4 ms·

At energy and cost levels that exceed airline travel, per passenger-mile.

crazygringo 5y ago
Do you have a citation for that? Quick Googling doesn't reveal any obvious authoritative answers (but a ton of guessing and unsubstantiated claims). The most authoritative/unbiased source seems to be this Wikipedia article: https://en.wikipedia.org/wiki/Energy_efficiency_in_transport https://en.wikipedia.org/wiki/Energy_efficiency_in_transport But the head-to-head comparisons are mostly gaps when it comes to trains, and the sections on trains and planes are in completely different families of units that makes comparison extremely non-trivial. :(
- redis_mlc 5y ago
  In the US, interstate and some other categories of rail require massive cars and locomotives to be used instead of light-rail cars. This affects efficiency in the US. An example is the Bay Area Caltrain, which shares track with a cargo train, so is required to use heavy-iron rolling stock. Considering that airliner jet engines increase efficiency 1% averaged per year since 1945, airliners could be more efficient than heavy trains used for passengers.
- beerandt 5y ago
  It was covered in a sustainable engineering class I took. There's not much generic into about it because every rail route proposal is different, even between the same destinations. Depends a lot on geography and what's already there. You basically need to do a full Life Cycle Analysis (LCA) for each route. Sometimes they're included in the EIS for a proposed project. That's prob the best place to start. But there's a reason most of the rail routes that keep getting proposed in the US are regional. Track and right-of-way is expensive, in both dollars and energy. Even moreso with high speed, where you need grade-seperated crossings and long, wide turns. Most people think track is shareable or reusable, but the real world limits to track capacity (trains per day) makes economies of scale difficult to implement. I posted it elsewhere, but the practical limit for non-high-speed rail is 300-400 miles, before airplanes start to make more sense. High speed is difficult to even estimate, since we don't have much here to base it on.
  - ClumsyPilot 5y ago
    China has more high-speed than the rest of the world combined, with even remote parts of China hooked up to the rail network. And when you compare energy, you have to take into account that Rail is already electric, powered directly by grid without batteries or any other efficiency loss in between. Airplanes use fuel that takes a lot of energy to refine and deliver, and will at best use hydrogen in 15 years which is 40% efficient to produce, plus losses in compression, delivery, engine, etc.
    - beerandt 5y ago
      I'm not against it. But it's usually not more energy efficient. Life Cycle Analysis takes all the inefficiencies you mention into account, down to the zip code, and includes thing like present and future mix of electrical generation. Doing it because China is, isn't really a reason. You can take into account electrifying rail, but it doesn't really change much. This all gets taken into account. >other efficiency loss in between. The grid has plenty of inefficiencies, especially if we have to start designing beyond capacity to account for intermittent sources. But electricity's main inefficiency is in its creation. LCAs take all of this into account. It's the whole purpose of doing one. Embedded energy involved in manufacture, refining, transport, everything, is all added up based on things like location and present and/or future inputs.
    - inglor_cz 5y ago
      One of the reasons why China built such a network so fast is the top-down structure of the state. If the authorities decide to build something just across your neighbourhood, you are in no position to challenge them. Although I like trains, I wouldn't want to live in such society.
  - crazygringo 5y ago
    Thanks. Is there at least some kind of super-elementary comparison? E.g. energy consumption per-passenger-mile for a fully occupied Japanese bullet train while moving at maximum speed, versus for a fully occupied Boeing 737 at cruising altitude? Obviously there are a million other factors, like takeoffs and landings, and trains stopping, as well as fuel vs electric, but wondering about even just the most basic operation.

Do you have a citation for that? Quick Googling doesn't reveal any obvious authoritative answers (but a ton of guessing and unsubstantiated claims). The most authoritative/unbiased source seems to be this Wikipedia article: https://en.wikipedia.org/wiki/Energy_efficiency_in_transport https://en.wikipedia.org/wiki/Energy_efficiency_in_transport But the head-to-head comparisons are mostly gaps when it comes to trains, and the sections on trains and planes are in completely different families of units that makes comparison extremely non-trivial. :(

redis_mlc 5y ago
In the US, interstate and some other categories of rail require massive cars and locomotives to be used instead of light-rail cars. This affects efficiency in the US. An example is the Bay Area Caltrain, which shares track with a cargo train, so is required to use heavy-iron rolling stock. Considering that airliner jet engines increase efficiency 1% averaged per year since 1945, airliners could be more efficient than heavy trains used for passengers.
beerandt 5y ago
It was covered in a sustainable engineering class I took. There's not much generic into about it because every rail route proposal is different, even between the same destinations. Depends a lot on geography and what's already there. You basically need to do a full Life Cycle Analysis (LCA) for each route. Sometimes they're included in the EIS for a proposed project. That's prob the best place to start. But there's a reason most of the rail routes that keep getting proposed in the US are regional. Track and right-of-way is expensive, in both dollars and energy. Even moreso with high speed, where you need grade-seperated crossings and long, wide turns. Most people think track is shareable or reusable, but the real world limits to track capacity (trains per day) makes economies of scale difficult to implement. I posted it elsewhere, but the practical limit for non-high-speed rail is 300-400 miles, before airplanes start to make more sense. High speed is difficult to even estimate, since we don't have much here to base it on.
- ClumsyPilot 5y ago
  China has more high-speed than the rest of the world combined, with even remote parts of China hooked up to the rail network. And when you compare energy, you have to take into account that Rail is already electric, powered directly by grid without batteries or any other efficiency loss in between. Airplanes use fuel that takes a lot of energy to refine and deliver, and will at best use hydrogen in 15 years which is 40% efficient to produce, plus losses in compression, delivery, engine, etc.
  - beerandt 5y ago
    I'm not against it. But it's usually not more energy efficient. Life Cycle Analysis takes all the inefficiencies you mention into account, down to the zip code, and includes thing like present and future mix of electrical generation. Doing it because China is, isn't really a reason. You can take into account electrifying rail, but it doesn't really change much. This all gets taken into account. >other efficiency loss in between. The grid has plenty of inefficiencies, especially if we have to start designing beyond capacity to account for intermittent sources. But electricity's main inefficiency is in its creation. LCAs take all of this into account. It's the whole purpose of doing one. Embedded energy involved in manufacture, refining, transport, everything, is all added up based on things like location and present and/or future inputs.
  - inglor_cz 5y ago
    One of the reasons why China built such a network so fast is the top-down structure of the state. If the authorities decide to build something just across your neighbourhood, you are in no position to challenge them. Although I like trains, I wouldn't want to live in such society.
- crazygringo 5y ago
  Thanks. Is there at least some kind of super-elementary comparison? E.g. energy consumption per-passenger-mile for a fully occupied Japanese bullet train while moving at maximum speed, versus for a fully occupied Boeing 737 at cruising altitude? Obviously there are a million other factors, like takeoffs and landings, and trains stopping, as well as fuel vs electric, but wondering about even just the most basic operation.