[pbhjpbhj]

See my other comment: http://news.ycombinator.com/item?id=1429494

Provided the nappies get re-used, you have a moderately good washing machine and don't tumble dry all the time then cloth are better - it's a very detailed study.

In addition if one has an A+ rated washer always line dries, reuses nappies for a second child (eg we bought ours 2nd hand on ebay and reused them and will sell them on or use them as clean-up cloths) then cloth nappies are substantially better.

>If it's cheaper to get it delivered via next day air, then it must have used less energy.

This appears to be specious reasoning. A company can charge more or less for delivery for competition purposes the actual cost of transportation is usually obscured. I can fly the 200mi to my in-laws more cheaply than taking the train, I don't believe it uses less energy to fly.

See for example http://www.seat61.com/CO2flights.htm which gives a figure of 90% CO2 saving by train (CO2 emission correlating with energy expense seems reasonable).

[ars]

If trains use 90% less energy, then why aren't they 90% cheaper? I mean the cost to run a train is almost entirely fuel, and the same is true for an airplane. (There is some staff, but it's about the same for both.)

So without even reading the study I'm already sure it's wrong.

And I found it - they assumed a load factor of 100% for trains, but 72% for airplanes. When actually in the real world airplanes are pretty full and trains are not - but they run them anyway. And trains will probably use more fuel if they were full, so their entire study is worthless.

(They do it a lot in the study - they use realistic or worse case number for planes and cars, but best case numbers for trains. And explain it by saying "This is how we can make the rail system better.")

Oh, and BTW the study they rely on doesn't say 90% anywhere. They just pulled that number out of thin air.

[pbhjpbhj]

>And I found it - they assumed a load factor of 100% for trains, but 72% for airplanes. When actually in the real world airplanes are pretty full and trains are not - but they run them anyway. And trains will probably use more fuel if they were full, so their entire study is worthless.

Fair enough, I can't be bothered to check your analysis, just like I cherry picked the citation. However assuming that the trains are full and aeroplanes aren't isn't really a problem here. Most long distance trains I've been on here are standing room only (except in 1st class). I've been on a few half full flights though most of the budget airlines are pretty good at getting full capacity.

There is a lot of competition in internal flight routes here but none on train routes. Train routes are monopolies. They do very strange things with train pricing - sometimes my MiL can get to us cheaper (via London, about 750km as the crow flies, 1 ticket) than we can visit the next town (about 20km, 4 tickets). Flights are priced using a scarcity model that makes early bookings almost the same as the taxes and later bookings as much as traditionally priced airlines.