?
- missedthecue 5y ago
  What about it? Since the major sink of methane in the atmosphere is by reaction with OH radicals, the NOx emissions from ship travel leads to a net global cooling, according to Wikipedia. The main threat of NOx is to the respiratory tract of mammals, very few of whom find themselves in the middle of Pacific.
- op00to 5y ago
  It all evens out. As the glaciers melt and sea levels rise, that will dilute the acidification from bunker fuel. (sarcasm)
- dredmorbius 5y ago
  SO2 and NO2 are fairly concentrated along shipping routes, and degrade fairly rapidly in the atmosphere. Concentrations over most regions are fairly limited, though concentrations in coastal regions (which tend to be where marine life congregates) is higher than the average. Their principle risk to humans is as lung irritants when concentrated in air near large populations. As is clear here, the concentrations even along shipping routes are far lower than in urban regions. SO2 (fuel contaminant, notably in bunker fuel and coal): https://earth.nullschool.net/#current/chem/surface/level/overlay=so2smass/winkel3/loc=84.568,2.392 https://earth.nullschool.net/#current/chem/surface/level/ove... NO2 (a result of any combustion using atmospheric air which is 70% nitrogen, not merely a fuel contaminant): https://earth.nullschool.net/#current/chem/surface/level/overlay=no2/winkel3/loc=84.568,2.392 https://earth.nullschool.net/#current/chem/surface/level/ove...
  - mym1990 5y ago
    I appreciate the thorough response! I was genuinely interested in the effects :)
    - dredmorbius 5y ago
      NB: not my specialty, so I've likely missed other effects. Searching scholarly literature for "SO2 impacts on marine life" and "NO2 impacts on marine life" could be illuminating. Sulfur dioxide in particular produces sulfuric acid. Small changes to pH and specific acid/base concentrations of seawater, even if limited to a narrow vertical column, could have large impacts. Say, non floating plankton, especially primary producers. There's also the potential for positive "seeding" effects by introducing limiting nutrients to water, though my understanding is that iron and carbon are more likely to play these roles.
JCharante 5y ago
I was under the impression that animals live in the ocean.
- missedthecue 5y ago
  As it happens, fish seldom travel to the upper atmosphere to take a breath.

jjk166 5y ago

In terms of carbon emmissions way way worse. Like not even close. A cargo ship consumes about 91 times as much fuel as a plane per trip, while transporting about 6000 times as much cargo, meaning the plane burns about 66 times as much fuel per unit of cargo. Jet fuel and marine bunker fuel both produce between 3.1 and 3.2 kg of CO2 per kg of fuel; jet fuel is slightly less dense at .74 kg/L vs .86 kg/L for marine bunker, but still planes are producing about 56 times as much CO2 per unit of cargo. Marine bunker has way higher sulpher content, which is a whole other issue, but as of earlier this year not by as much. Until this year, sulphur for marine fuel was capped at 3.5% by weight, now it's down to 0.5%. Jet fuel, for comparison, is required to be under 0.3% by weight. It should be noted though that planes release their emissions at higher altitudes, where both CO2 and sulphur do more damage, and ships can carry scrubbers to be cleaner (though many still don't) because they are not nearly as sensitive to weight as a plane. While in absolute terms there are larger sources of pollution, per unit of utility flying is one of the most polluting things humans do.

beambot 5y ago
> It should be noted though that planes release their emissions at higher altitudes, where both CO2 and sulphur do more damage [...] Stratospheric sulfur aerosols are largely considered one geoengineering solutions for global warming. How does this jive with your statement? https://en.wikipedia.org/wiki/Stratospheric_sulfur_aerosols https://en.wikipedia.org/wiki/Stratospheric_sulfur_aerosols
- jjk166 5y ago
  Considered and widely rejected due to issues like acid rain, ozone depletion, and decreased photosynthesis. Maybe if carefully distributed at optimal locations and altitudes you could maximize the cooling effects while minimizing damage, but random emission from flights in no way optimized for that purpose? No, it's just pollution.
- kortex 5y ago
  Seconding what jjk said, also airliners cruise in the troposphere, not the stratosphere. > From the planetary surface of the Earth, the average height of the troposphere is 18 km (11 mi; 59,000 ft) in the tropics; 17 km (11 mi; 56,000 ft) in the middle latitudes; and 6 km (3.7 mi; 20,000 ft) in the high latitudes of the polar regions in winter; thus the average height of the troposphere is 13 km (8.1 mi; 43,000 ft). Airliners cruise around flight level 310-380 (31-38,000', about 5.9 to 7.2 miles).

epolanski 5y ago

This is an environmental disaster.

freeflight 5y ago

Afaik ships can realistically run on LNG or hydrogen, there is no reason they have to use bunker fuel except it being the cheapest.

Ekaros 5y ago
I think there was some recent studies that LNG might not be that great sort term solution due to losses in handling it. That is higher methane emissions and with methane having higher green house effect. After all handling a gas is harder than handling liquid. So some of it tends to leak in many parts of use negating some of the gains.