The economics are quite involved, and can be easily skewed depending on what externalized costs you choose to include in your analysis.
Superficially, flying has relatively lower infrastructure costs because it only needs the two endpoints (no road, no track, no bridges, no tunnels -- all expensive items). That impacts both the initial capital cost, and the ongoing investment in maintenance.
Similarly, planes are fast: above a fairly short distance, it's much quicker to fly (by jet plane) than to travel by train or road vehicle.
But airports are difficult to access, being unwelcome in the middle of cities, and so there's a need to get to the airport as part of your journey. That part of the trip likely requires road or rail transport, and it's the most capital-intensive bits of the road/rail (ie. through urban areas).
The fuel cost of planes is also higher per passenger-distance. And beyond just simply purchasing the fuel, it's much easier (for instance) to electrify a train or car than a passenger plane. So how you account for the carbon cost will make a big difference to your result.
For the last 20 years or so, short-trip flights have been superficially cheap. The most obvious missing cost is the impact of using fossil fuel (and potentially that's even worse at high altitude), but there are other factors like the (ab)use of precarious labour, government subsidies for both fuel and facilities, noise impact, etc.
Whether it's ultimately sustainable or not all depends on what costs you choose to factor in.
I was expecting you to take a stance - either trains or planes, but your response was even better and painted a comprehensive high level picture. Thanks for taking the time. I agree with all these points, perhaps though I would challenge us about carbon-emissions with the following: If we want to progress as a civilization, is the idea to regress in and save energy expenditure in the short term; and/or in the long term become a space-exploring civilization with no limits on consumption? We kind of have an unlimited source of energy (the Sun) and if we could, we can do a lot more. Once Fusion is solved, we will have the ability to sequestrate carbon to offset everything we do on earth. I hope to see a day where talks about being miserable to save energy is completely out of the equation. Electricity and all forms of energy would be too cheap to meter for an average human.
It would be amazing to see humans build a large scale fusion reactors and Dyson spheres around the sun and never have to think about energy consumption :).
At the same time, I think we all should be disappointed in our approach towards energy production. We shouldn't have to ration it. Successful governments should be responsible for running sequestrators on tax funding.
> Once Fusion is solved, we will have the ability to sequestrate carbon to offset everything we do on earth
There are lot of IFs in your statement. Sure, it's theoretically possible to harvest so much energy that we can regard it as freely abundant without any real external costs. But this is not the case today, and probably won't be the case for hundreds of years - if ever.
* > Successful governments should be responsible for running sequestrators on tax funding. *
There's no such thing as large scale carbon sequestrations. It's unclear if this is a sensible solution to climate change in general. It makes much more sense to switch to renewables as quickly as possible and to limit emissions as much as possible. THAT's what a successful government should be responsible for, not for investing in false promises.
> It would be amazing to see humans build a large scale fusion reactors and Dyson spheres around the sun and never have to think about energy consumption :).
A Dyson sphère around the sun would make life on Earth rather miserable.
> Successful governments should be responsible for running sequestrators on tax funding.
“Sequestrators” don’t exist. There is some noise every now and then about a fancy new technology, and it gets accepted in pop science media as something that works, but we don’t really have anything practical. Besides, this would be a terrible idea, because it means we lower the cost of operations for the industry, generating profits for their private owners, whilst straining public budgets already stretched thin. This would need a radical change of how most governments operate.
Just leave a gap in the swarm for the light the earth needs (or have mirrors in the greater swarm rotate to do the same, if cheaper).
You can make hydrocarbons from c02 and water. Make digging up carbon illegal, so that only legal way to get your jet fuel is to buy it from a machine that makes it from the air (e.g. carbon-neutral fuels).
Under high temperature and pressure conditions, with expensive catalysts (I’ve had a grant to work on one of these processes a couple of years ago). It is completely uneconomical unless most government tax emissions very heavily one way or another.
Besides, this does not solve the capture bit, which is also a significant challenge, in similar ways (we have ideas about technologies, thermodynamics do not work in our favour, it would still require radical policies for it to work).
Nobody is going to wave their magic wand and make fossil fuels illegal anytime soon. It is a common techno-euphoria trap: technology is the easy bit, and we’re not there yet on that front. Policy is the struggle after that, and it is much more difficult.
Superficially, flying has relatively lower infrastructure costs because it only needs the two endpoints (no road, no track, no bridges, no tunnels -- all expensive items). That impacts both the initial capital cost, and the ongoing investment in maintenance.
Similarly, planes are fast: above a fairly short distance, it's much quicker to fly (by jet plane) than to travel by train or road vehicle.
But airports are difficult to access, being unwelcome in the middle of cities, and so there's a need to get to the airport as part of your journey. That part of the trip likely requires road or rail transport, and it's the most capital-intensive bits of the road/rail (ie. through urban areas).
The fuel cost of planes is also higher per passenger-distance. And beyond just simply purchasing the fuel, it's much easier (for instance) to electrify a train or car than a passenger plane. So how you account for the carbon cost will make a big difference to your result.
For the last 20 years or so, short-trip flights have been superficially cheap. The most obvious missing cost is the impact of using fossil fuel (and potentially that's even worse at high altitude), but there are other factors like the (ab)use of precarious labour, government subsidies for both fuel and facilities, noise impact, etc.
Whether it's ultimately sustainable or not all depends on what costs you choose to factor in.