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Bounty/Fee: Effective Travel, London <-> Barcelona, what is most effective?

-Offering GBP200 (or offer) for short analysis on effective travel

-I need to travel from London to Barcelona, return

-All in considering emissions, opportunity cost (time, and what we could donate to) etc. is plane better than train, or not? (And possibly electric vehicle car even better?)

I’m offering GBP200 for an analysis of effective travel, specifically London to Barcelona, but would take any general principles.


My trip is (west) London to Barcelona (Marriott Hotel). I did this basic analysis (see below and notes), for 4 days at end of Nov 2022.


  • Train, 12 hours, 2 changes. USD350-450.  Carbon est:  75 kg CO2 (eco passenger). Smog hydrocarbons at 67g
  • Plane, 3-4 hours, no changes. Price: USD 150 - 200. Carbon est: 108 kg CO2 (according to eco passenger and google calculator, which has range 80 - 120 kg CO2 so at the low end very close to the train) Smog hydrocarbons at 45g (vs 67 for train)

But ecopassenger has other polluting impacts which are higher for train (smog hydrocarbons - this is an issue for air pollution and ozone).  It’s not clear to me from London which is immediately better. How damaging are smog hydrocarbons? Do I need to consider plane water vapour? How accurate are thes models?

Then I think you need to consider there is likely a USD100 - USD200 type of saving, possibly more. Assuming you could put eg. half of that into something impactful (even at worse, just some trees) would that negate the estimated extra carbon?

Possible consideration: My company will offset my plane flight in any case, with variable quality carbon offsets. (My company has a form of operational “net zero”in that it will offset its scope 1 + 2 carbon emissions, the offsets are not great quality but that anlaysis is beyond scope).

Does the extra time used up in train travel count for anything? Do I or should I consider any “social signalling” effects (if I am considered someone who some people will look to my actions).



London —> Barcelona, by Place vs Train vs Car (diesel) via ecopassenger model.

The estimates and inputs also have enough variance to me that suggests a +/- 25% on the carbon dioxide element can vary a lot by load and other factors.  Hm. I’m also a little bit worried about the strength of the methodology for instance much depends on the mix of the train, is it electric or diesel? The model is also a few years old.  Also the RFI factors, or the indirect non-carbon impacts eg water vapour in the air, are vary hard to model - and currently so inaccurate as to be missing in most models.

The Google model is close to the same but, eg these 3 flights below, are in the 82 to 94kg CO2 range which is close enough to the train estimate (depending on how you get to the airport and train). If you book this far in advance, the price saving is substantial. One can make the argument that using this saving, or even only half the saving, and placing that in a good impact investment or charity would be more impactful.



Another clear item is that cars running on diesel are poor choices. But that electric battery cars are actually better than trains with a national mix (ofc, grid in France is a lot nuclear). This shows the importance of the electrification of cars. Below is the journey in a 2 person electric car, Paris to Barcelona. Of course, there are other impacts to think about but on these electric cars seem winners.


In sum, open questions:

  • Is more effective to travel by train or plane London to Barcelona and return? How should we consider this?
  • What are good estimates for carbon and hydrocarbon damages? Should we consider the water vapour impact of planes?
  • Is train much better than airplane given model uncertainties?
  • Considering the cost differences, and what money could be used for in terms of impact, does this negate any likely difference in carbon?
  • How should we weigh the travel time difference?
  • How should we weight any signalling effect, if any?
  • Anything else we should consider? (Other economic or social impacts?)  Any other generalisable effective travel principles?

Offer: GBP200 (half upfront, half on submission of report, or any other reasonable terms) for an analysis which answers these questions?

Or, has anyone done this type of expected value calculation for travel already, I could not find one with a quick web search.

Message me, to chat about more details. Assume this is 20 min chat, or can be done via email, and between 2 to 10 hours work, or less also. I can be found on Twitter @benyeohben with open DMs, or Linkedin.







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Sorted by Click to highlight new comments since: Today at 10:04 AM

Hi Ben,

Thanks for sharing!

It looks like plane is better. Trusting your numbers, you would save about 200 $ and decrease your travel time by 8 h. I think donating to Founders Pledge's Climate Change Fund (CCF) removes at least 1 tCO2e/$ (see "Conservative impact analysis example of innovation in
neglected tech" of this report), so you could potentially remove 200 tCO2e with the savings. This is much larger than the difference of CO2 you estimated, and so I guess it greatly outweights other environmental impacts too.

In addition, I think there are even more effective options than CCF, e.g. donating to the Long-Term Future Fund.

Thanks that's my instinct as well, but if anyone wants to dig into the numbers more deeply would be happy for it.

I've recently done a similar journey (London > Belgium >  Aachen > ... > Berlin > Paris > Barcelona), staying overnight at a Paris hostel. Overall, while the expense and time was greater than it would have been on a plane, I find that I am very productive during trains (say, x2 to x5 productivity multiplier) and comparatively unproductive during planes (decently productive on the plane while flying, but I tend to lose a lot of time during queues and the hassle beforehand). 

Overall I came away with the impression that for me the train option was significantly superior: because of my increased productivity, increased time is actually a plus.

One caveat is that the the queue at St Pancras is fairly lengthy and poorly optimized, and so the advantages vs a plane are a bit diminished. Another caveat is that I traveled light, with one backpack and a bag, which greatly simplified things for me. It's also possible that staying at a hostel in between is a bad move for older people. 

Overall I'd recommend the train, if only for the value of information about added productivity.

Simple Squiggle model (link goes to the model)

valueOfWorkperHourInDollars = 50 to 500 // <- input your own ehre

timeTrainInHours = 11 to 13
increasedProductivityOnTrain = 2 to 5
valueOfTrain = timeTrainInHours * increasedProductivityOnTrain * valueOfWorkperHourInDollars

timePlaneInSky = 2 to 4
timeHassleBeforePlane = 1 to 4
productivityWhileInSky = 2 to 4
productivityWhileHassle = 0
valueOfPlane = valueOfWorkperHourInDollars * (timePlaneInSky * productivityWhileInSky - timeHassleBeforePlane * (productivityWhileHassle-1))

  valueOfTrain: valueOfTrain,
  valueOfPlane: valueOfPlane

So overall I get a ~$2k (500 to 5k) for plane, ~$8k (1.5k to 20k) for train. This outweighs your other considerations (carbon emissions which are cheap to offset and dollar cost of tickets.)

But also note that I just really like trains, and for the figures above to be applicable to you, you should probably tweak them.

Thank that's very helpful to know. Thanks for the comment! 

To clarify, the above was meant in response to your 200GBP bounty.

Ah. In that case, if you'd like the bounty, I think I'd need a little longer explantory write-up whcoh takes into account the carbon cost challenges, and answers some of the questions.. As the above only seems to take into account productivity time while travelling, and not the carbon cost challenge.  Also, I'd have to change for the train etc. so I am not sure I'd have any productivity gains, I'm mostly interested in the emissions cost.